i have a 1991 Z28 and we'll say it has a 305TPI auto, i havent been able to completely identify the engine yet, im hearing mixed stories. my car has 2:73 gears. im considering going to 3:42's. would i see a general increase in street performance or would the gears hurt my 305s overall performance?


mods:
holley airfoil
TB coolant by-pass
Hypertech chip w/160 thermo w/low temp fan switch
headman shorty headers
headman Y-pipe also cat. converter delete
98 SS LS1 borla exhaust
wild 700r4 w/nasty shift kit


Thanks

 

you should feel more preformance, it's not like you'll be making more power just pulling harder

 

I loves my 3.45's in my nine bolt. It is the best overall gear you can still get good milage and good takeoff.

 

i have the 3:42's and the rebuilt kit for the rear end. i have a shop that will set up the rear end for $150. i'll have them do it on the first of november

 

as for your confusion about your engine:
check the RPO codes usually found in your center console. L98 is the code for the 350.

 

The L98 was the vette alluminum headed TPI. The f-body version had the RPO B2L. The vin code the 350 in 1991 was 8. The 305 vin was F.

 

How are those 3.42's treatin you on the highway? i love to cruise down the highway and i still want a decent top speed. anyone have any RPM/Speed numbers? (above 55) thanks!

 

nope.


L98 is the engine code for both cars. vettes had alum. heads on it ours didnt. but both are still coded as L98 (100% positive about this , no sense in arguing that point)
B2L is teh "package" that was automatically included with ordering the 350 cid engine.

for your reference:

B2L : PERFORMANCE PACKAGE & ENGINE PACKAGE V8 5.7LPFI

L98 : 5.7 LITER V8 TPI ENGINE

as i said, check your rpo codes to find L98, if you have it, you have the 350.
Youre correct about the VIN code.

 

Hey thanks for the clarification. I was always a little confused because in every chevy book I own they always listed the 350 TPI as B2L and talking with other board members we were under the impression that that is what it was. I was always told that the L98 was the vette version because of the differences and that out of habbit people just called it that. In the same books they use all of the other normal codes, LO3, LB9, LG4 ect. So I figured the 350 was supposed to be the same way. This makes sence now, I just wish all those camaro books would change that.

 

how much more power does the vette L98 have over the F-Body L98? if i was to go to a junk yard, i would look for a vette L98 then. what years were they found in the vettes?

 

They were rated at 275hp I believe. Not sure about the torque though but probably in the 350 range. The only differneces besides exhaust manifolds air intake and oil design are that the vette had aluminum heads with 58 cc chambers and they were 4 bolt main blocks.