I am installing and m6 and CC503 cam in an lt1. Gears in the car now are 3.42 and the math tells me my rpm at 70 will be around 1800. Do I need to go to 3.73 to use 6th gear on the highway without some lurching or similar issues? Not positive on the rpm it was just me and calculator doing percentage math. Car is an 88 IROC.

Thanks for any insight, I want the rearend repaird and compatable when I put the engine in....(rearend went boom)

 

IF it were me I would go 4.10 w/ the 6-speed.

 

I think the 3.42s would be fine for a street car. 4.10s are going to be easier to break in a 10bolt, will tach more rpm and will make first gear on street tires just about useless under heavy throttle.

Your math is about right in regards to rpm and speed. 80mph should put you right at 2000rpms.

If it was a weeekend car, or something that was more of a toy I'd say go for the 4.10s.

 

A cam is definitely going to like more gear, even in a M6.

 

what tires? on 245/50/16s with 4.10s you'll be taching 1830rpms in 6th gear at 70mph, and top out 4th gear at the dragstrip around 112mph(6000rpms)

 

Tires are 245/50/16 and it sounds like the 3.73 may be a good comprimise. Guy I work with said he did the 4.10 and first gear was useless. I want the car to have some "jump" but also want to be able to drive it on a two lane road where speed varies from 55 go 70...no more tickets..those dps effers.

 

either get the 4.10's and some sticky tires or the 3.73's...sticky tires wouldnt hurt even with the 3.73's. if it were me, id to the lesser gear.

 

Honestly man, the 224/230 isn't that peaky of a cam. It was FINE to drive in my 93 M29 car which is minimally steeper overall than a 94+ car with an M6. You'll be fine.

 

Thanks Fastbird93, that is the info I was seeking. The rpm "range" stated is 1800 on the bottom side and I suspected it would be ok. My last car modification experience was lots of years ago and all my car buddies grew up, I just never bothered.