LA 360 - Hits a wall at 4,000rpm - *not cam timing*

Engine Detail

• 360 LA
• J-heads
• upgraded cam [recent], upgraded springs, stock rockers
• Edelbrock Performer rpm intake
• Rebuilt Edelbrock Thunder AVS 650cfm
• Carter electronic fuel pump [new]
• Factory electronic ignition
• Parts house plug wires
• Stock replacement plugs [new]

Issue

• Engine runs great below 3,500rpm
• Idles great, good torque, smooth running
• Starts to "break-up" higher than 3,500 that and really hits a wall at 4,000rpm
• It just won't rev higher than 4,000rpm
• It will not rev higher in neutral [no load]
• It will not rev higher in first gear [under load]
• Wideband steadily gets leaner and will hold at 16:1 [LEAN]
  • Lack of fuel, or lack of spark
• No popping, it just surges slightly and will not gain rpm

Fix Attempts

• Swapped ignition ECU, no improvement
• Reset ignition pickup gap to 0.008"
  • Perhaps a slight improvement.
  • Distributor is of unknown age [factory style]
• Adjusted AVS air door to "very loose" to ensure it was opening and providing air over the secondary venturis
  • no improvement
• Took carb apart, verified secondary venturi ports and jets were clear
• Checked fuel pressure with mechanical, non-liquid filled gauge on the windshield.
  • Solid 5-6psi
• Coil is a parts house brand and is only a couple thousand miles old
  • But that doesn't mean it isn't failing me

What I have not tried

• New distributor
• New coil
• Adjust float height away from factory specs
  • [doubt that's the issue]
• Driving it off of a cliff, North Texas is very flat
• Verified actual valve lift - flattened cam?
  • The truck drives great other than this condition

Edit - This is from yesterday, it's not "as jumpy" since I tightened the reluctor gap slightly, however the issue still remains.



Any ideas?

I'd be looking at the advance and the distributor...
Any chance the timing marks are wrong on the crank?

Goody,

I agree with skicker above. I had this happen.
Put a timing light on your damper and look for scatter at 3500 plus rpm.
My issue was a worn out advance plate that wouldn't advance smoothly. I fixed mine with a new distributor, MP/Mallory.

(1) block the rods up & retry it which will give the enrichment from being on the power circuit to see if it is a too lean prob. (2) check rotor phasing. Holler back. EDIT Quicker, You might set the RPM up to where it starts to act up & spray something flammable into the carb (not sure what, I hear starting fluid is harmfull) & see if it gains RPM/straightens out and I would close down the secondary air door (just a WAG there but even a 2bbl will reach 5K by itself).

In the last year, I know of three people who have had customers cars in their shops to address the exact same problem.

In those three cases, the cam had been installed advanced by 2.5 teeth.
They had the bottom gear key way straight up, dot on upper gear straight down........ instead of “dot to dot”, which will have the bottom key way parallel with the #1 cylinder(not straight up).
The cam installed key way to dot is advanced 35degrees.

It sounds like some kind of valvetrain issue to me........ cam timing, springs, lifter preload, etc.

Verify good spark, an inexpensive tool is an open circuit spark tester, the best ones IMHO look like a spark plug with the center electrode removed, if the spark can jump that gap, with a clean blue spark, it's good.
Check fuel pressure and vacuum. A restricted exhaust can cause the symptoms you are describing.
Verify your timing, just set it for best idle, then rev it up and make sure it advances smoothly and doesn't break down or start retarding, weak P/U coils or modules can cause this.
Please don't go sparking carb cleaner down the throat with the car running, use a propane/MAPP torch to provide some enrichment.
You could still have a cam timing problem, dot->dot can fail you, if the idle vacuum is low, or take a lot of initial timing to achieve it's something to think about.
HTH, Steve

I am trying to think through your post...

The Cam gear Dot was at 6 o'clock and the Crank gear dot was at 12 o'clock...however I don't recall where the crank key was pointed.

That said, the balancer aligns at 0° on the timing cover with the #1 piston is at TDC. I don't think I can be off by 2.5 teeth if I am dot-to-dot on the gears and #1 is at TDC along with the balancer reading...Right?

In addition, I should mention that the truck never really ran over 4,000rpm before the cam swap. I attributed it to the engine's era and the max power rating for the engine was around 3600-4000rpm when new anyway.

Thanks for the feedback. Blowing out spark is something I was considering as a potential issue as well, I can't say that I am overly confident with the ignition system in it's current state. I do have an MSD 6A box around if I wanted to throw that at it and bypass some of the factory gremlins.

Best idle ignition timing seems to be around 14°, I can idle in gear quite well at 700-750rpm. To me, that doesn't seem "excessive", but I haven't messed with many of these engines.

I'll get a idle vacuum reading on it this afternoon.

This is from yesterday, it's not as jumpy since i tightened the reluctor gap slightly. This seems to be an obvious ignition/distributor issue to me.







Thanks. Dropping in another distributor I have on hand is an option, I'll go to storage and grab it. It can't hurt at this point.

many, many years ago, i built a 440 to race in my 68 GTX. it had a HUGE bottom end grunt, and revved like a pro stocker, but at 3500, it fell on it's face ! i had advanced the cam 4*, but had mixed up the marks. upon tear down, i found the valves had lightly kissed the pistons. pistons were ok, but had the heads re-done because of a couple of valves. re-indexed the cam and crank gears, this time DEGREEING in the cam like i should have done in the first place.
didn't rev like a pro stocker any more, but ran real good. as was mentioned above, it is very possible the timing chain set is marked wrong, or installed incorrectly. just my experiance, your mileage may vary.

I have run across this type of issue with a bad tach. Probably not your trouble.

There really isn’t any direct link to where you installed the cam vs the balancer being indexed correctly.
The balancer is indexed off the key in the crank....... period.

The cam could be installed anywhere and the balancer would still just slide over the key in the same place.

Imagine the piston is at tdc, slide damper off. Remove timing set, rotate cam to any random position, reinstall timing set. Who knows where the cam is.
Crank has not moved, damper still where it was.

If you used a typical “3 way” adjustable timing set, there are 3 key ways.
Each has a mark to denote zero, advanced, retarded.
There is also a corresponding mark roughly 2.5 teeth counterclockwise from the keyway, and it’s that mark that you would use to line up with the mark on the upper gear.

The three instances I referred to all had the dot at the keyway lined up with the mark on the upper gear.

They were using the wrong dot.

If you degree the cam when you’re installing it, you avoid this type of mistake.

I seem to recall a member here experiencing this same thing on a 340 6bbl.
I’m pretty sure his ended up being the cam was installed just how I described it.

Unfortunately, I think you're on to something. I believe the dot above the keyway is aligned with the dot on my cam gear.

I found this image online. I do not recall using the dot on the outer part of the crank gear. I can now see where the 2-1/2 teeth would come from. I'll need to ponder on it, but it sounds like I need to go ahead and pull the timing cover.

first pull a valve cover (whichever is easier to remove) & with a 1&1/4" socket/breaker bar turn the crank back & forth till either the #1 or #6 (either one is fine) rocker arms are (1) "moveing" & (2) even with each other (go back & forth with the socket when you get "close") & see if the dampener slit is on or very near zero TDC on the timing tab.

I made it a habbit to take a pic of the timing gear and cam-degree wheel on every engine build for if any doubts might arise about this later on.

I lean toward cam timing being the issue. I have done that before, not hard with the multiple keyway setups, esp if you have them on both the crank and cam gear. Another reason to ALWAYS degree your cam. Harder with the head on, but can be done.

That said, I'm going to throw this out there. Is your vac adv set up for timed vac and you're using the untimed port (or vise versa)? That will cause some erratic behavior and in combination with one or more of the carb adjustments being out of spec, it could cause this headache. Of course, assuming your advance mechanism integrity is where it needs to be in the 1st place.

Another though, more of a shot in the dark, but is your PCV valve functioning properly? I once new a guy that had the bright idea to "hollow out" his pcv valve (this guy put a Poncho 301 and metric 200 trans in his 68 Firebird). With his "enhanced" PCV valve, it would lean out and fall flat before 5000. The compression was super low in that thing, like 70lbs cranking pressure and within a couple of numbers cylinder to cylinder. The engine was reportedly from an early 80's turbo Trans Am, so the compression makes sense and I imagine the cam was pretty weak too. Not apples to apples, but an easy check to make.

Rapid Robert has it.

All I do is pull the valve cover and rotate number 1 cylinder to overlap, which is 180* after firing and look at the rockers for that cylinder.

If both rockers are off the seat the same amount, the cam is in straight up.

If the exhaust rocker is off the seat more the cam is retarded.

If the intake rocker is off the seat more the cam is advanced.

This doesn't tell you how far off you are but your cam should be in advanced a bit and straight up at the very worst.

That's the first thing I'd check.


This is why you never ever NEVER EVER install a cam dot to dot. The cam MUST be degreed in, especially with the advent of all these multi keyed crank gears and the directions that come with them can be confusing.

Degree the cam and none of that matters.

Just something to think about. Fuel pressure means that there is fuel at the gauge. It does not meam there’s fuel in the carb. I have to run the bigger needle and seats or I will drain the float bowls. Also I run a mechanical and electric pump together. I have forgotten to turn on the electric pump and it acts just like that 4000 just cuts out. Rpm drops comes right back.

Did the engine have exhaust valve rotators ? Did you eliminate them? My 318 would not rev over 4700rpm period {Valve spring limitedIf you have access to point dist try it simply get it to negative side of coil also that tach could have a 8-6-4 setting make sure its on the right one

First small block I ever built would not rev past 4500. Stock rebuild, stock rockers, small comp hydraulic cam, stock rockers. Heads and block decked just to true everything. Found the lifters were pumping up around 4500 holding the valves open. A set of 273 adjustable rockers cured the issue, allowing the lash to be set.

Geez.....looking at the video, it is starting to look like a cam timing or distributor timing issue to me. Have you taken a timing light to it to see exactly what your timing is doing at various rpm's? I'd try that first (easiest). 2nd, if the timing all looked good, I think I'd pull the timing cover and see what I see. It's not that major of a job.

OK, just to be clear.... is this a relatively new build or recent overhaul OR did the engine run great for years & now all of a sudden it won't rev past 4 grand?

I will eyeball the rockers but will likely go ahead and pull the timing cover. The more it sinks in the more I think it’s in there wrong. I just am crossing my fingers that valves didn’t kiss pistons.

Rookie move! Thanks all, I’ll keep you posted

You may get lucky as most of this mostly stock stuff has piston to valve clearance that can be measured with a yardstick.

Hopefully you get lucky.

Again, this is why you always degree the cam. Not only can there be errors in machining and tolerance stack up but there can be human error. If you degree the cam you eliminate all but the human error and reduce the human error to almost zero.


We can never eliminate human error. We are...human after all.

Are you sure you dont wanna check "rockover" as opposed to pulling the dampener/pump/tcover/new gaskets? (that's alot of work!) You know I ain't sure how a way advanced cam would affect compression but just me (I'm lazy) I would pull the plugs & do a compression test & even just (1) cyl would tell something (assuming a compression test will be way off if the cam is way off). I ain't a cam guy but if my thinking/math is right with a 23/46 tooth SB timing set, one tooth adv would adv the cam 15.7 degrees in addition to the built in adv (from LCA). Holler how it turns out, this is the weirdest one I have seen in a long time! I cant wait...

I haven't gotten my entire game plan together, but I may quickly check the "rockover"...I bet it's off.

All this talk reminded me that this happened to me in 1991.
I had a short block assembled at what should have been a respectable shop...Was charged on the invoice for degreeing in the cam and everything...
This was a dirt track 340 motor with a 284-484 Mopar Performance camshaft.
There were 3 marks on the timing gears the triangle...the square and the dot. They lined up the dots but the dot on the outside of the crank gear wasn't stamped well.
After two weeks of no RPM's...Changing intakes and carbs and distributor I pulled the timing cover...
Instead of the crank keyway being at about 2:00 and the cam at 4:00 and the dots aligning the cam was at 4:00 and the crank was at 12:00. The dots were aligned but it was the wrong dot on the crank gear.

When I pulled the "X" heads after finding this it had lightly hit the valves...
I remember that motor had a very small sweet spot where it would start easy and if the timing was off just a little it wouldn't start...
Worst thing about getting old is the things you forget...

What Madscientist said made me think of something to try: bump the dampener to TDC on the tab & look at the dist rotor & if it is at #1 then pull the pass VC & see if the #6 rockers are even & if rotor is at #6 then pull the dr VC & see if the #1 cyls' rockers are even. Alot of chain slop might mess this up, but just a thought.

Before I tore the motor down, I would check the ignition timing at 2,000 rpm and be sure the dist advance is working correctly.
I had one dist that had worn slots in the advance plate and it would actually retard the timing at higher RPMs. With a different dist, that motor made great power and spun as fast as you wanted it to go. Gene

Eyeballing rockers on overlap wasn't working for me. It's timed right. I was nearly certain I didn't pay special attention to other dots, but apparently I did.

The distributor advanced fine to ~35°, I checked it prior to tear down.

I'm back to square one, well actually square -1 on the issue.

You are up late. This must really be digging at you, huh ?
This stuff can really suck...You don't want to let them WIN...

I’ve been building motors for a long time. I did not always have the tools to degree a cam. I have run across it twice in my lifetime where the cam gears were not marked correctly. One motor was off 8 degrees and the other was off 16. These were factory assembled motors that had been running. Both were 340s and both were dogs. You must always degree your cams.

Yep. With two little kids I'm stuck working on things late at night, unfortunately this vehicle stays outside, so that adds to the fun.



Statistically another gear set would almost guarantee me to not have that problem, if it were the case. I'm only partially kidding, however

I need to see what it takes to degree a cam, with the head on, and the intake on, in the truck....

Good for you for getting back into it right away. I also have worked many late nights on stuff like this and can relate somewhat.

Yes definitely figure out how to degree it before putting it back together.

I bet it is not easy to do in the truck which I have never done before, so good luck with it.

FWIW years ago I rebuilt/ installed cams at least 5-6 times without degreeing the cam with no problems.

But in the last 20 I have degreed everyone since then.

Quick story, when I was running alcohol dragster I was stuck at 259 mph, Tom Conway who was helping tune the car always questioned if I had the cam degreed in right. So one year I took my engine stand to the US nationals and took the motor out of the dragster and put it on the stand to have Tom check my cam timing. We were changing the motors anyway so it was a good time to check and Tom would be there for the long weekend.

The cam timing was just where he said it should be. Still the car did not MPH like it should.

A month later I moved the cam myself different from where he said it should be and the car went 265MPH and did a big wheel stand on the first run.
So you never know until you know to begin with where the cam is in at then you can make changes to experiment.

Good luck with yours.

There is a simple way to degree a cam using feeler gauges.

Essentially when the cam is installed "straight up" the intake and exhaust lifters should be at the same height at TDC. Put a straight edge across both (sometimes you may need to substitute deep well sockets to get enough height)and measure any gap. No gap means straight up installation. If there is a gap then it's not installed straight up. How much gap and which one is low will determine advanced/retarded and how much. But I forget those details it's been a long time.

That tach might have a rev limiter in it, move the redline needle higher.

^^^ that's (way) too easy!

Have you checked to make sure the throttle cable is adjusted to allow full throttle opening? Yes, I have experience with such things.

I see you checked the cam timing. Your post says it has stock ignition. The pickup coil has a polarity, the engine will run if hooked up reverse polarity, but it will run like you describe. The stock mopar distributor has a plug so it can not be switched, but aftermarket distributors may be wound wrong polarity on the pickup coil. MSD had a tech bulletin about this problem. http://documents.holley.com/techlibrary_pickups.pdf

Is that a paint mark on the cam gear? Never saw one before....always had a machine mark. Is there a machine mark under it? or elsewhere

The AFR going lean makes me want to say ignition, coils are cheap and easy.

It’s machined I just added a paint dot

Weak valvesprings?

Pulled from the Cudas 318, they are the same heads actually. It spun to 6000 just fine when I took it off of the road. Comp upgraded springs.

I'm trying to think of something constructive. I think I would do a compression test & tho since the marks ain't off you should be good there but if it does show OK then the long block is OK & all that is left is ignition or mixture issue (vac leak).

The distributor rotor position looks skeptic, I am going to reset it along with a new distributor and try again. If that doesn't cut it, i'm grabbing the 600 AFB from the Dart and sticking it on there.

With the magnet dead even with a tooth the rotor should be at the CW edge of the cap terminal or even a bit "inward" from that CW "edge" cuz Rotor Phasing from vac adv & only vac adv will shift it back CCW (on a SB). The cap terminal is .214" wide & the rotor blade is .244" wide so you have a fair amt of leeway there. Also there is the radial distance between the rotor blade tip & the cap terminals & those 2 "air distances" add up together & if that total distance is greater than what the voltage can jump then it will miss. there is a longer rotor available (or make your own) but if the circumferential RP distance (around the arc) is good then you are likely fine. decades ago my mentor from the early 60's had a pontiac (iirc) & it would not go past a certain speed (not sure if it was missing or not) just a family car & they scoped the ign & no issue & he finally got so frustrated that he was gonna blow it up! so he revved it high under the hood & THEN he saw it, the FUEL FILTER was going almost dry/mostly clogged! New filter=all good!

Plugged exhaust?

I'd bet the valves are not closing completely when rpms go above 3500. I use adjustable rockers on every Mopar engine I mess with. I also set the valves at a zero lash and have yet to experience valve float. I have had stock bottom end 360's rev to 7400 rpms with no issues or valve float. I feel that when you push the lifter plunger down you allow the lifters to over pump up when running. My father was a big performance engine builder back in the 60's and 70's and taught me this early on.

I have a set of 273 adjustable rockers, but I do not have all of the spacers and shims unfortunately.

I measured the pushrod length upon assembly and determined that it had sufficient preload with the stock rockers and pushrods.

You say the original engine did the same thing? I'd be looking at things that you reused first instead of any replaced component or engine mechanicals.

Have you tried disconnecting the tach yet?

Engine isn't back together yet. Gaskets come in on Monday.

No improvement with a different timing set, verified straight up with feeler gauges, and a known good distributor, new cap & rotor.

Coil next, remove the tach and swap carbs if that doesn’t work..saga continues!

So I’m guessing you didn’t degree the cam in.

Nope. There's no reason why it shouldn't run fine installed dot-dot with two different timing gear sets.

Unless the grind on the cam is off.

I've got an entire kit to degree the cam with the heads on the motor. If you don't mind the shipping I can send it down to you.

Ran just fine in my 318...it's the same cam the 'Cuda had in it before the Hemi swap.

I agree but how far off does it have to be to be THIS bad?
A loss at high rpm would mean the cam would have to be WAAAAY advanced, right?

I had a 318 in a 74 Duster that was an absolute PIG out of the hole. It would not even peel out on gravel. It ran smooth as glass, quiet and nice. I swapped distributors, carburetors, spark boxes, I cranked the static timing to the moon...nothing made any difference worth mentioning. I pulled the timing cover to see that the cam sprocket was 2 teeth off the mark retarded ! I replaced the set since the chain had slop. Once back together, it would peel out easily on pavement and ran just as smooth as before.

Forget cam timing, it may end up being a fuel issue....

I rechecked the float heights and they are in spec for what edelbrock calls for. I can take it from a sustained idle right to 3500-4000rpm and it immediately misses. I don't believe that is a fuel volume issue, pressure is good.

I also ran shop air over all four venturis, they all seem to be flowing well.

I was just stirring the pot.

@Goody

You said in your original post that the AFR goes lean the closer it gets 4k, but the fuel pressure remains steady all the way through. I'm going to say carb and not just because it's almost the only thing left at this point. lol. It really does sound like fuel starvation. If it were spark it wouldn't go lean and right up where it noses over it would get real choppy like hitting a rev limiter.

Ignition misfires certainly cause lean AFR readings. The cylinders pump pure oxygen ["air"] across the wideband, it's an oxygen sensor, not a fuel sensor.

We'll see here soon, there are only so many things that can cause it. Coil is next, it's newer, but a weak spark could be dropping out, I suppose.

From there I'll rob the rebuilt 600 AFB from the Dart and stick it on there.

After that, I'll find some Tannerite.

Please hurry!

Did you happen to check float drop when you had the carb apart?

Yes, within the 15/16"-1" spec for edelbrock, 7/16" when shut

Fuel pressure does not mean fuel in the bowls. You could be out flowing the needle and seats add that to questionable fuel pressure and there you go.

I understand. The fuel height within the carb is to spec and to the top of the baffles, validated by running the electronic fuel pump then pulling the air horn. In addition the fuel pressure was validated at 5-6psi with a mechanical gauge on the windshield while driving.

I would fine it hard to imagine going from an idle directly to 4000rpm with no load could starve the carb. Perhaps a sustained 2nd/3rd gear pull, but free revving in neutral doesn’t demand much fuel.

I agree, I don’t think it’s fuel, but it might drop the bowls enough to screw around with the air bleeds a/f ratio. I had 5 lbs at the gauge and it would drop to 4 lbs. you would think if you have pressure you should be good, but I needed to increase the needle an seat and increase the fuel supply so the velocity of the fuel into the carb was quick enough not to let the level drop. I truly believe its your tach. The way it goes right to 4000 backs off a hair goes right back to 4000 and repeats. I have seen it before.

I’d be very surprised to find this was a fuel supply related problem.

I’m not 100% convinced it’s not valvetrain, but it certainly appears that area is decent, since the heads and cam have already been successfully run on another motor.

When it comes to troubleshooting electrical stuff, whenever possible I like to start out by swapping out “everything”.

For the ignition, I’d see if you could borrow an old points distributor and coil/ballast resistor, and hot wire it to the battery.
If not, then I’d swap in a “known good” distributor, and hot wire in another box/coil/resistor.

I would use none of what’s on the motor now in the ignition system, including the primary wiring.

All that being said........ disconnecting the tac is too easy to not try that first.

Is your battery good???

It takes 30 seconds to unhook the tach from the negative side of the coil, I've seen a bad tach cause your problem.

What he said

So you'll have no idea where the cam timing and evidently you don't care.

Try and not be offended when I say that you shouldn't assemble engines. For you, or anyone else. Until you learn how to degree a cam, and WHY you do it, every single time.


I can give you reasons why dot to dot is a bad way to do it, but you wouldn't care.


There is no reason EVER to skip the simple process of degreeing a cam. EVER.

Thanks for the feedback.

There actually are good reasons to not degree a cam every single time, but you wouldn't care so why bother.

Let us know when the coil or distributor fix your problem.

Make sure the tabs on the floats that touch the needle and seat are bent correct. People mess with them incorrectly and the float level may look to be correct but is not.

Yeah, don't degree the cam if it's the same cam and the same timing set. That's about it. Other than that, degree the cam. Takes less than 20 minutes.


I've seen name brand [censored] that when used together were 8 degrees off. And that was good, quality parts. They just had tolerance stack up.


Again, you degree the cam every time. Unless it's the same parts. It's not that hard.

I think you are wasting your breath. You can only help those that want to do things the right way.

Right! The factory is degreeing every single engine that comes down the line. Moving the cam 2 degrees changes its peak power band about 50 rpms. So moving it 8 degrees changes it about 200 rpms. You figure 8 degrees advanced or retarded that is a spread of about 400 rpm. Ooh, I can feel the difference already.

Wow. I guess I give some guys more credit than they deserve.

Changing the cam timing only changes the rpm that the engine makes peak power at thus changing the so called sweet spot a bit. It's not that important on a stock or near stock street driven vehicle and in fact is probably going to go un noticed. I degreed my race engines but only to have a reference point as I usually needed to move the cam to obtain valve to piston clearance.

If you are looking to make maximum power at a given rpm then moving the cam timing will help achieve that but it won't really produce more power, just at what rpm it makes it at.

All I can say is WOW.

It is beyond ignorant to claim the dot to dot thing is ok.

The factory did it because it was cheap and they didn't give a [censored] if the engine made the power it should.


You degree a cam every time. Or you are just [censored] yourself.

There are certainly legitimate reasons to move the cam timing such as a heavy vehicle with a tight converter or an engine that is rpm limited and/or carb or air flow restricted. In these cases you may see some power and ET improvements but in Goodys case here that is not the problem and degreeing the cam would not have done anything. It is not always necessary to degree a cam. I put engines together all day long and never degree a cam. Why you ask? Because it won't make a difference and there is no way for me to change it anyway so why bother?

For some unknown reason you THINK a cam can only be a degree or two off and that just isn't the real world. You'd know that if you ever degree enough cams. You'll quickly find they ain't as close as you'd like everyone to believe. I've seen plenty of name brand [censored] off 8 degrees and I've had reground and lesser brands be off more than that.

So again, keep posting crapola, it still makes you wrong.


Degree the cam, every single time.

My brother put together a mild 225 slant six years ago with a 4 barrel, header , ect., and the timing chain set from NAPA was 8 degrees off so ended up taking it back. They did not understand why he just didn't line the dots up and why he was being so picky over something so trivial. I'm sure they just resold it to the next guy who did just that.

This discussion is ignoring that Goody is trying to diagnose a severe engine operating malfunction; falling on its face at 4000.

In order to rule out a timing chain problem he installed a new chain, dot-to-dot, and the problem remained.

As Goody stated, statistically, this ruled out the timing chain. Do some of you not understand this??? If so, you need to enter the 21st century.

Degreeing a cam is important for many reasons. It was not necessary in order to advance (pun intended) Goody's quest for solving this engine's issue.

OMG...

Not really relevant to fixing the OP’s situation, but I’ll offer up why I degree every cam.......

In the grand scheme of the number of engines that get built, cams installed, timing sets replaced....... the number I’ve done myself since I did my first one on a 289 Ford in high school is minuscule. A tiny tiny fraction of the total number that have been done.

Yet....... even within that tiny tiny sampling of timing sets that I’ve used myself........ I’ve come across 4 sets where there was a dot on the wrong tooth.
Frankly, I’m totally shocked by that, but it is what it is.
One of those sets was a very high dollar belt drive system for a BBM.

When the top gear is off a tooth...... it’s like 14deg off...... and while the motor will still run “okay”, that’s far enough to make it not run “right”.

The first time I came across this I was degreeing a roller cam that had been run in a different motor.
When I built that motor I didn’t have cam degreeing equipment, lined up the dots and let it go.
It was always a dud down low, and just figured the cam was too big for the application.

New short block gets built with some dome pistons, 8” converter gets bought to use with new build(both to help cover up the lack of low end grunt)...... and I now have cam degreeing tools.
I’m still pretty new to it at this point, and am assuming I’m just doing something wrong as I keep coming up with the cam is retarded 14deg.
I have the bushing kit, but that doesn’t get you close to moving it 14deg.

I don’t recall what made me decide to do it, but we had an old factory Hemi timing set on the shelf, so I tried it with that.
Cam came right in.
I thought I must have just been off a tooth or something with the first set, so I reinstalled it, making extra sure it’s in dot to dot.
Cam is 14deg retarded.
Pull upper gear off, lay one gear on top of the other, line up the bolt holes...... slide the gears apart....... the dots are one tooth apart on the two gears.

I figured that would be a once in a lifetime type of thing, but since that first one in 1984, I’ve come across it 3 more times.
1- 3 bolt BB Mopar
2- 1 bolt BB Mopar
3- SBC
4- Jesel for BB Mopar

That’s why I degree every one.

I was the go to guy by my friends for degreeing in cams. I found two off by over 8 degrees and another one I won’t ever tell you how far off it was because some would call me a liar 🤥
I hope you find your issue. My 1972 (340) Duster had a factory electronic ignition box that about drove me crazy back in 1975 when I bought and raced it.

I didn't forget, in fact I mentioned it a couple times. It's the self proclaimed professionals that know more than anyone else that keep arguing. So let me just put this to rest one last time. I build import twin overhead cam engines with phasers on both camshafts. There are no bushings or kits to degree these cams, even if you could change it the computer is just going to move it where it wants it to be any way. And if I could move it beyond where it can adjust it I would get cam and crank correlation codes that will never go away. So no, it is not necessary to degree every camshaft. In fact I'm about to assemble a hybrid 4 cylinder Atkinson cycle engine. Am I going to degree the cams? Nope. Not all of us are stuck in the stone age as you seem to assume. So continue to assert your superiority if it makes you feel better about yourself.

Every engine is a compromise when it comes to the camshaft. Can gears be mismarked? Sure, can a cam be ground off? Sure, but in reality it is a very small percentage.

Goody,What if the keyway in the crankshaft was machined in the wrong place.I think you should at least verify TDC before putting the cover back on.

So....You build some NON Mopar oddball stuff, yet are somehow totally qualified to comment on the accuracy of timing sets and camshaft timing events and how degreeing a Mopar camshaft is a waste of time? Really ??????

Fast and furious engine builder. Lmao 😂
I live my life one day at a time.

From 1949 The first Road Runner Cartoon.

This whole deal here is cartoonish.

Chrysler doesn't pay to dial in the cam when replacing the timing chain or the cam. So if they don't think it's necessary that's good enough for me. I have built more engines than I can count and the only ones the dialed in the cam were high performance. Stock rebuilds don't need it. Some people scream and holler that it's necessary but I believe it's over kill for a daily driver. This is just my opinion with 50 years experience.

I was a Chrysler tech from 1975 to 2008 when the dealership lost its Dodge franchise. So yeah, I'm qualified, and infinitely more qualified than you Mr. Construction worker. I also didn't see where there was any stipulation on what engine or engines need to have the cam degreed every time. I stated there are legitimate reasons to not degree a camshaft and then was called ignorant and accused of spewing crap. I think I made my point. Chrysler also sells engines with twin overhead cams and computer controlled cam timing so, I don't see where you are going with that.

BTW helpful post.

I was genuinely interested in hearing the outcome of Goody's issue here. This thread was pretty good before people started breaking out yard sticks.

I'm still interested as well, don't know why this had to go down this worm hole.

I still think the problem is electrical, pickup coil, worn distributor, coil, plug wires, bad ground, etc.

I still want to say fuel starvation though. That's an incredibly smooth running motor even where it hits a brick wall. I wouldn't expect something faulty in the ignition to fail in such a controlled manner.

If the mechanical advance slots and pins are worn, and the combination of the mechanical, vacuum, and static timing fail to reach the maximum advance, the motor quits performing at what ever rpm level the reduced advance can obtain. Everything will work perfectly up to the point the timing can no longer advance. Total timing advance in the 20-25 degree range will limit the rpm the motor can reach, but it can run wonderfully up to that point. This would be an ignition issue.

There can also be a fuel pump that can not deliver the full amount (volume, not pressure) of fuel the motor needs, the rpm range will also be limited. It too can run wonderfully right up to the point there isn't enough fuel to build more rpm. This would be a fuel related issue.

I have also seen examples where the throttle pedal can not open the throttle to fully open (or even opens the throttle past fully open and begins to close it again by going past center). This could be caused by incorrect throttle cable adjustment, or something interfering with the pedal being pressed far enough to open the throttle to the wide open position. I've also seen the carb linkage bind and not allow the throttle to open fully. This would be a mechanical issue.

The problem does not have to be cam timing. Gene

Those of you thinking fuel issue, or cam timing I think miss one crucial fact. His video is with no load on it.

I cannot imagine a fueling issue that would cause it to do this unless it was massively rich and it'd be blowing great clouds of black smoke.

I cannot imagine a cam timing issue that would let it run at all and do this.

It almost has to be ignition.

There was a thread on here a couple years ago about a car going super lean in the upper rpm range. I can't recall if it was laying down like this one though. It turned out to be a fuel line sucking shut back by the tank.

This one still seems like valve springs or lifters though.

Well, that was pretty rude.
I can degree a cam...Can you build a house? Lay out a frame? Calculate roof pitch and cut rafters that fit? I would be very surprised to hear that you can but since this is a car forum, lets focus on that instead of insulting another mans trade.
You made it clear that you thought that degreeing a cam is pointless. Maybe it is to YOU but if nothing else, it can rule out an area that allows you to focus elsewhere.

Don't let guitar dude get to you. He was a line mechanic and not an engine builder or a machinist and they ain't the same thing.

IDGAF if Chrysler, or GM or ford or anyone else lines the cam dot to dot. The factory didn't give a single [censored] how they ran when they left the factory. They didn't care. It's quick and dirty to dot to dot and it shows lack of experience.


To the OP. I don't really care what is wrong with your engine. What I'm saying is to do the job correctly, and eliminating potential problems you need to STOP and degree the cam.


It's that simple. You can be a keyboard builder who cuts corners, or, you can do the [censored] correctly.

Degree the cam.

Any chance there are weak grounds in the system?

There is a huge chance of this. It's probably the single most frequent problem seen in these old trucks.

Truck is running well now as it appears to have been a combination of things.

Thanks for the help and drama!

I saw a mild 318 do this, would hit a wall at 3,500 and everyone was telling the guy valve springs but was I talking to some chiivy guys that had told me about one of those great 350 engines which did the same thing and it had AC plugs so we checked his plugs and were AC's. Problem was solved with a set of autolite copper tips!

Soo, you are just going to keep it to yourself?

Tick Tick Tick

That's more drama until

Let the truth bee told !!!

Lol

Hit a wall ? gotta hurt... Baad Ground volt drop, solution buy a mustang. Junk dat cam too an decree it already, Kongratz, I luv draamma. (Glad you got it figured out.)

I degreed the cam and now my exhaust smells like fresh baked cookies and unicorns lead the way everywhere I go.

Filled the gas tank, corrected not having full throttle, cleaned the batterery terminals, ohhhh and he readjusted the rev limiter. LOL.

So are you telling me that degreeing the cam is not going to give me the desired fresh baked cookie and unicorn effect?!?


I'm so disappointed.

That’s the kind of post I’d expect to see if one were a little embarrassed about what the problem actually was.

And....... doesn’t help the next guy who might find themselves in the same situation.

yep ^, so was it the tachometer???

I replace a fuel pump on a mustang with a 4 cylinder because it shutoff and wasn’t getting fuel. With the new pump still wasn’t getting fuel!!!!! Then I noticed the cam sprocket wasn’t turning. Dohhhh! Broken timing belt. Had a friend try to start his truck for two hours called me and I came over and found the rotor sitting on the core support. I could go on and on and on! If you haven’t screwed up your really haven’t done much.

and the answer is ???????????

Carb to small....

I'm still concerned that he didn't get the stars and rainbows too. Must still be a degree off.

I’m beginning to see why you have two old trucks and sold all your cars. For the monkey type every day drivers you are right by saying the cams aren’t degreed in. First off Mopar or other manufacturers could care less if it’s right or wrong. Performance cars are different and yours and others statements explain why some cars run and some don’t. I dought if 90% of the warranty shop guys could degree in a cam or even file fit a set of rings. Lol 😂 stick to what you do best

Some of us that have done a lot of this stuff also know to take a quick look at gears dot to dot and check #1 cyl lifters to check for and even overlap of ex closing and intake opening. This does apply to most chevs and mopar v-8's, but certainly not all. I've corrected, as many here have, the 3 way screwups when friends use wrong markings and are 2 1/2 teeth off after their install. Goodys got it covered so it's done, right?

Yep, and I'm happy for him. I'm sure it was plenty frustrating finding the causes. But it would be nice for all that helped, and even those of us that only followed the thread to know specifically what those causes were.

4 Russians caused the problem and the Chinese cured it.

Translation: Ain't tellin'

I have been hesitant to say "this" fixed since I have very limited mileage on it. It's been a combination of three things that I can attribute it to.

1)Distributor air gap - Fixing this fixed the sharp jump in rpm drop seen in the video. Replacing the distributor seemed to offer no further improvement.

2)Secondary venturis - Upon rebuilding the carb, I must have swapped sides on the secondary venturis. Apparently they aren't poka-yoked, like I thought.

3) Fuel volume - I still had leaning out issues after sustained high load, I had a pair of higher flow needle & seat assemblies in a donor carb that I transferred over, those seemed to help that.

The last run pulled much better but it was very fat [10:1], so I need to back out the jetting the other way. I may have 5-10 miles on it running "well", we'll see if anything comes back. The truck gets very limited use.

But....... it will easily rev over 4K now in neutral and the lower gears?

Not quite sure how to take your last statement. Is that an insult? Because you really don't know anything about me or my abilities. I sold my car because I'm nearly 62 years old, working 60 hours, 6 days a week. I'm looking to retire soon and just don't have the enthusiasm or drive to race anymore. I built my 4 link, strut front end car with a friend in a carport. I built my own engine and did much of the machine work myself at another friends shop. We cut the rear end housing down and stretched the wheel wells. We did all the tin work and plumbing. Just because I make a living working on imports doesn't mean that's all I know or all I do best. Could my car have been faster? Sure, but so much of it was a total compromise because I used what I had or what I got for cheap. But the car would hook in a car wash.


You seem to have some good running cars and since you are retired (and as I recall it's not from anything automotive related so is that what you do best?) they should, you have plenty of time that I don't. I keep the trucks because I like them. I enjoy driving them and working them and working on them. They will suit me well when I move to the mountains of West Virginia where there isn't any race tracks anyway.


Then there's the other proctologist in this thread taking shots at me. You know the guy that fosters pit bulls and laughed at me when I told him to be sure his insurance is paid up? Yeah well since my GF was attacked the medical bills are damn near $200K, she has lost her job because she can't work so there is no more health insurance or long term disability because the company paid for that. She can't do the yard work she did before so I have to take care of that as well. And to top it all off SS turned down her disability claim so now we have to pay $6K to a lawyer to try and get that accepted. But it gets better, it takes at least 6 months for that process and if it has to go to court that will take at least 2 years.

Seems like so many people here like to make assumptions, jump to conclusions and then look down their noses from their high horses it's just pathetic.

So I was right?! It was the carb? What did I win??

Someone mentioned cookies 🍪

I thought I was the winna!

Glad he solved his problem! When I was a young lad, with a 2 year old 69 Roadrunner, I was just starting to learn about cars and engines. Somehow, I can't really remember how, The wire to the points shorted out. It was obvious that it was fried and I went to the parts house and got a new wire. I started it up and it ran just fine, but when it got over three grand, it just laid over like it was out of gas. I screwed with the carb and checked the fuel pump- no joy. After checking out lots of unrelated things, I finally pulled the cap and took a close look at the points. You guessed it, the short had heated the points enough that it took the temper out of the spring(it was blue from the heat). Those points were floating like crazy over 3K. I threw in a spare set and the problem was solved. We have all been there at one time or another, nobody was born a master mechanic. We need to bring back the civility to this forum, we are all here to learn!

i'm here to remember what my old brain forgot ! [now where did i put my glasses ?]

Hmmmm needle and seats........ hmmmmmm cookies..............

I would have a look at the PTK linkage and make sure it is not keeping it from getting a FULL WOT.

I kicked myself for finding my truck would not pull any thing over 3500 rpm once. I tried a bunch of crap to find I goofed the linkage adjustment.

worked by hand under hood as I did not ever blip it fully open to see it. found it with a helper on the pedal while I watched and adjusted it out.

surly not your issue but thought I would mention it as I did not see any comment about throttle/PTK adjustment check for a full throttle.

the one piece rods on the trucks suck for adjusting and I swap them to a nice 3 piece set up.

my 85 runs a stock q-jet-intake/1 piece linkage set up and easy to only get 3/4 of throttle with it if not watching it.

Last time this happened to me, they were on top my head.
Now where is that big green crow bar?

I throw my single van door/ign key on a red lanyard around my neck & if I am bending over something I toss it over around to my back side, well the other day I spent a considerable amt of time looking for it till the office mgr out here pointed it out when she asked me what I was looking for. When she said that I was just kidding her of course I had to agree with her!

This post makes me feel a bit better about the stuff I tend to do.
Thanx.

To Goody, Glad you got it sussed out.
This whole thread was an interesting read.

That said, the engine still struggles around 4,000rpm. I would say it's not cured, but much better than it was initially.

I'll leave it as is until I can get some other form of carburetor on it, runs like a top otherwise. I've been wanting to get a Holley Sniper kit for it anyway..

Had an issue years ago with a 340 in a 70 Challenger. The engine would start and run just fine up to around 3500 rpm where it would shudder and cut off. Took a while to figure out, but the fuel line on the tank end was shot and had been temporarily replaced with about two feet of rubber line. The force of the suction from the pump was actually causing the rubber line to collapse and cut off the fuel. Not saying that's your problem but many times it's something stupid.