6066 (1960-1966) GMC Truck Club Bitcoin now accepted here! 
Pay Dues
Pay Dues or become a Site Supporter
 



Go Back   6066 (1960-1966) GMC Truck Club > 6066 GMC Truck Club Forum > GMC V6 and V12 Engines


GMC V6 and V12 Engines Engine repair and rebuilding

Reply
 
Thread Tools
  #1  
Old May 22nd, 2020, 02:06 AM
Mike Caldwell Mike Caldwell is offline
Member
 
Join Date: Feb 2013
Location: Elizabethtown, KY
Truck: 401 headed for '49 Willys PU
Posts: 38
Rep Power: 56
Mike Caldwell is on a distinguished road
Default 401 vs 432 torque ratings???

Chart has 432 rated at 336 lb-ft @2000 rpm and the 401 at 348 @ 1600.

Why does smaller engine with shorter stroke have more torque?

Is the 432 a Magnum????

I have a 401 but have a serious craving for TORQUE!!!!

Edit to add Wikipedia quote:
"In 1973 & 1974 there was also a 432.2-cubic-inch (7.1 L) version with enlarged crankshaft journals (4.875 in × 3.86 in (123.8 mm × 98.0 mm) bore and stroke). The 432 was a 401 with a 478 crankshaft. It produced 190 hp (142 kW) net at 3200 RPM and 336 lb⋅ft (456 N⋅m) net torque at 2000 RPM. The 432 was a Magnum engine though it was never designated as such."
Reply With Quote
  #2  
Old May 22nd, 2020, 02:45 AM
BillT BillT is offline
Senior Member
 
Join Date: Jan 2013
Location: Moneta, VA
Truck: Drove and Owned Many
Posts: 248
Rep Power: 109
BillT is on a distinguished road
Default Re: 401 vs 432 torque ratings???

Quote:
Originally Posted by Mike Caldwell View Post
I have a 401 but have a serious craving for TORQUE!!!!
I find that a little strange as my '62 478 had tons of Torque. It was like an old Mack. Even my 305 had some Torque for what it was in my '62 4000.
__________________
Drove and owned many, but some of the more interesting ones were:

-'60 GMC 2500 Dump, 305 V-6
-'62 GMC 4000 Flatbed, 305 V-6
-'62 GMC 6500 Flatbed Dump, 478 V-6
-'67 GMC 7500 Box, 6V-53 Detroit
-'71 GMC 9500 Flatbed Dump, 637 V-8
Reply With Quote
  #3  
Old May 22nd, 2020, 07:07 AM
BobBray BobBray is offline
-= Dues Paid =-
 
Join Date: Feb 2013
Location: Los Angeles, CA.
Truck: 1967 CM 2500
Posts: 150
Rep Power: 85
BobBray is on a distinguished road
Default Re: 401 vs 432 torque ratings???

Make sure you are comparing like figures. The 401 being older ws usually rated in gross figures, the 432 in net. The change happened around 1971. Net is usually 15-20% lower. Also, the 432 was tuned a little more for emissions, such as the standards were for heavy trucks in the early 70's. Nowhere near as stringent as passenger cars at the time, but still a factor. Yes, the 432 had Magnum heads, manifolds, and carb..
Reply With Quote
  #4  
Old May 22nd, 2020, 06:19 PM
BobBray BobBray is offline
-= Dues Paid =-
 
Join Date: Feb 2013
Location: Los Angeles, CA.
Truck: 1967 CM 2500
Posts: 150
Rep Power: 85
BobBray is on a distinguished road
Default Re: 401 vs 432 torque ratings???

Looked it up, in 1972 the 401 was rated at 298 ft. lbs. at 1600 r.p.m. net.
Reply With Quote
  #5  
Old May 23rd, 2020, 10:51 PM
Mike Caldwell Mike Caldwell is offline
Member
 
Join Date: Feb 2013
Location: Elizabethtown, KY
Truck: 401 headed for '49 Willys PU
Posts: 38
Rep Power: 56
Mike Caldwell is on a distinguished road
Default Re: 401 vs 432 torque ratings???

From the 6066GMCguy page
Quote:
Net Torque lbs. ft.
432
Quote:
336 @ 2000 rpm
401
Quote:
351 @ 1400 rpm
If the rating system changed what would be a good estimate of what the real numbers are?

Bottom line question: Does 432 make appreciable more torque than 401?

Enough to be worth the difficulty in finding one?
Reply With Quote
  #6  
Old May 24th, 2020, 06:46 AM
BillT BillT is offline
Senior Member
 
Join Date: Jan 2013
Location: Moneta, VA
Truck: Drove and Owned Many
Posts: 248
Rep Power: 109
BillT is on a distinguished road
Default Re: 401 vs 432 torque ratings???

The 432 seems to be pretty rare. You never even hear of them anymore.

If you would like to have a lot of Torque, why not go to a 478. They are around here and there.
__________________
Drove and owned many, but some of the more interesting ones were:

-'60 GMC 2500 Dump, 305 V-6
-'62 GMC 4000 Flatbed, 305 V-6
-'62 GMC 6500 Flatbed Dump, 478 V-6
-'67 GMC 7500 Box, 6V-53 Detroit
-'71 GMC 9500 Flatbed Dump, 637 V-8
Reply With Quote
  #7  
Old June 14th, 2020, 02:21 PM
POWERSTROKE POWERSTROKE is offline
Member
 
Join Date: Sep 2014
Location: Madison, WI
Truck: I don't own one - YET!
Posts: 98
Rep Power: 62
POWERSTROKE is on a distinguished road
Default Re: 401 vs 432 torque ratings???

I would think it would be REALLY hard to notice 12 #/ft of torque in a truck engine, especially when the higher torque is at 2000 rpm and the lower torque was at 1400 rpm.

I agree, if you want MORE POWER, drop a 478 in the truck. More HP and torque. NO replacement for displacement!

I got invited to join a Facebook group dedicated to Ford's new 7.3L gasoline V8 engine, 444 cid, I forget what the HP & torque numbers are, well over 400, more like 450 each. That engine is taking a BIG BITE out of diesel engine sales.
Reply With Quote
  #8  
Old June 15th, 2020, 04:59 PM
BobBray BobBray is offline
-= Dues Paid =-
 
Join Date: Feb 2013
Location: Los Angeles, CA.
Truck: 1967 CM 2500
Posts: 150
Rep Power: 85
BobBray is on a distinguished road
Default Re: 401 vs 432 torque ratings???

That Ford 7.3L gas is generating a lot of interest. Seems to have good power, but I have seen the insides of it and can't say I am super impressed with it. I have heard rumors that GM is working on a new V-8 even larger than their new 6.6L. Maybe GM ought to design a modern version of the old V-6!
Reply With Quote
  #9  
Old June 16th, 2020, 12:07 AM
POWERSTROKE POWERSTROKE is offline
Member
 
Join Date: Sep 2014
Location: Madison, WI
Truck: I don't own one - YET!
Posts: 98
Rep Power: 62
POWERSTROKE is on a distinguished road
Default Re: 401 vs 432 torque ratings???

Bob - The 7.3 was recalled, stop production order put on it for a couple weeks after only maybe 1000 engines were built. There's a tubular oil manifold used to oil the underside of the pistons sorta like the squirters on diesel engines, and they were formed incorrectly and were hitting the conn rods, made an odd noise and and there were chances the manifolds could break and foul up the rods and crankshaft.
Some guys are looking for wrecked 2020 trucks to get a 7.3 to shoehorn into their Mustang GT's. The 5.0L makes 460 hp, not sure how much of an improvement the 7.3 would be.
I was hoping the 7.3 would be more of a newer modern Super-Duty like the 401, 477, & 534 CID V8's Ford made back in the late 50's, 60's and I think early 70's. Back when GMC was building these great V-6's. GMC built in so many little features into the V6's that made them hold up to hours and hours of wide open throttle and fire up the next morning and do it all over again. The 637 cid V8 that replaced the 702 V12 is the largest displacement V8 built by ANY GM division, if GMC wants to offer a BIG modern gasoline engine I think there is a market for it. Lots of companies have a hard time justifying a medium duty truck, and a high priced diesel engine with higher priced maintenance needs makes that much harder. Company I worked for put about 50,000 miles a year on their 24 ft box truck. It was a Navistar with DT-466E, it was replaced with a little Sprinter van, also a diesel. But that was after ultra low sulfur fuel but WAY before DEF. SON's 2014 Ram 2500 kept setting Contaminated DEF codes, His Dealer kept complaining he wasn't using MOPAR DEF, he used Peak, ALL DEF is made at the same plant in Iowa, anyway, This dealer happens to be in Iowa. It cost $1500 but the truck was deleted, no longer used DEF at all. I can't imagine a contractor going through that kind of run-around, he would just buy a gas truck.
Reply With Quote
  #10  
Old June 16th, 2020, 02:00 PM
BillT BillT is offline
Senior Member
 
Join Date: Jan 2013
Location: Moneta, VA
Truck: Drove and Owned Many
Posts: 248
Rep Power: 109
BillT is on a distinguished road
Default Re: 401 vs 432 torque ratings???

I don't know a whole lot about DEF engines, but I believe it would be enough for me to go with a Gas engine.

If they ever brought back the 637 V-8 Gas, they would really need to work on the Fuel Mileage. I never did check it personally, but I believe the '71 637 that I drove only got about 5 to 7 all around. Although many times I would be maxed out at the full 46,000.
__________________
Drove and owned many, but some of the more interesting ones were:

-'60 GMC 2500 Dump, 305 V-6
-'62 GMC 4000 Flatbed, 305 V-6
-'62 GMC 6500 Flatbed Dump, 478 V-6
-'67 GMC 7500 Box, 6V-53 Detroit
-'71 GMC 9500 Flatbed Dump, 637 V-8
Reply With Quote
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Gasket Set for 401 and 432 Archiver Previous Forum Posts 2 March 25th, 2012 04:48 AM
RE: [6066 GMC Truck] 401,432, or 478 V-6 Archiver Previous Forum Posts 0 February 2nd, 2004 12:57 AM
Re: [6066 GMC Truck] 401,432, or 478 V-6 Archiver Previous Forum Posts 0 December 30th, 2003 12:52 AM
Re: [6066 GMC Truck] 401,432, or 478 V-6 Archiver Previous Forum Posts 0 December 28th, 2003 12:40 AM
401,432, or 478 V-6 Archiver Previous Forum Posts 0 December 28th, 2003 12:02 AM


All times are GMT +1. The time now is 05:26 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 1221597007911|1595953583|0
Feedback Buttons provided by Advanced Post Thanks / Like (Lite) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.