Ford Mustang Forum - View Single Post - Can You Racers Help Me Diagnose My Disappointing Track Results?
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post #7 of (permalink) Old 09-16-2014 Thread Starter
67Merk's Avatar
Joined: Sep 2014
Location: Midwest USA
Posts: 8
hi guys. sorry, been away. thanks for the feedback & input.

I have a T-5 trans (5-sp), hardened, in the car, all the usual upgrades, and a MGW short throw shifter. The rear tires are actually 26.5", 255/60R15's.

I know the 60' is horrid, which is surprising, given the fact I have full Cal-tracs, split mono leaf's and 9-way adjustable shocks, but I also know I have a lot of dialing-in to do there. I have done some adjustments and so far, without radical changes I'm dancing all over that 2-second mark. With street tires it was much worse, so there has been some improvement.

I launch the car from idle and try to step into it - if I don't it's sit and spin and the 60' will be 2.20 plus.

I did not lower the tire pressure below 26 lbs because I have not yet got the sub-frame connectors in. I have them, pre-fabbed sitting in the garage, just recovering from (another) back operation and can't do much under the car w/o the wife ripping on me. Hope to get them in soon so I can make another go at the track before the season ends.

I also have a rear stabilizer bar to put on the car to hopefully help tie it all together. I am of the opinion that with the horrid 60' and chassis flex I am losing maybe .6-.8 of a second - sound fair? With that assumption it's fair to call this a mid-12 car - does that sound right given the parts n pieces put into it?

I was just shocked initially, it feels a lot faster and I though it would do better, but I suspect the chassis is costing me a lot at this point, driver mod needs work (though I power shift well) and the Cal_tracs aren't giving me enough of a hit on those rear tires.

Timing is ~11deg initial, 34 total and is all in at 3500. Running a .35 plug gap with the plugs recommended by AFR for the heads.

Carb is a 650 thunder, per edelbrock's recommendations, running 6 psi fuel pressure and the fuel pump is a electric Jegs unit, #15913, 95 gph free flow. Running a Holly fuel pressure regulator. There isn't a hesitation in the car at all. You can floor it from idle and it opens right up. I do have a 750 on the shelf which I ran briefly - the car loved it but the wallet didnt. Didn't have any issues with bogging/hesitation with it but the driver has a heavy foot The 650 was on the car for the track day.

Correction - the rear gear IS a 4.11. Quick performance 9" trac-loc posi unit. Yea, there is very little first gear I'm not sure what the rpms are when I trap, around 56-5700. I trap well into 4th gear, probably hitting 4th right around the 1000' mark.

I have not been able to get to a chassis dyno yet. It's 90 miles one-way and dude seems to be busy when I'm not so far. That is a priority as I'm basically guessing on my carb setup and best shift point.

Again, thanks for your input guys. I really am just a shade tree, this is the most I have put into a build. While I read a lot I learn the most by listening to others that have the knowledge and experience - I appreciate it!

Last edited by 67Merk; 09-16-2014 at 12:50 PM. Reason: added shifter info
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