fabricating performance parts for a 305 GMC V6 - Page 5 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #61 (permalink)  
Old 03-02-2012, 01:25 PM
Registered User
 
Join Date: Apr 2010
Location: washington
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I have a 68 GMC with a 305 v6 that i have been working on for a while now. It bothers me that there are so many people on a hotrod sight that say "don't waste your time with that". Hot rodding is taking something that is sock and making it different or you own, not the same as everyone else has.

I have adapted a Carter 600 CFM 4v to my stock manifold, and the truck came to me with new dual 2 1/2" exhaust. my truck runs strong and will rev just fine. That cab that GMC put on at the factory is the big problem. I have been a heavy truck mechanic for over twenty five years and have never seen an engine that was designed for low RPM, they are usually limited by one component or an other, these engine just can't breath. with the new carb my engine will run 5,000 RPM all day long. I run light weight full synthetic oil in it and average 14 MPG, not the typical 7 MPG that you get with the stock set up. If my v6 were to bow I would find an other over a SB any day.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #62 (permalink)  
Old 03-02-2012, 02:41 PM
Registered User
 
Last wiki edit: Building a GMC 702 V-12
Join Date: Jun 2010
Location: Northeast
Posts: 16
Wiki Edits: 44

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by therammstein
I have a 68 GMC with a 305 v6 that i have been working on for a while now. It bothers me that there are so many people on a hotrod sight that say "don't waste your time with that". Hot rodding is taking something that is sock and making it different or you own, not the same as everyone else has.

I have adapted a Carter 600 CFM 4v to my stock manifold, and the truck came to me with new dual 2 1/2" exhaust. my truck runs strong and will rev just fine. That cab that GMC put on at the factory is the big problem. I have been a heavy truck mechanic for over twenty five years and have never seen an engine that was designed for low RPM, they are usually limited by one component or an other, these engine just can't breath. with the new carb my engine will run 5,000 RPM all day long. I run light weight full synthetic oil in it and average 14 MPG, not the typical 7 MPG that you get with the stock set up. If my v6 were to bow I would find an other over a SB any day.
That is one problem, "they can't breathe". Judging by the fact that you can't get your thumb into the exhaust port past where the internal water jacket casting is, a great hot rodding feat would be to come up with a performance head for this thing. I have even been told by folks who have ported these that the magnum heads offer no advantage over the smaller head when all porting is said and done. I have noticed that there are several varieties of these heads which include monster size sodium filled stems that definitely choke it down. Given the exhaust port limitation in flow, a turbo charger may be the easy way out to get the HP potential.

Yes... true hot rodding ingenuity in play. Anyone can bolt aftermarket parts together but who has the fastest 305 V6 GMC??? sounds like a Bonneville challenge in the works.
Reply With Quote Quick reply to this message
  #63 (permalink)  
Old 03-02-2012, 02:59 PM
Registered User
 
Join Date: Apr 2010
Location: washington
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
funny, I have been rounding up parts for a turbo setup for two years now. I have everything I need, but I think that I will be running EFI of some kind so that I don't have to mess with pressurizing a carb, that can be a pain.
Reply With Quote Quick reply to this message
  #64 (permalink)  
Old 03-02-2012, 03:52 PM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,657
Wiki Edits: 0

Thanks: 15
Thanked 60 Times in 57 Posts
Funny enough. This thread is 3 years old.
Reply With Quote Quick reply to this message
  #65 (permalink)  
Old 03-02-2012, 05:24 PM
Registered User
 
Join Date: Apr 2010
Location: washington
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I know it's old, someone posted on it last month so it is still live.
Reply With Quote Quick reply to this message
  #66 (permalink)  
Old 03-03-2012, 09:19 AM
Banned User
 
Last photo:
Join Date: May 2011
Location: N.E.
Posts: 385
Wiki Edits: 0

Thanks: 9
Thanked 6 Times in 6 Posts
i love this engine series, but for general hotrodding what advantage does it have over the chevy v-6 or inline 6?

It makes you wonder why gmc went to all chevy power by 69?
Reply With Quote Quick reply to this message
  #67 (permalink)  
Old 03-03-2012, 10:09 AM
ChevelleSS_LS6's Avatar
Jeep XJ and a Javelin
 
Last wiki edit: Compression test
Last journal entry: August 9, part III
Last photo:
Join Date: Dec 2001
Location: Grand Rapids, Michigan
Age: 29
Posts: 1,614
Wiki Edits: 7

Thanks: 6
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by against all odds
i love this engine series, but for general hotrodding what advantage does it have over the chevy v-6 or inline 6?

It makes you wonder why gmc went to all chevy power by 69?
Cost cutting. Why did Buick, Pontiac, and Olds get all Chevrolet engines a decade later?

Okay... I'm a bit wrong here... the Quad4 is the last "Oldsmobile" engine, and the Northstar (and its 'shortstar v6') are Cadillac, and the 3800 was a Buick design.

Currently, I think the only non-Chevy engine is the Northstar engine. Sure, Cadillac may have different heads for the direct injection on the 3.6L v6, but I'm pretty darn sure it's the same shortblock, perhaps with different pistons.

It's part of why GM killed off Olds. Olds is a luxury brand like Buick, and they were 'cannibalizing' each other. So, GM kills Olds so it can have operating costs for only one "nicer than Chevy, but not quite Cadillac" division.

As for Pontiac, they were just a sportier designed Chevrolet for the past 20 years, maybe with slightly different spring rates. But I'm sick of "cloning" cars. In a way I'm glad to see Pontiac and Olds go away after being "Chevy clones". In a way I'm sad, as at one time they were great divisions with significant differences from your average Chevrolet, differences worth (in my opinion) paying for.

As for building the GMC 302 v6, or any other 'oddball' engine for that matter, go for it! I have far more admiration for 'different' than "another sbc/LSx". I can't say I've ever seen a turbo'd straight six '69 Camaro.
Reply With Quote Quick reply to this message
  #68 (permalink)  
Old 03-04-2012, 04:41 PM
Registered User
 
Join Date: Apr 2010
Location: washington
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
there is a guy on youtube dynoing a 250 chevy l6 turbo. he is very low tech but it works well. I will try to find the link later.
Reply With Quote Quick reply to this message
  #69 (permalink)  
Old 06-05-2012, 09:22 PM
Registered User
 
Join Date: Jun 2012
Posts: 1
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
305 v6

not sure if its an upgrade but my 305 v6 has a 2 barrel 350 cfm holley carb on it with no apparent modifications to the intake
Reply With Quote Quick reply to this message
  #70 (permalink)  
Old 06-06-2012, 11:09 AM
Registered User
 
Join Date: Apr 2010
Location: washington
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
That carb should be much better than stock. How does it run?

Obviously I have lofty goals for my GMC 305 but I plan on doing it in steps, like now that I have a Big (too Big for now) carb I will be fabbing up some headers and maybe even an intake manifold. Then later the Turbo.

First thing is to get some better gears in the back, she has 4.11:1 posi stock, but all of that low end torque I would like to go with more like 3.50:1.
Reply With Quote Quick reply to this message
  #71 (permalink)  
Old 06-06-2012, 12:27 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 9,485
Wiki Edits: 0

Thanks: 20
Thanked 389 Times in 365 Posts
So are you still looking to fab an intake manifold? If so id tune your runner length and crosssections to give you peak power right at your cruising rpm. Id also go itb as it makes it easier to get your desired lengths with a decent package size. Properly done headers, induction, head porting, vj, and a cam may be able to double your power at cruise- which is a hell of an increase but everything needs to be properly designed.
Reply With Quote Quick reply to this message
  #72 (permalink)  
Old 06-06-2012, 03:38 PM
Registered User
 
Join Date: Apr 2010
Location: washington
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I was not the one that started this thread wanting to fab an intake, how ever that does seem to be the best solution to both the lack of any parts available and also excess weight.
As far as being properly done, I have done and will do my home work before I go all in. I have been a mechanic for 33 years and have built many hot rods and sports cars. That being said I would not be bothered if I missed out on 2% horse power because I didn't get the optimum plenum length. I care more about cool and unique.
I leave speed to my Bikes and sports cars. It already runs as strong as my buddies 72 chevy 350 and sounds cool doing it.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Has anyone ever seen a hotrodded GMC V6 or V12? FrankR Hotrodding Basics 19 03-03-2012 05:33 PM
93 GMC V6 with a odd 4L60E problem 93GMCv6 Transmission - Rearend 4 12-27-2005 07:09 AM
1954 GMC V6 3 speed on the floor swap out Flaming54 Engine 3 10-16-2003 06:02 PM
performance parts for Pontiac 2.8L 86birdman Engine 2 11-08-2002 10:41 PM
high performance parts for 5hp honda engine? atlantisjones Engine 1 05-19-2002 08:44 PM


All times are GMT -6. The time now is 08:03 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.