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I WANT THIS TO BE STREETABLE AND WOULD PREFER NO MORE THAN 10.5:1 COMPRESSION. i ALREADY HAVE 8.9:1 COMPRESSION PISTONS AND WOULD LIKE IT TO RUN ON PUMP GAS. wHAT DO YOU THINK IS THE BEAST STOCK HEAD COMBO FOR MY SETUP. THANKS, LOUIE
 

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I'm not sure what "8.9:1 Compression Pistons" means ... Compression is going to be determined primarily by the heads, secondarily by the pistons ... and in minor ways by a few other specs.

I'm going to assume you have flat tops


If you want it to run on "regular" fuel ... and you have "Flat Top" pistons ... you need "Open Chamber Heads" ... plain and simple.

This will put you very close to 9.5:1 and will most likely still run on pump "regular" ... You will not be able to exceed about 9.5:1 with open chamber heads though, so you will need to insure it doesn't get pushed up from there.

If you go to "Quench" (Aussie 2V or American 4V) heads ... you will be at or very near 11:1 compression and will have all the advantages that come with the compression ... you will need to run Pump premium fuel though ... Other than the need to pump "Premium" fuel (91/92 octane) there doesn't need to be anything that would make the engine "NOT Streetable". Your cam and intake are going to affect "Streetability" more than compression.

FYI ... 4V heads will not deliver much in the line of "Low End Torque" ... In this regard, the Aussie 302 Quench heads are a much better choice for "Streetability"




_________________

Larry Madsen
Las Vegas Nevada



<font size=-1>[ This Message was edited by: MonsterMach on 5/2/02 8:37am ]</font>
 

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Discussion Starter · #3 ·
Thanks larry. You have answered so many of my seemingly mindless questions that you need to be comended. you and everyone else on this page are the best. By the way I am building a 66' mustang fastback t-5(european Model) with a 351C. I have learned so much from all of you that I just wanted to thank you. now in response you are sure that 11:1 compression would not detonate with 91 premium( they dont sell 92 around here)?
 

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My 11.1:1 compression 351C 4V runs fine on 92 now ... I've been told by very reliable sources that even with the Aussie heads and slightly higher compression (which I am currently building) ... the heads will tolerate it


Now the "Disclaimer" ... If you build it and it doesn't ... Please, don't come hunt me down and kill my kids


Maybe some other Cleveland fanatics in here will chime in for us on this issue


OH ... Thanks for the kind words ... I just do my best to help, when and if, I think I can
 

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I run the '71 4V closed chambers and TRW flat tops with the stock deck block. That is supposed to be 10.7:1 compression, so says FOMOCO. After measuring and calculating,I found that it is really only 9.9:1. After grinding the combustion chambers to unshroud the valves, the compression would have only been around 9.7:1. I had to mill .030" from the heads to get it to 10.25:1. I would still have to mill the block .025" or .030" to get the 10.7:1. My point is, don't think that the factory rated 11.00:1 compression is accurate. It is most likely less. That's not all bad if your worried about detination. I run mine on pump gas with no problems.
 

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Clevelandstyle ...

None of the numbers I am using are FoMoCo "factory estimates", they are all caluclated using the best engine specs I can muster for the post in question
 

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I`ve run 12:1 pop-ups in my 4v closed chamber351c on pump gas w/o any probs on 92.Also put out 232hp to the ground in a 74 Ranchero on pump gas.I know it`s not a lot,but that was in Reno and w/o a good tune on it either.My 76 cobra w/351 Boss should put out about 370-400 on motor and bout 525 on juice.And is totally streetable.
 

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If you pick 2V OC heads, get only D0 or D1 castings. The D5 and up castings have a horrible exhaust port.

I've got the hots for an MII that's in a guys "pile". It's a 76~78, T-tops, 9", 14x31 Centerlines w/goodyears in the tail, ladders, coilovers, cage. It's really screaming for me to go get it and put a 400 in it.
 
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