[89 Irocz]

Good morning all I have a question i have a 1992 s10 pickup my dad bought new it originally came with a 2.8 and 5 speed his son blew up the motor.I decided it needed more power and have built a 4.3 using 40 over flat tops with 4 valve reliefs and i use the stock roller cam from a mercurser 4.3 and the heads. From what i have heard in the past the merc heads flow better than the stock ones it still has the stock tbi and manifolds but the rest of the exhaust was upgraded and it runs great. Im going to change the ring and pinon from a 342 to a 327 to give a bit better highway rpm can any one give any estimate on what kind of power this little mouse has and how much this gearing change will help because the truck will pull out in 3rd now like it is nothing and 70 seams to be running pretty hard. Also dose anyone have any advice for some one doing their first ring and pinion swap and can i mix and match gears to get a different ration. i don't know what the numbers are on the one in the truck yet but the 327 gears i have are 11 and 36. don't know if could mix the 2 to get a lower ratio.

[weedy64]

R & P are run-in as a set on a gear machine to establish check depth/backlash by the mfg and the #s engraved on the set for install. If you mix parts between sets of the same mfg and ratio you won't have correct dimensions for the install....it will be a guess. A guess is best left to experts not 1st timers and I doubt they would do it either. Second you don't mix/match a pinion from one ratio and a ring from another either, they won't mesh properly due the pitch being different (distance between teeth) and see opinion #1. The ratio change you are contemplating is not a lot different for the cost involved, a 3.08 set might make you happier if the 4.3 has that much go.

Good Luck.

[BOBCRMAN@aol.com]

Also the 4.3 isn't a bolt in. Trans won't work and mounts/accessories are all different. Mercruiser heads are no different than any other production head. Cam is for sub 4500 rpm use..

As mentioned above ring and pinion setup is not for a novice.. You are dealing with exacting clearances and specialized setting equipment. The small ratio difference is not worth the cost. Just change tire size...

[runn141]

for the trouble it will be too put in a 4.3 you can easily just put a smallblock in it. and the mount kits for them require 2.8 mounts anyway. oh and you will get better fuel mileage with a smallblock.

[89 Irocz]

ok guys i have already got the motor and trans swapped out and have it running and driving and it runs great thanks for letting me know about the gears i think ill look and see what rear is in my blazer it dose have a 383 with victor jr heads and a holley commander 950 efi set up running 10.5 comp and a trick flow cam all roller top end and if i can quit tearing out transmissions maybe i can drive it more than a few miles but that is for a different post dose any one have any idea on power and would a 308 gear would work better or should i go in to the 2s

[runn141]

Originally Posted by 89 Irocz

ok guys i have already got the motor and trans swapped out and have it running and driving and it runs great thanks for letting me know about the gears i think ill look and see what rear is in my blazer it dose have a 383 with victor jr heads and a holley commander 950 efi set up running 10.5 comp and a trick flow cam all roller top end and if i can quit tearing out transmissions maybe i can drive it more than a few miles but that is for a different post dose any one have any idea on power and would a 308 gear would work better or should i go in to the 2s

are you asking about the power of the 4.3? if so they are lazy. my dad had one with a 3.08 and it was too high it had to be ran in drive all the time. he now has one with a 3.42 and it isnt much better. but he still got 15mpg with both trucks though.