HELP! way too much timing!!!!

I have a 383 with 906 heads. I just had the valves done and installed a howards cam with 260° intake duration at .050 and 268° exhaust duration at .050. I have 140 PSI cranking compression, (seems low to me) My biggest question other than the carb trouble , is WHY IN THE HELL DOES THIS THING WANT 50° timing at 1000 rpm (that's where I'm stuck at idle) It absolutely hates anything less than 40°, wont run below it, and boils water pronto at 40°. MSD 6 AL, billet mechanical only distributor, doesn't buck the starter until 60°

Degreed cam with heads off, checked it again, after break in, it is where howards wants in on the advance side 102°.

Tied a summit MSD knock off box, same results
Tried a Summit knock off distributer, same results,
Tried a second carb lent to me from the shop that did my heads , same result.

The motor has a set of TRW dome pistons # L2293, that SHOULD give me 11 to 1 .. but i think they may have been milled .. I currently have a .050 head gasket.. If you guys think I have a serious lack of squeeze going on.. how much should I mill off these 906's????? I would love to run 93 octane and not have to run some crazy timing...

The guy that did my heads cannot explain it.. I never checked timing before I took this apart .. I just ran as much advance as I could before it would buck the starter.. and it ran solid, with a bigger cam.. now it is in a state of terrible shake rattle and roll at idle and is miserable. Thanks for any input in advance.

Solid or Hyd. cam?
Lash or preload settings?
Valves not closing?
Verified that "0" is accurate on balancer?
Heat crossover on intake open?
Firing order.
Vacuum leak.

Have you verified the timing mark, line, on the dampener is accurate at TDC on the timing tab on the timing chain cover?
If not do that next When things don't make since there is usually a reason for that
Let us know what you find

make sure you are on #1 (even #6 works) plug wire. borrow another light. EDIT if you were on #2 it'd be 90 deg off (+your timing amt) so that (wrong plug wire) wouldn't be it. Are you useing a timing tape or a dialback? Might try a non dialback & 0.0632683" is (1) degree & 2&1/4" (2.246") is 35.5 degrees for an easy start. MORE EDIT after rereading I'm thinking what Flash said, vac leak or firing order. & it ran fine before & you had the heads done & the different cam (bigger or smaller just curious?), you did post specs but I ain't a cam guy.

Your timing is off.. you missed it by most likely 1 tooth on the sprocket
which is easy.. to have that much and its getting hot... was this done with
a small timing wheel.. I think mine is 2' across

The last time I had that issue, I ended up repairing vacuum leaks.

The leaks were hard for me to diagnose at the time, because they were underneath
the intake manifold. Sealed fine on top, didn't seal at all on the bottom.

IMHO, 260* @ 50 seems like an awfully big cam for a 383 with iron heads. And you say that this is a smaller cam than you had before? 140 cranking does sound low for that big a cam. For comparison, my last 500" wedge had a 250* cam, ported Eddies, and 180# cranking compression. That combo had a bumpy idle and wanted a lot of lead at idle. I usually had 28* at idle. It wanted more, but would start hitting the starter when hot any higher than that.

With no idea what your compression ratio is its hard to say, but that's a big cam, if you've got 9.5:1 compression that could be what it makes. Is this with a stock style starter or mini-starter (mini starter is worth about 20 PSI in my experience)

Are you sure this cam is 260/268 @ .050 and not 260/268 advertised? If its really at .050 what cam did you have in it before?

Verify TDC on the balancer is TDC on #1. You do have the timing light connected to #1 right?

If it really is 50 degrees I agree with Mr P body your cam is off a tooth. EDIT I see you said you degreed it in at 102 though. Double check your valve lash, EOIC!



Zippy - how did you find your vacuum leak under the intake, and what did you need to correct?

this should have been done if the heads were off.

I just went through this same thing. I had a bad vacuum leak in the intake manifold. The only way it would idle was to advance the timing the way you are describing.

More than likely not 11:1 based on the cranking pressure numbers.

Verify the cranking pressure numbers with another gauge.
All plugs removed, battery charger on, check at 4 and 8 “pumps”.

Verify tdc mark is correct on damper.
Carb will need to have race calibrated low speed circuits and 4 corner idle.
Locked out dist.

If all above checks out, and it won’t run “fine” with 35-38* timing, I’d start looking for leaks.

My 383, which was a bit under 11:1, 256@.050 cam...... cranking pressure around 200 in 8 pumps.

440, oe heads, aluminum intake.

After trying carb cleaner and so on, which didn't work, decided to try water.

I tried a hand spray bottle, got me nowhere, not enough volume, couldn't really aim it where needed.

I then tried a garden hose flowing under the manifold...that showed the leak very quickly.

The repair was to open the bolt holes slightly since they were preventing the manifold from sitting down quite far enough,
and I also started using paper gaskets.

After that I always spent more time verifying manifold fit, once bitten twice shy etc.

Those pistons are usually pretty far down in the hole. Doubt it's 11-1.

When I ran them mine liked 42 for timing. Actually put flat tops in it and went faster.

Thanks guys, you hit all the other things I tried that were not in the original post.

I am using a dakota/magnum starter (its fast) and my cranking tests are with all the plugs out 3rd hit, i only gain another 5 pounds MAYBE on 4th and 5th hit, multiple gauges. (like you guys I try to verify every measurement with 2 devices or procedures to be sure)

I did verify 0 on the dampener both times with the tab on the timing cover, I did hit 102 and was actually driving everyone in the garage nuts by verifying tdc and .005 before and .005 after on #1 intake valve, repeatedly as I was hoping I simply messed up and could find a smoking gun.

I set initial lash at break in to .019 cold, verified with an indicator so I wasn't relying on just "feel" as some guys are comfortable doing (this is a flat tappet btw with harland sharp roller arms)

after break in I went back and verified they were at .022 +/-.001 hot like howard specs ask for, after much other messing about with the other ignition components I tried (along with reversing the magnetic pick up wires on both distributers, i heard that can drive a guy crazy) I went back and loosened them up 1/4 turn on the adjusters just to see what I would gain, and didn't gain squat except alot more chatter under the covers. I put it back to .022 and started playing with the carb and I'm getting nowhere. the looser valve adjustment gave me at least .050 in lash and I didn't gain any vacuum or cranking psi.

NOW , one thing I haven't attacked very seriously is the under manifold vacuum leak possibility.. I ran a propane wand under the intake on top of the tin to the point I had propane laying on the tin and it didn't care, no stumble no rev, BUT its not out of the possibility that I have one under the tin. The heads have been cut a few times now and I cant promise it sits perfect. I use paper under the tin and over the tin, I know this manifold was cut prior to my ownership as it fits MUCH better than the out of the box M1 I also have , that is near impossible to get the bolts in.any ideas other than punching a hole in the tin for the propane and to check under the tin? This also is hard to justify with suity plugs.

I know these pistons are old tech, I wish I would have done more measuring before I tore it apart, the old cam had over .600 lift using the math of over the lobe -base circle times 1.5 I still have the cam out in the scrap can I think if anyone wants to try to run numbers on it. The gaskets I took off were also standard felpro multi layer composites that mic at .043 I believe, the heads were re cut this round .005 just for a fresh surface. (.050 gaskets on it now)

So thank you all for assuring me I tried what I should have.. need new ideas. I wont get time to play with it much until saturday.

for sure post what it ends up being (we're been getting some toughies lately!).

Exactly what is the carb and how is the distributor set up?

If those things are “correct” and you’re confident there are no other mechanical issues, and the cranking pressure is really 140+/-....... then the cam is kinda too big.
I’d really want to see another 40-50psi.

Yes, you should be able to get it to run “fine”, but you’re not going to make real power out of that cam with 140psi.

Have you done a leak down test yet?

I agree.. I don't want "fine" I want it right.

The carb is an aluminum hp 800 cfm . Tried 70 jets, it came with 80s, power valve was a 4.5 even though that is correct it tried a 2.5 for shits and giggles. Its currently back to the 4.5 valve and 80s. Transfer slots in the primaries gets me 1000 rpm but no response on the idle screws.

I drilled blades yesterday as I had little to no response from the idle screws, I do now but I am at 1500 idle..so I get to buy a new set of blades 🤯. I noticed AFTER drilling the blades the secondaries didnt leave any transfer slot open on a hard shut...so I fixed that with another wrap on the spring and adjusted the stop. (Thanks alot holley, lesson learned never trust anything out of the box.) If I would have caught this first I wouldn't have drilled.

I have also tried a 650 quick fuel. A 625 edelbrock, a 750 edelbrock, and a demon that I run on my 400 truck. The 750 edelbrock was on it previous to this head freshening endeavor.

None of those carbs would idle, the quick fuel was lent to me from the shop and he swears it is his baseline carb. He has never had that carb not run. Well..until now....I didnt adjust anything as I didn't want to curse it so I held it part throttle until I was up to temp, let it down and had crap fall on its face and die results 3 times and pulled it right back off. The edelbrocks I use on other things to rule out carb issues..they are reliable machines just no frills and not responsive. Point is i keep them ethanol free and they work on other vehicles and needed 25% throttle to keep the engine running.

The distributer is an msd pro billit. Its currently locked as I didnt want to risk adding another 20 degrees of timing by accident. And this is not new hardware. The cap and rotor and plugs and wires are. So yes...it starts at 50 degrees initial..somehow.

Check the Dist plug for the pick up coil wires being backwards in the connector,or it is wired wrong, I have done that & engine would not run with less than 50deg timing

My dads stroker motor acted like this, had to have 40+ degrees to run good. Turned out it was the distributor pick-up, replaced it and it was back to normal.

Unless your 800DP(4780) carb has been modified, that’s a 2 corner idle carb.

That’s not likely going to work very well with your combo.

If it’s been modded to have 4 corner idle, then you’ll need to measure all the orifices in the idle circuit to see what you have.

What you really need is a carb with “race calibrated” low speed circuits....... something like the original HP950.
For a new style carb, something like a Race Brawler or QFT Q series is the type of carb you should be looking at.

The reason the 50* helps is because it increases the carb signal when the blades are closed.
The reason that’s necessary is because the carbs you’re working with are designed to operate with fairly normal manifold vacuum...... which you don’t have.
The race calibrated carbs are designed to operate at much lower manifold vacuum.

I’d still recommend the leak down test.

I have swapped the leads on the pickups in 2 distributers and it does change the timing when swapped but I end up with it right back at 50 degrees to run either way. It does start better the correct way with both distributors and both ignitions. But maybe I'll get a pick up coil for the msd and put it on the list. Along with a leak down test.

The carb is a brand new aluminum hp. With 4 corner idle, replaceable air bleeds etc.. The part # is 82851sa.

How much vacuum does it pull if any?

I swapped cam in a 318 pick up 35+ years ago that acted like this.
Turned out to be intake gaskets. Rebuilt the whole truck before I touched the right part.
It will end up being something simple and obvious. .......those are the hardest things to find LOL

Unfortunately....... not really the “right” carb.

It’s a “street” HP.

Does it have an easily adjustable secondary idle speed screw?

What size are the idle air bleeds?

How far out have you tried turning the mixture screws?

I’d also see what the idle vacuum is(my 383 with the 256-106 cam was around 6” in neutral @1200).
Also, 1000 in neutral is probably too low unless it’s a manual trans.

Do the leak down test before you go much farther.

I still feel like the 140psi is a big clue.

Ok..sorry for the delay. I have a 5.7 swap into a ramcharger that ate up most of my night but had the car warmed up and dropped into gear with help so I could get a vacuum number.

All the advise about swapping the dist. leads. Thank you...it does make a difference but still wants 50.

More carb info..

The secondary set screw is facing down. I can get to it with a 90 degree screwdriver.

Air bleeds are 24 and 70. I have dont the follow with them.
1, removed them completely, no difference.
2 plugged them with wire, also ...no difference.

Right now..after drilling blades and setting transfer slots on secondaries I have 1400 rpm in neutral and 9 hgs of vacuum, in gear warm I have 1000 rpm and 6 hgs vacuum.

The idle screws actually do respond now and I am about a turn out. (The air bleeds still do not respond)

One unfortunate new happening since drilling blades is it will not start without a few squirts. It used to re fire hot no problem, now I have to saturate it to get it lit.

So on the way here for the weekend are

A pickup coil for the msd
Another intake gasket set
And trying to find a leak down tester

Anyone want to walk me through a leak down check? Never done one..dont know what I'm looking for and dont realky trust everyone on you tube that has a camera

I am thinking of having the intake cut a bit to help it nest better.

Also wondering ..if my leak down proves my rings are healthy ...what can I cut off these heads to help get the compression up? I really am in the hole as with everything i bought already..i really cant spring for new heads this year. I'd like to get this thing out this summer.

I used to do driveability on Honda automobiles, back when much of what came in the shop was carbureted. Much of my diagnoses were for lean running @ idle & cruise. This was my 'bread and butter'.

We put a fitting in the end of a garden hose, that took a small ball valve and a couple feet of quarter inch hose off the end of it.

When opened, you could get a nice stream about the diameter of a number 2 pencil. This would find intake leaks that wouldn't show up with other methods, such as brake clean, or propane. Or that high $$$ Snap-On smoke generator (mostly smoked the boss' wallet...).

Pinpointing the area of the leak was really important on these cars, because they would have 100 vacuum fitting joints (literally) under the hood.

If there was a leak, other methods might find it, but water would.

Edit: in the original post... The car runs hot at idle. IME, heat can be caused by timing, and can also be caused by lean mixture (and also by a mechanical considerations...). I suspect Dwayne's question about where the idle mixture screws end up to make the car run is probably right on the mark.

In my world, people very rarely made adjustments to their cars, they just took them to the shop when they didn't run right. So, if they had an air leak, it would usually show up by feeding propane into the intake air 2 offset the lean condition.

But, if the idle mixture has been adjusted to compensate, that test would not necessarily do anything.

FWIW, I would try putting water over that intake before removing it. It's a far cheaper and easier test to run then removing the manifold, taking it to the machine shop, putting it back on... And if there's anything I like better than something cheap, it's something easy.

So, 9” @1400, in neutral.......@50* timing.

Imo, you should put the timing at a more “normal” place(like38*), redo the vac test, and reset the mixture screws.

The goal is to make it run right with normal timing....... not 50*.

With less timing(and theoretically less vacuum), I’d expect to have to richen up the mixture screws.

QFT sells a secondary throttle lever that has a screw on top so you can tweak the secondary blade position with the motor running.

It just replaces the original one....... takes about a minute to install.

I’d buy a package of really small Holley air bleeds...... that way they can be drilled to anything you want.

The 24 hsab should be fine, but the 70 iab is on the big side for that combo.
I’d start out with something like a 60.

Actually...... I think I’d be getting out the garden hose before I went any farther.

Garden hose it is ! I'll let you know tonight hopefully if the kids keep themselves occupied. Also..it will not run at 38..it will barely run at 45..at 40 it is immediate radiator cap blow and it needs 30 percent throttle to keep it running.

How do I upload a video here ? Is that even possible?

Sounds like it’s way more than a carb tuning issue if it won’t even run at 40* and immediately overheats.

This one is in neutral.

Distributor

Carb

I agree... I need to figure why the timing lead needs to be there first. With all the carbs I've rigged onto this thing in the last 3 weeks none of them have changed anything and actually this carb is the only one that let's it idle at all.

Just soaked it...not ruling out a leak under the tin I guess..but nothing topside. Its didn't change, didn't sputter, didnt do anything. I am posting a you tube link..hope it works.

I see you have MSD.
Is your light MSD compatible?

I have had some great stories to tell how the timing was not where it read with MSD.
Good ignition, but timing lights can be finicky with it.

Might just be the way the camera picks up the sound....... but the valve train seems noisy.

Did you check v/p clearance on this motor?

Exhaust sounds extra quiet.

I wouldn’t expect that can to be particularly muffler friendly(or a very good match for the stock 301 manifold)....... especially quiet mufflers.

I think you need to leak it down.

I also agree you should borrow a non-dial back timing light.

Good advice on the timing light..but.... been there as well, have 2 that are older than dirt, non dial back, and they read correct on the 2 other machines in this garage with msd ignitions.

The sound is terrible due to the exhaust ends at the mufflers right ahead of the axle right now. Its actually an echo from under the car you can hear I think in the unfair to sound video.

I did clay the pistons with no head gasket and didnt even hit the .250 layer I had slabbed on.

Leak down test will be next before I tear the intake off. ..well..after replacing the pick up coil real quick. But the 2nd distributor did the same so I'm not tooooooo hopeful with that path yet...I'm going to try it..as I havent yet..I'm open to whatever that's less than a $300 "maybe" possibility. Until I have to anyway.

Thanks again everyone for the input...I did alot of troubleshooting before I turned here but uts been helpful.

Polarity on the pick-up wiring was my issue when this happened on a 360 with a MSD (I know you said you already checked this). What about the wiring itself? Unplug it at both ends and check both leads for a short between them and check both against body ground as well.

Next thing I would try is a known good ignition/coil/distributor wiring it up completely with new wire isolated from the existing.

I hate to ask but did you degree he cam? I may be the audio but I agree with Porter, that valve train sounds noisy and it really doesn't sound right.

Yes...once with heads off, later after break in with heads on. I am at 102 intake centerline and Howard's card and tech support verify 102 to 104. The video is not representative of the sound unfortunately. Standing at the front of the car you only hear exhaust, with ears at the covers you here the lash . (Solid lifters)

Another one for fun...my brothers I phone takes horrible videos with good sound

I had a complete 2nd summitvdigita system wired to nothing but the battery direct and ran it with my msd distributor with leads both ways, and a summit msd knock off distributor, also, wired both ways, the summit ignition I borrowed had another brand new set of leads, I used those on both ignitions when testing the supposed correct polarity on both distributors and both ignition boxes, I cut my leads and put connectors in the middle so I could reverse them.

Odd question.....AM I IN NEED OF ANOTHER GROUND WIRE?

The two things that make no sense to me....... and I’ve thought about it some........ are the 140psi and the overheating with the timing at anything more “normal”.

It’ll be interesting to see what this issue turns out to be.

I really don't like the 140 reading, but if it is relatively even across the cylinders..might be stuck with it for now

Definitely shoot the water under the manifold too...you never know.

I have had the gasket between the baseplate and the main body of the carb fail, and it actually had an internal vacuum leak to
one of the barrels of the carb, and really ran strange. I couldn't have found it if my life depended on it, no testing showed
anything until I took apart the carb and there it was.

Questions

If you goose the throttle to 3 or 4000 rpm and let it come back to idle on it's own.....does it immediately snap back to idle rpm,
or does it slowly come down from the higher rpm point? If it comes down very quickly, it is probably not a vacuum leak and I'd start looking elsewhere.

Is TDC on the balancer 100% verified correct, by you personally (since you're tuning it)?

What kind of a timing light are you using?

Sorry if there's any redundancy and these things have already been mentioned

I'm with ya zippy...but read through if you have the time..its all been done, put a you tube video up yesterday with the garden hose all over the intake.

It does snap back to idle.

I did verify the dampener to zero on the tab. Twice.

Old school non dial back timing lights. 2 of them , verified they work with msd as I have two other big blocks in the garage with msd that time right.

I have had 5 carbs on here in the past few weeks, the one I bought for it has been off and on 4 times itself. And it leaves nice impressions on the new gaskets every time. I have also used 4 hole and open plastic spacers and one aluminum.

No worries about the redundancy..I'd rather have that and possibly a new idea lol.

I am going to go out and clean up my block ground and add another if I can with something around the garage real quick.


I should add for everyone watching..it does run pretty good once it gets out of its lump and hits about 3k or more with a load on it. Not great..but respectable. I'm betting the locked timing has something to with it.