68 RR, 383, auto, 160k miles, no rebuild, recently had sure grip, 3.73, and XE268 cam put in, MSD, TTI headers and exhaust. No head work, no intake work.

Auto on the column and when I do it manually, it shifts very strong from 1st to 2nd (to the point where the rear end gets a but swirly), but from a standstill if I floor it it won't break the tires loose. Why the hell not? Any thoughts?

My friend has a 68 383 runner and has to powerbrake in order to spin the tires. My 440 however, no problem.

advance the timing

So other 383's are like that- interesting. That worries me for when I get to the drag strip at some point. If I can't even light the tires up, it seems I'll have a horrible 1/4 mile time.

Advance the timing huh? I'll look into it. Thanks.

Spinning ain't winning. What kind of times are you ecpecting to run?

160K with no engine and head work? i would guess after the bigger cam your very low on cranking psi.

Not spinning is not much to go on here.

It may be an ignition timing or carb set up away from making you very happy.

I do remember my 70 Road Runner not being able to do much flat stab tire spinning but in stock form but with a few minor bolt ons like headers and a Holley and 3.54's. It would cut a 1.9 60'

I have a 383 roadrunner also. 4.10s auto.
906 heads,performer rpm,purple shaft,msd,header etc. Im pretty dissapointed also. i have 18.5 inital and 36 total timing. it will break the tire loose but barely. I think the 383's are just dogs unless you got some compression in it

Make sure you're at 34-36* total timing with the vacuum advance hose off.

Make sure the mechanical advance (weights) aren't sticking and keeping the timing from advancing.

Install Mr. Gasket #925B lightweight springs in the distributor to get the advance to come in quicker.

It's never going to be a monster but the little tuning tweaks will help...

What STALL is the converter? If it is an 12 inch unit from a New Yorker or another big car, the cam needs much more stall. The stock stall speed for a 383 Road Runner was supposed to be around 2350-2500. Those Big C body car low stall converters were about 1600-1800. Going to a cam that much larger than stock means a matched converter is needed.
The fat cam starts making real power from 3000 rpms on. If the converter stalls too low, the low rpm performance will be soggy, much like releasing the clutch in a 4 speed car at 1600 rpms and stabbing the throttle.

That sucks. What about all the talk of these cars having lots of torque? I understand that spinnin aint winnin, but come on. I'd expect with such high mileage and no rebuild to run 15's or 16's. After I do get a rebuild, the heads and intake, etc done, to get 13's.

I'm not sure what crank psi is. And if compression has to get up, I assume that's when the headwork should take care of that with the proper setup.

15s are realistic. You'd have to do a serious build to get into the 13s. In order to get much compression you will need to change pistons because the stock 2bbl pistons are dished. Right now you are somewhere between 7.5 and 8.5 to one.

I have to assume the stall is stock. Got the car 5 years ago so who knows. If it is stock and it is 2250 to 2500, then is the XE268 too big until I get a bigger stall???

So it looks pretty agreed upon that the timing has to be dialed in correctly. Thanks everyone.

Don't know, but back in 84 i had a 70 Sport satty with the 383 Commando, it was all bone stock & would light the fire out of the tires , had really good torque too, I eventually installed some 4.11s out of a charger, the car was a screamer, maybe leaving it stock would be better

You may have several issues; timing,carb etc. Even with everything tuned properly,383s just don't have a lot of low end power. It's a small displacement, short stroke, big bore, big block. It has a shorter stroke than a 350 chevy and a bore size the same as a 454. It likes to rev. Pistons are heavy though. Don't be afraid to put some stall in it. A swap from a stock converter that flashed to about 1700 rpm to a MP converter that flashed to 2800 was a big improvement in my XE268 equipped 400 RR. Would have put more converter in it but the MP unit was cheap( about $175 at the time) and this car is my economy car

Up until three years ago my Coronet with a 383 out of a '71 Newport would only spin the tires from a stop for about 5 feet, at best. Today, from a stop not power breaking, slamming the throttle to the floor from a stop, the 275/50/15's spin 40 or so feet in first and spins them slightly hitting 2nd.

1965 Coronet weighs 3,700 with me in it.

383ci, 15 degrees initial, 40 degrees total all in by 2,500 RPM's, XE262H Comp Cam, Performer RPM, 750 (3310) Holley, Tri-Y headers, stock "blended" heads w/3 angle valve job, MSD ignition, clutch fan, 2.5" exhaust with y-pipe, 727 auto, 12" torque converter that stalls around 2,200, 3.73 rear gears, 275/60/15 rear tires.

What got me there? Tune, tune, tune, tune, tune...and tune some more.

BTW, I shift at 5,700.

That's a fact Jack.

My old 4 door valiant 323" 4 speed beater, with streetmaster 318 single plane, 600 holley, 3.31 gears, factory HEI, and 4.30/.444" lift 340hp cam, had no problem. With 225/60/15's smokey burnouts are not the problem, but tire prices. There is something to be said for factory performance. In top form it did high 14'80's.



Keep at it. A 383 has the size for good power. All it takes is a little money. You will eventually learn the relationship between fuel and timing, and how it all works. Not rocket science for Sams' sake.