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

[TJ's GMC]

Originally Posted by Clyde

Don Meyer, GMC Historian can be reached at 248-693-1227, he is in Michigan. My 1966 Owners manual specifies 92 octane gasoline, back when these trucks were new this was considered regular gas, today this is considered high octane. Anyone over 65 will remember being able to purchase 110 to 120 octane gas without any problem at most all gasoline retailers.

Cool! Thanks for his number! Yeah, the good ol days when fuel was really fuel. lol

[Clyde]

The Pontiac Oakland International Chapter #93 (POCI) was established in 2007. The GMC Times is published 6 times a year by the GMC Truck Chapter of the POCI. The dues are $20 per year, I feel it is well worth joining as they are dedicated to our beloved GMC's. Anyone interested in joining can contact: Paul Bergstrom, 1165 County Road 83, Maple Plain, MN 55359 (763) 479-2248 pontiacpaul@gmail.com. You can also check them out at gtcpoci.info.

[TJ's GMC]

Originally Posted by Clyde

The Pontiac Oakland International Chapter #93 (POCI) was established in 2007. The GMC Times is published 6 times a year by the GMC Truck Chapter of the POCI. The dues are $20 per year, I feel it is well worth joining as they are dedicated to our beloved GMC's. Anyone interested in joining can contact: Paul Bergstrom, 1165 County Road 83, Maple Plain, MN 55359 (763) 479-2248 pontiacpaul@gmail.com. You can also check them out at gtcpoci.info.

Thanks for the info Clyde.

[TJ's GMC]

Well I did a test for the heck of it today....sorry...no pictures or video. Anyhow, I towed my 1947 Case VAI and that was loaded on a double axle trailer....so the load wasn't light....Bout 6000+ pounds. Well...I really hate the SM420 for towing applications because when you go from 3rd to 4th shifting at 3000 RPM things drop to 1500 rpm and pulling a slight grade things pretty much Stay there. lol I was at half throttle and slooooooooooooooooooooooooooooooooowly picking up speed. Good thing the highway leveled out. haha But on flat ground getting up to 55 no problem at all. GOOD torque in the low range....motor had NO problem at ALL pulling from 8 MPH in 3rd gear...bout 900 rpm lug if I remember right. Starting on Flat ground...rev it quick in granny then shift to 2nd and shift at 2700 rpm into 3rd then at 2700 rpm into 4th and sitting at around 2500 going down the highway...which was around 50-55. On a slight incline I would shift from 2nd to 3rd at 2700 then 3rd to 4th at 3000 and keep it half throttle the rest of the way. There was a hill I pulled in 4th no problem....bout 40 mph and hill ended before I needed to downshift. Motor has some guts for its smallish size as far as cubes go. But a gear vendors OD I think is needed now. Mainly to have something between 3rd and 4th for towing cause the engine hates that drop. I'll say one thing...I'm sure the 4 barrel and split exhaust helped a ton. lol If I ever run across a 478 I think I won't be able to resist a swap. LOL! Love my 305 v6 though! Good running engine...did what it needed to do with no problem and pulled hard with no complaints. She's a runner.

[TJ's GMC]

I do have a question though....anyone have an NP435 tranny behind their v6? Looking at the closer split between gears I may lean towards a swap. Looked into a gear vendors OD and said "**** No!!!" when I saw the price. lol

[bigblockv6]

In later years like 1967-69 there was a NP435GA that was a close ratio version, didn't have the granny 6.68 to 1 ist gear.

[Ed Snyder]

Originally Posted by TJ's GMC

I do have a question though....anyone have an NP435 tranny behind their v6? Looking at the closer split between gears I may lean towards a swap. Looked into a gear vendors OD and said "**** No!!!" when I saw the price. lol

My 2WD '67 has the NP435. Per the '67 sales brochure, it was the "heavy duty" optional 4 speed compared to the SM420. Starting from a stop in normal driving, you still start in synchro second, just like in the SM420. Non-synchro first is definitely a taller gear in the NP435, though, compared to the SM420. The shift pattern is different too -- reverse is to the right and down. The "bar" in the H between second and third is pretty narrow too. If you're used to shifting from second to third in an SM420, you'll overshoot third every time in the NP435 and go too far to the right and end up above reverse.

[BobBray]

My '67 has the NP435GA. The ratios are 4.56:1 1st., 2.28:1 2nd., 1.31:1 3rd., 1:1 4th.. Quite a bit closer than an SM420 as Peter and Ed pointed out! Be advised that Dodge and Ford also used a lot of NP435's, and most are wide ratio like the SM420's. Also, the NP435 was common in GMC medium duty trucks, but again these were wide ratio versions. The NP435GA was very well suited for the 351E, that engine's low r.p.m. torque didn't need the lower 1st./2nd./3rd. ratios.

[TJ's GMC]

Thanks guys! Yeah, according to the specs I've seen my SM420 has a 7.06 1st gear. I never did get what it was with GM and these crazily wide ratio trannys. They are horrible for towing heavy stuff. I mean 1st, 2nd, and 3rd aren't to bad....but 3rd is so low that you can't rev it high enough to shift to 4th. lol Unless on perfectly flat ground or downhill. Or you shift at 5000 rpm. haha For the occasional heavy towing I'm doing I think it'll work OK. Hoping to search so local yards though.

[68crackerbox]

Originally Posted by George Bongert

Greetings TJ!

As to who at GM came up with the design of the big block V-6, well, that's information that I don't have, although I also would like to know who that person was. As to the comparison between the 292 I-6 and the various versions of the GMC Big Block V-6's, I'll take the Big Block V-6's any day of the week before I would take the 292 I-6. As many here know, I once owned a 1963 Chevy 30 Series (1 ton) pickup originally equipped with the 292 I-6 which I eventually replaced with a GMC 305 V-6. Now, there will be those here who will disagree with me, but my feeling is that the 292 I-6 was nothing more than a glorified car engine put in a truck, and not necessarily designed to be a truck engine, although GM engineers would differ with me on that point. I know, because my Dad and I had plenty of problems with the 292. When I replaced the 292 with the GMC 305 V-6, those problems all disappeared. Now, having said that, yes, the 292 would be faster on acceleration and rev higher than a BB V-6, but as you indicated, the GMC V-6 will outlug the 292 six ways from Sunday, and all in all is a much more durable engine than the 292 ever was or will ever be. I know you have several 292's in your collection, and that you are very pleased with them. My experience has been the 292 is an engine (along with a few other GM engines) that I do not strongly favor.

On a lighter note, Merry Christmas to all here in the 6066 GMC Truck Club!

we had 292's in c/50 ten wheelers back in the 70's and they pulled and ran better than 350's and we were young then, alway kept to the floor(4000 rpm) and never had one come apart. they did a good job.