I have a stock 318 setup on TBI in a 90' truck, the motor shows some wear but I only get about 10 mpg in town. For the rebuild I'm haveing a hard time picking between a small 4 barrel carb or my stock TBI. Setting aside the cost differences of parts which route is going to be better? I'm not going for lots of hp, nor drag racing. I hope to have a stock 318 plus say... 20 hp when im done. In either route I plan for factory exhaust manifolds but putting dual exhaust from the manifolds on out. Stock 318 heads (cleaned up of course) And mabye a different cam, (I'v read that stock cams are not the highlight of the 318).

Gas milage is something that I am going to be considerate of, since after all this will hopefully be a daily driver and a road worthy toy, but able to hold its own off a red light.

I have read that both routes are about the same, mabye a little more power from the carb but a little less mpg. I dont have tools or fancy equiptment for adjusting the TBI, so I like the user friendly concept of the carb, plus I will have no computer to take a dump on me in the future. Although I like the idea of having no choke to mess with, almost no chance of flooding it, and factory finish of the TBI.

Perhaps I'm making this overly complicated but I would like some advice and personal experiance from you guys, mabye some pros and cons as well if there are any that I'm not aware of.

 

Sound's like an intresting experiment I always favored the old school system until I started spending time with the efi and tbi system's. The deciding factor for me was when I was getting 8.6 on the 1987 w150. with a carb and 3 coverters. The bad part was the fuel consumption was killing the bank. Worse I guess was the emmisions I was putting into the air we breathe . I wish I would have had a tbi but it was time for the old technolagy to be parked. Guess I felt I needed to do my part in keeping the air clean. I still use the old truck to plow my driveway in the winter but the 95 cummins is getting 20-23 and the bank acct. likes it . Good luck with you project.

 

I have an '89 D250 with a 360. Came from the factory with TBI and about 10 mpg. I swapped out the TBI for a 670 spreadbore Holley and mileage and performance increased greatly. Mpg went from 10 to 15 or so. Also had to change to regular electronic ignition instead of computer controlled. With choke set properly, cold starts are close to as easy as with FI. Hope this helps....

 

I guess I'm changing the plans up a little bit. Going to stay with my TBI for now anyways. Couple questions remane for me though.

I still don't know which cam to get for it yet though, any ideas?

Anyone know what sort of compression ratio a stock 318 would/should have? And whats the highest CR that would work pretty decently with that 87 octane fuel, though I'd normaly like to run 91, if it is available.

In the event that I would take a little off the block and/or heads would rocker shims work for me? Keep in mind I'm staying with the original heads, though I dont know if it matters here.

 

I don't have the grind number, but the cam I used was from Lunati. Hydraulic roller cam and used factory roller lifters. Just remember you will have to use a bronze dist gear. Call their tech line and they will tell you exactly which one you need.