New Nailhead engine won't start --- HELP !!

We are trying to start new re-built 55 Naihead engine.

Took all spark plugs out and cranked to prime oil pump --- good oil pressure. Good fuel supply. Double checked timing, strong spark. Engine has NO compression.

Took rocker covers off and valves moving freely up and down.

Poured oil into cylinders to try and raise some compression , but nothing . Any ideas please.

Ken.

Its either a ring problem or valves, just because they are going up and down does not mean they are seating correctly. Can you pump air into a cylinder to get the answer?

Did you crank engine enough to pump up lifters? I usually remove distributor and spin oil pump with an electric drill for a few moments to pump up lifters. Assuming they are pumped up and you have no compression I'd suspect you have the valve timing set wrong. Did you get 12 timing chain teeth between the timing marks?.......Bob

Yes, it has to be one or the other. We reckon it's all to do with the lifters. They are either not filling up with oil or have air in them not allowing the valve spring pressure to seat the lifter and hence the valve onto it's seat. How can we get rid of the air in lifter while it is still inside the engine.

Ken.

I could be dead wrong on this but if the lifter is not getting oil it would be colapsed, which would mean the valves are not opening far enough, this would not cause the no compression issue. Correct?

Correct. There would be no pressure only if the lifter was so far collapsed that the intake valve was not opening at all. In that case with the compression gauge sealing the spark plug hole, on the intake stroke the piston would be creating a vacuum then on the compresson stroke the pressre would go back to ambient ( no pressure rise ). If the valves are observed moving even a little this would not happen and the engine would at least try to fire or run. The fact that he has no compression at all makes me think there is a serious valve timing problem. The nail heads are kind of funky to time requiring counting timing chain teeth with the # 1 and 4 pistons at TDC.....Bob.

Thanks for the clarification! Hopefully it is a valve timing issue so the engine does not need to be pulled.

Distributor is 180* off?

Timing chain installed correctly?

We have eliminated the lifters as a problem. There is good oil pressure and they are all moving the required amount.

Sounds like it could be a timing issue and we are getting the timing cover off to check. The engine was put together by an engine shop. Apart from the 12 link issue , what other sequence should we be checking ?

Thanks.

Ken.

This is straight from the book....

"If there has been doubt about valve timing, turn crank shaft until the CAMSHAFT sprocket keyway is straight down towards the CRANKSHAFT and the "0" timing marks on both sprockets are toward left side of engine (not YOUR left). If the chain is installed to provide correct valve timing, there will be 12 teeth between the "0" timing marks, including the teeth aligned with the marks".

BTW, looking at the engine both "0" timing marks should be at about the 3 o'clock postion on the sprockets. If you do need to retime, both sprockets must be pried off their shafts and reinstalled with the chain already on them, both at the same time.......Bob

We've got the timing cover off. There is 12 links between O punch marks. We will take off both srockets to check the keyways. Still confused as to why there is NO compression on any of the 8 cylinders. Surely even if the timing was way out there would be compression on some ?

Ken.

Boy this is indeed a mystery. I would have bet my wallet the valve timing was screwed up. I can't think of any other cause for no compression, assuming the valves are functional, and you said they were. You did have the throttle fully open during the compression test, I hope.......Bob

We have taken the rocker shafts off and cranked engine.

With all the valves closed there is plenty of compression, enough to blow your finger out the hole.

We're back to square one. It has to be in the lifter , push rod area. Can only think we've got the wrong push rods in there ( new ones - too long ? ) or air in lifter not allowing valve spring pressure to compress lifter back.

Ken.

If it's any help, 56 push rods are longer than 55's. 56 push rods measure 8 3/16".......Bob

Just thinking out loud, have read about this but you are probably right, the wrong lifters are installed. Someone had 56 lifters in a 55 or something like that and found they are not interchangeable. Suggest pulling a lifter and getting the specs, or having the engine shop get the specs and find out whats up. Just glad ya don't have to pull the engine.

56 lifters and push rods will work in a 55 if used together. You can't mix them or the total length will be wrong. To the casual observer they look the same. Sounds like that is the problem, at last.......Bob

Houston , we have a problem. A big problem. But first let me tell you about last week's episode. The engine builder FORGOT to replace the plug in the rear oil gallery , the one behind the flywheel. And when we cranked over about 1/2 gallon of oil pumped out onto the ground. So unfortunately we already have pulled the engine and tranny last week.

But this week sends us more problems ( on top of the lifter issue--won't go into details here)

But you may be on track here with the 55 , 56 interchange.

The push rods we have are 8 3/8 inch long. The same length as a member's 56 engine. This sounds like it could be our problem ? The lifters are new and appear to be the same length as originals. We did not keep the old push rods to compare. Bob can you confirm the correct length for the 55 pushrod.

Thanks for your continued assisstance.

Cheers, Ken.

Sorry ken, I don't have any 55 push rods laying about. You say yours are 8 3/8". Curious, the 56's I have here are 8 3/16". The 55 and 56 lifters are the same length but the piston sits at a different hight giving a different over all lifter/push rod length.....Bob

loosen the bolts on the rocker stands a little and let the stands "float" a little above the head. That will shorten the pushrods. If it starts, or at least has compression, you know the problem is the pushrods. It only has to run 5 seconds to tell you if you are on the right track.

Yes we tried that. Put a 2mm washer under each post to raise it and still no compression. Bob are you sure the push rod you have is 1956 @ 8 3/16 inches long ? Could that one be a 55 and the 56 is 3/16 longer , which is close to the point we need to achieve on the rocker deck.

Ken.

Interesting question. The push rods I measured were sold to me as 56's along with the lifters which were supposed to be 56's. They functioned perfectly in a 55 322. The only reason I removed them is that there is a service bulleten against using 56 lifters in a 55 due to cam material incompatability. There are no markings or part #'s on either lifter or push rod. I'll go up and measure the total lifter/push rod length. I know that length worked fine.......Bob

OK. Just measured everything. The total length of lifter/pushrod with the lifter fully pumped up is 10" even. That length worked perfectly in my 55 322.

The piston in the 55 lifters I have on hand are 3/16 lower which means the push rod length of 55's would be 6 3/8 to make the 10' total length. It appears you have 56 lifters and 55 push rods. That would mean your over all length would be 10 3/16 which would not let your valves seat. take a look at your lifters. if the top of the piston is almost to the top of the bore you have 56 lifters and need a 6 3/16 rod. If the top of the lifter piston is down about 3/8 or so into the bore then you have 55 lifters and need a 6 3/8 rod. If you have lifters with the piston high and 8 3/8 long rods I think you have found your problem.......Bob

BTW Ken, If you find that you do indeed have 56 lifters and 55 rods I would reccomend you keep the rods and change the lifters. There is a long thread on this forum in the perf/mod page outlining the 56 lifters with 55 cam problem.....Bob

Thanks heaps for all that Bob. We will check the measurements etc and post results.

Ken.

Mystery solved !!! At last.

We have been the sold the wrong lifters , they are indeed for a 1956.

Thanks to your measurements Bob we were able to confirm this straight away.

Pity we had to go through much grief and lost time ( and now $$ )to find out.

Thanks also to all others who gave advice and took an interest in our drama.

Cheers, Ken. ( aka Rooster )

Glad to see your mystery solved, Ken. BTW, when ever I rebuild an engine I always run it for a half hour or so in an engine stand before I put it back in the car. That might have saved you a bit of hassle, especially with the forgotten rear galley plug. Now I'm off this AM to take my 57 to Meadow Brook..............Bob

Ken

I'm a little late getting to this tread since I have been playing in the streets between central Texas and Seattle. Lots of sound advice so far. Before you start the engine be sure the machine shop did not install shims under the valve springs... if they installed generic shims that cover the recess that the inner valve spring sits in you will get spring bind after the lifters pump up fully after starting. This has happened 3 times on heads that machine shops serviced even after alerting them. The first time resulted in bend push rods, broken rocker arms, bent and broken rocker shafts and a bent cam. I check that and all machine work before assembly and installation due to sloppy work and poor attitudes: "it's just an old car that will be driven in parades a few miles a year, so it need not be perfect"...that is one excuse I got for substandard work!

Willie

Will do Willie, that's good advice.

It wouldn't surprise me to find that , considering all the other faults we have found.

The trouble was the engine was aquired in pieces so who ever re-built it did not have the benefit of pulling it down and setting parts out.

Ken.

As an aside...Bob, I saw your '57 at Meadowbrook yesterday--nice car! Lots of nice cars actually!

Hey Aaron. Roger the lots of nice cars. I wish you would have said hello, but I might have been strolling or trying to stay dry somewhere.......Bob

I looked around when walking near your car, and nobody who looked like an owner was hanging around at the time...sorry I missed you!