Threw a pair of slicks on my car for today's trip to the Dragstrip. The all cast iron 350 went 12.89@102 with a 1.79 60ft. I tried a couple things to either prove positive or negative gain. I tried flipping the air breather lid, which proved to be zero gain, nor loss. It may work on bigger cubic inch cars, or maybe a car with a restrictive air breather, but on this car, was worth nothing. Tried launching the car off idle, to flash converter, which slowed it down, just didn't like it. Lastly, plugged the PCV port on the carb. The car had gone a 12.94,95,96 prior to the PCV plugging. It immediately produced a 12.89@102 which was both best E.T. and MPH of the day. Last pass car spun and had some heat soak, worst 60 ft of the day, a 1.82 but still went 12.97
I should probably say on the flipping of the breather lid comparison, I run a 3 1/2 inch high flow WIX filter that has the lid raised 1/2 inch off the breather housing. As far as my build, it's a .030 over balanced 350 with 11.66 measured compression ratio, no porting or port matching, mild cam adjustable pushrods, stock GM valves, blocked heat crossover, Qjet by Ken at Everyday Performance,TH350 trans with 2200 converter, 4.10 gear. No magic, it just works together pretty well.
Impressive. With 11.66 SCR, even with a mild cam (like the TA212), the DCR would be well into Race Gas territory.?
Very impressive! Could I ask what size slicks you're running and shift points, trap rpms? 4.10 gears would kill my highway driving, but sounds like they are a lot more fun than my 3.23 gears! You must be almost at the point of a little air under the front tires at launch!
Larry, yes, race gas only 22initial,33 total dist curve. Ken, 14" slicks 26.5x8 5400rpm shift points, about same through the traps. Daylight under the left front every pass yesterday, on a well prepped track it has seen daylight on the redlines as well. If you're running mid 13's on pump gas with 3.23's, I wouldn't touch a thing. That is a strong running, street friendly car. Mine is purpose built, and I'm handcuffed to the local airport for aviation fuel/race gas.
Nice car and engine bay too! That's some big compression there with iron heads for sure!! Your street drive it much or mostly track with those 4.10 gears?
What Tom is not telling you is how beautiful this car is in person.... a maybe 20k mile gramma car, done with incredible eye for detail. His approach is so simple - compression, gear and converter - it had really made me rethink my own strategies..
We must have better air here in Michigan is why our cars run so good!? Although I prefer to use pump gas to go fast, you really can't deny the results of what huge dynamic compression can do(kind of like using N0S without having to use N0S), nice job Tom. What track is that in the picture? If its an eastside track I wouldn't mine seeing a sbb 350 run in the 12s sometime! Derek
My old 350 (built mid 90's) ran very low 13's with a 4-sp., 3.73's (very streetable - drove it 600 mi. to the Nationals w/245/60R15's) 10.5 SCR (measured) Hooker Headers, 2-1/2" exhaust, ported heads, T/A intake (no port matching) KB 113 cam (IIRC - been a while), '73 rods, balanced. I never really even got it dialed in - 60' times were awful but the with the MPH I'm assuming it had high 12's in it. Like Tom's it just seemed to all work well together. We didn't have much info. back then to work off of.
Same thing I was thinking. I'm thinking the gear contributes the most to the combo. The convertor is mild, BUT it matches the cam's characteristics. That static comp ratio has me WOWED! Good for Tom for stuffing compression into it, and A LOT of it What made you try plugging the PCV? Never heard of that, but it sure made a difference! I'm thinking it richened up the fuel mixture a tad by doing so You really don't rev the snot outta it, which I like, even with the 4.10's
Plugging the PCV was suggested by Rob Ross. With the PCV hooked up, you basically have a fluctuating vacuum leak that is introducing polluted crankcase air right into the air/fuel mixture.
Nice run Tom you are rocking now. I use the one way check valve at the header and run a hose on each side to the valve cover with a push in breather and have a filter at the back of the valve cover on each side, I never run the PVC. The pvc will dilute the gas mix some. You do need something to pull the air out of the crankcase if you run with out the pvc. I chose to run the hose into the header.
