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I am thinking of pulling the big block out of the truck and dropping in a 305. My thoughts being that I want to drive the truck over the road a bit, and want something reliable and much cheaper on gas. The 305 will still sound good, push the truck well, and be MUCH better on gas. (especially with a 700R4) At the moment I just drive it here locally because it is geared so low that going any distance is far too expensive & slow (can't cruise more than 60). Any ideas/thoughts?

In my experiences a 305 has sucked as much gas as a 350 and had less power.

I agree with Barry. I've been driving an '84 K10 with a 305 for 11 years now. The axle ratios are 2.73(no, not 3.73) and I get a pretty consistant 14mpg. I think a 350 would get about the same and have better power.

engine swap won't make it less expensive and faster if the gearing is too low, but better gears will, no matter what the engine - I agree you should dump the BB, and also that the 305 is not a great choice, but a 327 would be appropriate for the vintage, and w/ better gearing give you plenty of power and speed and reasonable economy

Bill

Agreed with above. I had a 305 in my 85 truck, and Barry's comment is exactly true.

350's are next to impossible to get around here (dirt track guys get them the minute they hit the junk yard). What did the 327 come in? I don't have the money for a new engine, so I am going to have to find one (that is more fun anyway)

If you can't sell that big block and have enough money for a fantastic 350, I'd be surprised, I live about an hour from you, 350s readily available in Mobile and Pensacola from what I have seen. 327s are like gold though. 305s are dirt cheap and might make sense based on you rmoney situation, ducking...

How about making it easy and dropping in an olds small block where you have the big block? Olds 350 with a 200r4 should be a pretty simple task due to your motor mounts, etc. This would give you a smaller engine with an overdrive tranny, your could probably buy a good early eighties donor car for the sale price of your big block and BPO turbo 400

I like an Olds 307 for fuel economy, I'm ducking again
I have one in an 89 wagon with a 200r4 pushing 200,000 miles, blowing smoke everywhere and still getting 24 mpg (highway gears though)

Chris

Where should I advertise the BB? Sell it on E-bay? I can get a reman 350 from autozone for about 900. But I will have to get the pan, intake, carb, and valve covers for it. What do you think the BB will sell for?

In the Mobile area, I'm pretty sure that BPO455/THM400 goes for about $1000-$1200 if you can hear it run. I regularly find 350s for $300-$400 running and the same for an OD trans, of course you are taking a risk on used parts.

I highly recommend the Chevy crate motor for $1300 and the Chevy Crate TH350 for $700. But I understand money doesn't grow on trees and I am very frugal often chasing used parts.

I still think finding a donor olds 98, buick roadmaster or cadillace fleetwood with a running V8engine and T2004r is the way to go for you, it will bolt in except for needing a longer driveshaft.

If you want this 307/2004r out of this wagon, you can have it if you want to drive to Foley, Alabama.

Chris

Break out the calculator and cipher the payback miles (brain's a little rusty but you'll let me know if I'm wrong):

Let C = Cost of the conversion in dollars
G = Price of gas per gallon in dollars
P = Present Miles Per Gallon
N = New Miles per Gallon
and
M = Miles driven to break even

Then

M=C/[G*(1/P - 1/N)]

For instance if I spend $1000 (C) to boost my mileage from 17MPG(P) to 20MPG(N) and gas is $2.25 per gallon (G)

1000/[2.25*(1/17-1/20)] = 50370 miles to payback

but if I went from a paltry 3MPG to 6MPG (same 3MPG difference)

1000/[2.25*(1/3-1/6)] = 2667 miles to payback

From your description, a rear end swap might be more cost-effective.

C the T, I smell 'TECH TIPS' all over your formulation; makes sense to me. Nothing like the appropriate tranny/rear end combination to get the best performance fuel-wise out of your engine.

1sic64, with the above in mind you might look to do 'what's cheapest to do?' What is your differential?

I agree wholeheartedly, rear end swap should be the way to go, but he asked about engine swaps, that BPOBB should just lug along with the right gears. You could easily get away with 3.08s (or even higher like 2.73s) with all that torque and most likely bring your mileage into the high teens if you can keep your foot out of it. Also a properly built 2004r (like one out of a cadillac fleetwood) would give you the OD without a lot of expense, again, just sell the BPO TH400 for the cost of the 2004r.

Chris

the 305 tbi 700r4 in my camaro will get 23 mph on the highway.

1955 2nd series.350 from 1974 truck.Edlebrock intake and 600 cfm carb.700R4 tranny.Stock 3.90 rear.20 MPG on road.

Dale,

What size tires on that truck? I've got one of the lightest foots I know and that is fantastic.

Chris

Dale is right on, my 64 w/350/700r4/3.42 gets 16mpg town/20 on hwy, has 275/60/15s, ps, a/c. I vote overdrive. Brian

Brian,

I'd agree with your numbers with a 700r4, 3.42 rear and 28 inch tall tires should easliy produce 16/20, but Dale has a 3.90 rear, to get the same gear ratio as you he would have to be running a tall tire.

I know everybody's engine is slightly different and therefore gas mileage varies.

Also, sometimes people forget to correct their speedometers for changing tire size.

Chris

From what I understand regarding a 350 small block engine is that you have to check the block numbers and make sure your getting one that is dated 1977 or older cause they have a higher nickel content.
With so many people responding to this post I am really suprised that nobody has mentioned it to you so far, otherwise your going to be getting that BAD GM Mexican 350 engine that is not near as good as the the older ones, for example the Mexican engines have a soft cam and it has a softer cast iron crankshaft and the engines wear out faster due to low nickel content.

And also make dame sure that the 350 you buy is not been bored more then .30 over or better still get one not bored out at all, check your numbers out and make sure you know what you are looking for before you go looking around, also with small black some heads are way better then others the newer heads are not as good on gas as the older double bump or otherwise called Dolly Parton heads.

I would say don't buy a crapy crate engine at Autozone or GM crate its not the best instead rebuild an older 350 core engine if you can't find a good running one, and a standard overdrive is probably more reliable then a 200 or 700R4 overdrive, a 342 gear ratio is your best bet.

One last thing put an add in the paper and look for one in the fall and winter I have better luck looking for parts at that time, untill then most people are so busy that they have no time to look at a paper. take care.

I agree the overdrive tranny will be the trick set-up,and with the right gearing you can get pretty good mileage with your bigblock.But it IS possible to over-gear your truck. If you run the 700R4,you might want to stay close to a 3.55 or so rear ratio. You can fine tune your final drive ratio a bit by changing tire size. Otherwise,you could spend a lot of time in the reduction gears or with the pedal floored trying to maintain road speed. ( Ask anyone with a late model,tall geared 4X4 with big tires)At least with a big block,it'll cope with too much gearing better than a smallblock.
BTw-a guy I know drives a '77 Nova with a 700R4,2.73 posi rear end and a built Caddy 500.It just flat HAULS A$$,and gets 19 to 23 mpg on the highway.

i am running 235,70,15s on the rear.The 20 MPG is down the road miles.Around town it gets about 16 to 17 MPG.

I think that I'm going to try the rear end swap first (308's) and see how that goes. Right now it has 225/70/15's on it. Today I was given a 750 CFM double pumper Holley. It isn't on the truck yet, but I have been told that it is going to make my MPG MUCH worse. However, it is better than the Quadratrash that is on it (refuses to run right). I will probibly keep the TH400 for now. Maybe the rear-end swap and bigger tires will make enough difference to make it manageable for the short term.

How much are you asking for it????

The rear end and tires should make a huge difference for mileage. Try just the rear end first. That double pumper is going to pump a lot of gas. Get the quadrajet rebuilt, it is a good carb for that motor. For ease of use I like an edelbrock 750 on that motor, but I'd use the Qjet.

The wagon is free to good home.

Chris

find a stock 66 or 67 283 20+ mpg

Have you thought about going with a 250 6 cyl. mine gets 20 to 21 mpg with 4 speed tranny and 3;55 gears it aint no race truck but it is dependable and cheap to operate, it will cruise 65 to 70 mph with no problems.

Hey Guys!!! I've got a wonderful little 350 sitting here with about 900 miles on it. I would trade it strait up for a good running BUICK 455.
Not for my '53, for my Camaro.

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