The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 02-19-2012, 10:24 AM   #1
aprilg57
Registered User
 
Join Date: Feb 2012
Location: Westminster, MD
Posts: 7
1968 C10 6 cyl to V-8 conversion

I have a 1968 C10 that I am converting to V-8. The bell housing, flywheel, pressure plate, clutch & starter all work with the V-8. The problem I have is that the clutch linkage interfers with the exhaust on the drivers side. I'm using a 68 Impala exhaust manifold to be able to use the alternator mount. The angle to the rear appears to be the same as on my 1968 GMC 3/4 ton with a 327. The difference appears to be that the GMC engine is mounted a little further forward than the C10. There are 3 holes in the frame for the engine tower. The GMC uses the front 2. The C10 uses the rear two.
Question 1: Under what configurations were the front 2 holes used? i.e. my GMC has the 4 speed. Is that the reason or is it the fact that it's a 3/4 ton or ?
Is there another manifold that dumps straight down but still has the alternator mount bolt holes on the end that I could use?
April
aprilg57 is offline   Reply With Quote
Old 02-19-2012, 11:05 AM   #2
lolife99
Old Trucks and a BelAir
 
lolife99's Avatar
 
Join Date: Nov 2002
Location: Mid-MO
Posts: 19,593
Re: 1968 C10 6 cyl to V-8 conversion

V8 trucks used the front 2 holes.
6-cylinder trucks used the rear 2 holes.
There is also a V8 specific and a 6-cyl specific set of frame stands for the enbgine mounts.
__________________
Keith
lolife99 is online now   Reply With Quote
Old 02-19-2012, 11:35 AM   #3
Dano69c10
Senior Member
 
Dano69c10's Avatar
 
Join Date: Jan 2005
Location: Ontario, Kali
Posts: 2,282
Re: 1968 C10 6 cyl to V-8 conversion

Also the manual transmission crossmember is different between v8s and L6s.
__________________
'69 Fleet

It ain't yours, if you didn't build it!
Dano69c10 is offline   Reply With Quote
Old 02-20-2012, 10:15 AM   #4
aprilg57
Registered User
 
Join Date: Feb 2012
Location: Westminster, MD
Posts: 7
Re: 1968 C10 6 cyl to V-8 conversion

Thanks for those inputs. Based on those I would assume that there is also a different length driveshaft for the V-8?
aprilg57 is offline   Reply With Quote
Old 02-20-2012, 10:20 AM   #5
50bomb
Registered User
 
50bomb's Avatar
 
Join Date: Jul 2010
Location: Southern Califas
Posts: 1,315
Re: 1968 C10 6 cyl to V-8 conversion

for my 67 chevy c10 longbed it was originally a inline 292 with the 3 speed manual overdrive. I converted to sbc350/th350 and the trans has the short tail. I had to get a longer front driveshft to trans. Paid $50 for a used on at a local salvage truck yard. and for the motor stands/trans crossmember i bought them off a member here for $40-50.
50bomb is offline   Reply With Quote
Old 02-20-2012, 10:23 AM   #6
lolife99
Old Trucks and a BelAir
 
lolife99's Avatar
 
Join Date: Nov 2002
Location: Mid-MO
Posts: 19,593
Re: 1968 C10 6 cyl to V-8 conversion

Quote:
Originally Posted by aprilg57 View Post
Thanks for those inputs. Based on those I would assume that there is also a different length driveshaft for the V-8?
yes
__________________
Keith
lolife99 is online now   Reply With Quote
Old 02-20-2012, 10:30 AM   #7
aprilg57
Registered User
 
Join Date: Feb 2012
Location: Westminster, MD
Posts: 7
Re: 1968 C10 6 cyl to V-8 conversion

Another good input.
Since I already have the engine installed and everything else matches up except the exhaust, I'm going to try a straight down exit left exhaust manifold. I have some from late 50's/early 60's cars. They have the mount holes for a generator to which I can mount an alternator bracket available from many sources.
aprilg57 is offline   Reply With Quote
Old 02-21-2012, 09:50 AM   #8
aprilg57
Registered User
 
Join Date: Feb 2012
Location: Westminster, MD
Posts: 7
Re: 1968 C10 6 cyl to V-8 conversion

I had another thought this morning. If the engine were to be moved foreward to the front set of holes in the frame, I don't believe the Z bar stud would match up. Was there a bracket that would center the stub between the 2 bolt homes in the engine?
Those of you changing over to an automatic wouldn't have to worry about this. Anyone change from a 6 to a V-8 and retain the MT?
aprilg57 is offline   Reply With Quote
Old 02-21-2012, 10:00 AM   #9
502ms
Registered User
 
502ms's Avatar
 
Join Date: Aug 2011
Location: Atlanta, GA
Posts: 1,453
Re: 1968 C10 6 cyl to V-8 conversion

One question I would have is will the transmission/clutch hold up to the torque of the new V8? What trans do you have?
502ms is offline   Reply With Quote
Old 02-21-2012, 11:02 AM   #10
lolife99
Old Trucks and a BelAir
 
lolife99's Avatar
 
Join Date: Nov 2002
Location: Mid-MO
Posts: 19,593
Re: 1968 C10 6 cyl to V-8 conversion

Quote:
Originally Posted by aprilg57 View Post
I had another thought this morning. If the engine were to be moved foreward to the front set of holes in the frame, I don't believe the Z bar stud would match up. Was there a bracket that would center the stub between the 2 bolt homes in the engine?
Those of you changing over to an automatic wouldn't have to worry about this. Anyone change from a 6 to a V-8 and retain the MT?
Is the pivot point on the 6-cyl block and the V8 block the same distance from the back of both blocks?
__________________
Keith
lolife99 is online now   Reply With Quote
Old 02-21-2012, 11:44 AM   #11
old Chevy guy
Registered User
 
old Chevy guy's Avatar
 
Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 835
Re: 1968 C10 6 cyl to V-8 conversion

Id have to check to be positive ly sure on the complete answer but I do know SBC has two holes for the pivit ball,not always tapped with threads . What I dont know for sure is there might be a bracket that bolts between the two holes on a 67-72 truck. I will look at my truck and post the answer later.
old Chevy guy is offline   Reply With Quote
Old 02-21-2012, 08:56 PM   #12
aprilg57
Registered User
 
Join Date: Feb 2012
Location: Westminster, MD
Posts: 7
Re: 1968 C10 6 cyl to V-8 conversion

The 6 cyl had a bracket that was bolted to the engine in 2 places and brought the pivot ball out about 10? inches. There is a bracket welded or rivited to the frame with a slot in it for the pivot on the other end of the z bar.
I do have 2 holes tapped for the pivot ball on the V-8. I used the front one which is directly across from the slot on the frame. I'll have to measure to be sure-but I believe the rear one is further back than the distance the engine would move forward if I changed the mounts.
Regarding the clutch being good enough for the V-8, that is a concern since this is the standard 10" clutch. I don't plan to do any drag racing. This is a pleasure truck. If it becomes a problem, I'll buy is new flywheel, clutch, pressure plate and throwout bearing of the 11" variety.
This one has the 3 speed on the column.
I'll do some measuring tomorrow.
aprilg57 is offline   Reply With Quote
Old 02-22-2012, 02:47 AM   #13
smoknbarrels
Registered Mail
 
smoknbarrels's Avatar
 
Join Date: Jun 2006
Location: Alberta, Canada
Posts: 503
Re: 1968 C10 6 cyl to V-8 conversion

I have a big block mind you... I had to modify my own z bar, nothing lined up and the L-6 z bar was too long, even though it has long bracket mounted to the block, still ends up being too long of a bar for a V-8. you might have to do the same thing, just knock a few inches out of the center of it. you are lucky if the sbc has a hole that lines up pretty close... i had to make a bracket on the engine side.
smoknbarrels is offline   Reply With Quote
Old 02-23-2012, 08:58 AM   #14
aprilg57
Registered User
 
Join Date: Feb 2012
Location: Westminster, MD
Posts: 7
Re: 1968 C10 6 cyl to V-8 conversion

Thanks to everyone for their responses. I was able to answer my own question as regards the pivot bracket on the engine side. I looked at my GMC mentioned in my opening message. It has a bracket mounted to the 2 engine bolt holes with the pivot about an inch and a 1/2 forward of the rear bolt. So from you all told me, I should have changed out the motor stands, the rear crossmember (which appears to be rivited in) and bought or fabricated a bracket to mount a pivot onto the engine. Since I didn't this information when I started the project, here's what I ended up with: I took out the 6 cyl. I installed the V-8 using the 6 cylinder motor stands. I bought a pivot from LMC truck that screws into the block. I installed that in the front hole. The Z bar lined up perfectly. I changed the LH exhaust manifold from the 68 to an earlier manifold that exits straight down. I used a new Y pipe that I had left over from an earlier project. The only issue left to address is the alternator mount (a piece of cake). I end up with a single exhaust with 2" pipe so I lose a little power (not an issue for me). About to be on the road!!
aprilg57 is offline   Reply With Quote
Old 02-23-2012, 09:06 AM   #15
aprilg57
Registered User
 
Join Date: Feb 2012
Location: Westminster, MD
Posts: 7
Re: 1968 C10 6 cyl to V-8 conversion

Just a little more background. I bought the GMC out of the Kenny's Klunckers section of Old Cars Weekly a couple years ago. It was advertised as "rusty but runs good" and the price was $750. It had the original 327 with 97xxx miles and the Quadrajet had recently been rebuilt. I bought it (primarily for the 327) intending to use it as a donor truck. I drove it from Illinois to Maryland and am getting some use out of it. It has just over 100,000 miles on it now. At some point in the future it may become a donor to the C10. If that happens, I'll have everything I need to do the job right.
aprilg57 is offline   Reply With Quote
Old 02-25-2012, 10:26 AM   #16
old Chevy guy
Registered User
 
old Chevy guy's Avatar
 
Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 835
Re: 1968 C10 6 cyl to V-8 conversion

Glad it all worked out. Thats what is so awsum about GM stuff in general,you can mix and match so many parts and make stuff work.Try doing what you just did with ford or dodge truck. Probably wouldnt work out so well. Just saying don't anybody get excited.
old Chevy guy is offline   Reply With Quote
Old 02-26-2012, 05:09 PM   #17
hungarian1964
Registered User
 
Join Date: Feb 2012
Location: Lacrescenta, CA
Posts: 62
Re: 1968 C10 6 cyl to V-8 conversion

would you be interested in selling the brackets that bolt to the engine? Not the mounts but the brackets that bolt to the engine
hungarian1964 is offline   Reply With Quote
Old 09-06-2012, 06:41 PM   #18
454C10CHEVY
Registered User
 
454C10CHEVY's Avatar
 
Join Date: Aug 2012
Location: PITTSBURG,CA
Posts: 89
Re: 1968 C10 6 cyl to V-8 conversion

whats the difference between the i6 and v8 manual crossmember can it just be moved up or is it different altogether?
454C10CHEVY is offline   Reply With Quote
Old 09-06-2012, 07:15 PM   #19
SS Tim
"Just the facts, Ma'am"
 
SS Tim's Avatar
 
Join Date: Aug 2010
Location: Edwards, CA
Posts: 4,755
Re: 1968 C10 6 cyl to V-8 conversion

Quote:
Originally Posted by 454C10CHEVY View Post
whats the difference between the i6 and v8 manual crossmember can it just be moved up or is it different altogether?
Funny, but my parts manual doesn't show the I6 crossmember. However it does show 8cyl and BB manual crossmembers as seperate applications with different P/Ns.
__________________
Thanks,
Tim
***** MISSING STILL ***** LOST HUSKY ******************
Day 150
If you are in the Antelope Valley within or about the area bordered by Mojave/CalCity to Vincent Hill and Adelanto to Neenach please keep an eye out for my boy and read the "Found Husky" ads.... http://losangeles.craigslist.org/ant...636348994.html
Thank You! Everyone!, For all your kind words and ongoing support.
SS Tim is offline   Reply With Quote
Old 09-06-2012, 07:19 PM   #20
454C10CHEVY
Registered User
 
454C10CHEVY's Avatar
 
Join Date: Aug 2012
Location: PITTSBURG,CA
Posts: 89
Re: 1968 C10 6 cyl to V-8 conversion

I guess ill b needing one of those i didnt see it in the classic industries book(i could have just missed it) which one are you looking in?
__________________
72 C10 SWB Stepper 350/TH400 (might sell)
70 C10 SWB Stepper I6/4SPD (CURRENT PROJECT)
00 Silverado Rc 1500 2WD 5.3
09 Silverado Cc 5.3 2WD 4/6 DROP
04 Silverado ext 5.3 4WD
454C10CHEVY is offline   Reply With Quote
Old 09-06-2012, 07:39 PM   #21
SS Tim
"Just the facts, Ma'am"
 
SS Tim's Avatar
 
Join Date: Aug 2010
Location: Edwards, CA
Posts: 4,755
Re: 1968 C10 6 cyl to V-8 conversion

GM... I'm guessing you don't follow my posts. :-)
Attached Images
  
__________________
Thanks,
Tim
***** MISSING STILL ***** LOST HUSKY ******************
Day 150
If you are in the Antelope Valley within or about the area bordered by Mojave/CalCity to Vincent Hill and Adelanto to Neenach please keep an eye out for my boy and read the "Found Husky" ads.... http://losangeles.craigslist.org/ant...636348994.html
Thank You! Everyone!, For all your kind words and ongoing support.
SS Tim is offline   Reply With Quote
Old 09-06-2012, 07:43 PM   #22
ZMAR
Registered User
 
ZMAR's Avatar
 
Join Date: Aug 2012
Location: Breck, tx
Posts: 131
Re: 1968 C10 6 cyl to V-8 conversion

I just did the same swap on my 67. I used the old ram horn center straight down exit because of the Zbar mess. does anyone know of the similiar setup but w/ a brand name header?
__________________
71 c10 swb
ZMAR is offline   Reply With Quote
Old 09-17-2012, 02:35 PM   #23
Tailgate20
Registered User
 
Join Date: Jun 2012
Location: Guelph Ontario Canada
Posts: 5
Re: 1968 C10 6 cyl to V-8 conversion

I'm also deep in this swap. I6 to sbc while keeping the manual 3 in the tree.

I used a ball stud which almost perfectly lined up my bell crank but my clutch isn't disengaging and my floor shifter conversion is to close to the seat to be useful. I'm not sure if i need a new clutch. My clutch seemed to be in good shape when I took it off the I6 and bolted it on my 350. Are they even interchangeable or do I need to find a V8 clutch?

Dynomax block huggers fit this application with slight engine tower mods for clearance.
Attached Images
  
Tailgate20 is offline   Reply With Quote
Old 09-17-2012, 03:02 PM   #24
Fitz
Registered User
 
Fitz's Avatar
 
Join Date: Jan 2007
Location: Tucson
Posts: 1,420
Re: 1968 C10 6 cyl to V-8 conversion

The trans crossmember is not a problem. My truck started out as an I6 manual and, as you can see, it grew a few new cylinders and a built turbo 400. I cut and punched out the rivets holding the crossmember in the forward set of holes...just behind the cab mount... and moved it back to the second set of existing holes....so nice of GM to provide correctly spaced holes for a motor and trans that didn't even exist in 1967!
Attached Images
 
__________________
You can never be too pretty, too rich or have too much horsepower!
Fitz is offline   Reply With Quote
Old 03-27-2014, 08:28 AM   #25
jpmanyhearts
Jer's Rod's & Customs
 
Join Date: Apr 2009
Location: Havre Montana
Posts: 195
Re: 1968 C10 6 cyl to V-8 conversion

Quote:
Originally Posted by SS Tim View Post
GM... I'm guessing you don't follow my posts. :-)
where do you get one of those books at ?
__________________
Jer's rods & customs
jpmanyhearts is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

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

Forum Jump


All times are GMT -5. The time now is 01:56 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 1997-2013 67-72chevytrucks.com