What is it and how does it work(pic)

[northern 85]

1967 gmc big block 305e turbo 400 tranny. Is this a govenor switch that is on the backside of the carb linkage, if so how does it work?

[royo]

WOW kool motor . I dont know about that part but that motor looks kinda like a big block. the sparkplugs are in the wrong place lol could it be a kick down for passing gear on the t400

[uncle]

Royo is correct.

[northern 85]

All t400 run this type of switch?

[Sport/Truck]

That's the switch that activates the N2O.
+1 on the cool motor.
s/t

[Longhorn Man]

all TH400's from 1970 and older used that, in 71 to 90-something, it was located on the throttle.
Just as clerification, so more ppl aren't misinformed, that isn't a 'big block'... it's just a V-6.

[bankone1]

nice motor i think this is the first time i seen a set of GMC valve covers looks like a keeper to me

[LONGHAIR]

Just as clerification, so more ppl aren't misinformed, that isn't a 'big block'... it's just a V-6.

I just knew that someone was gonna say it...........I almost did a few hours ago.

[67_C-30]

Just FYI, V6's with auto trannys are pretty hard to come by. The transmission adapter, flexplate and converter are worth some coin. Did you ever try to get it running?

[northern 85]

This respones is for Longhair and Longhorn Man. I found this information on this website just for clarification... http://www.6066gmcguy.org about the big block v6.

[Longhorn Man]

nope, that's a generic nick name chevy guys have given it. If you look at GMC lit from back in the day, it was neverr ever refered to as a big block.

[northern 85]

Did you look at the website?

[WyoRoadDog]

I don't know, at 795 lbs. for a 305e, it's a pretty "big block"! But I would be willing to bet Longhorn Man is right, that is was never originally referred to as a big block, and that designation came about later, as V6 engines became more available and popular. IIRC, there is no "small block" vs. "big block" on the GMC V6, they all used the same block, unlike the Chevy V8's.

[ChevLoRay]

A classmate of mine in high school drove a '60 GMC that had the same V-6 but with a 3-speed. It would pull from a low RPM in high gear without missing a beat. Gobs of torque.

[northern 85]

So you are saying that my 4.3 v6 is the same size block as my 305e v6?

[67_C-30]

Originally Posted by northern 85

So you are saying that my 4.3 v6 is the same size block as my 305e v6?

Of course not, but the 4.3L didn't exist in 1960 when these came out. The only real big block engines are the big block Chevys, big block 429-450 fords, and 383-440 big block Chryslers. Pontiacs, Olds, Buicks and Caddys are often referred to as big blocks, but they really aren't, even though some of them are big engines. Jolly's 60-66 gmc website does refer to them as big block V6's, but it is technically incorrect.

[abebummy26]

subscribed for the lmao factor!

[LONGHAIR]

Google "big block pontiac" and I guarantee you that you get some hits on that term.....Don't make it so though.

All of the Pontiac V8s from 1955- to the late 70s when the "corporate engine" mess started used the same size block. 287-455, they had different bore sizes and stroke lengths...I think there was a main bearing size thing in there somewhere too, but the blocks were the same externally.


It's just like all of the "head" names for Harleys. They(HD) did not use those names..Knucklehead, Panhead, Shovelhead, Blockhead, were terms used by the riders/bikers/mechanics, given to the various year groups of what Harley Davidson called OHV. Meaning "Over-Head Valve" as opposed to Flat-heads of the same era. Harley picked-up and even trademarked those words later, but they didn't create them.

[northern 85]

Thats why i thought it was true because this motor is huge compared to any other v6s

[Spray-Bomb]

The GMC V-6's are some really cool old engines

big block or not, they are some BIG HEAVY engines
When you do get it going, dont try to rev it very hard, as they are big & heavy with no harmonic balancers & they wont last well if you twist em... ask me how I know this

[Down south truckin]

I know it is not an official big block but it makes me wonder was a 396 427 454 ever call big block officially by chevy??or was it a slang term that caught on and with the 305 having a bore size of 4.25 the same as a 454 and the 351 having a bore of 4.560 way bigger than even a 502 I would say it could be called a big block V-6 but it does have a in line valve train system like the small blocks so who knows??????

[northern 85]

I guess i should be calling them a large block v6 seeing how its bigger than any v6, and bigger than any small block chevy ive seen.Hearing the history of these i cant call it just a v6 Its all good because anything that sparks interest in our hobby and these trucks maybe will save one more from beeing chrushed! I used to have that attitude of its just a v6 pull it, junk it,not now. i love small block chevys, but this thing is cool.So far everytime i have opened the hood for someone they say what the - is it? Its a305e that only came in in a GMC TRUCKS thanks for your time and help guys.

[Sport/Truck]

It's a small block-and-a-half! You definitely have something nice and worth keeping - and it's got GMC on it!
s/t