Carb woes at the drags

[Cream79L82]

Well I finally got my slightly modified L-82 out to the Thunder Valley raceway in Noble, OK to see what she would do. I was holding my breath for 13's or anything, what with the stock TH350 and the 3.36 posi rear end. I was quite saddened, however, when my baby began to cut out around 4 grand and snailed it's way to mid 17's. Which of course brings me to the question section.

The car seemed to do alright, except of course that the tach needle does little more than creep its way towards my max power band with that rear-end, until what seemed to be about 4000 rpm, when it was as if the engine suddenly shut off or someone stepped on the brakes until I let off the gas.. then the trans shifted and I could gas it again. The obvious problem arises when the tach drops nearly to two grand shifting into thrid gear, and then absolutely craaawls back up to finish the 1/4. The carb is the stock Rochester quadrajet and seems to do an excellent job around town, but I have noticed this problem before at those rpm's. Do you think this sort of problem is most likely the carb or something else? Ask me questions as need be to help pinpoint the problem. :help :help

In unrelated news I gave the ole starter a mild rebuild as the flywheel engagment had worn its teeth to some jagged nubs. I was so pleased that I could fix the no starting problem in one afternoon, I took it torquing around the neighborhood at some law defying balls out delight.

 

[sscam69]

Well don't get your hopes up on that E.T. I have a 79 L82 as well. After 4k rpm the car was just making noise and couldn't feel much pull after that. I had a 3.73 in the rear but put 3.08 for highway use. Now I want that 3.73 back in again. Why o Why did my dad put that gear in I don't know.

Are you shifting manually or are you letting it shift itself?

Frank

oh I have an M4

 

[69MyWay]

I can't remember what mods if any you have already done to the car.

It sounds to me like a very restrictive exhaust (possibley plugged Cat converter), bad timing curve on the distributor (maybe the advance curve plate is sticking etc), and overall timing issues.

The truth is, a bone stock model like yours would be lucky to do better than 15 in the 1/4 mile. A 16-17 second run would be in line if zero mods are on the car. The heads, manifolds, intake, exhaust, and overall tuning on those cars was all geared to putting out cleaner emissions, 0-40 mph performance, and that is about it.

If you don't mind, how about listing your mods if any for us one more time.

Plus, before you go too far, get a timing light that has the ability to dial the settings in to read max curve. Warm up the engine, then have somebody hold the throttle at 2K, and 3,500 rpm while dialing the degee wheel on the timing light so that the strobe flashes at ZERO on the timing mark on the engine. Then, look at the back of the timing gun to see what total degree of advance it is swinging. This will give some idea early on if you have a serious issue with your distributor. You should be up to 30 plus degrees at that point to peak the performance potential of that motor.

 

[Evolution1980]

Well I finally got my slightly modified L-82....

What's slightly modified mean? :confused

The L82 was rated at, what? 220-225HP max? And figure after 20+ years, you've lost a couple HP, but maybe made them back with your modification. Depending on what your 'mods' are, exhaust and whatnot, if you pulled even 15's you should be happy.

I'm running a ZZ4 (355hp/405lbft) with straight back exhaust. My best quarter is a 13.44 @ 106.14mph. (Look for the video sometime this week, posted by Rob.)

It's relatively hard for any of us to offer suggestions to your problem without knowing your current setup...

 

[Cream79L82]

Sorry I didn't put my setup on that last one. The guy I bought it from said it had a cam in it, and it sounds like it, but I don't know what kind of lift. It has long tube headers, no cats and dual flows. The carb is the stock q-jet with a K&N. It has stainless steel brake calipers too. I think pretty much everything else is stock as best I can tell, and I haven't opened her up yet. I talked to a good ole boy at the drags who seems to think it could be timing too. I haven't even checked that yet :eyerole.
I should get to that this week. Thanks all.