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Discussion Starter #1 (Edited)
Can anybody tell me the compression on the Ford 427W (m-6009-427F) if I put on a set of Edelbrock RPM heads (60cc/2.02 intake valves).

FORD RACING 427 CUBIC INCHES BOSS SHORT BLOCK -- M-6009-427F

Is this block a good deal? It's going into a 74 Bronco with a NV4500 5-speed (.73 final), 4.88's, Edelbrock Proflo (1st gen - 29lb injectors), 35" tires. I would like something in the 500hp range with plenty of low end torque. I want to run pump gas (91).

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Using an online calculator and the .040 thick gaskets they recommend I get 11.08..
You will be limiting the engine pretty good with those heads...I would go with something larger.
 

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Thanks for your reply. Where did you use the calculator? Also, I already have the heads from a 393w that popped the corner of the #4 hypereutectic piston off (everyone is telling me improper ring gap). So, the heads I have will need to be gone through since the valve seat took a beating and passed all the pieces of the piston out my exhaust.

My question is, is it possible to fix the head and get it ported to get the volume I need, or would it be cheaper to buy new heads, and which ones?

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Thanks for your reply. Where did you use the calculator? Also, I already have the heads from a 393w that popped the corner of the #4 hypereutectic piston off (everyone is telling me improper ring gap). So, the heads I have will need to be gone through since the valve seat took a beating and passed all the pieces of the piston out my exhaust.

My question is, is it possible to fix the head and get it ported to get the volume I need, or would it be cheaper to buy new heads, and which ones?

Thanks
AFR 215's. :)
 

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... I already have the heads from a 393w ... My question is, is it possible to fix the head and get it ported to get the volume I need, or would it be cheaper to buy new heads, and which ones?
That depends on what the 393W heads are. If they are stock heads - absolutely no. Ported stock heads cannot be made to flow anywhere near what the 427W needs to see it's potential. If the heads are something else, then tell us what they are.
... that popped the corner of the #4 hypereutectic piston off (everyone is telling me improper ring gap).
They are right. Urban legends persist for a very long time, and HE pistons got a bad name because engine shops ignored the warnings to use a larger cold ring gap so they would fit perfectly when hot. Of course, when the rings were heated, they grew more and end-butt. This seizes the ring in the bore and rips chunks off the top land of the piston. The failure is with the builder - not the piston design.

In-fact, HE pistons are both reinforced with greater hot strength, and use closer bore clearances for better power and efficiency. This is why the 5.0L HO and GT40 (Cobra) engines and most makes of factory turbo cars switched from forged to HE pistons as the technology matured. In most ways, they are simply as good or better, and less expensive to boot. Unfortunately, the urban legend continues, and HE pistons are still regarded by the general public as second-rate.

David
 

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Discussion Starter #6
That depends on what the 393W heads are. If they are stock heads - absolutely no. Ported stock heads cannot be made to flow anywhere near what the 427W needs to see it's potential. If the heads are something else, then tell us what they are.
David
The heads are Edelbrock RPM (60cc/2.02 intake valves). Here is the flow chart:

Valve Lift .100" .200" .300" .400" .500" .600" .700"
Intake 70 128 183 219 251 255 246
Exhaust 57 104 142 163 170 174 175

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Here for comparison are the numbers from my RHS 200cc heads out of the box, for my 289.


lift int. exh.
.200 122 107
.300 185 142
.400 236 171
.500 274 183
.600 292 191


It makes 400 ft lbs of torque from 2800 rpm to 6000 rpm with a peak of 445 @ 4500, peak hp is 455 @ 5900 rpm! I would think a larger head for a 427 would be needed.
 

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Discussion Starter #8
I'm starting to get the idea that edelbrock rpm heads suck. From all the posts in this forum for the last 5 years I don't think they've been mentioned once. Can they be ported to flow like RHS's, TW's or AFR's, or should I cut bait and get different heads?
 

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I'm starting to get the idea that edelbrock rpm heads suck. From all the posts in this forum for the last 5 years I don't think they've been mentioned once. Can they be ported to flow like RHS's, TW's or AFR's, or should I cut bait and get different heads?
I wouldn't say the rpms suck..They have their place and are a huge improvement over a stock ford head..On a nice 289/302 they would work great..What you are looking at is a big block in small block clothing..It needs lots of air flow to reach its potential..I would be looking at cylinder heads with intake runners 200ccs and larger..
There are lots of online compression calculators if you do a google search and everyone has their favourite..Here is one at the top of the list when I searched. http://www.csgnetwork.com/compcalc.html
 

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Discussion Starter #10
I have the following components from my old motor:
- 351w will be bored to 060
- 393w Scat cast crank (stroke = 3.850)
- Scat H-beam rods (length = 5.955)
- Edelbrock RPM performer heads (2.02/1.90)

My RPM band is idle to 6500, and I want low end torque for street fun and off roading. I'm thinking of switching to AFR from everything I've been reading...essentially the Edelbrock heads are not big enough for the potential of a stroker.

My questions is, if I want a 500HP motor and low end torque, what size AFR's do I go with? 195's, 205's, 58cc, 72cc?

I know the piston height will play a role in the compression ratio,and according to the CR calculator, if I use a piston deck clearance (.016), 72cc chamber, & 5cc valve relief, I get a 10.6:1 compression ratio - perfect right? But will that small of a valve relief limit my cam lift options and lower HP?

Thanks
 
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