# '69 GTO 400 push rod lengths



## Teknoid (Mar 25, 2021)

I bought a '69 GTO with a rebuilt 400 from Razors Edge Motors in Pompano Beach Florida. They seem to be out of business. The phone number doesn't connect to anyone.
The engine rebuild invoice from July 28, 2011 shows a Z-280-2 Crane camshaft was installed. New 1.65 aluminum roller rocker arms. No mention of the push rods. 
On tear down and rebuild this winter, I discovered two different push rod lengths were installed. I have eight that are 9.350" and eight that are 9.400". Naturally, I didn't notice the differences until I went to reassemble the engine. 
Can anyone tell me which length goes to which valve (intake or exhaust)?? I'm guessing that there is a pattern...
Or should I replace them all with the same size? If so, which length?
I would like to replace the rocker arms with 1.5 rollers too. The 1.65 arms are causing the push rods to rub against the journals in the heads. 
Thanks!


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## Jared (Apr 19, 2013)

If you change the rockers, you will need to measure and use new pushrods anyway. You should always do this on both, an exhaust and an intake valve, and preferably recheck on a second cylinder. The pushrods will be the last thing you order. Have the cam, and timing set installed with the heads and head gaskets installed and torqued. Use the lifters and rockers you plan on using to do the measuring. Remove the valve springs from the cylinder(s) you use to measure and replace with light weight check springs (see link). Install an adjustable pushrod and set to the correct length. Turn the engine over a few times to make sure the rocker tip rides in the center of the valve stem, and repeat. Take your time with it will go just fine.

I hope this helps.









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## Baaad65 (Aug 29, 2019)

Also you need to elongate the pushrod hole in the head for 1.65 rockers and have the correct springs to prevent coil bind, with your description of their build no wonder they're out of business.


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## Teknoid (Mar 25, 2021)

Thanks guys!


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## Jared (Apr 19, 2013)

If you run into anything else, just ask. I went through a lot of this recently when I tackled my first build. The guys on here were great with help and advice which is why I had some input for you. Another recommendation, if you don't already own them, is to pick up the Rocky Rotella engine books. They are great reads and have a ton of useful information on building these engines.


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## armyadarkness (Dec 7, 2020)

It sounds like the engine builder already modified the heads for the 1.65 rockers.... If Im reading you right? 

Never heard of different length rods.


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## Jared (Apr 19, 2013)

armyadarkness said:


> It sounds like the engine builder already modified the heads for the 1.65 rockers.... If Im reading you right?
> 
> Never heard of different length rods.


I've heard of it but didn't run into it on my build. Since the engine had 8 and 8, it sounds like different sizes for the exhaust and intake valves. Could have been done as the result of head modifications such as installing larger valves or something like that. They tell you to measure the intake and exhaust lengths for this exact reason.


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