The '60-'69 GMC 305 V6 conversion to a Pontiac V8.
 

I have heard the GMC trucks from '60-'69 have a GMC 305 V-6. By any chance, has anyone converted from a V6 to a Pontiac V8? Just that I have seen some of these trucks for sale, and would rather convert to a Pontiac V8 instead of a "Chebbie".

Something else to add.
 

Have some pics and responses, please.

That 60 degree V6 is not a chevy engine it is a GMC design, chevy never used it in their trucks. Since a Pontiac was available as an option in 55-57 GMCs there should be plenty of room for the swap and possibly I have a feeling that if you could find GMC/Pontiac mounts you might have a starting point to work from. These early trucks(55-57) used one central mount under the cast iron timing cover and I believe 2 side mounts on the bellhousing area.


If not you would have to fab later style motor mounts (2 side mounts and a single central transmission mount) and which should not be too difficult if you have decent fabrication skills. I've never done this particular swap but it can't be any harder than putting a Pontiac Stratostreak V8 in a 4X4 Jeep Wagoneer or a Jeep pickup truck which I have done.

They also made a 351,401 & 478 cid version; very tough engines. Pisses me off when I see one of those yanked for a 350 Chebby :gag:

I had one in a 65 GMC truck, would climb a mountain but didnt like going over 60 mph LOL

That was 1960-1966 model years. In '67 they went "corporate" (SBC).

As Brad said, Pontiac engines were used as the V8 option in light/medium GMC trucks (up through series 500)- in model years '55 - '59. But the '60 GMC was so totally redesigned (torsion bar front springs, etc.) that this doesn't help you at all- I don't think a single chassis part carried over from '59 to '60.

Try oldgmctrucks.com- some member there has probably converted a '60 -'66 to a V8.

I had a Jimmy with one of those V-6 motors, not sure what cube but in a pick up. Damn thing had Scotch Pladd valve covers on it....from factory..think it was the "thrifty" version..:D Pulled like a draft horse...I changed it over to a truck style 4 speed....and promptly twisted drive shaft in pieces !! Neat motor...but not fast.

Agreed Brad. My Uncle still has a 2 ton grain trunk under his barn with the 305 V-6. I keep trying to get him to give it to me as it has been sitting for years but he is wont. I remember driving it as a kid loaded with corn and it had no problems at all. Top speed was 55 as we just kept the gas pedal on the floor at all times. :) I love to find me one of those engine for a generator project I'm building.

Here ya go:

http://www.google.com/imgres?imgurl=...9QEwAg&dur=404

OMG, brings back memories, 19 yrs old, was wrenching at a Gulf gas station in Easton Pa. guy bring in this GMC pu says it either has cracked head or head gasket, so after getting the intake off and undoing all of the headbolts I pry up on the corners just to break the seal.

Now I was fresh off the farm and would normally just reach in with both hands and "yank" the head off the motor and out of the engine bay. This time the head "yanked" me into the engine bay. Pistons like coffee cans! LOL

I also think that the water pump weighed about 200 lbs, thanks for taking me back 35 years.

I read that they even made a 702 ci V12 with two 351 v6 inline with a single crankshaft! Yikes. Need a pic of that.

http://thunderv12.com/

http://www.google.com/search?q=702+c...ient=firefox-a

I have one of the 702's. I bought it from a guy in Oklahoma. It was used as an irrigation engine and ran its whole life on natural gas. One block, 4 heads, 2 intakes and carbs and one distributor with two distributor caps

Here are a couple on Epay
http://motors.shop.ebay.com/i.html?_...2+v-12&_sacat=

Cool.. thanks for the link to the the Thunder ...pricey..yikes