[71466Mach]

I hope I don't sound like I am beating a dead horse, but I really want to be sure I'm going the right way AL vs. iron heads. Right now I am building a 95% street 466, going into my 71 Mach 1. The shortblock is an early 70 block, so it should have the shortest deck height. I have the TRW dish pistons (2404s) and in an earlier post the consensus seemed to be that it would not be worth swapping these out for flat-tops. So I am thinking I would be around 9:1-9.5:1 with small CC heads.

I like the idea of AL heads because of the weight issue, but lately I have been reading posts here (actually on the old board, this one looks great by the way) that make me think that if I use AL heads then I would need more compression than the 9ish:1 I would have.

Right now I have some DOVE-Cs basically fresh w/ no port work whatsoever. I have talked to a couple of people here about some ported DOVEs and some Edelbrock RPM CJs they have for sale, plus there is the option of buying some heads new.

I'm hoping for a decent 475-500hp at the flywheel by the way, and I would like to be able to run 93 octane. So--what would you do in my situation heads wise? Should I start looking at changing to flat-tops again? I want to do this thing right the 1st time.

 

[The Mad Porter]

Jason,

With those pistons at .020 below deck and 77 cc early chambers your C/R is about 9.2 to 1. The TRW / Sealed power pistons have a short compression height and always sit down the hole some at TDC unless the block is decked.

If you set the pistons you have at "0" deck by decking the block and then go to a 72 cc chamber your static C/R will be just shy of 10 to 1 which is fine for your application and power requirements.

I have been doing some reading that suggests that the differences between an iron and aluminum head at the same c/r with identical ports are minimal so do not concern yourself with that aspect.

Large valve ported early castings with a comp XE274H, rpm intake, 750 carb, recurved dizzy and headers will get you 475 to 500 HP pretty easily. The combo will run on pump gas all day long with iron heads and might run with 89 to 90 octane with aluminum heads.

This way instead of buying new pistons you would only need to disassemble your short block and have the block decked enough to bring the pistons a few thousenths above deck. You would be out some time and about $125.00 or so for the decking plus gaskets etc.

Hope this helps some...


:mrgreen:

 

[71466Mach]

Thanks for the info Scott. One question--when you say I should get the piston a few thousandts above deck, ballpark what should I be going for?

Is the XE274 a cam you can grind?

 

[The Mad Porter]

RE: Part 2

Thanks for the info Scott. One question--when you say I should get the piston a few thousandts above deck, ballpark what should I be going for?

Is the XE274 a cam you can grind?

Jason,

"0" deck to .002" above deck will be fine with the felpro gaskets that are .041" compressed.

I can most certainly grind the above mentioned cam. The december cam special has been extended until Jan 16th.



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