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 January 19th, 2023, 02:00 PM
GMCNUT's Avatar
GMCNUT GMCNUT is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: Arab Alabama
Truck: 60 1001 Wideside Custom BBW, 62 K1001 Wideside BBW and 1966 1001 Wideside BBW w/ Sport Trim option
Posts: 688
Rep Power: 254
GMCNUT will become famous soon enoughGMCNUT will become famous soon enough
Default 305E vs 351E design differences

Someone on a Facebook group page asked me what made a 351E engine have that displacement if it was based on a 305E block and the 305 already had the largest diameter piston anyones ever seen at 4.5" across already - he was asking if the 351 had the same diameter piston but maybe just a longer stroke to make more cubes or if it seriously had even larger diameter pistons and if so how big are they?
I do not know whether a 305 and 351 share a block with different bores, or both are unique, or if the pistons are bigger in the 351E vs 305E or what makes a 351 a 351 vs a 305. I assume the heads or valve sizes in the heads are likely also different between the two engines, and I do know about the exhaust manifolds and carbs / intakes being different but don't know about what is different inside one really.
__________________
My 60-66 GMC Projects:

1960 1001 Custom Cab short wideside BBW, 305A V6, factory PB, Hood Jet, Radio and Hydramatic.

1962 K1000 4x4 short wideside, BBW, 305D w/ SM420, PTO Winch

1966 1001 Custom Cab short wideside, w/ super rare Sport Trim option interior (bucket seats)
Reply With Quote
  #2  
Old January 19th, 2023, 05:15 PM
sclor's Avatar
sclor sclor is offline
Senior Member
 
Join Date: Jan 2013
Location: New Orleans, LA
Truck: 1966 GMC 1000 series fenderside
Posts: 202
Rep Power: 128
sclor is on a distinguished road
Default Re: 305E vs 351E design differences

Nut:
I'll take a crack at your question. Others feel free to embellish.
* 351e is a magnum with bigger valves, bigger intake and exhaust ports.
* 351 has larger bore than 305. I believe it's 4.25" for 305 vs. 4.5" for 351.
* 351 has steel crank vs cast crank in 305. Unsure about stroke?

Hope that helps.
Regards
Steve
New Orleans
Reply With Quote
  #3  
Old January 19th, 2023, 10:20 PM
Prowbar Prowbar is offline
Senior Member
 
Join Date: Dec 2020
Location: Friesland, the Netherlands
Truck: 1965 GMC 1500, 478 V6, SM420
Posts: 383
Rep Power: 181
Prowbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the rough
Default Re: 305E vs 351E design differences

All blocks 305-478 are the same size. 305 has the smallest bore at 4.25". 351 is 4.56" and 401 is 4.87". All have the same stroke, 3.58". The 478 has a 5.125" bore with a 3.86" stroke. The 379 and 432 are a stroked 351 and 401 respectively.
Reply With Quote
  #4  
Old January 19th, 2023, 11:51 PM
Ed Snyder's Avatar
Ed Snyder Ed Snyder is offline
-= Dues Paid =-
 
Join Date: Jan 2013
Location: Medford, Oregon
Truck: 1962, 1965, 1967
Posts: 868
Rep Power: 343
Ed Snyder has a spectacular aura aboutEd Snyder has a spectacular aura aboutEd Snyder has a spectacular aura aboutEd Snyder has a spectacular aura aboutEd Snyder has a spectacular aura aboutEd Snyder has a spectacular aura about
Default Re: 305E vs 351E design differences

Quote:
Originally Posted by Prowbar View Post
All blocks 305-478 are the same size. 305 has the smallest bore at 4.25". 351 is 4.56" and 401 is 4.87". All have the same stroke, 3.58". The 478 has a 5.125" bore with a 3.86" stroke. The 379 and 432 are a stroked 351 and 401 respectively.
All this data and much more is available at Jolly's original site -- http://6066gmcguy.com/ which Jolly started in January of 2000, and continued to moderate it until January 2013 when he "passed the torch" onto our friend Jeannie. See http://www.6066gmcguy.com/EngineData.html for lots more data.
__________________
Ed Snyder
Medford, Oregon
1962 1000 Pickup 401M & Muncie 318 with overdrive
1962 K1000 Suburban 401M & SM420
1965 2500 Suburban 351C & SM420 with Watson overdrive
1967 CM1500 pickup 351E & NP435
Reply With Quote
  #5  
Old January 22nd, 2023, 06:21 AM
BobBray BobBray is offline
-= Dues Paid =-
 
Join Date: Feb 2013
Location: Los Angeles, CA.
Truck: 1967 CM 2500
Posts: 246
Rep Power: 148
BobBray will become famous soon enoughBobBray will become famous soon enough
Default Re: 305E vs 351E design differences

Quote:
Originally Posted by sclor View Post
Nut:
I'll take a crack at your question. Others feel free to embellish.
* 351e is a magnum with bigger valves, bigger intake and exhaust ports.
* 351 has larger bore than 305. I believe it's 4.25" for 305 vs. 4.5" for 351.
* 351 has steel crank vs cast crank in 305. Unsure about stroke?

Hope that helps.
Regards
Steve
New Orleans
Correct, except the 351E and certain other late 351's have cast cranks. Stroke is the same for the 305, 351, 401, and 702 as others have pointed out.
Reply With Quote
  #6  
Old February 18th, 2023, 06:12 PM
beerman beerman is offline
Member
 
Join Date: Feb 2016
Location: Yardville, NJ
Truck: 1968 GMC K1500 305E SWB
Posts: 47
Rep Power: 65
beerman is on a distinguished road
Default Re: 305E vs 351E design differences

CID Bore Stroke
478 5.1250 3.86
432 4.8750 3.86
401 4.8750 3.58
379 4.5625 3.86
351 4.5625 3.58
305 4.2500 3.58
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
351E Camshaft same as the 305E Cam? lizziemeister'sV6 GMC V6 and V12 Engines 3 April 12th, 2022 10:28 AM
Interesting Article on Engine Design Archiver Previous Forum Posts 0 November 30th, 2010 12:53 AM
Re: [6066 GMC] Re: t shirt design Archiver Previous Forum Posts 0 November 16th, 2004 12:34 AM
Re: t shirt design Archiver Previous Forum Posts 0 November 10th, 2004 12:23 AM
t shirt design Archiver Previous Forum Posts 0 November 10th, 2004 12:19 AM


All times are GMT +1. The time now is 02:54 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 681711554703|1710510855|0