SO who came up with the GMC V6's???

[TJ's GMC]

Thanks for all the knowledge guys!

[bigblockv6]

Originally Posted by TJ's GMC

Big improvement for sure...and that's with the 4 barrel mounted on a 4 to 2 adapter. It should help even more when I have the intake machined to directly fit the carb. The split exhaust made for a nice improvement as well. I'll check out the sight for that issue! Thanks!

It will definitely make a bigger improvement once you machine the manifold. Many years ago I tried the 4 to 2 adapter and the results were abysmal, the idle would fluctuate and when the secondary's kicked in it would stumble for a couple of seconds. I suspect it was a very poor quality adapter that leaked vacuum. All in all there is only so much fuel that you can squeeze in a small opening.

[TJ's GMC]

Originally Posted by bigblockv6

It will definitely make a bigger improvement once you machine the manifold. Many years ago I tried the 4 to 2 adapter and the results were abysmal, the idle would fluctuate and when the secondary's kicked in it would stumble for a couple of seconds. I suspect it was a very poor quality adapter that leaked vacuum. All in all there is only so much fuel that you can squeeze in a small opening.

Mine idles perfectly, but has the same problem when the secondaries kick in....In 4th if I stuff it to the floor the thing jerks and rattles then clears up. lol I suspected either no vacuum advance or to much fuel for a small opening. But if I quickly ease into full throttle it responds fine. So for now I've left it cause its running so good. But when I get my 66 done I'm gonna get into this one. The improvement was major over the 2 barrel. With the 2 barrel I couldn't even rev the thing past 2500 rpm to shift or it seemed to take a month of sundays to get there...hence why I'm sure that old carb was plugged up. Lugging it into 4th proved faster than reving it. It actually would accelerate faster when I had the truck loaded down, least it sure felt that way.lol But once the 4 barrel went on, shifting at 2500 has been the best rpm. And when I split the exhaust, 2700 is now a good rpm.

[bigblockv6]

Talking about who at GM designed the V6, well about 14 years ago a GM engineer that was involved with the development of these engines stumbled into Jolly's site and was quite surprised that there were people that were interested in these engines. His last name was "Cleary" and that's what he went by. He had mentioned early prototypes let loose and scattered easily, more balancing was required. Also the reason for the spark plugs inside the "V" was because during testing one of the engineers went to change the spark plugs and ended up burning his hand on the manifold so spark plugs were relocated inside the "V". Cleary stepped away from that in 1960 or so, he mentioned at that time they were working on Diesel versions. I did save the emails in my old computer, if I get it hooked up I may be able to retrieve it to share with everyone. I also contacted Cleary once myself.

[TJ's GMC]

Originally Posted by bigblockv6

Talking about who at GM designed the V6, well about 14 years ago a GM engineer that was involved with the development of these engines stumbled into Jolly's site and was quite surprised that there were people that were interested in these engines. His last name was "Cleary" and that's what he went by. He had mentioned early prototypes let loose and scattered easily, more balancing was required. Also the reason for the spark plugs inside the "V" was because during testing one of the engineers went to change the spark plugs and ended up burning his hand on the manifold so spark plugs were relocated inside the "V". Cleary stepped away from that in 1960 or so, he mentioned at that time they were working on Diesel versions. I did save the emails in my old computer, if I get it hooked up I may be able to retrieve it to share with everyone. I also contacted Cleary once myself.

If you could find those that would be cool! By the way I read the article...Lot of neat info right there. On another note I've been driving my gmc around in the snow today. lol Even did a burnout! haha Headlights, windshield wipers, and heater all on and no problems. PO took the original heater cables and control panel out cause they were seized up so I settled for a select switch from Napa and manually set the vents so I get hot air. No fogged up windows now(hopefully). lol Need to drive it some more and see how well the defrost works, but it only took a couple seconds for that cab to get warm.

[George Bongert]

Originally Posted by bigblockv6

All the Chevrolet engines whether small or bigblock V8 and sixes were nothing but passenger car engines. Chevrolet even converted the big block V8 into a truck engine by adding an extra compression ring to the pistons, adding an inch to the deck height and there the 366 and 427 trucks engines were born, truly over glorified passenger car engines and GMC was forced to drop their V6 for these junk piles in the mid 70's.

Greetings bigblockv6!

I can't help but agree with you, and I too am saddened by the fact that GM discontinued the Big Block V-6 engines. Their durability put all other engine designs to absolute shame, no matter who the engine manufacturer was. By the way, I failed to mention that my old '63 Chevy was traded in for a brand new Dodge one ton pickup. Apparently the original owner of my '63 Chevy was not too happy with the fact that he had to replace 3 pistons in the original 292 I-6, and the fact that they probably were not all replaced at the same time resulting in more than one engine tear down. I'm not sure what engine (V-8 or Slant I-6) the Dodge truck that he bought had in it, but I will go as far as to say that even the Dodge Slant I-6 was a better engine than the Chevy 292 I-6.

[Funky61]

I found one email in the archives that Pete (referenced) YAY for the Archives and Jeannie.

http://6066gmcclub.com/forum/showthr...eary#post16253

[TJ's GMC]

Originally Posted by Funky61

I found one email in the archives that Pete (referenced) YAY for the Archives and Jeannie.

http://6066gmcclub.com/forum/showthr...eary#post16253

That was neat! Thanks for sharing!

[bigblockv6]

Originally Posted by Funky61

I found one email in the archives that Pete (referenced) YAY for the Archives and Jeannie.

http://6066gmcclub.com/forum/showthr...eary#post16253

Thanks Funky61, you saved me the hassle from looking it up for now anyway. I do have one email to look up where I directly contacted Cleary with some more questions. For now though this is really good

[bigblockv6]

Originally Posted by George Bongert

Greetings bigblockv6!

I can't help but agree with you, and I too am saddened by the fact that GM discontinued the Big Block V-6 engines. Their durability put all other engine designs to absolute shame, no matter who the engine manufacturer was. By the way, I failed to mention that my old '63 Chevy was traded in for a brand new Dodge one ton pickup. Apparently the original owner of my '63 Chevy was not too happy with the fact that he had to replace 3 pistons in the original 292 I-6, and the fact that they probably were not all replaced at the same time resulting in more than one engine tear down. I'm not sure what engine (V-8 or Slant I-6) the Dodge truck that he bought had in it, but I will go as far as to say that even the Dodge Slant I-6 was a better engine than the Chevy 292 I-6.

That was a sad day for me back in Nov 1974 when went over to our GMC dealer to pick up a new light switch for the 68 before my father found out I broke it to pieces, I was only 15. Anyway there was not one Medium duty truck or larger 7500 series truck on the lot with a V6. I was quite surprised to see a J-7500 series with a 427 V8 for the first time. Some 6 months prior to that just about every medium duty( at least 25-30 trucks) all 7500 series trucks were V6 equipped, my impression then was the V6 was alive and well and they had no problem selling them off. Funny thing was in November there was still quite a few V8 74 medium duty trucks left over with the mix of 75 models.