# Ohio 67 gto 400 Engine rebuild



## gtocwp (Nov 12, 2014)

Ok folks, this is newbie again. I am looking for a central Ohio mechanic to rebuild my 67 gto 400. From the odometer it appears that the 400 and numbers matching M20 4 speed has approximately 82k miles on it. The 4 speed appears to be in good shape. The motor, missing both heads, 4bbl carb. and intake manifold, sat in a barn for at least 10-15 years completely undressed waiting for a rebuild that never happened (the owner died). I do not have any information as to the condition of the motor prior to its disassemble. There are no obvious defects, cracks or damage to the motor. I am doing an off the frame restoration of the body/frame so i thought i should get started on the motor.

When i got the car/motor 5 years ago I basically put it on an engine stand and bathed the motor in oil for awhile, got all the cylinders to move freely, cleaned up all the surfaces i could reach and covered it with oil rages. All of the cylinders felt smooth and the pistons move with ease. That is how she sits today. My goal is to rebuild it substantially stock, but make what ever changes are needed so that it can be a "daily driver" if i so choose. So nothing fancy or crazy.....but, I do want to put a tri power on it verses the 4bbl. I already have purchased a restored tri-power supposedly from a 66 gto that has three 2 Jet Rochesters on a manifold with casting GM 9782898. I just really like the tri power look and concept and since the original 4bbl and manifold were missing......went for the tri-power..

I am looking for a reputable motor guy in central Ohio to do the rebuild. I am about 1 hour north east of Columbus, OH and i am willing to drive a couple of hours if needed.

Any suggestions regarding a mechanic? Any suggestions or thoughts about what I have and what I want to do with it?


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## Old Man Taylor (May 9, 2011)

I don't know personally, but a friend of mine in Toledo would. He's a racer, in the Royal Club, etc. I don't see how to PM on this board, so you can email me at [email protected]


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## PontiacJim (Dec 29, 2012)

gtocwp said:


> Ok folks, this is newbie again. I am looking for a central Ohio mechanic to rebuild my 67 gto 400. From the odometer it appears that the 400 and numbers matching M20 4 speed has approximately 82k miles on it. The 4 speed appears to be in good shape. The motor, missing both heads, 4bbl carb. and intake manifold, sat in a barn for at least 10-15 years completely undressed waiting for a rebuild that never happened (the owner died). I do not have any information as to the condition of the motor prior to its disassemble. There are no obvious defects, cracks or damage to the motor. I am doing an off the frame restoration of the body/frame so i thought i should get started on the motor.
> 
> When i got the car/motor 5 years ago I basically put it on an engine stand and bathed the motor in oil for awhile, got all the cylinders to move freely, cleaned up all the surfaces i could reach and covered it with oil rages. All of the cylinders felt smooth and the pistons move with ease. That is how she sits today. My goal is to rebuild it substantially stock, but make what ever changes are needed so that it can be a "daily driver" if i so choose. So nothing fancy or crazy.....but, I do want to put a tri power on it verses the 4bbl. I already have purchased a restored tri-power supposedly from a 66 gto that has three 2 Jet Rochesters on a manifold with casting GM 9782898. I just really like the tri power look and concept and since the original 4bbl and manifold were missing......went for the tri-power..
> 
> ...



You always want a machine shop to hot tank the block and magnaflux it for cracks before going any further. If it passes, then they will check the main bearing bores, cam tunnel, and cylinders and let you know what work will be needed. They will let you know what piston size will be needed.

The tri-power will fit on all heads, 1965 and up. The 1967 "670" heads were the last of the "closed chamber" heads and 1968 and up were the "open chamber" heads. Pontiac heads have different sized combustion chambers to change compression ratio's. But, you can also get pistons that have a dish in them to lower compression. Some times you use a combination of chamber size and piston CC's to get to a compression ratio of near 9.0-9.2 for iron heads so as to run on pump gas. The lower the compression, the lower the octane gas you can use. Low compression does not mean a low HP engine as you can select a cam that can help with this.

You will find many engine builds and head/compression/cam choices by doing a search through the forums using the search box above.

I would expect that your budget will be $4,000-$4,500 for the rebuild unless you use aluminum heads and roller cams - then it goes way up.


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## Old Man Taylor (May 9, 2011)

A lot of good information from PontiacJim. W/R/T the cam journals, be very careful. Do not let a machine shop align bore them. The attached pictures show the second rebuild I went through before I figured out the problem. Many Pontiac cam journals are not in line. Therefore when my cam journals were line honed it made one o r more of them egg shaped. This meant there was not enough crush on the cam bearing, allowing it to rotate in the journal. That blocked the oil hole(s) resulting in the damage you see in the pictures. I could not save the 4-bolt 428 block. It could be used with larger cam journals and roller bearings, but I didn't want to tackle that at the time. A lesson learned the hard way is never forgotten.

How did Pontiac deal with this? They installed the cam bearings, and then they line honed the bearings.


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## Old Man Taylor (May 9, 2011)

B/T/W, that engine had 50 miles on it.


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## LATECH (Jul 18, 2018)

Good info from both Jim and OMT (Jim also) here.

X2 on the cam tunnel ,dont line bore it. My machine guys has a pontiac cam he ground off the lobes and cut grooves in the journals, making it a "reamer" of sorts . Works pretty clean.

I would however have the crank line bore checked/corrected if needed, sonic test the cylinder walls, before boring and after, and also consider decking the block. You will want to have pistons sorted out well before the engine goes to machine shop, so you can measure/calculate the "stack Height" of the reciprocating assemblys.Then you can calculate how much you want to deck the block.
I used RPM 5140 rods (forged) in my build. The price for a set was only a fraction more than rebuilding the cast rods in the engine as it were, and the peace of mind is worth it. The rods are the weak link in a Poncho engine.

I for one do not like a dished piston.I believe you obtain better performance with a flat top piston , as the flame front propogates more eficiently.IDK.Flat tops will require some creativity hen choosing cylinder heads as that is all part and prcel to getting a good streetable compression ratio for pump gas. You dont want to be buying race gas just to go to dairy queen. The right build will run all day long on weasel wizz gas that youget at the pump these days.
Anyway, ask lots of questions, take notes. Learn the math neccesary to build your engine correctly for the purpose you want, Street engine ...right?
You need a good "recipie" for the parts you put in to get the most out of your build.


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## Old Man Taylor (May 9, 2011)

If you dish a piston correctly, you leave the top flat at the quench point, and open it up where it will be under the combustion chamber. Works like a charm.


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## Old Man Taylor (May 9, 2011)

This is the piston I used in my last 428 build. It resulted in 9.67:1 compression and it does not ping on 91 Octane California gas. If I remember correctly the quench is 0.038. I was trying to hit 0.040, but there were issues in the decking of the blocking.


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## LATECH (Jul 18, 2018)

Nice.


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## Gribbuckeye (Jun 11, 2014)

If you are looking in central Ohio Dave Baurle rebuilt mine. 1967 400. He is in Delaware and I would recommend him


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## Chad (Jan 15, 2016)

gtocwp said:


> Ok folks, this is newbie again. I am looking for a central Ohio mechanic to rebuild my 67 gto 400. From the odometer it appears that the 400 and numbers matching M20 4 speed has approximately 82k miles on it. The 4 speed appears to be in good shape. The motor, missing both heads, 4bbl carb. and intake manifold, sat in a barn for at least 10-15 years completely undressed waiting for a rebuild that never happened (the owner died). I do not have any information as to the condition of the motor prior to its disassemble. There are no obvious defects, cracks or damage to the motor. I am doing an off the frame restoration of the body/frame so i thought i should get started on the motor.
> 
> When i got the car/motor 5 years ago I basically put it on an engine stand and bathed the motor in oil for awhile, got all the cylinders to move freely, cleaned up all the surfaces i could reach and covered it with oil rages. All of the cylinders felt smooth and the pistons move with ease. That is how she sits today. My goal is to rebuild it substantially stock, but make what ever changes are needed so that it can be a "daily driver" if i so choose. So nothing fancy or crazy.....but, I do want to put a tri power on it verses the 4bbl. I already have purchased a restored tri-power supposedly from a 66 gto that has three 2 Jet Rochesters on a manifold with casting GM 9782898. I just really like the tri power look and concept and since the original 4bbl and manifold were missing......went for the tri-power..
> 
> ...


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## Chad (Jan 15, 2016)

Hi gtocwp,
Calling upon my Geography, I'd say you are around the Mansfield area. I'm from the far East side of Cleveland, near Mentor so I would recommend the shop that is doing my engine. Check out Gellner Engineering in Brookpark, Ohio, on the West side of Cleveland. It's a family business that's been around for a long time. Dean Gellner's father was doing engines in the 50's and was involved with Joe Hrudka in the early days of Mister Gasket. They are doing my engine, a 455 for my GTO for the street. They will tear it down and check the motor completely and rebuild it to as I put it to them " something that will have a very noticeable idle, be reliable and will push you back in the seat when you get on the freeway!" They will also break it in and tune it and offer dyno services. My build will be in the hi 5000 range, but they will do what you want and will work with you also. Another builder that I have heard good things about would be Victory Engines also on the west side of Cleveland. Good luck!


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