The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Anybody running a big block with th400 and 3.55 gears?

Racie · 04-19-2012, 02:19 PM

I'm about to do some upgrades to my rearend in my 68'. Right now I have an open 3.73 setup. I'm cruising on the highway with normal flow of traffic at 3500 rpms. This is really not a problem besides drinking up the gas lol...but if I'm going to change to a limited slip set up I might as well change gears if I'm going to do it while I'm in there. I've been thinking about running 3.55 limited slip or 3.42's what you guys think and list you mods if you could and what rpms you are seeing.

Here's what I have...

1968 SWB
502 H.O. Crate Engine
Minor head Work still has 2.19/1.88 valves
Bumped the Compression up a bit over 9.5:1
Howard's Hyd Roller cam-Duration:235/241(ADV 288/294)Lift:618/618 LSA:112
Air Gap Intake with Holley 950HP
DUI ignitionHooker Comp Headers 2" primaries 3.5 collector3" Exhaust
Race Built Stage 3 TH400 2800 stall
3.73 gears open carrier

Loving the way my truck is performing but the open rear is killing me!

04-19-2012, 02:19 PM	#1
Racie Registered User Join Date: Sep 2008 Location: Dallas,TX Posts: 328	Anybody running a big block with th400 and 3.55 gears? I'm about to do some upgrades to my rearend in my 68'. Right now I have an open 3.73 setup. I'm cruising on the highway with normal flow of traffic at 3500 rpms. This is really not a problem besides drinking up the gas lol...but if I'm going to change to a limited slip set up I might as well change gears if I'm going to do it while I'm in there. I've been thinking about running 3.55 limited slip or 3.42's what you guys think and list you mods if you could and what rpms you are seeing. Here's what I have... 1968 SWB 502 H.O. Crate Engine Minor head Work still has 2.19/1.88 valves Bumped the Compression up a bit over 9.5:1 Howard's Hyd Roller cam-Duration:235/241(ADV 288/294)Lift:618/618 LSA:112 Air Gap Intake with Holley 950HP DUI ignitionHooker Comp Headers 2" primaries 3.5 collector3" Exhaust Race Built Stage 3 TH400 2800 stall 3.73 gears open carrier Loving the way my truck is performing but the open rear is killing me!