Larger pushrods in Buick Nailhead

[machinedave]

We recently machined a set of nail head cylinder heads for a customer and about 10 minutes into running it on his break in stand some noises started so he shut it down and he pulled the valve cover and and one push rod is bent and or broken to the point that it cannot be removed until the head is pulled off. The intake valve is also stuck open. The short block was built by another shop years ago. The customer will not have time to pull the heads and intake until next week. The push rods that he installed are bigger than the thin stepped down factory push rods. It seems I remember a while back that some of the Buick guru's were talking about problems with installing bigger push rods in nail head engines. Can some of you Buick Guru's refresh my memory?

[panic]

Try the question here: http://tinyurl.com/h4ooml5

[GOSFAST]

We recently machined a set of nail head cylinder heads for a customer and about 10 minutes into running it on his break in stand some noises started so he shut it down and he pulled the valve cover and and one push rod is bent and or broken to the point that it cannot be removed until the head is pulled off. The intake valve is also stuck open. The short block was built by another shop years ago. The customer will not have time to pull the heads and intake until next week. The push rods that he installed are bigger than the thin stepped down factory push rods. It seems I remember a while back that some of the Buick guru's were talking about problems with installing bigger push rods in nail head engines. Can some of you Buick Guru's refresh my memory?

Hi Dave, when doing these "Nails" we've found there has to be a whole bunch of "mockup" time spent on the unit.

These are so critical due to the 45* "penthouse" design a simple item like a +.060" longer set of valves will "mess-up" the entire rocker geometry. Those pushrod passageways are like "targets" from the lifter cups to the rockers. Every little item affects their clearance, like milling, head gasket thickness, etc.

Once you step up to heavier pushrods even on a bone-stock build there tends to be issues. Many times we've clearanced the pushrods holes through the heads. If I recall correctly the OEM pieces were .250" (solid) thick with larger ends.

Thanks, Gary in N.Y.

P.S. You'll have much more time in building a "Nail" than almost any other brand. We have one running in Massachusetts built some years ago running in the low 11.0's in a Henry-J. Pump gasser, probably out 10 years or more now, not a single issue on our end!

[machinedave]

We recently machined a set of nail head cylinder heads for a customer and about 10 minutes into running it on his break in stand some noises started so he shut it down and he pulled the valve cover and and one push rod is bent and or broken to the point that it cannot be removed until the head is pulled off. The intake valve is also stuck open. The short block was built by another shop years ago. The customer will not have time to pull the heads and intake until next week. The push rods that he installed are bigger than the thin stepped down factory push rods. It seems I remember a while back that some of the Buick guru's were talking about problems with installing bigger push rods in nail head engines. Can some of you Buick Guru's refresh my memory?

Hi Dave, when doing these "Nails" we've found there has to be a whole bunch of "mockup" time spent on the unit.

These are so critical due to the 45* "penthouse" design a simple item like a +.060" longer set of valves will "mess-up" the entire rocker geometry. Those pushrod passageways are like "targets" from the lifter cups to the rockers. Every little item affects their clearance, like milling, head gasket thickness, etc.

Once you step up to heavier pushrods even on a bone-stock build there tends to be issues. Many times we've clearanced the pushrods holes through the heads. If I recall correctly the OEM pieces were .250" (solid) thick with larger ends.

Thanks, Gary in N.Y.

P.S. You'll have much more time in building a "Nail" than almost any other brand. We have one running in Massachusetts built some years ago running in the low 11.0's in a Henry-J. Pump gasser, probably out 10 years or more now, not a single issue on our end!

Yes you are correct. I saw the original factory push rods that are solid and thin in the middle(I'm guessing about .250") and he used push rods that appeared to be 5/16". We were not aware that he was changing the push rods.

[Dutchman]

The pushrods come real close to the spring pocket,not much room for a larger spring.
How much lift on the cam ? At 550 I had to elongate the holes in the head for max lift,hits by the head gasket surface.
Is the vale train adjustable,rockers or pushrods. Mr. Geometry likes to rear his head here.
A stuck valve sound like something is not happy.
Keep us posted,thanks
Gary

[Adger Smith]

If you used real good seals on the guides it might have taken away enough lube to stick a valve.
The ones I've done I didn't seal all that good.
I also put the heads on my mill and enlarged the push rod tubes .070.
If I remember right I had to take more out of one side than the other because the head sat down due to block milling and head surfacing. We had a lot of time in mock up doing the PR geometry.
You will also need to look closely at the valve spring shims, if you use any. They will rub the PR if they have too big an OD.
The customer should have told you of the intended PR change. In the 44 years of Engine/Race engine building these are the absolute worst engine where one change has dramatic effect on other parts of the engine fitting.
Wait till you get one where the customer is trying to cross breed parts from 2 engine & brings you boxes of parts and internet new parts that are "Supposed" to fit.
Yep, they have some odd rod length engines, too.
You could have a mess
Good luck
BTY: I found this helped me make some decisions in the builds I did.
http://nailheadbuick.com/15-most-common-mistakes
http://nailheadbuick.com/nailing-down
Look at the cutaway pictures in this link. They give a good visual illistration of what things look like and where the changes take place.
http://www.curbsideclassic.com/automoti ... rangement/

[machinedave]

Thanks guys. Good information. The customer says that he purchased the bigger push rods from the Centerville auto repair Buick specialist. I called the customer this morning and asked him to call me when he removes the intake manifold so we can go over to his place get a better look at valve the geometry.

[Adger Smith]

Take a close look at the head gaskets he used...

[machinedave]

I went to the customers shop and looked at the push rods and the geometry and it was a little tight by the spring pockets but nothing too alarming. The customer removed both heads and I brought it back to our shop. We pounded the stuck intake valve out of the brand new guide (reamed and honed to size) and noticed some serious galling on the valve stem. The valves have had less than 1 hour on the previous engine. The stems were polished. In 20 years in the machine shop business we have never had galling. This has 10 minutes of run time on a fresh valve job. It was ran on the customers run stand.

[machinedave]

Take a close look at the head gaskets he used...

[Adger Smith]

I can't tell from the pictures, but what I wanted you to look at was the matching of the water passage holes. I had one engine that would not pass water to the heads . It would fill the block and heads, but it had some holes blocked that should allow water to go to the heads. It was a gasket the customer supplied, so I don't have a clue what brand or where it came from or what series Nailhead it was for. I suspect it was a cross breed for an early engine or different Cu In....
Another issue you might have ( I've had it, too) is if he changed the water pump. It may not be pumping. There are 2 different water pump housings and they will interchange and there are two pumps that will fit both of them. The issue is the pump blades. OK memory may be faded on this, but it goes something like this. The non air conditioned prior to 61-62 took a pump that had fewer blades and a different housing. The later engines with air conditioning had a pump with way more blades and will pump the water at low and High speeds. They also had a housing that put the blade clearance closer to the back of the housing. Better pump blade clearance. BTY: Too thick a gasket can get you, too. You can check water flow with a temp gun when it is on the stand. I had a customer "Buy a new pump because it was safer to keep it from over heating" Tried everything I knew to fix the low speed overheating and finally told the customer there was nothing that I did wrong. It was working fine, what have you changed? The pump.!!! The pump blades also need to be as close to the housing as you can get them. since you didn't put the assy together you might be in for a little "forensic Tear down" of the water pump and housing. These guys have a better flowing pump. http://www.flowkoolerwaterpumps.com/sto ... index.html The problem is at low (idle) to mid RPM. If you take most any of the pump/housings combinations to high RPM they will flow enough to cool.
I just spotted this on You tube. This 3 blade impeller is the one you don't want!! https://www.youtube.com/watch?v=mnqrsiwD4ds
Again, Memeory is sketchy, but the 5 blade is the pump you want. BTW: The local Auto Zone store has the part numbers for air conditioned and non air conditioned reversed in their computer. That didn't help me find my customers problem...
I hope this info about what I've had happen to me helps.
Good luck.

[Dutchman]

I went to the customers shop and looked at the push rods and the geometry and it was a little tight by the spring pockets but nothing too alarming. The customer removed both heads and I brought it back to our shop. We pounded the stuck intake valve out of the brand new guide (reamed and honed to size) and noticed some serious galling on the valve stem. The valves have had less than 1 hour on the previous engine. The stems were polished. In 20 years in the machine shop business we have never had galling. This has 10 minutes of run time on a fresh valve job. It was ran on the customers run stand.

. Just throwing a few things out there and not trying to be a ass.
The valve arrangement does not allow for guide oiling as well as a wedge type engine,what type of seal did you use if any at all. Russ Martin swears you cannot use a bronze guide in these motors,as he wrote in his home page. Mine have been fine for a few thousand miles. I set them up at .0015 and .0025. Are the valve stems soft,I got bit by that a while ago with a galling issue,file on the stem and it cut in like peanut butter.
Was the pushrods length,stem heights checked,possible ex valve not closing all the way causing a overheat condition.

[machinedave]

I can't tell from the pictures, but what I wanted you to look at was the matching of the water passage holes. I had one engine that would not pass water to the heads . It would fill the block and heads, but it had some holes blocked that should allow water to go to the heads. It was a gasket the customer supplied, so I don't have a clue what brand or where it came from or what series Nailhead it was for. I suspect it was a cross breed for an early engine or different Cu In....
Another issue you might have ( I've had it, too) is if he changed the water pump. It may not be pumping. There are 2 different water pump housings and they will interchange and there are two pumps that will fit both of them. The issue is the pump blades. OK memory may be faded on this, but it goes something like this. The non air conditioned prior to 61-62 took a pump that had fewer blades and a different housing. The later engines with air conditioning had a pump with way more blades and will pump the water at low and High speeds. They also had a housing that put the blade clearance closer to the back of the housing. Better pump blade clearance. BTY: Too thick a gasket can get you, too. You can check water flow with a temp gun when it is on the stand. I had a customer "Buy a new pump because it was safer to keep it from over heating" Tried everything I knew to fix the low speed overheating and finally told the customer there was nothing that I did wrong. It was working fine, what have you changed? The pump.!!! The pump blades also need to be as close to the housing as you can get them. since you didn't put the assy together you might be in for a little "forensic Tear down" of the water pump and housing. These guys have a better flowing pump. http://www.flowkoolerwaterpumps.com/sto ... index.html The problem is at low (idle) to mid RPM. If you take most any of the pump/housings combinations to high RPM they will flow enough to cool.
I just spotted this on You tube. This 3 blade impeller is the one you don't want!! https://www.youtube.com/watch?v=mnqrsiwD4ds
Again, Memeory is sketchy, but the 5 blade is the pump you want. BTW: The local Auto Zone store has the part numbers for air conditioned and non air conditioned reversed in their computer. That didn't help me find my customers problem...
I hope this info about what I've had happen to me helps.
Good luck.

Good information Alger.The pictures are not the same nail head block but another nail head block that I am working on for another customer but it does appear that the gasket he used did not allow for water transfer on the upper portion of the block.

[machinedave]

I went to the customers shop and looked at the push rods and the geometry and it was a little tight by the spring pockets but nothing too alarming. The customer removed both heads and I brought it back to our shop. We pounded the stuck intake valve out of the brand new guide (reamed and honed to size) and noticed some serious galling on the valve stem. The valves have had less than 1 hour on the previous engine. The stems were polished. In 20 years in the machine shop business we have never had galling. This has 10 minutes of run time on a fresh valve job. It was ran on the customers run stand.

. Just throwing a few things out there and not trying to be a ass.
The valve arrangement does not allow for guide oiling as well as a wedge type engine,what type of seal did you use if any at all. Russ Martin swears you cannot use a bronze guide in these motors,as he wrote in his home page. Mine have been fine for a few thousand miles. I set them up at .0015 and .0025. Are the valve stems soft,I got bit by that a while ago with a galling issue,file on the stem and it cut in like peanut butter.
Was the pushrods length,stem heights checked,possible ex valve not closing all the way causing a overheat condition.

No seals at all on intake and exhaust. Brand new SBI guides reamed to.0015" intake and .0025" exhaust and a few light passes with the Sunnen P-190 guide hone. The exhaust valves were all brand new and the intake valves had less than 45 minutes of run time in a previous engine.

[Adger Smith]

That is great... Over heating killed the guides..Check the water pump!! The one that had the gaskets also had the mismatched water pump/housing for me. Double trouble!!