440 Compression Test Results

Been working on friends Challenger that has a 440 engine. He dropped it off and said it just started smoking out exhaust.Swap carburetor out to rule running rich. Compression check only showed 90 to 95 dry. Wet only increase reading by 5 lbs. The engine has only has twenty thousands miles on it. The reading seems low to me anyone one know the numbers I should be seeing. I was told it was built with 6 pack pistons.

You should be seeing 160-170 min. I gotta question the test basics: all plugs removed? Throttle open? Battery charged? Battery charger hooked up? Engine warm?

Did you do an oil test to see if readings improved?

The fact the readings were consistent is good, the fact they are that low is not.....hence the questions

Yeah that's pretty low. I healthy motor should be in the 130-140+ range...and fairly consistent between cylinders.

Were all cylinders this low or just two? If it's two adjoining cylinders, it could be a blow head gasket. If it's pretty much all of them, new rings are probably needed.

However if it just started smoking all the sudden, I would suspect a blown gasket or (hopefully not) cracked block. Check the oil and make sure it doesn't look like a milkshake indicating coolant is getting into the oil which is bad news for the rest of the motor.

Good luck.

Warm engine ,one plug at a time, good battery spins engine great, couple of shots of oil in cylinder only increase reading by 5

Oh man. One plug at a time? You need to do it over. Pull all plugs, open throttle and test.

Remember to disable ignition!

smokes all the time or on decell or? If "just started" that makes me think valley pan tin gasket leaking

Thottle was wide open, The instructions with compression tested said one plug at a time. What is advantage of removing all plugs To make the engine spin over faster. The engine is spinning pretty good as is.I understand the open thottle to help draw air in. But what does the other cylinders have to do with the one I have the gauge hooked to.

Already changed valley pan gasket. That is was my first move

Wrong stagger on the piston rings......

Numbers this low will not come up to acceptable with proper ring stagger.


Smoke can come from a minor mark in a cylinder wall. For the same reasoning that a compression test is not a good tool. It's a quickie to tell if a motor is great or shot, like burnt valve shot.

That engine needs a cylinder leak down tester with compressed air, 2 gauges and a regulator.

It sounds like the cam was installed dot to dot and not checked for cam timing, it is probally retarded 2 to 6 degrees Did you get to drive it before the smoking? If so was it lazy and not real responcive to the throttle? If so check the cam timing to make sure it is installed correctly

All the plugs have to be removed for the engine to spin fast enough to get a proper reading. You will never get the proper reading out of it by leaving them in and pulling just one plug at a time. I think you may have misunderstood the instructions. Yes, you are checking only one cylinder at a time, but with ALL of the plugs removed.

Big cam, low compression ratio will give low readings across the board. Second thing is check with the same gauge on a known good motor. Gauges can be inaccurate. Seen plenty of motors in the 125 psi range with low compression ratios. The first thing I'd check is a poor fitting intake manifold.
Dou

If it has 6 pack pistons in it that is an extremely low reading. What cam is in it?

Seen that b4.


Yep. My 8.x:1 440 with the MP 509 cam was pulling 110psi on all eight (cam was straight up).

first we gotta fix the smoking. secondly improper breakin might have fubared the rings. You might read "breakin secrets" at www.mototuneusa.com for my take on that. As said I would do a leakdown. keep us updated

if the rings are shot, can he ball hone the cylinders and slap some new rings on and be good to go? or do we think we need to remachine the block?

I don't see why not. I burned up #3 twice (cast pistons w/ 6psi of boost) all I did was pull the old unit out hit with quick hone and slap it back together. Do a leak down 1st. How do the plugs look?

I believe so with the correct grit on the ball hone. (I'd want file fit plasma moly rings and Brush Research Manufacturings' recommendation on the grit). You would wanna check taper/out of round & you'd sure think it'd be good with that few miles but I would square up a ring gap & use it to check out of round/taper at least on 1 cyl just to see where you are at or if the block is coming out then have your shop use a dial bore gauge for a spot on check

I don't think its rings or it'd have come up more than 5 PSI with oil. 95 PSI is LOW no matter how you cut it.

How does the engine run and what cam is in it? I'd suspect that the pushrods are too long or lash adjusted wrong if it has adjustable rockers. OR it doesn't have six pack slugs in it.

Are you sure the gauge is good?

Read the instructions again today,remove one plug installed gauge crank engine over until needlle on gauge no longer moves, write down reading replace plug go to next cylinder and repeat. But just for giggles I removed all plugs and took reading, Got same reading as with the plugs installed, Also checked gauge by installing it in the stock 440 in my Daytona got a reading of 130 only checked one cylinder, but is the readings I felt I should be getting on the Challenger engine

If it wasn't flooded on start up and the hone was done by somebody reputable I doubt if if killed the rings. Pull the intake, 8 bolts. I'll bet its sucking oil.
Doug

O.k. talked to the owner of the car today and got a little more history about the car,He was not sure what cam is installed but the guy that built it told him it was a big one. Ask if had any other problems in the past and he told me that he had a electric fuel pump on it and it ran 6psi , which I think was fine, but he said they took it off a couple of weeks ago and put a mechanical pump on because after the car set over night there would be gas on the intake, he said it was like pressure would build up and push it out thottle shaft. Changed to a mechanical pump and no longer has gas on intake, So my thinking is it was probably leaking gas into intake and was washing the cylinder walls down and it got the rings. And that's the cause of the low readings.I am going to try a leak down test the next day or so.

Already changed gasket and it made no difference, the old one looked as it was sealed fine.

If adding oil didn't fix the problem, it isn't the rings.

Several months ago, there was a rescue story in Hot Rod. The guy's Cobra was running so bad that he never drove it, it sat in the garage. It had a really rich condition and compression was low. The expert used a borescope and looked inside the chambers. He found "loose, fluffy carbon deposits" that were keeping the valves from seating all the way.

They got the fuel problem fixed and put several hard miles on the car, and compression went up to where it should have been. They mentioned that back in the day, it was thought necessary to take a car out on the road and "blow the carbon out". I had heard this too and thought this was a gasoline-fume-induced myth, but it seems to have some basis in fact.

R.

I've heard that referred to as an "Italian tuneup"

Wrong stagger on rings would be a impossible thing. even if installed with all the gaps lined up with in about 10 revolutions they would no longer be in the same position as the rings constantly turn in the lands. Remember that this is engine that had been running good so IMO this eliminates a improper cam install. A blown or leaky head gasket would not effect all cylinders either.

what do the plugs look like ? if it is burning any oil you will see it... bad valve seal-s guide issues ?? a large cam with pistons in the hole a mile and big open chamber heads can get you 100 psi all day long...

Back in the day the literature frequently referenced "taking it out & blowing the carbon out of it" With the oil burning happening all of a sudden I'd stay after that as some gasket somewhere let loose & I'd find/fix that then onto the low comp. I would do a leakdown tho I'm wondering if fubared oil rings will show definitively on that % & I'm sure it will to some extent but we gotta keep after it with what we got till something develops. As said it might be as simple as low DCR but that is real low numbers. keep us posted!

Plan on leak down test tomorrow. when I done the compression test (I have done four so far and got same reading each time).If it was just blue smoke I would say oil.But it seems to be more bluish gray.Vacuum gauge shows 5 to 10 very rapid between the two at idle.bring engine up to about 2000 rpms and vacumn smoothes out at 15. It is like the exhaust valves are not closing all the way.I could see this happen to one head but not both. Leak down test tomorrow we will see.

the grey points more toward fuel enrichment, like you see when your behind someone & they floor it.

I know and that is what at first i felt was wrong. Changed carb and intake ran the same. You stand in smoke and it doesn't smell rich and there is just enough blue to it make you think oil.

Alright, I keep coming back to the valley pan tho not sure about valve stem seals (not convinced but I would check them) & they as the culprit would be more likely to show up on decell (I'm assuming it smokes all the time)

Ditto. It makes us feel better we stagger them when we assemble but you are correct, they turn.

That is a very large jump/swing in vacuum. It sounds to me like it has poorly seating valves, sticky valves, worn guides, worn springs, a burned valve, or some combination of this. Some valve issue IMO. You need to check all 8 too, 1 may be higher or lower and tell us something.

I went to borrow leak down gauges from a friend today and his was kid was having surgery today so he was not at work.Said to come by Monday and i can get them.So I decided just to go ahead and pull the heads and see what I find. When I pull up the intake I could see in the intake ports and they look wet with oil so maybe the intake gasket I installed did not seal.After seeing this I feel it going to be intake seal or rings. Anyone have any good tips on installing intake gaskets I have installed maybe thirty intake gaskets on 440 & 383 in my life and never had a problem. But looking at the valve this doesn't look like all of sudden thing. Carbon build up on valves very black tar looking . But I am half way of pulling heads so maybe pull them and have them worked and worry about sealing intake after reinstall of heads. I would hate do all of this and it turned out to be the rings. Anyway maybe get heads off tonight and what I have.these are the plugs after abut thirty minutes run time on new plugs

Dead rich. Needs more timing.

You say valves but you show us plugs. Which is it?

And did you remove just the intake manifold or intake plus heads? It's confusing how you are telling the story.

It doesn't take long at all for such carbon deposits to form if the engine is running max rich.

I just don't believe it is rings with what you've told us. But if it is, you have to take the heads off anyway, right?

For valve stem wear, Chrysler had a test in the FSM, with no spring on and valve closed how much would the stem move sideways. That would be quick and dirty. Then get some lapping compound and lightly lap the valves to see if there are any spots that aren't seating. I mean the carbon should be gone by this time and what I'm looking for is a nice shiny ring on the valve seat and the valve face. I'm not suggesting you do any more than find out if the valves are seating.

If they are and if the valves pass the sideways test then reassemble with new valve stem seals, stock type are OK,and get ready to reassemble.

Bigblock people will be happy to tell you their tricks for intake sealing.

R.

Photos show plugs darker in photos than they are, I showed plugs because someone asked what they looked like and to show it was not rich. That didn't work out from the photo. I couldn't get the camera down in ports to show the valves so plugs was it.As far the timing goes . When it showed up the timing was one of the first thing I checked. It was set at 42% btc. And the advance was not working. It has MSD distributor and someone set it up with the advance locked out and weights removed. The car started fine the starter spun over fine , Makes me think the cam wasn't degreed in when built. The owner had the weights and spring so reinstalled them and now I have 18 btc at idle and 34 btc at 3000. So much on this engine is over done for the way the guy drives it. Six pack carb setup ,big tube headers,3 inch exhaust,big cam, 5 speed Trans he never turns over 3000 rpms , Drives it a lot on interstate said it turns about 1800 at 70 MPH. With the A/C on

This is great feedback. It tells us many things. For one, there are often more than 1 way to get great results.
2, you have a great starter and battery.
3, There will never be a mix up of firing order with your method.

What heads? I'm thinking exhaust valves and seats eat up, guides too(unleaded gas). But usually the intake guides will suck oil. Did you have the intake off? Look at the intake valve for heavy deposits on it, a sign of bad guides.

Yes a lot of carbon build up on intake valves. Should have heads off by end of day. And drop them off to the machine shop Monday.

The plugs would be black because if you are sucking oil it causes the fuel not to burn correctly. Try adding the paper gasket to the head side of the pan gasket, if need be use paper on both sides.

X2 X2. Both sides. member superformance (sp) has .015" paper gaskets to use on the valley tin. Permatex 99MA "high tack" the red spray thin glue/cement. mockup dry first to check bolt hole alignment

O.K. got the passenger side head off , don't care anything about big tube headers. Anyway I am not wasting my time by pulling the heads check out the valve stems . What would cause this type of wear?

Head advice , It has 346s which is going to need all valves.Which I don't think has harden seats. Should I look for different heads to have worked or buy some rebuilt 542 heads from Aero racing. Or some other vendor. The guy was told when he had it built that the builder install larger valves had Sixpack pistons, Which he got neither just flat tops pistons and upgrade valve springs.Just a big cam in a low compression engine.

I don't believe that is valve tip wear, just a difference in stems for intake/exhaust. I think by the time you have heads reconditioned or purchase reconditioned stock heads you'd be better off getting some nice aftermarket aluminum heads. They will make more power and shave weight off the front end. That is, unless you need to keep it OEM.

346's were right on the cusp of the changeover (reportedly some were hardened some werent). I would NOT get rebuilt heads from Indy (aero)

Good valve job on inexpensive 452 heads, they have hardened seats. Unless he has big bucks be done with it. He could spend a ton of money and not show much difference on a street car running pump gas. These guys on here will have you building a 1000 hp $50,000 engine for the street.

Found some 452 heads local that looks pretty good . Going to have them rebuilt and install springs from other heads. It is valve stem wear. Some of the exhaust has wear and some of intake. If you lay a straight edge across the valve spring there is height different of 1/8 inch between some of the spring which tell are sitting lower in the valve seats.11

That was from the unleaded fuel, I have a set of 340 j heads that did the same thing, about 20,000 miles on them.

they werent rebuilt 20k miles ago for sure

Since the heads are off, it's too late to try, but.......

Since there was talk of fuel pressure, puddles of fuel, etc...... Anyone change the oil and get that gas diluted stuff out of there?
A motor with gas diluted oil will usually smoke pretty good.

The OP's test of the "known good" motor was a stock 440 out of a Daytona?
I assume correct 69 engine specs?
If so, the 130psi observed on that test is about 20-25psi low, so to me the accuracy of the gauge is still in question.
Best to do the test on some late model engine to verify the gauge accuracy, IMO.

Since the heads are already off, does the motor indeed have 6 pak pistons in it?
Deck clearance?

I think the actual cr needs to be determined, along with the cam specs and installed position, so a better idea of what the cranking pressure "should be" can be determined.

The Pistons turn out be standard flat tops, The owner of the car was told by the builder he installed 6 pack pistons. The heads were also said to have been rebuild with larger valves, which also did not happen and I am not sure the guy did any thing other than change the springs. Half the seat for valves intake and exhaust are just terrible. The cam the owner told me has a 509 lift intake and 513 lift exhaust and he could not remember the duration, But the builder had the cam special ground. After looking at all that has been put on this engine by the builder I would say the special grinding was to the owners wallet.Even the head gaskets were installed wrong. On the head gaskets the word top is stamped on the gasket that means when installed you should see the word top when you set the heads on. The gasket is coated different from top and bottom so there is a right and a left for these gaskets. but they put the right on the left and left on the right.I would like to thank everyone who has offer advice and their opinions. I have been working on these old Mopars for about thirty five years mostly my own cars so when I have to trouble shoot someone else's car and they are telling it just started smoking all of sudden it kinda throws me a curve ball. The owner finally told me the car always smoke some but the guy told him he had setup rich. The car has a MSD ignition system it will burn anything up that come in the cylinders. I guess i have always been luck with my cars I have never had to trace down a problem like this, but I always went the conservative route with my cars. The way I look at it you either build a street car or a race car , you don't build it half and half and want to drive it everyday. So thanks again everyone and I will update you in about two weeks the heads should be ready then and I should have the time to install them. THANK YOU Moparts

Ray Charles can see that thing is pig rich.

O.k. a few people has made comments about how rich looking the plugs are, And have i said the photos make them look dark , so I took another photo outside laying on concrete to show what they really look like. The problem with the car has been found it was the valve guides. The heads are in terrible shape,some of the darkness you see was oil burning on the plugs. Ray should have smelled the plugs and then he would have known it wasn't a running rich problem. Thanks again Moparts

Good humor bro! EDIT it looks much better in the last pic & there is the gas smell (hard to mistake that). OP keep us updated

I'd go ahead and pull it. Look on Moparts for a good mill and drop it in. You will/he will save money and have a nice done engine.