Last Friday night I made it out to the track to see how the new combo would run. Here's an overview of the old combo and new.

Old-
TFS heads ported-Peak flow 281@.500 Cam=solid roller .645 266@50 108lsa 106icl-single pattern

New-
Dart Pro-1 215's ported-Peak flow 309@.700 (down about 15cfm in the mid flow from .300 to .450 compared to the tfs heads) Cam=solid roller .689/.673 273/281@50 107lsa 104icl.

Old combo best was 10.58@125 with a 1.46 60' run in January in -300ft DA.

Friday the new combo went 10.58@127 with a 1.51 60' in +2300ft DA with what I'm hoping was poor track prep. The car never really hooked well and 60's ranged from mid 1.8's down to the 1.51 with tire spin on all passes.

Today I put the car on the chassis dyno(Mustang brand dyno). I left the tune-up the same as the best pass from last Friday. The only change was to relash the valves. Previously I lashed them at 20/22 cold but today I lashed them hot and found all of them to be 26/28 hot. So I tightened them up before dyno time to 22/24 hot (per cam card).

The first pull netted 443hp@6700 and 397ft-lbs@5600. This was with 38dg timing and 74/82 jets. The a/f ratio during this run was in the 11.5 to 11.7 range so we decided to lean it out a bit. After a few jet changes and timing adjustments the best run netted 459hp@6850 and 403ftlbs@5700. Timing ended up at 42dg and jets were 71/79.

I'm hoping once the traction issues are worked out the car will run some mid-low 10.40's@128 in the heat and 20's@130 in cold air.

Also, I think a converter tweak may be in order once I've got a better hold on traction issues. The old combo made peak torque in the 4700-4900 range and this combo is a solid 600rpm higher. The converter still flashes to the same 5200 as it did before but I'm thinking the car would like something closer to 56-5800 now.

Wow. 130mph. That would be pretty damn awesome for the "mighty mouse" motor! Colder air is just around the corner. :cool:

Sorry for not knowing, but what is the car and its race weight?

Woops, sorry Mike, its a 67 Chevelle. Race weight with my 250 on board and a full cell is 3520.

Nice! thats one fast ride!

42* timing? yikes!!!! am i readng this right? in a 12.5-1 motor. John, when you head back to the track call me. i want to be there again. i plan to go back myself in bout 2 weeks. Dave

John,

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It looks like you are in for some LOW 10's this winter with optimal tuning and some good conditions. Finding 16 RWHP isn't too shabby either. You've got a 10.48 in it in 60' alone, not to mention the added power from tuning.

Any idea on what is causing the tirespin other than poor or hot/greasy track conditions?

Which carb are you running? Maybe more left there? Higher vacuum = less jet.

Where were you shifting on the passes last week? 7200? What does the HP curve look like after peak HP?

John,

Could you see the TQ curve rise from 5200 (stall) to peak TQ at 5700 or does the curve just drop from peak?

What RPM were you crossing the stripe?

Brian, thanks. I've been following your progress and I have to say I'm impressed with your initial results and workmanship on your ride. Very nice!

Dave, as per our conversation today it looks like the first Friday in August will be my next track trip. After that I think I'm gonna take it easy and fix some of the "issues" I was dicussing until some better conditions roll around.

Jason, I think alot of the tirespin is due to track conditions. I've been riding the coat tails of a well prepped track in the past (since I usually don't run in the heat) and now my suspension short comings are popping up. I'm definitely in need of some tweaks. I'm still running the 750 BG and yes I think you're right about the vacumn/jet deal. After studying the charts a little more I can see that the converter is actually flashing to 5350. On the best peak hp run the torque was 393@5361 and climbed up to 403@5774 and stayed above 393 until 6000rpm. The hp is actually what I would call peakless. It jumped up to 459@6870rpm but it was making 445@5832 and that pass was shut down at 7000. I did make a pass to 7100 but hp did'nt fall off by more that a few hp from the 6800pk. Basically the hp curve is flat (within 15 of pk) from 5800 to 7100.

Last week I was trying to shift by 7200. I set the shift light at 6600 for the 1-2 and shifted at 7200 for the 2-3. I did hit the rev limiter (7500) on the 1-2 a couple of times on the 1-2 before I started to get a feel for it again. My tach was reading 7000 at the stripe but according to the chassis dyno my tach reads 200rpm high so I guess I'm crossing around 6800.

thanks John, good luck with your next outings, if the weather around here clears up i'll be making a few more passes this weekend.

Any dyno numbers with the old Heads?

Mark, I never chassis dyno'd the old combo. I did dyno the motor though (twice). The 1st trip it made 603hp@6200 and 583tq@4800 and the 2nd trip it went 585hp@6000 and 575tq@4700. After the 2nd trip I found the lash to be a bit loose and it was also run in April as opposed to January for the 1st trip and that's what I attributed the cause for the drop in power.

John,

After some more figuring, I'm going out on a limb and going to say that with a 0' DA or less, optimal traction, and bigger carb optimally tuned, you should see around a 10.12 @ ~132. Slightly quicker with a converter tweak.

Now for all of the stars to alighn appropriately for it to happen. graemlins/thumbsup.gif

Hey John, are you using a GM production 400 block for your stroker?

What brand crank and rods are you using?

To say the least I am very impressed with the times your knocking down with a 3500lbs car and SBC.

Those are good numbers. The Mustang dyno give lower numbers than the Dynojets that most shops use. On a Dynojet you'd see 470-490 rwhp.

One thing though: You will always end up with too much timing when you tune on the dyno. I'm sure some gurus on the forum can give you the scientific reasons for this (something about how the motor accelerates on the rollers and less load than on the track), but suffice to say you should drop the timing 2-4 degrees on the track compared to the dyno.

You will also often find that dyno jetting is a little lean on the track and you may well be faster by going up 1-2 jet sizes.

/Markus

Cable, this is a GM production block (2 bolt) thats been fitted with an Oliver splayed cap kit. The shaft and rods are Eagle. I've been chasing some "issues" with my set-up and I believe I've got them identified and should be fixed by week's end. Possibly some track time this coming weekend.
Just for reference, for the parts that are in the motor, my car is about 2 tenths off the mark. Hopefully fixing my issues this week will rectify that.

The Eagle set-up is "ok" but if you can afford American stuff I'd encourage you to buy it. You can get COLA s now for around 600 bucks and Lunati Pro-Mod rods or Crower Sportsmans very reasonalby priced as well. I have a new 18dg standard deck 427 with all American stuff going in it. The 422 will be freshened and kept as a spare for now. All of my Eagle parts were machined within spec but from what I've read of other accounts, I got lucky. Feel free to email me for further info if you need it.

Zwede, your comments could not be more correct! After returning to the track with the "dyno" tune the car slowed down. I progressively returned it to my previous "track" tune and the car picked back up to where it was.

So much for chassis dyno tuning ehh?

What gear and tire size are you running?

I ask because of your trap RPM.

I have 3.69 gears and 26/10.5/15 slicks. I am worried I will be well around 7000 RPM going through the traps too.

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ROCK-N-ROLL Mr. Wilson! Can't wait to see where the ETs settle in!