My mechanic needs help

[Patrick]

My 67 New Yorker has been in the shop for a few months now why they try to get as compression problem fixed. The heads have been machined to factory specs and new valves installed. The cylinders and pistons look brand new (the engine has been rebuilt by PO at some point). What the mechanic suspects is that the head or engine have been ground and the lifters are now too long, but not by much. The valves aren't adjustable so he need to source the right length lifters but can't find any adjustable lifters. If he can't find those he thinks he'll have to pull the heads and grind the valve stem a little. I'm hoping someone here has some thoughts or parts recommendations so I can get my car back some day.

 

[thrashingcows]

How does he not know about adjustable push rods? Quick and simple fix to your problem.

But you can also get new pushrods made up as well. One adjustable pushrod to find out what the new length should be, and then order up a new set of 16 rods in the desired specifications.

 

[Patrick]

How does he not know about adjustable push rods? Quick and simple fix to your problem.

But you can also get new pushrods made up as well. One adjustable pushrod to find out what the new length should be, and then order up a new set of 16 rods in the desired specifications.

Can you point me to where I can get those? I have done some searching but I am not confident what I found is correct for my year and engine. I suspect my mechanic, being an older fellow, doesn't Internet very well.

 

[67Monaco]

Can start here;

http://search.store.yahoo.net/chuck.../chucker54.stores.yahoo.net/newprodmonsp.html

 

[thrashingcows]

Can start here;

http://search.store.yahoo.net/chuck.../chucker54.stores.yahoo.net/newprodmonsp.html

Good link.

You will need to get a ball/ball pushrod length checker set-up.....since that is what our cars run.

Your mechanic should be able to see if the heads, or block deck has been milled. It will show up when you install the intake. If you remove material from either the head, or block, it will change the angle of the seating surface for the intake. Perhaps this is where your engine problem lies...more so then with the lifters, or push rods.

 

[70bigblockdodge]

67 had different lifters, small socket if I remember if later pushrods are put to them they will not seat all the way, not sure about old pushrods and new lifters but something to look at anyway, make sure parts are compatible. Then order correct length if too long

 

[Patrick]

67 had different lifters, small socket if I remember if later pushrods are put to them they will not seat all the way, not sure about old pushrods and new lifters but something to look at anyway, make sure parts are compatible. Then order correct length if too long

Not sealing all the way appears to be the problem. He says when he puts 30psi in the chamber it leaks down. When he puts 100 it holds a bit. He describes it as "not seating all the way".

 

[70bigblockdodge]

No the lifters are different if PO that rebuilt it used the correct lifters for 1967 later pushrods will not fit properly. Check for compatibility

 

[66/440]

http://www.pushrods.net/

 

[66/440]

If the heads have been milled and too much material was removed then you could have the problem described. Also if the block has been decked this could in conjunction with head milling could cause/add to the same problem.
Has the engine ever run? Have you checked to see that the compression rings are in the correct positions, i.e. the gap's are not aligned? This would allow compression to leak out quickly. If it has never run and you have tried unsuccessfully to start over a long period of time and the cylinder walls have been gas washed then there is not enough oil in the cross hatch to seal the rings.
Can provide more back ground?
BTW you can shim the rocker shafts to get the correct push rod length if the distance is not too great, perfectly fine for a street cruiser. Would not do it for a hot street or race motor.

 

[Patrick]

If the heads have been milled and too much material was removed then you could have the problem described. Also if the block has been decked this could in conjunction with head milling could cause/add to the same problem.
Has the engine ever run? Have you checked to see that the compression rings are in the correct positions, i.e. the gap's are not aligned? This would allow compression to leak out quickly. If it has never run and you have tried unsuccessfully to start over a long period of time and the cylinder walls have been gas washed then there is not enough oil in the cross hatch to seal the rings.
Can provide more back ground?
BTW you can shim the rocker shafts to get the correct push rod length if the distance is not too great, perfectly fine for a street cruiser. Would not do it for a hot street or race motor.

It ran, and I thought it ran well. I drove it on some long trips, even, but it began to run rough and I couldn't get it back to what I considered normal. The shop I took it to said compression on 6 and 7 (IIRC) were down. They sent the heads for rebuilding and said the pistons and cylinders look almost new. The mic'd them and know they are .0 something something over.

I'll call the mechanic and pass on some of the suggestions. Hopefully he will be receptive.

 

[66/440]

Does it run at all now?
Can you run a vacuum check? It will tell you a lot about valve condition and possible manifold leaks and timing issues.
When you purchased it from the PO how many miles did it have on it since the rebuild? -
Could the cam not have been broken in correctly and you have a couple of lobes (6&7) that are wearing and causing issues?
When you began to notice issues was it after you returned from a trip? if so any time that you noticed the performance degrading after filling up with gas?
Any back firing? I have a friend that had a back fire from a carburetor that was running rich and it caused the intake manifold gaskets to blow out in several places, which caused idle issues. If it runs now you can check for cracked gaskets with WD40 or the like. Just spray it around the manifold gaskets and if you can detect the engine speed up or smooth out when you spray it you can locate the source of the leak.


Since it was running well ( no smoke at idle, under load or deceleration ) I would not think it was a ring issue, which leaves valves, carb and ignition.
Valves: bad gas (contaminated by water etc.) could cause burnt valves. You have covered that with the rebuilt heads ( did it ever get hot?) Did they check (Pressure and Magnaflux) for a cracked head or a cracked seat that would only show up when the engine is at operating temp and expands due to the heat otherwise.
Ignition issues - lots to cover but start with basics - fresh plugs, check cap for carbon tracking inside cap and check for cracks inside and on towers - rotor - in phase and contacts clean, check inside that goes over the distributor shaft to make sure it is not cracked or wallowed so that it remains in-phase
Wires - different ways to check but can be tricky to find an intermittent short.
Carb - issues - which carburetor are you using?
Timing Chain and sprockets - check play
Distributor - check vacuum advance diaphragm and make sure that the advance plate is free and working correctly.

Man this looks like a bunch to do but most of it is really simple and can easily be done by you.

Here is a link to the rocker shaft shims: http://chucker54.stores.yahoo.net/rocshafshim.html

 

[Patrick]

The car runs now, just not perfectly. It is still in the shop and I talked to the mechanic this morning regarding the possible issues. He figured the best solution to the problem was to install a set of adjustable rockers. It's about $250 and that will allow the valves to seat properly. Seems like the best way to do it because shimming or new push rods will be hit or miss depending on the size difference, adjustable rockers will definitely do it.

 

[66/440]

Who's rockers are you planning on using?

 

[bajajoaquin]

I'm no mechanic, but something sounds off to me. If it's pushrods or lifters, it wouldn't have run right from the beginning. The fact that it ran fine and now doesn't says something changed.

I don't see how adjustable rockers affects this other than masking some other, underlying problem. That underlying problem might be your mechanic. If he's an old guy who doesn't internet well, that would imply that he's old enough to remember when these cars were new. That should give him the experience to deal with this problem. That it hasn't speaks volumes.

 

[Patrick]

Who's rockers are you planning on using?

He mentioned JEGS so I think these ones: http://www.jegs.com/webapp/wcs/stor...ponse=submitMMYCmd&storeId=10001&YEAR=1535425

 

[Patrick]

I'm no mechanic, but something sounds off to me. If it's pushrods or lifters, it wouldn't have run right from the beginning. The fact that it ran fine and now doesn't says something changed.

I have to admit that the idea that it ran well is totally subjective based on my perceptions. I have never owned a car with a 440 before so I have nothing to compare it to.

 

[66/440]

I'm no mechanic, but something sounds off to me. If it's pushrods or lifters, it wouldn't have run right from the beginning. The fact that it ran fine and now doesn't says something changed.

I don't see how adjustable rockers affects this other than masking some other, underlying problem. That underlying problem might be your mechanic. If he's an old guy who doesn't internet well, that would imply that he's old enough to remember when these cars were new. That should give him the experience to deal with this problem. That it hasn't speaks volumes.

I have to agree. That is why I was asking questions about when it began to run differently. Maybe the question should be how was it different? Power loss/ rough idle/ stumbling on acceleration? And where/ how far had you driven the last trip before you noticed the difference or was it something that just kept getting worse?

 

[1966newport]

time to find A qualified mechanic

 

[Big_John]

My 2 cents.

If there's been too much cut from the deck and heads along the valves sunk down a bit it is possible to have too much preload on the lifters. If this is the case, then yes, you are going to have to do something to change the preload amount. There should be about .040 preload.

You also could have lifters that are "pumping up" and even though they might have the right preload, they aren't bleeding excess pressure and the lifters top out and lift the valves open slightly as the preload length goes to zero. That's kind of a high RPM issue though, but it could be bad lifters.

If it were me, I would check the preload on the lifters first and see if that is the issue. If the preload is right, you have a lifter issue.

If I needed to change the preload, I would use the adjustable rocker arms... and I have my reasons... Shims can crack the rocker stands. I've seen and experienced this myself and unless the heads are apart and you are looking for it... you probably won't see the cracks. Even then, you may only see the cracks during magnaflux. I will never use them again. I tossed an expensive set of heads once...

Adjustable pushrods aren't all that great. They are great for figuring what length to cut new pushrods, but IMHO, they aren't reliable enough for a street engine. Cutting pushrods to length is good, but it's a bit of a pain and not something you want to pay someone to do.

Adjustable rocker arms are the way to go. Easily adjustable and reliable along with the advantage of the ratio between rocker arms being closer to nominal. The stamped rockers are no where near as good.

Regarding the 67 pushrod and lifter combo. A later pushrod just won't fit the 67 lifter. You would never get it bolted together. I'm not sure if the 67 pushrod and later lifter will work or not. It will probably bolt together but it brings an interesting question... Any chance the 67 pushrods are longer? That would not surprise me at all. That could be the whole problem.