Head Deckers -- I need some info!!! <---

6837 Views 12 Replies 6 Participants Last post by bust0023, Feb 17, 2020

reefstar

Discussion Starter · Feb 2, 2020

OK, so the original 3.5L in 1990s produced 10.4:1 compression, which has been reduced back to 9.9:1 in our engines. So does anyone have the calculations made already to deck the heads to get it back up to the 10.4 ratio? I believe even 10.6 should be possible for pump gas. How much timing can the knock sensor retard?

Also, I think I have a solution for the cam timing retard issue with decked heads. Starting from the top going down, set the CAM at top dead center. Then work back down to the CRANK pulley and create a new slot in the crank pulley to re- TDC the pistons. That should do it, unless I'm missing something. Right?

Also, has anyone found a set of light weight pulleys that are compatible?

Love to hear some input...

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DBL.DWN

· #4 · Feb 14, 2020

do you have the ptv clearance to deck the heads with the new cam?
I would go to 11:1 if youre going to do it. Youll need to cc the chambers and then do the math to see how much to take out. Can you find thinner head gaskets ? Also keep in mind that you may need shorter pushrods.

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DBL.DWN

· #6 · Feb 14, 2020

reefstar said:
Well the pushrods are no problem. It's an overhead cam. LOL.

LOLOLOLOL:doh:Good point haha.
Overhead cams are not the first thing i think of.

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DBL.DWN

· #10 · Feb 14, 2020

Cam timing for sure makes a big difference. But again, ptv will need to be watched for.
Rather then shaving the heads. Have you thought about getting the chambers welded up? You'll be able to up the compression more accurately, and not have to worry about the cam timing as much. also will be able to shape the chamber to control the flame travel better.

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