hey .. i have a 1991 camaro convertible z28 with a 5 speed tranny

i am rebuilding the motor and it has about 130,000 miles .. i was puttin in the new comp cam 08-501-8 (xe264hr-12) .. and i was comparing it to the old one .. the only noticible difference is the lobe seperation is smaller ..

i looked on the stock cam and it said 773 ..

according to this they 773 cam was in the G92 version .. does that mean i have a limited slip diff .. and did they even put this cam in this car or has someone changed it .. even thought this car was never "taken care" of by previous owners and highly doubt it has been changed before

1990-1992

305 5spd / 305 AT 4500 5000 10088155* .350 .384 179 194 109.0

305 G92 5spd / 350 AT 5000 5500 10111773* .413 .428 202 207 114.5 (116/-116)


thanks,

Adrian

 

All the tuned port motors in 1991 got the '773 cam, whether it was 305 or 350. The only 305's that got the '155 cam in 1991 were the L03, throttle body injected cars. In 1986 and 1987, the tuned port 305's with the auto trans got the wimpier cam, and the manual cars got the better one. Around these boards, the '155 cam is commonly referred to as the "peanut cam". The G92 package involves the gears and exhaust system, not the camshaft. A G92 optioned 1991 f-body got 3.42 gears (LB9), or 3.23 (L98), posi (G80), rear disc brakes (J65), and the dual cat exhaust system (N10).

 

oh .. thanks ..

what gears do i have in my 91 convertible .. i dont think the g92 option was available on the convertibles and i dont have dual cats

 

I see arguments of this peanut cam. I have a lb9 auto in my 91 and it redlines at 5k so that shows a peanut cam right?

 

idk thats what im wondering .. everywhere online it says our 91 lb9's are supposed to have the peanut cam if they redline at 5K

now i dont know if theres a difference between your auto and my 5spd ..

but mine redlines at 5k but has the bigger 773 cam in it (just tore it apart b/c of a blown head gasket, plus im doing some "upgrades" .. lol ) ..

guess there information is wrong ..

 

Redlining at 5K doesn't necessarily mean it has the peanut cam. Even the L98 motors top out around 5K with the stock cam. It's more the restriction of the tpi intake system that causes them to hit a brick wall at that rpm. Besides that, the 773 cam is still pretty puny compared to some of the aftermarket cams you can run while still using the stock chip. As far as figuring out the gears in your vert, do you still have the service parts sticker in the console glove box? If you do, look for the G codes listed on it. G80 indicates posi, and the G codes for the gear ratios go like this: GU2=2.73, GU4=3.08, GU5=3.23, and GU6=3.42. Sometimes the sticker is on the storage box door in the rear hatch, but most of the time it's in the console. Of course pulling the rearend cover and actually looking is the only way to be 100% certain, unless you're the original owner and know for a fact that no one's ever changed the rearend.

 

no ... we mean the tach redlines at 5000 (red mark) ..


theres no way a stock tpi setup would make power up there neways ..

thanks for the codes .. ill look tommorow .. i saw some sticker when i was messin around one day ..

adrian

 

yeah I have heard answers go both ways, but I was always told to look at the tach.

 

All TBI engines got the "peanut cam." The 90-92 TPI engines got the better cam, but there is still misinformation out there that hasnt been updated.

Your z28 convertible would have 2.73 posi drum brake 10-bolt rear end with an automatic, and 3.08 posi drum brake 10-bolt rear end with a stick shift.

 

So can somebody explain why the redline on the tach is 5k and not 5.5k rpm if we do not have peanut cams?

 

Because all the "low performance" 305's got the 5000 rpm redline, TBI and TPI and LG4. The "high performance" 305's and 350's got the 5500 rpm redline.

 

So what is the difference in my auto LB9 and the t5 LB9 if they both have the same cam, what gives them the 25hp or so more?

 

for 90-92 305's, auto vs manual is a big difference in performance due to gear ratios. they shouldnt have more power or less. Unless the prom/tune was different for the auto cars vs the manual cars.

edit: also i think G92's had better exhaust a dual cat y pipe that suppose to give 10% more power

 

The difference is in the exhaust. The low-power cars got the smaller TBI/LG4 exhaust with 2 1/4" cat back. The high-power cars got the larger L98 exhaust with dual cats and 2 3/4" cat back. The cats alone were rated at 10 more horsepower (not 10%), and the other 15 is in the rest of the exhaust and the computer tune. Gear ratios have no affect on the engines output, only the output at the rear wheels.

Otherwise the LB9 auto and LB9 stick shift are identical engines.

 

The tach is a worthless way to find out what cam is in the engine. I have an 86 that has the 'wrong' tach based on everything out there about what my cam and redline should be, but its the original tach. GM was totally non-specific about it.

 

cool .. well that explains everything ..

also im glad i got posi ..

just to make sure .. i can just jack up the rear and spin the tire and if the other one spins the opposite way then i got posi right?

im about to get my nordskog digital gauge cluster .. there still making it .. i pre-ordered it back in november .. $462 i think w/ shipping .. and its supposed to recal my 0-60 time, top speed, and 1/4 mile e/t

ill let yall know how it goes ..

thanks again

adrian

 

I have seen non posi rears do that when you spin the wheels in the air with no resistance on them.

 

oh .. well i gotta 89 mr2 s/c too and thats what you do to see if its posi .. i thought it would apply to all posi's ..


edit:

actually i just went and checked (its friggen cold out there ... lol) .. i got the G80 and GU4 .. so i guess i got a posi 3.08 gears

 

I didnt know they had posi 3.08's, but I guess they did.

 

They are supposed to spin the same way with the Posi.

 

oh .. i got it mixed up then ..