Performance Lacking in a 383 Build.

[Ptjsk]

Originally Posted by '68OrangeSunshine

Is this in a Blazer [K/5] type truck? Even though GMC called them K/1500, not ''K/750''.
Or are you using Jimmy as a nickname for a GMC pickup?
4.56:1 is unusually low for a rearend on a light 1st gen suv. Most are 3.73:1 or even 3.07:1 in a half ton.
If you're talking about a 3/4 ton GMC, never mind. But 4.56:1 on a half ton Blazer is real low. And you'd do better with higher gears, like 3.73.

No, it's actually a Jimmy. It's GMC's version of the Chevy Blazer.

I placed the 410 gears in it when I restored the vehicle last year.

I'm running 33's on them, and I did install a gear vendor overdrive unit.

Pat

['68OrangeSunshine]

Originally Posted by Ptjsk

No, it's actually a Jimmy. It's GMC's version of the Chevy Blazer.

I placed the 410 gears in it when I restored the vehicle last year.

I'm running 33's on them, and I did install a gear vendor overdrive unit.

Pat

OK, I get it. I thought the gearing sounded low, but with a GV/OD it makes more sense. With 4.10s your focus is off road, and a personal choice.
With three broken piston rods we know why you had no power. You were actually running a pumped-up 5 cylinder.
Better luck on your rebuild.
My '71 Jimmy is a 350/SM465/NP205/12Bolt-3.73Posi/ 33x12.50x15.
Yours is pretty.

[72c20customcamper]

Seems that more than one company is or had problems with their pistons TRW paid for the rebuild for my 66. Mine was catastrophic though 3 others had cracks around the wrist pins.

Absolutely no noise prior to damage

[Ptjsk]

Originally Posted by 72c20customcamper

Seems that more than one company is or had problems with their pistons TRW paid for the rebuild for my 66. Mine was catastrophic though 3 others had cracks around the wrist pins.

Absolutely no noise prior to damage

Wow, that's crazy! Sorry you had to go through similar issues too!

Pat

[Ptjsk]

Originally Posted by '68OrangeSunshine

OK, I get it. I thought the gearing sounded low, but with a GV/OD it makes more sense. With 4.10s your focus is off road, and a personal choice.
With three broken piston rods we know why you had no power. You were actually running a pumped-up 5 cylinder.
Better luck on your rebuild.
My '71 Jimmy is a 350/SM465/NP205/12Bolt-3.73Posi/ 33x12.50x15.
Yours is pretty.

Thanks for the comments.

Probably highly unlikely it will see much off road use, I just want to be able to pull a car trailer, or a camp trailer periodically.

Thanks for the better luck wishes. I'm hoping for far better luck too!

Pat