Okay, I've seen some of you get really close when predicting Hi Perf combos, now lets put the skills to a test with a Lo Perf combo. I'm going to run the quarter mile for my very first time tomorrow (God willing everything goes okay).

I'll post my complete combo and my previous 1/8 mile times.

Combo

355

882's-stock
252/260 206/212 .425/.440 112LSA 108ICL
8.3:1 CR
Hooker Comps (very dented collector bottoms)
Dual 2.5 pipes, no crossover.
Flowmasters
2.5 Tails to rear bumper
GM Aluminum Q-jet manifold
Holley 600cfm 4160 vac sec
1in thick open carb adapter.
KN airfilter (14x3)
GM HEI (099 module)
Accel Coil/8.8wires
Stock springs/weights
Mobil 1 10w30
(water temp=190, oil press=30idle, 40+ running)

Stock TH350/2.73open

Full steel body, full enterior minus sound system, half the AC equipment, plastic inner fenders, disc brakes.

14x7 Rallys up front. wrapped in 245/60/14s (36psi, 1psi above spec)

Corvette 15 Rallys back, 275/60/15 (35psi, spec)

1/4 tank of gas or so. Spare front tire in trunk.

This is how it ran the 1/8. best time was 10.17@69.5 MPH.
Best MPH was 70.23MPH.

Changes

Rear tires are now 255/60/15s (1 inch shorter) mounted on Aluminium GM IROC-Z wheels.

I put a "hi-flow" t-stat just to see if its beneficial during street driving.

I will be moving the total timing from 36 to 40 in 2 degree steps. My best ET came with 36 total while my best MPH came with 40 Total.

Alright guys, predict away.

14.30

15.30-15.50

I have no business making an educated guess, but I love contests:

ET: 15.63 @ 87MPH

:D

15.09 @ 88 MPH

15.85 to 16.20 depending on the weather

15.1x @ 91 mph

16.3 @ 86

15.8 at 87

14.80 @ 92

15.60 / 88

15.55 @ 89mph.

Here's a tip for you. Try manually shifting it and keeping it in sencond through the lights.

David
70 Malibu

Let's see, your previous 10.17 e.t. would be ~ 15.97 e.t. for 1/4 mile, and your 69/70 1/8 mph would have been ~ 87.5 mph in the 1/4 mile.

Did you weigh the new rear wheel/tire combo vs the old? The 1" reduction in tire diameter will change effective gear ratio ~ 3.5%. The skinnier tire will also have less rolling resistance. Probably lighter wheel/tire too, which could help reduce 60' times.

If, and only IF, you can leverage that into quicker 60' times, then you may see a tenth or two reduction in 1/4 mile e.t. It could just as easily run exactly the same as before - not enough power there, and it is already handicapped by a lack of complementary hardware like better gear ratio, no posi, torque converter etc.

Have some fun, and I hope you prove me wrong.

Thomas

Thanks guys.

**Last minute change**

225/60/15 tires up front mounted on Alum IROC-z wheels

adjust your predictions accordingly.

I'm going to stick with my prediction - unless you have some other last minute changes planned.

When you do post back with your results (from Fontana?) please be sure to post all the details from your time slips, incrementals and all.

Thomas

Oops.. missed the previous 1/8th time. 15.50 @ 86-87 may be more like it, although we had a bone stock '69 Chevelle 255hp 350 (stock manifolds, 2" dual exhaust) w/ 2.56's running 15.9x @ 89 mph a few years ago. I would think there may be a bit more in your combo.

I'll post incrementals tomorrow.

16.79@80MPH was my best.

I think there was more left in the car as my first run (16.9) i didnt have full throttle (fulled my double-springs throttle return. And the second run I shifted just over 4000RPM because my car was close to overheating in the stagine lanes (went from 210F to 235F when i shut her down in the staging lanes to wait for the track to clear) and I didnt want to red-line it and blow a gasket/crack a head.

I won't be returning to the 1/4 track until i better my 1/8 times. But i will not be racing at all until I make some upgrades to the car.

1. Electric Fan so I can cool the car while the engine is shut down.
2. 3 or 4 row radiator (still using the stock 2 row or 2 core or whatever it was that came on 307 cars).
3. Check water pump and replace if needed (still the stock GM unit that came with the car.
4. Add a trans cooler.
5. Add Edelbrock RPM (yeah i know, the Performer might be better but I'm thinking ahead to furture engine builds)

Should I run an Eng Oil cooler also?

Enrique, I've always considered it a good day at the track when I can drive up, make passes, then drive away at the end.

You have nothing but potential, and Team Chevelle will help you get there.

All of those cooling system upgrades are nice, but there are some funamental tests that you should do first. You 307 is so mild that your symptoms of overheating mean that something is definately wrong.

Go to your neighborhood radiator or car repair shop, and ask that your cooling system be checked for combustion gasses. This is a super simple test whereby they bring your car up to operating temperature and then put a test guage over the radiator filler neck and draw an air sample to see if it changes color in the test fluid. I actually have to take the heads off my 496 (today?) because it was getting combustion gasses into the cooling system. In my case it will probably be a head gasket issue or possibly a warped head - I did overheat the car twice at the drags. One time my water pump broke off, another time my belt went away halfway down the track.

A 307 usually has no special cooling system needs, even for drag racing. Your planned list of mods are a fine start, but get your cooling system professionally checked - especially for combustion gasses in the cooling system. Remember that not always does a gasket or sealing issue mena that your water level will be going down - but you could be on the verge of that happening.

Thomas

Well the car no longer has a 307, it has a stock rebuild 355 that I listed on the firt post on this thread.

The car usually runs okay, it won't usually get over 200F and most of the year I drive it daily and it doesn't get over 190F. I think the problem may have been from letting the car idle at about 1000RPM in the staging lanes. As you know, at Fontana there are waaaay too many cars on Street Legal Night. I ended up letting the car Idle for about 20 minutes before I noticed that nobody was running. Two car broke down on the track and they were cleaning up. By this time the car was at 210 running and I shut it down and it spiked to 230F. From then i would only start it to move foward and shut it down quickly. By the time I go to the starting line i was at 190, I ran the quarter mile and at the end i was at around 185F.

I'll make another post with all my timeslips so far (1/8th and 1/4th)