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picking heads for my 385 series

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Discussion starter · #21 · (Edited)
eshaw said:
Basically what you've got there is a 71 block, which was probably chosen because it and the prior years had a higher nickel content than later ones. The pistons skirts have been treated to reduce friction, that's the purpose of the coating on the sides. If you look at the top of the pistons they should be marked if they are over standard size. Since you're going to have an approximate redline of 6k based on the cam combination you chose you should be ok with stock heads. You will gain a weight savings by going to after market heads and they will allow for a little more compression because they can dissipate heat better. I'd look for something used with close to stock compression ratio and it should also have stock size valves or close to it. The 460 is basically a stroked 429. I also noticed from your picture on the pistons that the rods appear to have stock rod bolts. This is another very good reason to maintain the 6k redline. I'd also make sure that the heads have screw in studs and guide plates. This will also require that you get hardened push rods. Hope this helps you out a little.
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thanks eshaw most of that I already know. I will look on the pistons for stamps. don't want stock heads. buy loosing the stock waterpump, ac ccompressor, and power steering, intake, and heads im dropping over 100 lbs off this old girl. probably closer to 150 lol.



 
#23 ·
You are going to need more like a 92cc combustion chamber with those to get around 9.7:1 compression. Need to make sure your builder checks piston to valve clearance to with them. Bending brand new valves would suck!!
 
Discussion starter · #24 ·
well crap.......no trick flows with that big of CC. I tried to use the calculator and I get even higher with the 466.6 displacement (30 over bore). Edelbrock has a 92, IDK? I emailed Trick Flow we'll see what they say.



 
Discussion starter · #25 ·
OK,OK I got it....according to the calculators on a bore this big the head gasket thickness varies a lot. from .027 all the way to .120 this highly effects CC size.
with a gasket thickness of .080 compressed the calculator brings the recommended CC size down to 79.4cc now if I can just figure out intake valve size.:D



 
#27 ·
Should have got a SBC..... :co:
lol good luck brotha hope it all works out and screams like a banshee!!:drunk: :pop::pop:
 
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#28 ·
Deck height on your block will also play a big role in compression. 460 had 2-3 different deck heights that they used (varied like .030") with the early ones being the highest compression (shortest deck). Really need to do a mock up and lay crank and one piston and rod in and measure how far down in the hole the piston is from the deck in the up position with a dial indicator. Hard to guess compression not knowing what deck height the block is and if it's ever been milled down or not. I wouldn't hesitate to go up to 10:1 compression but you will have to run 91-93 octane most likely. My small block in my car is a good 10.5:1 and runs awesome on 93 but has a much bigger cam too which helps some.
 
Discussion starter · #29 ·
afflicted said:
Valve size does not change compression. What sizes R there to choose from on those heads?
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I don't know enough to actually figure my heads. I don't know the deck clearance, haven't looked to see if there's a head gasket, or do I know exactly what the bore size is. if its 4.39, the deck clears by .10 and I use a avg .060 gasket then ill get a 9.3:1 ratio with 74cc CC. beginning to understand the numbers. guess I need to look at the whole "air speed" and valve size again.



 
#30 ·
whiteriverrambo said:
I don't know enough to actually figure my heads. I don't know the deck clearance, haven't looked to see if there's a head gasket, or do I know exactly what the bore size is. if its 4.39, the deck clears by .10 and I use a avg .060 gasket then ill get a 9.3:1 ratio with 74cc CC. beginning to understand the numbers. guess I need to look at the whole "air speed" and valve size again.
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Deck clearance won't be .10. Should be more like .010-.035" depending on block with zero deck being ideal.
 
#32 ·
whiteriverrambo said:
:cf: sorry, you lost me
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Just seen you said that you put deck clearance as .10" in the compression calculator to get 9.3:1. Your piston to deck clerance will be nowhere near that, more like .010-.035" depending on block and if it's been milled could be zero. Change that measurement and see what compression it is with 74cc heads, it's gonna change a bunch.
 
#34 ·
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Discussion starter · #35 ·
yea ive read all that multiple times. 2.19in/1.76 ex on his build. but he doesn't say what pistons he used either. ive also read that any intake over 2.125 can see clearance issues unless you use a dish piston or another racing piston that's been cleared for the larger valves. Stock 385 heads actually came with 2.25 intake valves but they were intended for the 429 since its stroke was .26 less than the 460 there were no clearance issues. biggest problem was the exhaust port being constricted on all the iron originals, hence my reasoning for wanting to go with the "trick flows" but some of them have a 2.2" intake valve.......need to look for smaller but I need to know my deck height first.

..........more important things to deal with right now, gun season opener is tomorrow!



 
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