Thread: Fords are expensive!!!!

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Originally Posted by josh bichard

Thanks for taking the time to get those figures for me tech. And trust me, this is one subject I dont mind spending money on. I got a couple questions for ya though.
1. Are those the performer rpm heads?
2.Are those out of the box figures?(no port matching or bowl work)
3. What kind of loss of power could i expect by using my 429 crank?
4. With a tko 5 speed, what rear gear would you run?
I am not set in concrete about that tranny, but am considering it.
Thanks for you time sir.

1. Performer RPM 460 CJ #61649 is what I had in the DynoSim. They are 75cc chambers, 310cc intake runners. The other heads Edelbrock shows are the Performer RPM 460 heads with 292cc intake runners and are available with either 75cc (#60679) or 95cc (#60669) chambers. Strangely, the published flow numbers are the exact same for all 3 of these heads, so I feel better about using 0.90 to factor the heads I used for the DynoSim pull. It's hard for me to understand how a 310cc runner and a 292cc runner can flow the exact same numbers. I guess it's possible, but it doesn't seem plausible.

In retrospect, I might be more inclined to use the 60669 heads with a flat-top piston such as this...
http://kb-silvolite.com/performance.php?action=comp
With a 95cc chamber, 9.89:1 static compression ratio would be achieved.
After reading more detail, I think the RPM or Stealth intake would match up better with the head ports of the 60669 or 60689 heads. I might even order the 60689 bare heads and install my own valves and the Comp springs that work with the roller cam. I'm not sure the springs that are installed on the 60669 heads would work with the lift of the roller cam. All this would take some digging on your part to make sure everything is compatible before laying down the green, but I'm passing on the information that's available to me in good faith.

2. Those figures I posted are the published figures factored by 0.90 with no work done to them. Straight out of the box, factored.

3. Plugging in the 3.59" stroke and changing to a shorter cam to work better with the tall 5th gear of the 5-speed, I get the following results.....
This is with 9.89:1 SCR using flat-top pistons with one valve relief along with the 95cc chambers.
I used this cam advanced 2 degrees. It has a more reasonable power range of 2200 to 6200 to, like I said, work better with the tall 5th gear of the manual transmission.
http://www.compcams.com/Cam_Specs/Ca...csid=1025&sb=0
RPM HP TQ
2000 187 491
2500 237 497
3000 301 526
3500 372 558
4000 434 570
4500 485 566
5000 522 548
5500 530 505
6000 489 428
Peak volumetric efficiency 96.8% @4500
Peak BMEP 197.5 @4000
The problem will be finding affordable pistons. They're readily available for the 3.85" stroke, but not so much so with the 3.59" stroke. Of course, if money is abundant, anyone can make a set designed any way you want them.

4. I would counsel closely with the cam manufacturer on this, but with the shorter cam, you might use something like a 3.55:1. You don't want to go too deep because of the short 1st gear, but you also don't want to use a gear that is so tall that you will lug the motor in 5th. This is a real juggling act and should be discussed with the transmission supplier and the cam supplier. There is a 0.83:1 5th gear available in the TCET4615 trans if you haven't bought the trans yet. That might be more desireable than the 0.68:1 5th gear ratio. 2200 rpm's (low limit of the cam) with a 28" tire and 3.55 gear would give you a 11.6:1 1st gear ratio and a 2.94:1 5th gear ratio for cruising at 62 mph. 2300 would cruise at 65, 2400 would cruise at 68 and so forth.

5. The DynoSim makes no distinction between the style or construction of the rockers, only the ratio. I used 1.73:1 for both pulls.