one thing leads to another

[wibilly]

i wqas telling a buddy i was gonna change the rear end in my truck. i have 3.73 thinking about going to 3.07's to save a little fuel. i drive my 69 350 4 speed truck 30 highway miles a day to and from work. then he offers up a 72 chyanne super thats been sitting in his pasture as long as iv'e known him. it was restored 10 plus years ago 2 owners ago and driven very little since. had all new suspension and brakes then and has a 3.07 posi. he says just do a body swap. i'm thinkin ok. i don't wanna be without my daily for long but do have several other rides. so i start thinking about this over the last week you know get the frame ready then do it one weekend. then i'm thinking about the crosmember swap and this and that, not gonna happen in a weekend. then today i think about that 500 caddy moter and 400 stashed out back.you see where this is going right? now i'm thinking back to the miliage thing that started all this. am i gonna gain anythig or should i just keep the 500 for the c/20 it gonna go in way down the road?

[ed2552]

If the Super was restored, why was it in his pasture? what kind of condition is it in? why not use that as a DD in all seasons but the longest, winter, and use the current DD in the winter?

[wibilly]

it was given to a teenager who abused it some and banged it up some before it was taken away and left to rot before he got it. it has since been kind enough to be a doner to other projects

[ed2552]

Oh, i see... Sounds decent, but your truck will be SLOW compared to now if you go that much higher in gear, can't you put in like a 3.30 or something? IMO

[Longhorn Man]

3.07s are fine in all reality.
You sure your 4 speed doesn't have a 3.07? It was included with the tranny unless optioned otherwise in 1/2 ton trucks.
That 500 would probably get better MPG than a small block.

[ed2552]

What was the stock axle ratio in 4x4 4spd trucks w/ the SM465?

[wibilly]

i drive my truck gental. i use it as a truck not a hot rod. i have a corvette if i wanna beat somthing

[wibilly]

my truck was origanily a 3 speed 307 truck i belive. i think the 3.07s with the 500 would make a purdy good combo but might get me in some trouble

[Longhorn Man]

ok, if it was a 3 speed, then it woulda come with 3.73's
the 500 does tend to cause rubber erosion... I'll say that much.
I won't admit to ALL those marks being mine... at least, not on a public forum where the owner of that black top (my boss) could read it.

[wibilly]

andy how do you think a well tuned 500 with a new near stock cam would do with the 3.07's mileage and performace wise. i see where you clamed 14 mpg at 70mph [3200 rpms]in your longhorn with the 425, i got 20 of them too

[Longhorn Man]

I know a local cat who used to post on here, he has a SWB 1/2 ton with a 472 and 2.76 gears if I remember right... I know it was high 2.something gears.
He reported a consistant 18 - 20 mostly highway.
Performance wise... this isn't gonna make you run 12's in the 1/4 mile... but it'll make you giggle when you hit the gas.

[hgs_notes]

I have a hard time believing a 500 caddy will improve mileage in anything, no matter the gearing or how it's driven, but I can't say it's impossible. If you started out just wanting to improve mileage with a gear swap, you could just buy replacement gears in the ratio you want and install them.

If you get 15 mpg now with gas at $3.25/gal, that is $.22/mile. A 2 mpg increase would save you $.03/mile. At 30 miles/day, that saves you $.86 per day. It would take 116 days to pay for $100 in parts, etc. for a swap. Economically speaking, do a gear swap on the daily driver, save the big engine for a project.

[Longhorn Man]

I can only say what I've seen in my own real world experiance. The best I ever got out of a small block in either of my small block trucks was 14 MPG (once... which may well have been a math issue). This is 2 trucks, and 3 engines. One worn out, one semi worn, one fresh cammed out engine, which ended up worn out junk before it died. I got 10 MPG every day, every trip, ever pizza I delivered, ect ect.
Then a fairly worn 425, with 4.10 gears, boom. Instant 14 MPG the only 2 times i was able to check... but I was not driving for MPG, nor was the engine tuned for crap. The exhaust was so rich it'd make your eyes burn. While I can't do an acurate MPG check on that truck (speedo is WAY off) very easily, I know it gets betterr than the burb ust by time between fill ups with my regular daily grind, and the burb gets 10 MPG.
The whole "I can't see how added displacement can help MPG" is following the same mindset of "I can't see how added RPMs can help MPG. Yet, that's been proven time and time again, even with factory offerings.

[suville]

For what its worth I get better mileage out of my 472 burb than I do in my 350 pickup, the big Cad turns at a MUCH lower RPM than a 350 and an engine is basically an air pump the more rpm the more fuel used to accomplish the task. And the torque is absolutly amazing! You will definately want as tall a gear as you can get starting with 3:08 Cad Eldos used this gear and the RWD cars used 2 something, theres several Cad forums and lots of info in this area. Hope this helps! Be happy to share info and experience on the swap, its a bolt in with all GM pieces and NO frame cutting!

[Longhorn Man]

suville, how did you do yours.. do you have a thread or a site covering it? Heck, were you one of the guys that followed my swap and finished before me?

[john@thepier]

The way I understand it is, that if you have highway gears and drive in the city the gas milage stinks and vice versa. Being up north( hows the weather there?) I would think that most your driving would be 45-55mph everywhere you go so the highway gears should be nice. Don't get cought off tract the axle swap was to better the milage and save $$$ey. Still have the bait shop for sale here and trying to move to Hayward, my wife wants Bayfield. Take care WiBilly

[suville]

Longhorn, been into the Torque Monsters for 15 years or more, grew up in the hotrod scene (50's-current)when ya went to the local bone yard and got the biggest V8 you could afford or find and wedged it in the hole and had fun. Dont misunderstand a SBC is without a doubt a very efficient engine but cookie cutter! And I did follow your swap with interest as I had already swapped one into a 68 burb, heck I enjoy bench racin and sharin info! I aint much of a confusor geek so shoot me your email and I'll shoot sum pics your way, maybe you could post em for others if their interested.

[wibilly]

yea john i live just 1/2 mile off 53 and work on 53 so i have a 65mph comute all the way. if i go to town thats only 1 mile from my house so my driving is pretty much all 65 mph faster if nobodys looking. i'm 20 miles from hayward. if you get up this way look me up. it's nothing like summer here yet but have had some nice days. snow is going fast but the mud is as deep as the snow was. i wanted this frame for my 67 that he wanted for his frame but he said if i'm gonna cut it it's going under his 67. the cost new shocks and bushings is what started me thinking about the frame swap rather than just grabing anothe rear axel from the yard and throwing it in after work one night. like i said one thing leads to another