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
  #11  
Old November 24th, 2016, 04:39 AM
bigblockv6 bigblockv6 is offline
Senior Member
 
Join Date: Jan 2013
Location: Rohnert Park, ca.
Truck: 1968 KM2500
Posts: 1,325
Rep Power: 415
bigblockv6 will become famous soon enoughbigblockv6 will become famous soon enough
Default Re: Proper sized exhaust

While calculations show 500 CFM to be overkill on a 305 running at factory designed engine speeds, as with many things, calculations do not represent real world results. More than likely, the same engine with a 500 CFM carb will make more horsepower than the same engine with a 350 CFM carb, or the factory carb.

[/QUOTE]

Turbobill. I fully agree with you on that Years ago I tested all 3 of these carbs on my 68 305E and the Holley 500 was still by far the top performer, it's all about the real world results
Reply With Quote
  #12  
Old November 25th, 2016, 02:43 PM
WDShaffer's Avatar
WDShaffer WDShaffer is offline
GMC Advisor
 
Join Date: Feb 2013
Location: Bakersfield, CA
Truck: 1961 Short Fenderside
Posts: 145
Rep Power: 106
WDShaffer is on a distinguished road
Default Re: Proper sized exhaust

Back to JB's question. Funky's video spells it out in the opening screen: 2 1/4" opening up to 2 1/2", with an X-pipe and dual exhaust. You can change the sound with different mufflers and pipes after the mufflers. Thanks Funky, I enjoyed every note. The PO of my truck put the mufflers under the cab--with no pipes after. Talk about loud with a "Wheels of Tragedy" scenario.
Reply With Quote
  #13  
Old December 2nd, 2016, 03:22 PM
TJ's GMC's Avatar
TJ's GMC TJ's GMC is offline
Senior Member
 
Join Date: Mar 2015
Location: Cave Junction, Oregon
Truck: 1964 GMC 1500 LWB Wideside 305E V6.
Posts: 1,341
Rep Power: 399
TJ's GMC is on a distinguished road
Default Re: Proper sized exhaust

My exhaust manifolds measured 2.25 so I went with 2.25 inch pipes to the muffler and exited the muffler with 2.5 inch tail pipes. True duals. No cross over.

https://www.youtube.com/watch?v=RCfanx30JO8
__________________
"Excuse the rust I use my truck"
1964 GMC 1500 305E/sm420 4 barrel intake mod and dual exhaust.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

1964 Chevy C20 292/SM420
1966 Chevy C10 292 hotrod 6/TKO600


My youtube channel aka Military Chevy:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #14  
Old December 2nd, 2016, 06:22 PM
Funky61's Avatar
Funky61 Funky61 is online now
-= Dues Paid =-
 
Join Date: Jan 2013
Location: Corona, CA
Truck: 1961 Suburban 1962 GMC Utility
Posts: 1,130
Rep Power: 409
Funky61 is just really niceFunky61 is just really niceFunky61 is just really niceFunky61 is just really niceFunky61 is just really niceFunky61 is just really nice
Default Re: Proper sized exhaust

I always thought those 40's would sound too loud ,
but they seem tame enough on you video TJ.
How are they on the highway?
__________________
1961 GMC Suburban 305A Overdrive
1962 GMC Utility 305D
Reply With Quote
  #15  
Old December 2nd, 2016, 07:03 PM
TJ's GMC's Avatar
TJ's GMC TJ's GMC is offline
Senior Member
 
Join Date: Mar 2015
Location: Cave Junction, Oregon
Truck: 1964 GMC 1500 LWB Wideside 305E V6.
Posts: 1,341
Rep Power: 399
TJ's GMC is on a distinguished road
Default Re: Proper sized exhaust

Quote:
Originally Posted by Funky61 View Post
I always thought those 40's would sound too loud ,
but they seem tame enough on you video TJ.
How are they on the highway?
I am a young buck so loud may have a different meaning to me. haha

Personally I like a little bit of Loud so it may be harder for me to say. The 40's were actually Quieter than I expected. Cruising down the highway at 2400 RPM they are very quiet. At 2000 RPM they Can get a little annoying if you don't mind some cab noise. But floor that sucker and rev it out and at 2500-3500 that tone will bounce off of fences and canyons and put a big smile on your face. lol I will be doing a wot run/driving video soon.
__________________
"Excuse the rust I use my truck"
1964 GMC 1500 305E/sm420 4 barrel intake mod and dual exhaust.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

1964 Chevy C20 292/SM420
1966 Chevy C10 292 hotrod 6/TKO600


My youtube channel aka Military Chevy:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #16  
Old December 2nd, 2016, 07:06 PM
TJ's GMC's Avatar
TJ's GMC TJ's GMC is offline
Senior Member
 
Join Date: Mar 2015
Location: Cave Junction, Oregon
Truck: 1964 GMC 1500 LWB Wideside 305E V6.
Posts: 1,341
Rep Power: 399
TJ's GMC is on a distinguished road
Default Re: Proper sized exhaust

Quote:
Originally Posted by bigblockv6 View Post
While calculations show 500 CFM to be overkill on a 305 running at factory designed engine speeds, as with many things, calculations do not represent real world results. More than likely, the same engine with a 500 CFM carb will make more horsepower than the same engine with a 350 CFM carb, or the factory carb.
[/QUOTE]Turbobill. I fully agree with you on that Years ago I tested all 3 of these carbs on my 68 305E and the Holley 500 was still by far the top performer, it's all about the real world results[/QUOTE]

Exactly!!!! Math results aren't Everything.

According to Math the small 2 stroke chainsaw engine is not supposed to even run. BUT! They run very well and very efficiently. Real world is what matters.

Math would show that my 600 edelbrock 4 barrel would drown my 305 out, yet it performs rather well!
__________________
"Excuse the rust I use my truck"
1964 GMC 1500 305E/sm420 4 barrel intake mod and dual exhaust.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

1964 Chevy C20 292/SM420
1966 Chevy C10 292 hotrod 6/TKO600


My youtube channel aka Military Chevy:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #17  
Old December 3rd, 2016, 02:25 AM
TJ's GMC's Avatar
TJ's GMC TJ's GMC is offline
Senior Member
 
Join Date: Mar 2015
Location: Cave Junction, Oregon
Truck: 1964 GMC 1500 LWB Wideside 305E V6.
Posts: 1,341
Rep Power: 399
TJ's GMC is on a distinguished road
Default Re: Proper sized exhaust

Here is a video of a 305 with flowmaster 50's. Bout the same, but at RPM they are supposed to be tamer than the 40's.

https://www.youtube.com/watch?v=FkpTLxOj-rI
__________________
"Excuse the rust I use my truck"
1964 GMC 1500 305E/sm420 4 barrel intake mod and dual exhaust.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

1964 Chevy C20 292/SM420
1966 Chevy C10 292 hotrod 6/TKO600


My youtube channel aka Military Chevy:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Last edited by TJ's GMC; December 3rd, 2016 at 03:56 PM.
Reply With Quote
  #18  
Old December 3rd, 2016, 01:10 PM
jbgroby's Avatar
jbgroby jbgroby is offline
Senior Member
 
Join Date: Jan 2013
Location: Lacombe, LA.
Truck: 1960 8' fleetside
Posts: 696
Rep Power: 268
jbgroby will become famous soon enoughjbgroby will become famous soon enoughjbgroby will become famous soon enough
Default Re: Proper sized exhaust

Ok thanks Guys, I'll go the dual exhaust route with 21/2 pipes and a cross over.

Jake
Reply With Quote
  #19  
Old December 3rd, 2016, 03:56 PM
TJ's GMC's Avatar
TJ's GMC TJ's GMC is offline
Senior Member
 
Join Date: Mar 2015
Location: Cave Junction, Oregon
Truck: 1964 GMC 1500 LWB Wideside 305E V6.
Posts: 1,341
Rep Power: 399
TJ's GMC is on a distinguished road
Default Re: Proper sized exhaust

Quote:
Originally Posted by jbgroby View Post
Ok thanks Guys, I'll go the dual exhaust route with 21/2 pipes and a cross over.

Jake
Be sure to post a video!
__________________
"Excuse the rust I use my truck"
1964 GMC 1500 305E/sm420 4 barrel intake mod and dual exhaust.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

1964 Chevy C20 292/SM420
1966 Chevy C10 292 hotrod 6/TKO600


My youtube channel aka Military Chevy:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #20  
Old December 3rd, 2016, 04:10 PM
bigblockv6 bigblockv6 is offline
Senior Member
 
Join Date: Jan 2013
Location: Rohnert Park, ca.
Truck: 1968 KM2500
Posts: 1,325
Rep Power: 415
bigblockv6 will become famous soon enoughbigblockv6 will become famous soon enough
Default Re: Proper sized exhaust

I'm pretty happy with 2 1/2 inch duals and 50 series mufflers on my 68 478M, of course that's the same system when I had the 305E, In the future I may switch over to 3 inch pipes and 40 series mufflers
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
305 V6 over sized pistons Archiver Previous Forum Posts 13 January 21st, 2013 07:18 PM
interchange of parts across different sized V6's Archiver Previous Forum Posts 0 March 21st, 2012 04:29 AM
proper hardware for valve covers Archiver Previous Forum Posts 4 February 11th, 2012 05:20 AM
Proper 637 thermostat Archiver Previous Forum Posts 0 February 5th, 2005 07:49 AM
Proper Spark Plug Archiver Previous Forum Posts 0 May 19th, 2004 01:53 AM


All times are GMT +1. The time now is 10:52 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 681711554703|1710453144|0