MPG Pt.1

[Stewart G Griffin]

Stew- whats up with your picture?

1) It's just something i was fooling around with as far as a hotrod idea;  i'm not real good at drawing or with creativity.  i have better napkin drawings which i may reveal later.

2) As far as the 4.3/700r combo, this intrigues me as well;  i'm thinking maybe 18mpg IF 2WD and shortbed.  Did you see the article at Jeff Drew's site?   The article claims 21.9 mpg with 4X4 which i do not believe but hey, maybe it is possible.   
p.s. the vortec concept was actually started on cavalier engines.

[Canadian 4X4]

the truck is 2wd swb i was thinking around 20

[Stewart G Griffin]

If it IS possible, then great.   The question to me is will losing 40 more cubic inches from 305 and 80 inches from 350 really make much a difference when there is not that much weight loss?  (although the article claims 200lbs lighter!)

The v-6 concept does intrigue me deeply though.

[Canadian 4X4]

i agree the v6 will have to work harder than a v8 to keep the truck at speed but i am very curious as i am looking into buying this truck and using it as a dd

[Stewart G Griffin]

Ok, after looking at the brochures, the 4.3 v-6 has 9.3 to 1 compression.   That plus the vortec heads maybe 20mpg is possible after all.

i like the v-6 even more now.

[zieg85]

OK I know I have only driven my V-6 a couple of hundred miles but the gas mileage was terrible, 10 at best...  Truck ran well but I had to keep a heavy foot to keep it going down the highway at 65.  I would play with the jets until you got the exhaust pipe a light grey and the spark plugs burning right.  I did that with a 2 bbl on a 350 on my 1972.  It had an ever slight hesitation starting out but I managed to squeeze 16 mpg out of it.

[Stewart G Griffin]

256 miles even, 16.9 gallons to fillup = 15.14 mpg  This is at Exxon and it's confirmed---  "contains ethanol" on the pump.

Not quite sure what is happening here;  The choke is still not right, still too rich and the carb itself may need some tuning.   This is a remanufactured carb from Champion, and i can't say i'm too pleased with it right now.  If you need something to get your car running ok, but other than that i don't know.

2) If you're still interested about 4.3 v-6 mpg, there is a former gm engineer getting 20mpg with a shortbed in the 67-72 forum;  Will post link if i get around to it.

[howlinwolf]

it normally costs me about 80 bucks to fill up but i can get around 840 out of a tank of fuel

[bobcooter]

I took my Aluminum intake off and replaced it with the factory one. I replaced the headers with the factory cast iron manifolds. I put my stock factory heads back on and went from 2 1/4" duals with headers to 2" duals with manifolds. Mileage went from 12MPG down to 10.7. Still have the flat top pistons and around 9.5 compression. Would love to see anything anywhere close to 15.14. But hey, it's a 3/4 ton. So I don't expect much anyway.

[eventhorizon66]

I took my Aluminum intake off and replaced it with the factory one. I replaced the headers with the factory cast iron manifolds. I put my stock factory heads back on and went from 2 1/4" duals with headers to 2" duals with manifolds. Mileage went from 12MPG down to 10.7. Still have the flat top pistons and around 9.5 compression. Would love to see anything anywhere close to 15.14. But hey, it's a 3/4 ton. So I don't expect much anyway.

Why did you do all that?  In an attempt for better mpg?

[Stewart G Griffin]

267.6 miles,  16.00 gallons  =   16.725 mpg.

$41.27 to fillup @      $2.579 per gallon Exxon


i don't drive it very much hence the slow responses.

More choke adjustment----almost there.   And both idle mixture screws were adjusted using a vacuum gauge;   Trying to get as lean as possible while keeping max vacuum---about 21-22 hg's.

i continue to try to only make one change at a time, so i/we can accurately see what works and what doesn't.

But for anyone who hates 305's, this is what a 305 can do.  And i think i can get more out of it.

[Stewart G Griffin]

259.4 miles       16.105 gallons to fill

16.1 mpg

$44.43 @ $2.759 per gallon, exxon.

$42.02 after rebate.

Looks like this is a 16mpg truck and i have to accept that.

[bobcooter]

I took my Aluminum intake off and replaced it with the factory one. I replaced the headers with the factory cast iron manifolds. I put my stock factory heads back on and went from 2 1/4" duals with headers to 2" duals with manifolds. Mileage went from 12MPG down to 10.7. Still have the flat top pistons and around 9.5 compression. Would love to see anything anywhere close to 15.14. But hey, it's a 3/4 ton. So I don't expect much anyway.

Why did you do all that?  In an attempt for better mpg?

No, I just got tried of that stuff. It started when my truck ran hot and I cracked one of my 882 heads. A 3/4 long bed is no way ever going to be a hot rod and still have any reliability if I build it. While I had it down, I just decided to put the factory stuff back on. I  feels like it has more torque now but you tell the difference in HP around 60 to 70 MHP. Correction: I meant 2" duals with glasspacks, not manifolds. I just noticed that.

I do have an update: I replaced the factory air intake with the big hose to an open element air cleaner I had and my mileage is back up to almost 12 again. Like 11.7 MPG. That's with a K&N filter. It rides a little better with the extra weight of the cast iron back on the front.

[comp]

I took my Aluminum intake off and replaced it with the factory one. I replaced the headers with the factory cast iron manifolds. I put my stock factory heads back on and went from 2 1/4" duals with headers to 2" duals with manifolds. Mileage went from 12MPG down to 10.7. Still have the flat top pistons and around 9.5 compression. Would love to see anything anywhere close to 15.14. But hey, it's a 3/4 ton. So I don't expect much anyway.

which intake,,heads and headers do you have ??

[Stewart G Griffin]

278.3 miles,  16.72 gallons =   16.6 mpg

$2.799 per gallon @ exxon = $46.80

$44.30 after rebate.