'87 SO bottom end with HO conversion...

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'87 SO bottom end with HO conversion...

March 26, 2007, 10:36:20 PM

Due to the crank snappage/block damage in my HO, I will be getting an SO short block in trade for headers and a valvebody. I'm going to try and salvage my E7 heads if possible, but may end up going with gt40-p heads.

My question is, will there be a valve to piston interference problem with a stock HO cam and 1.7 roller rockers or a TFS stage 1 cam with 1.6 rollers? I know this has been done to death, but I never paid attention to these threads as I just swapped a whole HO motor in 3yrs ago.

Thanks,
Don

'87 SO bottom end with HO conversion...

Reply #1 – March 27, 2007, 07:23:13 AM

You shouldn't have a problem either way..... The TFS cam with 1.6's will give more lift and duration than the HO with 1.7's.....

'87 SO bottom end with HO conversion...

Reply #2 – March 28, 2007, 04:43:36 AM

#1 tfs-1 intake lift is .510, be careful w/the GTP smaller chamber heads

#2 GT40P heads are in the book as 58-61cc chamber sizes, and your SO block has flat top pistons which is another plus of 5.5cc so be careful w/your compression going to high.

'87 SO bottom end with HO conversion...

Reply #3 – March 28, 2007, 04:54:22 AM

This post might help. Keep in mind the numbers i came up with i used "0" for piston crown clearance. Though when I did my motor it was a +.007 w/kicked compression up a bit.
http://www.foxtbirdcougarforums.com/showthread.php?t=11718

this site is good to for compression.
http://www.csgnetwork.com/compcalc.html

don’t go over 9.8:1-10:1 or you will need additives in the gas but you probably know that.

'87 SO bottom end with HO conversion...

Reply #4 – March 31, 2007, 06:40:34 PM

Yeah, I'd really like to keep it around 9.7:1...if I can afford a 1.94/1.60 valve job in my E7's, I will go that route...and if necessary buy an Isky fly-cutter which will change calculations a bit. Thanks for those links.

-Don

'87 SO bottom end with HO conversion...

Reply #5 – March 31, 2007, 08:55:21 PM

intake lift on a tfs stage 1 cam is .499". and i believe most SO 5.0's (crown vic, t-bird, f-150) had dished hyper pistons. meaning your compression would be lower. unless you mill the heads your E7's a bunch. also most SO pistons due not have valve reliefs, so you might need that cutter tool.

'87 SO bottom end with HO conversion...

Reply #6 – April 02, 2007, 11:03:04 PM

Yes your correct TFS-1 intake is .499. The exhaust is .510. And I do not know if the stock SO pistons are flat or dished, I never opened one up first hand. I assumed they were flattops. cause if they are there goes my whole write-up http://www.foxtbirdcougarforums.com/showthread.php?t=11718
Dose any one know this for sure if so please chime in so we could mention it on my write-up before to many people get bad information.

'87 SO bottom end with HO conversion...

Reply #7 – April 03, 2007, 09:28:21 AM

Well I know my old '88 SO had dished pistons...but i've heard of different years using different pistons...not too sure on that...I'll find out when I get the short-block for sure.