373 rear end question

[johnson1967]

I have a 1967 c10 (WAS A 6 CYL) with a 12 bolt rearend geared 373 that I am assuming is original ...the thing is its not posi whats the best option for making it posi ...or is there some kind of swap I should consider. ..

[Jmiller022]

auburn gear or Detroit truetrac make limited slips to replace the factory open carrier.

[GASoline71]

Eaton posi-traction unit. Best $400 bucks you'll ever spend on your truck. Get it, install it, love it...

Gary

[johnson1967]

Another thing idk how much of a difference it makes between the namebrands listed above but I bought the 500 hp 383 stroker frim proformanceunlimited .. he told me by adding a 3 in supersucker carbrator spacer id get an extra 50-60 hp so what would be the best for lets say 550 hp

[storm9c1]

Originally Posted by johnson1967

Another thing idk how much of a difference it makes between the namebrands listed above but I bought the 500 hp 383 stroker frim proformanceunlimited .. he told me by adding a 3 in supersucker carbrator spacer id get an extra 50-60 hp so what would be the best for lets say 550 hp

Brands listed above -- I prefer the Eatons. The clutches hold up better than the Auburn cone design. If you fry the Eaton, it can be rebuilt. Auburn's cones wear into the carrier and destroys the carrier, therefore it cannot be rebuilt.

As for the "SuperSucker" -- gosh I wish I had the conscience to invent snake oil and claim that a 5-minute bolt-on will give you 50HP. I'd be rich. But I don't have the conscience for those gimmicks. Nor do I have the patience as a consumer to buy them. BUT what I can recommend is any style of 4-hole phenolic spacer 1/2 - 1" range to help with fuel boiling in the carb. That will always help prevent hard starting when hot (and prevent vapor lock).

[GASoline71]

The Eaton posi or Eaton Detroit locker will handle it. However... will your transmission and TC hold up? You're gonna need a stout transmission, and at least a 3,000 RPM stall converter I'm guessin'.

Gary

[storm9c1]

After reading back, I don't mean to be confrontational, but 550hp from a naturally aspirated 383 seems a little high unless this sucker is being built for race only and $$$$$$. Are you sure your builder is being straight? Or are you planning nitrous or induction? Or running it on alcohol? 500hp+ at the wheels from a SBC starts getting expensive quick! Just tryin to watch out for ya.

[johnson1967]

Lol I hope hes not lying about the spacer he doesnt sell them.he said he put one one the motor in his truck and is pushing right at 560...i dropped a little over 10,000 for the motor and trans well I didnt it was a graduation present ..but as far as the motor and transmission gos it is a turbo 350 and has a 3000 stall..... but if youd like to see full specs check of the motor
http://www.proformanceunlimited.com/...383_500hp.html

[johnson1967]

I cant remember exactly but mine was dynod at 490 something on 93 so I hope hes telling the truth id realy like to get 550 out of it ....how much hp do u lose going to the wheels

[71K20chevy]

usually 15-20%...and sorry, I have to agree, 550 hp does seem pretty high. I can tell you he's full of crap with the carb spacer adding 50 hp.

[storm9c1]

Well that build is on the right track with the forged hardware and roller cam, I'd do some things different (chrome tinware, really?), but no specifics are mentioned, no cam specs, no piston specs, no heads specs, no compression. Pretty generic. So honestly I can't say for sure based on that website alone. I'm a little skeptical. Good luck! Keep us posed.

[GASoline71]

All I can say... is if you start dropping in an engine making that kind of power. You had better have the rest of the drivetrain ready as well. Or you will break stock parts. When an engine gets to that extremem... it will cost a pretty big chunck of cash to wring 50 more hp out of it.

Also... no bolt on spacer will net you 50hp in gains. Unlesss it happens to be a nitrous plate.

Gary

[johnson1967]

Finaly found my paperwork on the motor ...

[johnson1967]

Yeah I didnt want chrome on mine so I went with the chevy kit

[Rollo McFlurry]

"Comp Cams hydraulic roller high performance street camshaft with a muscle car chop"

Red flag!

I really don't want to come off as a dickhead, but that line makes me question everything.

I would suggest getting some real information from the guy (if you can). That parts list screams "bull****!"
I would ask for part numbers on everything.

I would love to talk with this guy in person. Really really.

[storm9c1]

+10000

I would never buy an engine without the cam specs and compression ratio agreed on in writing (which was not mentioned on that list). Saying "muscle car chop" for a cam could mean a Thumpr cam which is NOT what you want. Without knowing compression, you could have some nightmare compression ratio for the street and he could be running this with alcohol on the dyno.

The good news is that it's a roller cam and a forged crank. The (somewhat) bad news is that this is a 2-piece rear main seal block.

Be careful. This engine might run strong, but 500hp is dubious, depending on the cam, you may be giving up low-end torque to get close to that hp rating, which will hurt on the street. But yet it's supposed to be a "street" cam. Some of these facts aren't straight.

In my perspective, for my hard-earned $9100, I'd need to know much more about this build before I'd be happy. Sorry.

Or you could just get it and run it, and not worry. It will certainly move your truck.