Hello all,
I have recently rebuilt a 360 and have added an rv cam and put a 600cfm holly on it? Wow am i getting bad gas mileage, I knew i wouldn't get great mileage at all but what do you guys get? Are there any tips on ways to get better MPG? Oh on my engine everything else is stock. ( I did find out that i have Exaust manifolds from like a 68 or earlier truck. I have that What i think is called a heat riser * a valve type thing to help the engine heat up faster* and they didn't make them after 68 is what i have been told)

1973 F100 360

Thanks so much

Matthew

 

Pull the heat riser out and pull the butterfly plate out of it and reinstall just as a exhaust spacer. How to get better miles?? Build a 390!

 

Don't forget the rear end ratio.

 

my opinion on gas mileage is that an efficient engine will get good mileage. so that said, things like getting the exhaust gasses out easier are going to help. one way is to install headers, which good headers like tri-y headers will pull exhaust gasses out of your engine at normal driving rpm's. then down the line in the pipe you should have a less restrictive mufflers or my preference is good glass packs. the heat riser will make your engine warm up faster and help you from freezing over your carburater venturis in cool damp weather. BUT it also robs the engine of cool dense air, as warm air is thin and so therefor the engine gets less oxygen in the same amount of vacuum as it would with a cool dense charge. thats why you dont want it unless you have problems freezing the carb. I manage without mine, I live up north. I havent tried this but I read an article on routing the intake from your air cleaner up front to get cool air from outside the engine compartment, as to get something besides 180 degree air. the other changes require a rebuild to change those if needed. I am a big fan of compression, those imports dont run high compression for nothing, its efficient. one of the problems with stock 360 builds is the low compression, 8:1 with small chamber heads. if youre unlucky you have a bigger chamber head like a 72 or 74cc and then end up even lower compression. see, ford used a longer rod in the build of a 360 to take up the length of the shorter stroke, but not all of the length like they should have. they use a 390 4v piston to take up more of the length but still fall short leaving the compression down. they planned this because they wanted the lower compression for different reasons. but its almost like they did it in such a way as to leave no options for stock pistons if you want higher compression. thats more than you wanted I'm sure sorry.

good machine work and a good cam are also key in being efficient. if your engine has to use more of the power to turn over than it should, then it will rob you. also if it has to work harder to pull in air or exhaust air out, it will rob you. how bad is it? 8mpg, 6mpg? 10mpg is average