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No compression on a rebuilt 440 #2272497
03/19/17 07:10 PM
03/19/17 07:10 PM
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Buzzardbreath Wyoming
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I recently rebuilt a 440 out of a 76 New Yorker for a project I'm working on. This weekend was time for a first start. When cranking it showed no compression in any cylinder. Pulled the rocker assembly and it has compression (about 75psi but no air in I didn't expect it to be real high). Put the rocker back on lose and no compression. All new parts, pistons, cam, bearings, heads rebuilt (surfaced but not more than a few thousandths removed). Parts came from the engine guy that did the machine work. Cam should be like a 70 magnum grind, pistons were 30 overbore with a bump to 9.5 to 1. I did the assembly on the block, no problems during bolt together. Any ideas what might be the problem? Possible wrong cam? Pulled another 440 valve train and checked the lifters for difference (Where the push rod sits it is same height but overall length 1/6" taller) , push rod length, all the same. Checked it for another type new lifter but they were the same.

Re: No compression on a rebuilt 440 [Re: BigBird] #2272506
03/19/17 07:21 PM
03/19/17 07:21 PM
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sounds like something in that rocker assembly is holding open the valves. not much else it could be. i would pull the intake and see what i could see

Re: No compression on a rebuilt 440 [Re: BigBird] #2272508
03/19/17 07:23 PM
03/19/17 07:23 PM
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Check the cam timing.

Re: No compression on a rebuilt 440 [Re: stumpy] #2272520
03/19/17 07:42 PM
03/19/17 07:42 PM
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I was thinking of the cam timing this afternoon. If I had the chain off 180 that might do it.

Re: No compression on a rebuilt 440 [Re: BigBird] #2272548
03/19/17 08:55 PM
03/19/17 08:55 PM
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first thing I would do is use a cylinder leakage kit/ gauge and check leakage that way first. hear air through the intake, then intake valve open,noise out exhaust-then exhaust valve, air leaking through the crankcase, then piston/ ring problem.rings are groove location specific and dots up. if leakage is present through a valve, then try again with rocker arms off.eliminate pushrods, or could also point to valve timing.

Re: No compression on a rebuilt 440 [Re: moretoys] #2272565
03/19/17 09:37 PM
03/19/17 09:37 PM
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Checked the cam timing. TDC both lifters are at the bottom. 1 turn of the crank and the exhaust lifter is up as it should be. Tried to push the lifter down and it is rock solid with no movement. The center should move as it is a hydraulic. I pulled 2 lifters and took them apart, drained the oil and they push down like I would expect. Is it possible that they are all pumped up and acting like solid lifters keeping the valves open? If so how does one keep that from happening?

Re: No compression on a rebuilt 440 [Re: BigBird] #2272582
03/19/17 09:59 PM
03/19/17 09:59 PM
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If the lifters are all pumped up, and that is not a real problem, let it sit over night all assembled , then try it in the morning. You should be able to easily spin most of the push rods with you fingers then. Did the timing chain/gears get installed by a novice by the way?

Re: No compression on a rebuilt 440 [Re: BigBird] #2272584
03/19/17 10:00 PM
03/19/17 10:00 PM
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it isn't the lifters being pumped up too much. That is normal not being able to push them down by hand.

Did you try to start the engine yet and it won't fire?

Re: No compression on a rebuilt 440 [Re: buildanother] #2272595
03/19/17 10:17 PM
03/19/17 10:17 PM
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Timing chain was installed by myself (done 20 or so) so I'm comfortable that it is correct. Not my first engine rebuild so I am comfortable that all was assembled correctly. Rings were set as per the factory service manual, checked ring gap with a feeler gauge and filed for fit. Engine shop fitted the pistons and installed them on the rods for me.
Went to start the engine and it was blowing the gas back out the intake as well as pulling it in. I know hydraulics lifter should feel solid when working correctly but they don't bleed down when it sits overnight either.
The engine never even back fired. Has spark and fuel (another story with FITech). As I have stated it has no compression with the rockers on.

Last edited by BigBird; 03/19/17 10:21 PM.
Re: No compression on a rebuilt 440 [Re: BigBird] #2272607
03/19/17 10:27 PM
03/19/17 10:27 PM
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The only odd thing you said yet was that at tdc(cyl # 1 I assume), the cam lobes are away from lifters, and you said that if you then turn crank 1 revolution, that the exhaust valve is open. Well the exhaust AND intake should be open then BUT only a minimal amount. I'm thinking that if you cannot turn any pushrods easily after it sits a spell, that some components are mismatched. (pushrods, lifters, rockers etc.)

Re: No compression on a rebuilt 440 [Re: BigBird] #2272616
03/19/17 10:43 PM
03/19/17 10:43 PM
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MYRTLE BEACH SOUTH CAROLINA
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if the timing is out by 1 tooth it can shorten the intake cycle........... you said it blows fuel out and in ......?

Re: No compression on a rebuilt 440 [Re: buildanother] #2272617
03/19/17 10:44 PM
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It was #1 cylinder. The exhaust was defiantly open and the intake might have been just barely open due to overlap. Rockers and push rods were in the running engine when I tore it down. The cam and lifters were new and bought as a set. Lifter part numbers cross reference to a Mopar #3004647.
Off by a tooth it should at least fire. I've had a gear go bad and jump a tooth but I could still make it run. Wouldn't hardly pull it's self but would run and still had compression.

Last edited by BigBird; 03/19/17 10:48 PM.
Re: No compression on a rebuilt 440 [Re: BigBird] #2272620
03/19/17 10:46 PM
03/19/17 10:46 PM
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Originally Posted By BigBird
Timing chain was installed by myself (done 20 or so) so I'm comfortable that it is correct. Not my first engine rebuild so I am comfortable that all was assembled correctly. Rings were set as per the factory service manual, checked ring gap with a feeler gauge and filed for fit. Engine shop fitted the pistons and installed them on the rods for me.
Went to start the engine and it was --- "blowing the gas back out the intake as well as pulling it in. -- " I know hydraulics lifter should feel solid when working correctly but they don't bleed down when it sits overnight either.
The engine never even back fired. Has spark and fuel (another story with FITech). As I have stated it has no compression with the rockers on.
THIS.......WHEN AIR COMES OUT THE INTAKE ... THE VALVE IS OPEN AT THE WRONG TIME.

Last edited by ek3; 03/19/17 10:48 PM.
Re: No compression on a rebuilt 440 [Re: ek3] #2272623
03/19/17 10:51 PM
03/19/17 10:51 PM
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Originally Posted By ek3
Originally Posted By BigBird
Timing chain was installed by myself (done 20 or so) so I'm comfortable that it is correct. Not my first engine rebuild so I am comfortable that all was assembled correctly. Rings were set as per the factory service manual, checked ring gap with a feeler gauge and filed for fit. Engine shop fitted the pistons and installed them on the rods for me.
Went to start the engine and it was --- "blowing the gas back out the intake as well as pulling it in. -- " I know hydraulics lifter should feel solid when working correctly but they don't bleed down when it sits overnight either.
The engine never even back fired. Has spark and fuel (another story with FITech). As I have stated it has no compression with the rockers on.
THIS.......WHEN AIR COMES OUT THE INTAKE ... THE VALVE IS OPEN AT THE WRONG TIME.

As stated lifters are holding the valves open and no compression so the pistons pull and push air in and out of the intake valves/intake.

Re: No compression on a rebuilt 440 [Re: BigBird] #2272627
03/19/17 10:54 PM
03/19/17 10:54 PM
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what changed ? the heads shaved ? your push rods are orig and rockers ? did you deck it ? try shimming the rocker shafts with some tin foil [just to check] to see if that corrects it .or maybe you have some rocker shims.. ?

Last edited by ek3; 03/19/17 11:00 PM.
Re: No compression on a rebuilt 440 [Re: ek3] #2272636
03/19/17 11:03 PM
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Originally Posted By ek3
what changed ? the heads shaved ? your push rods are orig and rockers ? did you deck it ?


Heads and block were milled less than 10 thousandths total combined. The only thing new were the cam and lifters in the valve train. I've milled a pair of 440 heads 60 thousandths with out issues on the valve train in the past.

Last edited by BigBird; 03/19/17 11:04 PM.
Re: No compression on a rebuilt 440 [Re: BigBird] #2272650
03/19/17 11:31 PM
03/19/17 11:31 PM
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SO WHY WOULD THE VALVES BE HELD OPEN ? nothing changed . maybe the .010" lower added to the push rod length and you need to shim the shafts to get the preload back ?? maybe a lifter variance ? that's about it . .something had to get longer to hold them open .

Last edited by ek3; 03/19/17 11:37 PM.
Re: No compression on a rebuilt 440 [Re: BigBird] #2272655
03/19/17 11:36 PM
03/19/17 11:36 PM
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I'm assuming that the motor is in the car with the starter working, correct? If so pull all the push rods out except the two for number one cylinder and pull all the spark plugs out so you can spin the motor over on the starter with your finger or a compression gauge in the spark plug hole to see if that cylinder is making any compression or not scope
If the dots on the crank gear and the cam gear are marked correctly and you do not have the dot directly above the crank gear tooth aligned with the cam gear dot you should be close enough to get the motor to start and run. Check and see if you aligned the crank gear dot out near the teeth or the one directly above the crankshaft key way, if you used the inner dot on the crank gear remove it and retime it with both dots nearest the gear teeth scope thumbs


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Re: No compression on a rebuilt 440 [Re: ek3] #2272669
03/19/17 11:55 PM
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Originally Posted By ek3
SO WHY WOULD THE VALVES BE HELD OPEN ? nothing changed . maybe the .010" lower added to the push rod length and you need to shim the shafts to get the preload back ?? maybe a lifter variance ? that's about it . .something had to get longer to hold them open .

That's why I posted here. I've worked on my own Mopars for close to 40 years and not seen this before and was hoping some here had. I've rebuilt at least 6 440's as well as several small blocks and several different Chevy and Ford engines. I always have made sure the timing marks are correct as it is so hard to go back and check once it is installed.

Re: No compression on a rebuilt 440 [Re: Cab_Burge] #2272674
03/20/17 12:04 AM
03/20/17 12:04 AM
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Originally Posted By Cab_Burge
I'm assuming that the motor is in the car with the starter working, correct? If so pull all the push rods out except the two for number one cylinder and pull all the spark plugs out so you can spin the motor over on the starter with your finger or a compression gauge in the spark plug hole to see if that cylinder is making any compression or not scope
If the dots on the crank gear and the cam gear are marked correctly and you do not have the dot directly above the crank gear tooth aligned with the cam gear dot you should be close enough to get the motor to start and run. Check and see if you aligned the crank gear dot out near the teeth or the one directly above the crankshaft key way, if you used the inner dot on the crank gear remove it and retime it with both dots nearest the gear teeth scope thumbs

Motor is in the car. I am trying all the options before pulling the front off the engine as it has AC and all re-installed. I bleed 2 lifters off on #1 cylinder and will install them tomorrow while taking all the rest of the push rods out. That will tell if that is what I'll have to do.

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