I have a BB 427 30 over 10.5-1 and a 74 st10 12 bolt not shure what gear ratio yet. I was thinking 3:73's but, don't know what would be best. The car is a 69 x11 car and plan on cruise-in's and taking it to a few out of town shows.
Thanks for the replies but, I need to know if the ST-10 will hold up with the big block? I also have a L 88 cam in this motor. Would I be better off selling the St-10 because I don't have the funds for a tremec 5 speed.
I have a 427 10.5 to 1 with a 4 speed trans and 355 gears and this is great for driving and highway. do not go any lower than 355 . The cam range and low rpm throught parking lots and stuff make the car buck. 373 is the best but i went for 355 for longer cruises and am pleased with that. I got 11 miles the gallion on my drive to PA. 350 miles to show. cam is solid 375 hp cam.
The problem with a 12 bolt truck rear end (which I assume you are referring too with the ST-10 logo, even though most ST-10s came with 10 bolts) is that they have a small weak pinion gear, overly large axle bearings with 1/2" studs on a 5" bolt circle and the Posi, if it has one, is of a ratchet design that will break the first time it slips a tire on asphalt because they were designed to play in the dirt (pawl breaks when it attempts to latch onto the mechanism under load unlike the clutch type designed to be used on paved roads).
st-10 means super T-10 4-speed.
I think you'll be happy with 355 to 373's in combo with the 4-speed(which first gear ratio?), but you HAVE to GET RID of that rediculously large CAM. that cam needs 12.5+ :1 compression or it will run like a turd, and even with 12.5:1 it will HATE to be lugged down to lower RPM's (like highway w/ less than 373's), or anything slow speed in town.
I'd put a XE 274H, or comparable solid, comp cam in it . It will be WAY happyer overall with the smaller shaft.
just my opinion.......I been there.
I think he just wants to know if the Super T-10 will hold up to the big block. Not about what ratio to run.
As for the Super T-10 and the big block, I had a 26 spline, aluminum case, super T-10 behind a blown 468 cuin big block in a Pro Street 57 Chevy with a narrowed 9 inch rear with 15.5 rear tires. It was in the car for about 10 years and held up. I was far from easy on it. I didn't get much traction though, so that may have helped. It would probably be a different if the rear tires "hooked" up better. Slicks would have probably killed the trans. I launched it once, got good traction, and broke both axles in the car and the trans didn't break. So the T10 will take some abuse. The trans was bone stock out of a 1979 Z/28. I just rebuilt it before I put it in.
Also, after seeing how mine held up, a friend of mine put a Super T10 in his 67 Camaro that had a crate 454 LS6 with a 4:11 12 bolt and didn't break it. He also had some traction issues..lol. For the street, cruse nights, shows, I'm sure you'll be fine with the T-10.
I have a Super T-10 in my car now. Close ratio's. The guy I bought my Camaro from had a 12 bolt w/ a full on spool an 4:10 gears in it w/ c-clip eliminators. The trans seems like it can take a beating. Sorry but I don't know the ratio's in mine. All I know is first gear lasts about 15 feet and by the time I'm at the end of the block it's already in 4th gear at 3,000 RPM's and I'm at high way speeds. That's why I'm looking to go automatic with overdrive or gear vendors. BTW, It's the aluminum case.
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