I apologies if this isn't the correct spot for this.
I just got a 79 l82 vette and it doesn't have much takeoff power . I've never had a corvette so maybe I expect more out of it than I should but it seems to run fine it has edelbrock carb and intake long tube headers and a 700r4 trans witch I think might be my problem it does have a slip in 3rd but I'm not sure if that would effect the takeoff. Do y'all have any input on this ?

Thanks Dan.

 

Try bumping the timing up. Turn the distributor counter clockwise about 1/8 of an inch.

 

Hello Dan,
The slipping in 3rd shouldn't really effect take off. Unless I'm wrong someone will correct me. Might be timing or tuning like stated. Or possibly something else?

I also have a 79, but mine had a L48. The power difference is around 30hp in the L82's favor. (L48 = 195hp , L82 = 230hp). Mine when I first got it probably had around 230hp because it was straight piped with few extra mods including 3.23 gears.

The thing is about these later year C3's, is that they were dogs. With all the smog emission stuff and other detuning they've done, that's why they have such low hp. Not to mention these cars are heavier than you would think. With that said, it isn't surprising that you find the take off to be not what you expected. Because I went through the same thing when I bought it when I was 18 (3 years ago) . But, that makes them great cars to mod to hell IMO. Plenty of guys on here with crazy drag cars or even road racing cars. They will guide you to the hp amount you seek.

Btw, not sure you know or not. But the rear end in our cars is NOT strong. Many stories of half shafts snapping due to too much hp. I highly recommend looking over the rear end and so on to make sure no flaws. The guys here can point you in the right direction for such a task. Your car with the mods you stated I'd think you'd be around the 260hp range. So the rear end should be just fine for that. It's just when you reach above 300hp or slicks for that matter that I'd be more concerned. I'm sure people have ran their stock IRS's with higher HP c3's. But just be cautious is all I'm saying. But there are people on this forum that know much more than me. They should pitch in.

Best of luck Dan,

Blake

 

Hey Dan,

Since this is a new car to you start with the basics and check spark plug wires, plugs, timing, clean fuel (these cars sit), exhaust clear and not clogged, if you have the Qjet carb have it and the distributor overhauled by someone like "Lars" who really knows how to set them up.

This will improve not only power but throttle response and will make the car more fun to drive. This car doesn't put out a lot so it will need to be hypertuned. After this is done you will know what you have and what direction to go with power upgrades if needed.

Don't underestimate what a quality tuneup will ad to this Vette. Also make sure the engine has the right parts such as distributor for you application.

Kevin

 

Why not tune it and begin from there?

 

Yep, start from the basics just so you know it's all correct.

 

You stated it has a 700r4 transmissoin. That is not stock and operates with a TV cable that mounts to your carb. Take it somewhere for them to test pressure and properly adjust your TV cable as necessary. An improperly adjusted TV cable can lead to transmission problems. Torqure converter stall speed could be causing your issues too. Perhaps a 3000 stall converter was installed during the transmission swap and your engine is stock. If you are looking for instant response from the throttle you need a lower stall converter. Just a few other things to check out.

 

Thanks for all the imput its really appreciated. The timing is at 12° I'm thinking the engine isn't original to the car it's definitely been out and all the smog/ac has been removed .another thing if you just punch it from a dead stop it'll die not sure what's up with that either.this is the first chevy I've owned and probably 2nd carburetor vehicle I've had so it's all pretty new to me

 

I found a good th350 so I plan to put that back in it.

 

I'd keep the 700R4. if it is stalling when you drop the pedal, you may have ignition and/or carb issues. Get the carb refreshed and both it and distributor/coil/wires/plugs tuned to the rest of your combo.

The 700R4 has a DEEP first gear and really helps with quick launches. I run a conservative 2000rpm stall converter in mine (it is practically the same stall as the TH350 but with the 700's 1st gear, it really launches). today, I roast the tires from a dead stop through the 1-2 shift. Doesn't say much for how (non) sticky my tires are but it sure has more oats than it started with in 1980. I also had my Dana 44 blueprinted and rebuilt by a good shop in FL when the 3.54 Spicers were added (same time as the 700R4, shortened drive shaft, and Van Steel rebuilt half shafts).

With all my mods and upgrades, I conservatively rate it at 330hp/400tq at flywheel. Would like to visit a chassis dyno in 2014 to see what my retro-roller conversion added.

With the blueprint on my Dana 44, I am confident it will tolerate up to 450hp/450tq.

Your '79 has the cast iron 12-bolt differential. It is strong to begin with but a blueprint with better gears can't hurt also.

 

Get rid of the Edelbrock carb. those things are junk

 

Is that an Edelbrock quadrajet or is it the renamed Carter AFB carb? Both can be repaired. Have Lars or equivalent rehab it if an option. Well worth the peace of mind.

 

It's an edelbrock it says weber on the side edelbrock on the front I have another I might throw on it to see if it helps
Another thing my tach wraps out if I barely touch the pedal .

 

ok. Sounds like the repackaged Carter carb body that Edelbrock bought rights to. I've heard those are rated around 600cfm.

if the Tach acts squirelly, it could be a failing or missing tach filter. It is a small cylinder with 1-wire entering/leaving both ends mounted near the distributor on passenger side of intake manifold area. if it is missing (ie. the wire is just spliced together and no filter), that would definitely explain the wild tach performance. If it has bare wire, may just need some electric tape. Most do not fail altogether as they are packed with epoxy that protects the filter from solvents/dirt.

This thread speaks to a missing tach filter that can contribute to your erratic tach behavior (spikes). The filter eliminates noise from the tach wire. New and even some good used filters can be found on eBay and corvette parts shops online:

http://forums.corvetteforum.com/c3-g...-starting.html

Tach filters on ebay have skyrocketed in price. Must be high demand. I got mine several years ago for under $25 shipped.

On eBay:
http://www.ebay.com/itm/C3-C4-Corvette-Tach-Filter-/350988087588?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3ACorvette&hash=item51b8853124&vxp=mtr
Tach filters @ Ecklers. Better price of $30 plus S&H:
http://www.ecklerscorvette.com/corve...1975-1989.html

And, if necessary, the tach circuit board for 78-79:

http://www.ebay.com/itm/1978-1979-Corvette-Pre-Calibrated-Tachometer-Tach-Circuit-Board-/170993313204?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3ACorvette&hash=item27cffee5b4&vxp=mtr
Let us know if the filter is missing. Usually, if filter is present but failed, tach will behave as if it is 'dead'. Erratic if missing or possibly a bare wire in the filter circuit.

 

Really?


Ya....them guys at Edelbrock don't know what they're doing.....

 

I'm pretty sure his 79 had the cast iron 10-bolt differential, as did most c3's except 80-82 which had the Aluminum 10 bolt which was even weaker. Not entirely sure about 69-74, might have to research that. But I know my 79 has a 10-bolt differential. And it is one of the weakest parts on a C3, from what I read and researched.

Unless it was an option from the factory to get a 12-bolt differential? Then I stand corrected. Not trying to seem rude, just wasn't aware a 79 came with a option for a 12-bolt differential.

Blake

 

As stated above, your problem could be the transmission and/or carb. With that said fix one then try running it again. Process of Elimination.

If your car dies when you try to mash the throttle, then I would think it's either the Distributor or Carb. Definitely start with a tune and basics. And as stated above get the carb fixed, as well as new wires and plugs. Should fix the problem. Still have the problem try getting a new ignition/distributor. If that doesn't fix it, then it could be the engine (not sure what though). To the best of my knowledge I can only see something that just drops dead to be a carb or ignition problem.

As for transmission, I stuck with a built th350. I thought of getting a 700r4 because the access of more gears, but I heard they are not as strong as a th350 or th400 for that matter. They can be built to handle power, see plenty of high horsepower cars using them daily and beating the **** out of them. But IMO can't be as strong as a built th350 or th400. Idk what the gear ratios are for a 700r4, guy above says they have a tall first gear, so that would help in a lot of cases. I'd say rebuild the 700r4. If it continues to give problems then make the switch. I never used a 700r4, yet. But the 700r4 will help you get better mileage.

 

I tried a few back in the day when I didn't know anything and thought anything that said Edelbrock on it was awesome. they are junk, and they corrode really fast also. if the OPs car has been sitting for a while I would look into the carb for sure.

 

My mistake on the '79 Diff I knew it was cast iron but assumed 12-bolt. Cast iron diff can take a lot of punishment if properly blueprinted (along with the t-arm bearing assemblies and the half-shafts). Dana 44 a bit less but still stronger when blueprinted with correct parts.

 

Totally agree, if you put in good pieces it could take a lot of abuse even for being a 10-bolt. The t-arm assemblies I heard can be a pain to replace, but completely worth it imo as well as half shafts which I plan on buying some after market ones. Idk whether to go with the Iron 3.0" Half shaft or the Aluminum 3.5" Haft Shaft. Even though the aluminum is thicker still worries me that it's aluminum. Any suggestions? I apologize for leaving the current subject of this thread.

Blake