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

[1967GMCC20]

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

[jimijam00]

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

[1967GMCC20]

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.

[1967GMCC20]

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

[Palf70Step]

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

[1967GMCC20]

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.

[Ironangel]

Originally Posted by 1967GMCC20

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

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

[RustyPile]

Originally Posted by Ironangel

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

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..

[factorystock]

Originally Posted by 1967GMCC20

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

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

[MikeB]

Originally Posted by 1967GMCC20

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

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!

[1967GMCC20]

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

Truck has 4.10 gear Dana 60.

[Palf70Step]

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

[1967GMCC20]

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

[1967GMCC20]

Originally Posted by Palf70Step

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

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

[67km1590]

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.

[1967GMCC20]

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

[1967GMCC20]

Originally Posted by 67km1590

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.

You pay shipping, you can have them.

[1967GMCC20]

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

[67km1590]

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

[1967GMCC20]

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

[67km1590]

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

[1967GMCC20]

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.

[1967GMCC20]

Originally Posted by RustyPile

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..

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.

[67km1590]

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.

[1967GMCC20]

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.