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460 big vs. small cc head chambers=? piston...
August 21 2001 at 4:19 PM
No score for this post 67F100 (no login)
from IP address 209.162.57.91

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Some one posted a test result a while back on heads. The Edel heads, without porting, did a stand up job against everyone else's heads. I think I'm going to creak open the purse, and pay the $1,700 for the Edel heads, and be done with it. I have a question for everyone though. Which cc heads do you use...72 or 95? The test results said they didn't know which castings where used. I'm putting a 460 in my old 67' F100 for the street, and so far, playing with Desktop dyno, I have an engine that's putting out about 550 to 574 hp. Is this realistic? On page 25 of the new Summit catalog, 'Speed Pro' pistons have a listing for a TRW-L2443NF30. It shows 10.43 comp. with a 92 cc head, and 9.98 with a 97 cc head. If I used the 95 cc Edel, I should have about what I'm shooting for...10.20 comp. Can someone steer me in the right direction concerning the cc's on the heads please? Thanks in advance...

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67F100
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209.162.57.101 Revised hp figures...
No score for this post August 21 2001, 5:11 PM

I took another look in Desktop Dyno, and I must have taken one too many codeine that night! Here are the revised figures I come up with for my engine combination:

1) 460 +.030
Edelbrock Aluminum heads (used the flow figures)
Crane Hydraulic Roller cam 354561 .556/.563 lift 296/300 Duration - 110 deg.LC.
10.20 Comp.
Large tube headers with mufflers
870 Holly Avenger Carb.
Dual plane manifold
=514 hp 491 ft.lbs torq. @ 5500 rpm

2) 460 +.030
Edelbrock Aluminum heads (used the flow figures)
Crane Hydraulic Roller cam 359351 .590/.614 lift 290/300 Duration - 114 deg.LC
10.20 Comp.
Large tube headers with mufflers
Dual plane manifold
870 Holly Avenger Carb.
=527 hp 503 ft.lbs torq. @ 5500 rpm
* Retarded the cam 2 degree's
=530 hp 463 ft.lbs torq. @ 6000 rpm

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Bob M
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63.26.4.185 Those combos sound great...
No score for this post August 22 2001, 8:49 PM

And I'd say that the H.P. numbers are close...Maybe even conservative.

suggestions on compression below

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Bob M
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63.26.4.185 Pistons...chambers...
No score for this post August 22 2001, 9:00 PM

I agree that it would be better to use the small chamber heads, but you will have to use a dished piston to get the compression down.
If my memory serves me...A 460 with a flat-top piston at 0 deck clearance will have around 12:1 compression with the small chamber head. A 429 has about 11.5:1 set up similarly.
And always run as close to 0 deck as possible for effeciency of combustion.
Here's a good site with calculators to help.
http://www.brcpistons.com/calculations.html

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Bob M
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63.26.4.185 Also...
No score for this post August 22 2001, 9:03 PM

When running a dish piston... It's better if the dish matches the shape of the chamber as closely as possible.



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RJP
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198.81.16.51 Pistons/ Chambers
No score for this post August 22 2001, 1:02 AM

Better to run small chambers and flat top pistons that big chambers and domed pistons, less prone to detonation. While your at it square and zero the deck.

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Walt Barnes
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206.160.223.168 flat tops
No score for this post August 22 2001, 5:45 AM

I agree with the smaller chamber heads and flat top pistons. I'm running the CJ 11:1 compression and get away with it on the street with pump gas and 37 degrees total advance. With aluminum heads you'll be able to do 10.5:1 for sure.

Are you HP figures with ported or unported heads numbers? I'd love to see the differences?

Thanks,
Walt

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67F100
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216.224.155.224 Horsepower figures are for...
No score for this post August 22 2001, 11:01 AM

the Edelbrock heads stock, out of the box. The Edelbrock catalog gives the flow figures for different valve lifts for each engine it makes the heads for. The figures given in the head test post I refered to, are pretty close to stock figures. Thanks for the advice.

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67F100
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216.224.149.222 Yup, you're right!...for the classic reason...
No score for this post August 22 2001, 11:14 AM

domes shroud the combustion chamber, slowing the ignition, and produce less efficient combustion. I'll take your advice RJP. Do you have a recomendation for a flat top piston to use with the smaller Edelbrock 72 cc chambers, to get 10.20 to 10.50 comp? I want to do this without going to a custom piston, and the higher cost?

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RJP
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198.81.17.33 Pistons and things
No score for this post August 23 2001, 12:13 AM

For a piston that is priced right is the TRW L2404F with a 19cc cup, gives a compresson ratio of 9.67 with a 72cc chamber. If you have the block squared and zero decked then you will have a comp. ratio of almost 10 to 1. If that isn't enough for you then you might look at a set of JE pistons with a reverse dome [dish shaped to the combustion chamber] but they will be more money but you can spec. the rev/dome voluume. The TRW L2443F domed pistons can be cut flat but you will have a bit too much comp. almost 12 to 1 with a zeroed deck. If you have a later block with a 10.310" or a 10.320" deck then the flat top pistons look better for your targeted comp. ratio. Hope this helps.
 
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