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Thank you, Thank you, and Thank you.

I appreciate your response.

I have 2 other thoughts......Would there be any reliability issues with the stock Pontiac crankshaft up to my intended level of 400hp?

Also, my builder will be installing new valves ( intake and exhaust ) along with the changing the rockers to roller tips and increasing the ratio from 1.5 to 1.65 on the intake valves and 1.5 on the exhaust side. According to him it will give more of a lift and change the duration a little as well. Any disadvantages or reliability issues with this scenario? Any noticeable Hp increase? The heads are the 4x heads that came with the engine. He is also putting in bronze valve guides and putting in exhaust seats I think he said.
 

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If the stock crank is checked OK for cracks, then it should be fine. As to the 1.65 rockers, I would have to know the cam specs, but it is unusual to look for more lift on the intake alone.
 

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Hello everyone! I'm new to this forum.

I'm in the middle of a rebuild but not on a GTO but a Trans Am. Hopefully, I could share and receive some advice as well on the drive train side.

The engine is a 400 manufactured in 73.

I'm in the aftermarket selection process with replacing the old pistons ( which were forged from a previous rebuild about 25 years ago or so ) and replacing them with possibly 4032 forged JE SRP Pistons. Also changing out the rods from the stock to 4340 Forged Eagle H-beam.

My intended use is street/strip with some hard driving and once in a blue moon at the drag street.

I believe this is a strong enough set up, but I would like know if there are any disadvantages running this combo in daily driving. My daily driving consists of going to weekly car shows. I have a lot of country roads and highways with some city driving.

I have read somewhere that these pistons are noisy??

Reusing my original cast crank and the builder is beefing up my heads. He produced a sheet which shows our intended CR is in the 9.1 or bit higher. Cam is 216/228 @ 50, .454/.480, 112 LSA . .
How does your builder plan to raise the compression to 9+? If memory serves, '73 motors were low 8's for compression.
 

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How does your builder plan to raise the compression to 9+? If memory serves, '73 motors were low 8's for compression.
He is using aftermarket pistons - the pin height can be moved to raise the piston higher in the bore. Or, you can mill the block/deck to get a "zero deck" height which can increase compression.
 

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Thanks Jim for stepping in to explain. I saw my builder today and we are going to try and clean and mag another used 6x-4 from 1977 and apparently from a Trans am as well. This should get us closer to 9.5.1. The heads will be worked over with 30 degree valve job and a very minimal amount of porting ( around the intake and exhaust areas ) My builder has a machine that spits out this info after knowing the numbers including the heads flow numbers. Hopefully, it checks out cause I’m paying the machine shop another charge to have them check it out. I will have to sell the other 4x heads to try to recoup some of my losses. On the brighter side, some of my shiny new part came in. Stainless steel Ferrea valves, 4340 Forged Eagle h beam rods( they felt very light but look sturdy, Jp performance Billet gear set ( made in Australia! ) Hasting performance rings, top will be 1/16 th instead of the thinker 5/64 normally used. This will reduce friction and more ductile then the thicker one ( more hp to a degree ). The pistons are 4032 forged flat top with only 2 relief valves as opposed to 4 reliefs for more compression. They are being made so made another week or so before arrival. Hopefully.
 
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