Some ?? about 318 build vs 360 build for my truck

[moturbopar]

Hey all. I'm looking at putting together the engine for my 84 d150 (sorry not an a body) I'm not looking for a race engine so I put together a couple combinations for engines. The truck is 2wd short-bed, keeping the lockup 904 for now will be swapping in a overdrive trans. The rear is 8.25 with 3.55 gears.

the engine choices are.......
freshened low mile 318, new rings, bearings. The cam is a performer plus, cam dur int and ext is 204 at .050. lift is .420 with 1.5 ratio rockers 110 lc. The heads are small port 318 heads, with 1.88-1.60 valves. pocket ported, nothing crazy. Performer intake, thermoquad carb. 1 5/8" headers, merged into a 3" single exhaust, 3" hi-flow cat, and 3" race bullet muffler.


next engine is rebuilt .030 over 360 stock style replacement pistons .098 down in the hole (UUHHHGGG). Its been balanced. the cam is a crane cam. dur int & ext are 216 at .050 and lift is .484 with 1.6 ratio rockers on a 110 lc. The heads are pocket ported magnum heads, stock valves. intake is edelbrock airgap. Carb is a holley 750 vac secondary. Will be using same exhaust as above.

So my couple questions. what kind of mpg difference do you think I would see between the two engine. I know the 360 will get worse but would like to get a general idea. I'm not sure the lockup 904 would even hold upto the 360, what do you guys think? The truck wont be towing anything, but will be hauling stuff in the bed. Like I said, not worried about speed really, but would like to have a nice boost in performance over the tired worn out 318 that was in it.
Thanks

 

[moper]

Gas milage will be similar if they are properly tuned. Maybe 2-3mpg better with the 318 but I think the 318 will work harder and need more throttle. I've had /6, 318, 360, and 400 powered trucks. I like the longest stroke you can get. I'd take the 360 over the 400 any day.

 

[moparlover]

lol I was goin to say the same thing. if you are hammerin the 318 constantly you will probably get worse mileage than with the 360.

plus with a 3.55 rear you will get more pickup/get up than mileage anyways.

so the next best thing you can shoot for is durability. either one is as good as the other. i'm assuming the 360 has new bearings / fresh as well since it was balanced?
if the 360 is not fresh go with the 318 instead.

make sure whichever one you use has **new oil pump*** / freeze plugs / gaskets etc.

*** important since you don't want to have to change that after you have the engine in the truck if you see low oil pressure or something lol. $45 part will save you a lot of headaches later.

 

[RustyRatRod]

If you drive the two engines in a similar fashion, the 318 will win out on MPG, while the 360 will win out on torque. You just need to decide which is more important.

 

[MoparDaddy]

I say put flat tops in the 360 and run it!

 

[moturbopar]

Thanks guys. The 360 is rebuilt, has been pulled apart since its been sitting since 1990. the assembly lube is dried up and sticky, so everything needs to be cleaned. but all of it is new.
the 318 is basically new now. engine only had 40,000 on it when I went through the lower end.

Found out the tag on the dif said 3.55 gears, but counting the teeth on the ring and pinion it look like it has 3.26 gears?

 

[moper]

What does the part number on the ring gear say?

 

[moturbopar]

Crap, I didn't get the part # its all sealed back up now. I was in a hurry to get it back together, with new fluid.

 

[moturbopar]

Oh I do have a set of flat top hypereutectic piston I was going to put in it, but found out the flat tops are 100 grams lighter and don't want to spend the $$ on having the engine rebalanced.

 

[dirty white boy]

put the teen in the truck,..find a A body for the 360 an flat tops to go behind the truck!

 

[moturbopar]

Have a 72 dart that's getting another, 360. Might just put the stock 360 in the truck and save the 318 for my sons 71 swinger, he doesn't need a lot of power for his first car anyways.

 

[jerry6]

I'd go with the 360 , better in a truck than the 318 . MPG will not be that big a difference between the 2 .

 

[goldmember]

Hey all. I'm looking at putting together the engine for my 84 d150 (sorry not an a body) I'm not looking for a race engine so I put together a couple combinations for engines. The truck is 2wd short-bed, keeping the lockup 904 for now will be swapping in a overdrive trans. The rear is 8.25 with 3.55 gears.

the engine choices are.......
freshened low mile 318, new rings, bearings. The cam is a performer plus, cam dur int and ext is 204 at .050. lift is .420 with 1.5 ratio rockers 110 lc. The heads are small port 318 heads, with 1.88-1.60 valves. pocket ported, nothing crazy. Performer intake, thermoquad carb. 1 5/8" headers, merged into a 3" single exhaust, 3" hi-flow cat, and 3" race bullet muffler.


next engine is rebuilt .030 over 360 stock style replacement pistons .098 down in the hole (UUHHHGGG). Its been balanced. the cam is a crane cam. dur int & ext are 216 at .050 and lift is .484 with 1.6 ratio rockers on a 110 lc. The heads are pocket ported magnum heads, stock valves. intake is edelbrock airgap. Carb is a holley 750 vac secondary. Will be using same exhaust as above.

So my couple questions. what kind of mpg difference do you think I would see between the two engine. I know the 360 will get worse but would like to get a general idea. I'm not sure the lockup 904 would even hold upto the 360, what do you guys think? The truck wont be towing anything, but will be hauling stuff in the bed. Like I said, not worried about speed really, but would like to have a nice boost in performance over the tired worn out 318 that was in it.
Thanks

I ran a 360 in my truck with the same combo(except compression was 9.8to1) and it was a very nice unit,better mileage than the stock 318 that came out and ran nice.