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3.08 ran 13.9....4.11s run 13.9

400hp_76

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I have hit a brick wall. I finally got my vette back from the body shop after the fire. few bugs, worked them out, went to the track ran a 13.90. pulled the tranny for a new 700r4(used) and put 4.11 gears in. 700 burned up the next day(and no it wasnt the pressure) so i put the th350 back in. ran the car and got 13.9 once ONCE. car isnt burnin the tires off the line like i think it should. something is up. i have the engine becuase before i ran a 13.9 with the 3.08s. the engine is putting out an estimated(should be) 385-395 horse. opinions. im thinkin its in the fuel or distributer. anyone have opinions. thanks T
 

Evolution1980

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Could be lots of things... If you are running that much horsepower on the TH350 tranny, you should be down in the low 13's. I have 355hp (ZZ4) and pulled a 13.5 (and I think I can squeeze a 13.4 or better with practice).

Your used 700R4 probably blew up due to too much torque. The base stock 700R4 can't really handle that much horse, according to www.700R4.com. As for your other problem of just not getting what you expect, it could be a worn torque converter, out of tune carb, timing issues, etc... there are a lot of things that can shave a few 10ths. Then there's the factors of climatic conditions at the time of the run. Was it hot and humid? Cool and dry? All sorts of things to figure out...
 

400hp_76

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I have run the car with g tec and compared the engine build up to other motors very similar if not the same, but it is, just an estimate. The hp numbers are not to the ground just to make that clear. And to the response about it could be a lot of things, its probably all of them. I know the timing is too high for sure and the car needs jetting. as for the torque converter. it is a 2400 stall tci(brand new) . could be the plugs. whatever it is i dont think its any thing major. thanks for the input.
 

400hp_76

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yes there is a place to get it dynoed, but im low on funds and i dont think there is any reason too. The only thing that i can do during an hour is move the timing, uncap the headers. There isnt much adjusting i can do with the carb. when my timing is where it is supposed to be the car bogs when i nail the gas and + it smells extremely rich. so jetting is a must.
 

Rowdy1

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Something's Wrong

You're saying you ran the same time with the same trans but once with a 3:08 & once with 4:11? You may very well have a timing adjustment needed, and some jetting, but if you didn't change anything but the rear end ratio, it doesn't add up. Are you sure you got a gear change, did you do it or have it done? What I'm saying is, there's a MAJOR difference between those two ratio's. I could understand the times not being all that different with a closer ratio change, 3:08 to 3:30 or maybe a 3:55 but not that big a change. For instance, with a 3:08, for arguments sake, 60MPH might be 2400 RPM, with a 4:11 60MPH would be like 3000 RPM. Your acceleration should be a seat slammer compared to your 3:08, not to mention your mileage going down the tubes.
 
R

RalleyRed

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Is it possible that the tranny that burnt up after one day is the cause.

It sounds to me that the first run with the 3:08's were run with the original tanny, then the 4:11's and the 700r4 were installalled
for the 2nd run.
Couldn't it have been slipping so bad that even with 4:11's the times were the same as the 3:08's
 

400hp_76

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I never ran with the 700r4....only with the th350 both times. See? thats why im so confused. I never never never even touched the motor while i did the gear swap. Rowdy hit it on the nose. with that big of a gear swap and the motor not even touched, i should be peeling my back off the seat. O and rowdy its definatly 4.11s. the rpm match up with what they are supposed to be with the swap and part #s checked out correct. so its for sure 4.11s in the car. Im spinning the tires about as much as i did with the 3.08s ???????? i should be wasting them and running low 13.0s high 12s. Ive tried fooling with the timing but it still doesnt run right. ive thought maybe it would be my vacuum secondaries but they dont open right off the line so thats not it and because i can feel when the secondaries kick in. ive checked my valves.. i just dont know
 

Rowdy1

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No Way

I did that exact same gear change in my 62, went from 3:08 to 4:11. I could smoke 1st as long as I wanted to, never hooked up. Now, the wheels catch the RPM's much faster. Don't get me wrong, I can still do awesome hole shots, but the difference is night and day. Are you running up to redline? Shifting smooth without slipping? I don't doubt what you're saying, it just doesn't make ANY sense, which, is why you asked in the first place right? Sorry man, I have to ponder this one, it just doesn't add up.
 

69MyWay

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Granted the E.T.s were almost the same, but what was the mile per hour one each run?

You seem to simply have a calamity of missmatched parts.

What is your goal (ET wise).

You may need to tear it down and start from scratch. Your cam may not be suitable for running the 4.11 rear gear, no matter how much you tune the rest of the car.

I watched a fellow over a period of weeks take an otherwise bone stock 87. He went from 3.08 rear gears to 4.09. The car was much slower in the quarter mile as a result. The L98 engine, intake, and cam did not perform well when being pushed up the rpm band. He went back to the 3.08, tweaked on the motor, and started getting faster times.

In the inverse, a lot of guys will stick a higher RPM bumpstick in the car and forget the rear gears. Therefore, the car goes slower after the cam change.

The intake manifold plays a crucial role in this balance as well. You need one that is suited to the rpm and cam combo that you intend to run. The rest of the adjustments as long as they are in the ballpark (timing,carb) should net minimal changes in overall track performance as compared to all out gear, cam, intake, and head swaps.


Give us more info. How about the 60 foot times, 1/8 mile, etc.
 

400hp_76

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350 bored fourty thousanths with 10.25 compression pistons

Dart iron eagle heads (Valve size-2.02int/1.60exh/ 200cc int. runners 72cc combustion chambers)

Lunati street master cam-285 degrees advertised duration. 235 degrees duration at .050"....507" lift on int. and exh. 108 degrees lobe seperation (rpm range 2,200-6,200rpm's)

Lunati hydraulic lifters. Proform roller rockers 1.6 ratio. Manley one piece pushrods.

Edelbrock air gap int. manifold (1,500-6,500+ rpm range)

670 Street Avenger carb with vacuum secondaries

TCI flywheel .140 thick with extra welding on the ring gear

Holley strip fuel pump 7-9 psi

TCI torque breakaway torque converter (2,200-2,400 rpm stall)

B&M transpak shift kit

Melling high volume oil pump

Griffin 19" by 31" aluminum radiator with electric fans.
thats what i ve got
 

69MyWay

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You have a high RPM combo there, so it is going to require maybe a tad more loose torque converter to really boil down the back tires from a dead stop (if that is what you are into).

I would suggest a mechanical secondary design carb for that engine combo.

How about the MPH, 60 foot times, etc. from your drag race runs? Or, was all this done on the G-tech?
 

400hp_76

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with the 3.08s i got 5.8 0-60 and 8.9-1/8...those numbers are from the track. with the gtec and 4.11s i got 5.7 0-60 and it does not read the 1/8 but i got 14.0 in the 1/4.. the only thing about the mechanical secondaries is that with the vacuum i have now i bog off the line a touch when i nail it...if i had mechanical im sure it would bog extremely bad as i have experience before earlier with my car on the first engine.
 

400hp_76

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Little picture of my vette,

http://www.patrickrice.com/phoenixedge/
just scroll down and you will see it. The two guys at the top of the screen are my friends. The blonde one has a toyota supra turbo and the other one has a integra type R. They have some pretty coold vids from them racing and from others. check it out.
 

69MyWay

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Re: Little picture of my vette,

400hp_76 said:
http://www.patrickrice.com/phoenixedge/
just scroll down and you will see it. The two guys at the top of the screen are my friends. The blonde one has a toyota supra turbo and the other one has a integra type R. They have some pretty coold vids from them racing and from others. check it out.

Man, that hood is awesome looing. If I saw you in my rearview, I would yield the right of way in a heartbeat!!!!!!
 

400hp_76

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mobile,al,united states
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Black 1976 STINGRAY cpe, T-tops
69 my way,

Thanks for the compliment. I love when other corvette owners turn there head. It gives me so much pride in corvettes when you ride by someone else you dont even know, but you can wave because theres just some kinda brotherhood you feel.
 

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