11 mpg Small block HELP.
 

Oky I am getting 11 MPG in my C20 Highway. driving it nice and easy in OD. (it's a 84 but I thought it would not hurt to post it here) It's 350 30 over, A lumpy Cam and unknown specs. Performer RPM, 1406 Carb, K&N ,filter, 1 5/8 Headders 2 1/4 duals, HEI with a curve kit, NGK platinum plugs gapped at 45, Taylor wires and a Accell Super Coil. 700R with Stage 2 shift kit and a open 3:54 rear.


Should I expect any better ? When I am driving it in 4 th and I have the Lock up switched on It' basically will not go up hills with out droping it down into 3rd and unlocking the tranny. I was wondering if 3:73 gears might be of any help? That way the motor is runnning in it's power range.

Any help would be Great !

Mario

you are talking about a heavy truck but wit hsome timeing tweeks and carb tweeks you might be able to squeek out another 1 or 2

What kind of MPG does it get in drive as opposed to overdrive?
Lower RPMs doesn't always mean more MPG.

I agree, you probably need to tweak the carb a bit. What bothers me is your comment about it's lack of pull. My 96 is a stock 350 with 3.42 rear and I can easily cruise at 70 and get about 16-17 depending on terrain. I almost never see it kick out of OD unless I stomp on it, or I get into some serious hills in Tennessee or West Virginia.

You should be able to tweak a bit more out of it, but I get the feeling your cam may not be one set up for low/mid end and you won't be running at peak until way higher RPMs. If that cam is making it lug like that, going to a 3:73 may help with that problem, but I don't think it'll increase your MPG much. To me that's not that big a gear change to where it would matter much.

im with those guys i think your cam is probably too big for your combination and blowing fuel out the exhaust as well as take your power band too high for a street truck

I agree thats why I said maybe 1 or 2 mpg more is all you can expect

I guess I should consider changing the cam. It's got lots of power in the top end that's for sure! It will throw you right back into the seat. I cant even get traction at the top of first and second gear if I put my foot to the floor and sideway I go.. And in the rain driving it nice It goes sideways when it shifts. I have nott been driving it like that for the last month or so though. I had a Vacume gauge in the truck for a while and in drive doing 100 km is where the gauge said I was getting the best economy. When I put it into OD and switched the lock up on it dropper to the poor spot.

I have not tried driving it in D yet I just filled up and I am going to try it with lock up and in D and see what I can get out of it.