O.K. guys ~ a question : Those of you who run milage checks , what's your fuel milage ? . I do regular fuel milage checks on some of my rigs . I figure a V-8 should get what , 12 ~ 14 MPG's in mixed driving ? . Lemme know .
'57 GMC 102 (123" wheelbase) original Pontiac based 347" V8 with HEI and a Edelbrock 500 CFM carb original Hydra-Matic original 3.08 rear gear 235x75x15 tires daily driven gets ~ 12.5 MPG, mostly around town On a slow (50 MPH) highway trip I've seen 14.5, but a 70 MPH highway trip drops back to about 12.5 to 13.
i had a '67 swb stepside with a 283 powerpack, powerglide tranny, 4.11 rearend that got 10 mpg no matter what. Highway, city, pulling a boat. anyway you looked at it 10 mpg. At 99.9 cents per gallon, i just couldn't afford to keep gas in it.
Gee Nate, our pull truck uses 6 gallons to pull the sled 300 ft. That figures out to 105 gallons per mile. Seriously, I've had a ranchero with the 221 V8 that got 20-21 mpg and a chevy with the 400 small block that clicked off 8-9. My 283 two barrel 1/2 ton got around 14. What really is shocking is your asking about a VEE EIGHT.
I figure Nate is gathering all this info in preparation for him to brag about the 73 MPG he is getting from his 216 with a home made injection system that burns left over trans fat cooking oil from McDonalds.
Nate asking 'bout an ate? Say it aint so! If you want to do a swap, there's plenty of good info already listed! My '95 Jeep gets @16 MPG with 70% of that zippin' down the highway at..........the speed limit. (Hi Boopster's dad!) My (this is the best of BOTH worlds, Nate) V6 gets @19 with this same mix! All it lacks is that lil' bit-o-kick to get around the slow poke driving 5 under. 'course they're both helped out with that EFI thing... Besides the fact that I think I'd have to rebuild the straight six twice to every one time with my V, I am not sure the mighty six gets that much better milage anyway. The six I had in my '64 only got 13 on a good day. And that was on the highway with a lid over the bed. We've told you, now please tell us what your trucks make with that 235 everyone raves about. K? I haven't put a V(somthing) between my rails yet- This may be your last chance to keep me or any other (should-I, should I not,) from "the dark side"...
By the way Nate- how many miles at highway speed do you think my 228 would endure before a rebuild was needed? Just a guess. When I do something, I try to do it my very best. I hate not being 100% on my direction. There are just too many compelling ideas from both sides. I want to keep mine as original as I can, but yet run the highway daily. The six I had in my '64 was stout, but I put a BUNCH of miles on every year. It just seems like MPG/MPH/MPY lean towards an 8. ? (You started it!) =^)
Fuel mileage is going to be determined (as you probably already know) by how you build you 8 (H.P., and torque) to what trans you put in it (overdrive or three speed) and your rear end ratio. You're probably going to get better fuel mileage out of fuel injection verses carbs. My dad's old 79 chevy only got about 6-8 mpg, but I work on BMW M5's everyday with 500HP and 500 ft lbs of torque that get in the mid to upper 20's. So it really depends on what you want, a technical fuel injection with more horse power and fuel mileage or a carb with more horse power and less fuel mileage. It's sounding like you're thinking of coming to the "dark side" as Zig put it. I never thought I'd see the day that you asked about an 8
You're ALL On The Wrong Track But .....Keep the good replies coming ! If you'se Guyze think I'm pulling out my 235 for anything other than a 261 , you're all crazy Once I get the info I need , I'll let you know why I'm asking
Oh boy! I love fuel economy posts since I have some info that's not the norm. Flame away...I'm just a messenger. Not that it's a AD pickup, but my father has a 76 half-ton Chevy. Truck is a bit of a family heirloom that has seen some rough duty the past few years. It still had it's original a 2-bbl 350 with TH350 tranny and 3.42 rear. We had the carb tune down pat, but for all we know it may have been lean or something. It never missed a beat tho. It would get about 12-17mpg depending on driving conditions. Last summer he had a 700-R4 installed (no other real changes) and the mileage skyrocketed. He posted a high of 26mpg driving 55...very easy driving. There may be some error in what he calculated (tho he doublechecked the fuel level after filling). I drove the truck a few weeks back and I calculated 20 with driving 70mph, so he may be pretty close indeed. No matter, it's hard to knock it's drivability and economy after the overdrive. It's not a racer, that's for sure, but day-in day-out it works. We've had a few others do pretty well, mostly EFI engines with OD getting 25-30. His newer truck is a 5.3L V8 Chevy that lays down 23mpg (went up after installing a supercharger...go figure). Not sure if my reply fits the intent of the post or not...Oh well! Andy
Well? It's been 8 days... That must be quite the math problem you're trying to figure. Just wanted to let you know that I for one plan on keeping this post up front until you tell us what the info on 'ates was needed for. By the way, happy (late) birthday! For a late present, I have a question for you! (One you didn't answer earlier...) What kind of fuel mileage do your in-lines make, and how many miles can you expect to get on these old blocks before they need rebuilding? Okay- that was two questions again, pardon me. Just don't think we are going to forget about you asking about V8's! Come out of the closet Nate, it's okay. We understand!
Well ; I was hoping for more replies before spilling my beans (as it were) I can do the math O.K. if I take my safety shoes off.... If you can exceed 14 MPG in a 216/235/261 you're doing very well indeed . these engines were not designed for our concept of fuel economy . As far as longevity , there's -so- many variables it's hard to say but these engines should go 150,000 between routine overhauls , no need for total rebuilding unless the engine has been poorly maintained or abused . they're incredibly tough , when operated within thier design parameters ~ this means NO overspeeding and keeping them not only in tune but full of fresh , clean oil at all times too . This is why I keep telling the NOOBS to not tear thier engine apart for rebuilding as 99 % of the time , proper care will awaken a long dormant engine and return it to a long service life whilst the truck owner can rebuild the body and paint whilst enjoying it.....
My '57 GMC V8 (Pontiac based, 347") had its engine overhauled at about 80,000 miles in 1979. The original owner kept the parts sheet from the overhauler, which shows a 0.030 bore, but that the crank is still std/std. Two years ago with 178K miles I dropped the pan in the driveway and popped out two main bearings. The main bearings measured less than a half a thousandth of wear. I put them back it. I then pulled two rod caps. The lower bearing shell (in the cap) measured less than a half a thousandth of wear. The upper bearing shell (in the rod) was worn thru to the copper-colored metal. The rod journal on the crank measured less than half a thousandth of wear. I replaced all the rod bearing inserts with new std sized inserts and bolted it back together. Increased the hot idle oil pressure by about 3 psi. Truck is now at 185K miles (it has been my daily driver since 1990) with 37 PSI oil pressure at engine speeds > 1200 rpm vs. the Owner's Guide recommendation of "35 psi at speed". On a really hot day after a 20 mile trip at 70 mph the pressure drops to around 12psi at 450 rpm idle speed vs. Owner's Guide recommendation of "at least 5 psi". So I'm at 107K miles of Nates 150K between routine overhauls.
I'm surprised they needed to bore an 80K engine to .030" ~ of course many rebuilders just do that right off the top without ever bothering to measure it.... When you slipped in new rod bearing shells , I'da prolly replaced the cam chain too as keeping the valve timing on spec. makes for a " crisper " power delivery . If you keep on top of it like this , next time you'll maybe replace the pistons but likely -not- need to re-bore it...
You are most likely right about rebuilders and the 30 over bore. If they offer a warranty they don't want to chance the standard bore being OK, or if it will clean up with 10 or 20 over. I did the timing chain and both sprockets at the same time. It WAS a little sloppy.
I am getting 20-23 mpg on the highway with a Chevy SB350, Holly 650cfm with out-of-the-box jets (and live at 5600'), 400R, and Nova 10-bolt 2.73 open rear-end. Almost too much gear except for 80+mph on the highway, in town driving is not as enjoyable.
Yes I have pics. I need to correct my typing, I have a 700R tranny. Here is a link to my pics right after the major rebuild. It is still work in progress. http://pg.photos.yahoo.com/ph/fatpanel/album?.dir=/f7a3&.src=ph&.tok=phNNl2FBxaTSMPAX
