Putting miles on 67, 402bbc VS 67 V6 305E
 

Amazed how much better this GMC drives after pulling 305E and upgrading to 402 BBC. conversion.

Drives like a car, smooth, V6 was unique, but seriously under powered.

305E V6 7.5mpg. 170hp

402 bbc 12mpg. 310hp

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

What year is the 402? GM didn't punch out the 396 until 1970.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

I got the 402 from a 1970 SWB CST takeout.
All date codes are correct for vehicle it came from.

All I changed was intake to a Holley cast iron 1966 hi rise.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Thinking next upgrade, is a gear vendor over drive. Then I can run freeway speeds..

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Gladyou like it. Theb6 can rip a building out of its foundation, but definitely lacks hiway guts. The OD will definitely help calm the BBCon the hiwY also

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Yep, V6. Had good low end lugging torque, but also lacked RPM. It went to a good home, guy restoring K20 4x4 GMC V6 truck.

This 402.. goes up steep hills in Drive that put my V6 in 1st.

I only need OD and then this is a true parts chaser.

I have the NP435G trans, and trans cross member and mounts, and engine mounts for V6 if someone needs them.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Your very likely ruined for life! Once you feel the torque and the pony's them BBC's make, they own you! "Jus sayin" ;)

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Got a 454 in my '71.. It's a disease I tell you. The first symptom is you go around with a smile on your face. Also makes you forget about gas mileage..

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

When GM started offering the 396-402 in 3/4 tons, a 3.54 Dana became standard equipment, but, if you have the wallet......................

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

What's the current axle ratio? A mild 402 with all that torque should work just fine with a 3.08 or even a 2.73, depending on tire height and desired highway speeds.

My 82 C10 had a mild 355/TH350 with a 2.73 and 29.5" tall tires. Cruising at 70mph was ez-peezy, but it would spin the tires in first gear.

Just trying to save you from OD expense and hassles, although the GV should be less of a PITA than a 700R4. And it will never break!

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Ran another 100mi + today, with 10gal of premium thru the big block.

Truck has 4.10 gear Dana 60.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

So 8 to 10 MPG whether your driving easy, towing or whatever then. ;)

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Front sway bar is going to be next.... lot of nice winding roads to be seen.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

12mpg rolling empty road trip, 55mph is. 402bbc

V6 7.5mpg uphill, down hill, hauling water.. it just liked fuel. But since designed in late 50s, looks like ports from a 348...anchor, neither designed for fuel economy, but fuel was cheap. Massively heavy built, designed for durability. My old V6 is going in a 67 4x4 restoration, his block was cracked. Win-Win

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

If your friend would happen to know of a extra set of V6 4X4 engine perches I'm in bad need of a set for my restoration. My truck had been converted to a sbc at one time but it did have the original V6 with it. Thanks for any help.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Are the front mounts the same? Bell housing on mine was 4spd,
If yours is a stick, it might be the same.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

You pay shipping, you can have them.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Where in ohio? Pick them up, you can have three mounts, brackets, x member.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

I'm in Batavia, mine is a 4sp. Could you send me pictures, if they're right I'll be on the way. Thanks

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Bet it's same, not too many ways to mount that V6. Heading down to barn.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

I may not be able to get back to you until tomorrow.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

No problem, bet there is only one set of mounts for V6, big engine tight fit. I have eng mounts and frame mounts. And crossmember for bell housing to frame with mounts.

My 67 is here to look at frame hole locations.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Had a 78 suburban with 454, ran good, ended putting eng and trans TH400 in a 78 Silverado that was originally a diesel. It had 2.73 gears. Was perfect for Texas freeways and FM roads.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

The frame mounting brackets (perches) and front crossmember are different on 4X4 vs 2WD. I have the brackets on the engine and a crossmember I've found (same as chevy 292 4X4) but I'm short the frame brackets. The rear mount crossmember I have as it was the same for chevy V8 or GMC V6 4X4's.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

So the rear X member on bell housing is same. Mine is all there. The engine Bell housings were (Not HD SAE), so I suspect similar.

I chisled the rivits, not torched.

I have the dust shield from Bell housing. Got left behind when I sold engine.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Here’s a mileage kicker for you!
Bought a 70 chevelle ss454 back in 1978. LS6, m22 and 3.08 gear. Previous owner didn’t like the solid lifter cam so he had a stock bb cam installed. Same basic cam as in your 402.
Highway driving at 65 mph it would get 22 mpg. That’s a Canuck gallon. Same as 18 mpg in US gallons. While it sipped fuel it was a real dawg to drive. Ran out of breath at 4500 rpm.
Drove it like that over the winter. In the spring swapped the cam to a LS6 spec but it was a hydraulic cam.
Took care of that gas sipping dawg. Dropped it back to 15 mpg in Canuck gallons. Awesome power difference. Would light em up all the way thru 3rd even with the 3.08 gear.
And now back to your regular programming.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Could you call me, five one three, five one eight, three five zero one.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Very cool story. 3.08 gears would favor stock low speed, high torque cam. With that gear, you can win "farthest distance awards"... my truck runs great, but needs OD or lower gears. I do like going up hills in drive with 4.10s.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Biggest problem with the V-6 in pickups was GMC usually geared them too low.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

No Lie My Brutha! I've always said "if your worried about gas mileage your drivin the wrong truck..." ;)

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

I think I saw that phone number on a bathroom wall at Playpen Gentleman's Club. The name above the number was Trisha.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

My 67 has Patina, but when I open hood with BBC 402, people step back woooo. Is Big Block that big a deal in trucks?

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Not to hijack but I have a GMC V6 to SM420 bellhousing. They're not SAE patterns, http://67-72chevytrucks.com/vboard/s...mc+bellhousing

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

My 402 just recently came back to life after a 7 yr. hibernation, SWB truck. It's a low mileage rebuild, I only installed new pumps, timing and such since. It runs better than it ever has, I couldn't be happier. It's not quite stock, the heads are 1967 GM HP 396, Delco HEI distributor and high RPM cam.

Differential is a low RPM under-achievement at 3.73:1, there's no burning tires in first gear. On shift it can chirp, that's it. But loves the highway, it just wants to fly. That's what I've always liked about it. No matter how steep a hill it gains speed under little acceleration, and without more.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Well I got that from 6066. V6 site, they have volumes on the V6. Just checked. Bet it was the larger V6, Larger trucks with 5spd. https://www.smokstak.com/forum/threa...gmc-v6.145198/

I mis read that on the GMC site on design of the engine. V12, large HD truck V6.

Your trans, bolts to my bell housing, same as NP435G (the real 4spd).

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

A big block with 3.73s should be melting tires. What's wrong with yours?

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

I have not opened 4 barrel yet, still enjoying cruising.
Kinda wonder how it would run down qtr mile.


Hauled 10ft posts for grapevines today from Farm Store.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Couldn't tell you. It's never burned off go, or very little.

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Weird. If I cob mine, even with the shell on it and a 3.56 axle, it'll lay rubber and chirp second. No wheelies like the farm truck, though. :lol:

Re: Putting miles on 67, 402bbc VS 67 V6 305E
 

Right, and my block sports HP heads off a 67ish 396 SS.

Don't mind me, I don't know what I'm talking about. First off my kick down never worked. Second I had 8" wheels and 70s, so on and so forth, and I probably baby it too much. Everything works now, lots rebuilt, timing chain, trans., axle, carb. etc. I just changed the oil today and figured it's time to really test her out. It runs like a bat out of hell, I'm really surprised. Burns rubber all kinds of ways, but I still refuse to jump from a dead start:lol: Too many rocks.