318 or 318 ?? which one

-
1970-dart

1970-dart

Well-Known Member
Joined
Mar 16, 2012
Messages
1,763
Reaction score
134
Location
Vermont
i have two perfectly good running 318s one is a 1969 and the other is a 1974. i got the 69 out of a 70 pickup but then found the 74 complete factory v-8 car. I planned on just pulling the complete setup out of the 74 and dropping it in my 70 swinger but then somebody said the 69 motor would be better


thanks
 
1970-dart said:
i have two perfectly good running 318s one is a 1969 and the other is a 1974. i got the 69 out of a 70 pickup but then found the 74 complete factory v-8 car. I planned on just pulling the complete setup out of the 74 and dropping it in my 70 swinger but then somebody said the 69 motor would be better


thanks
Click to expand...

compression = 1969 engine is better so.....
 
I have been leaning more towards the 74 because it is all together as a unit with no leaks or issues. so i am not really worried about it if there are just small gains or not much different
 
...here we go again...

I can't recall who said it on the other thread just like this roughly a week ago, but he difference in compression between the '69 and '74 is nearly inconsequential for stock purposes. Use the one in better condition.

EDIT: 69 CR, rated 9.2:1...reality? Probably closer to 8.5~8.8:1
'74 rated 8.6:1...really closer to 8.2:1

...the gain of performance between the two would depend more on actual cylinder balance/compression and tuning than the negligible difference in static CR.
 
higher compression should be more efficient...better mileage.
would the '74 have hardened exhaust valve seats?
 
the other guy never said anything about compression and only that the 69 motor had more HP. I dont care about small gains and it will stay stock because if i was going to ( now or later) build a motor it would be a 340 or 360
 
1970-dart said:
i have two perfectly good running 318s one is a 1969 and the other is a 1974. i got the 69 out of a 70 pickup but then found the 74 complete factory v-8 car. I planned on just pulling the complete setup out of the 74 and dropping it in my 70 swinger but then somebody said the 69 motor would be better


thanks
Click to expand...



whats the ?they both are running good.
 
ir3333 said:
higher compression should be more efficient...better mileage.
would the '74 have hardened exhaust valve seats?
Click to expand...

Mileage isn't solely determined by static compression ratio between the two engines...it's also about state of tune and intrinsic condition. And yes, the '74 should have hardened seats.
 
Flip a coin. It will be better than askin here.
 
.5 bump is worth MAYBE 5HP, 10 for 1 point. Big deal, run the one that's newer or in the better shape at compression test. Check the valve guide seals too, might as well change em. Whatever is the most reliable.
 
IIRC, the '68-70 318 was rated at 230hp. And the '74 was about 125hp(?).. Not an inconsequential number I drove (long term) both a '70 Swinger and a '75 Duster. The performance differences were much more than "minor".

A previous poster suggeted that the '74 engine would have hardened exhaust seats. If this is more than just an occassional driver, personally, I would consider swapping on the later heads. At the same time, consider swapping in a set of aftermarket roller lifters and comparable cam, along with a decent 4bbl intake and carb. For a relatively small investment, you should see some real improvements, possibly even exceeding 300hp.

My .02 cents.
Mike in FL
 
..a few guys claim back in the day the '69 318's ran quite well..
What years did the truck 318's have forged cranks?
 
69 may be a forged crank, if original. I don't think cast cranks started till the 70's. I'd say run the 74 and build the 69. I'd put in new brass freeze plugs and a double roller timing set. Main difference in HP between 69 and 74 is gross and net. You can get really good mileage with that 74 2 barrel carb.
 
dodgedartgt said:
IIRC, the '68-70 318 was rated at 230hp. And the '74 was about 125hp(?).. Not an inconsequential number I drove (long term) both a '70 Swinger and a '75 Duster. The performance differences were much more than "minor".

A previous poster suggeted that the '74 engine would have hardened exhaust seats. If this is more than just an occassional driver, personally, I would consider swapping on the later heads. At the same time, consider swapping in a set of aftermarket roller lifters and comparable cam, along with a decent 4bbl intake and carb. For a relatively small investment, you should see some real improvements, possibly even exceeding 300hp.

My .02 cents.
Mike in FL
Click to expand...

Aftermarket roller conversion is more than a small investment...the lifters alone are like $400, then you have to run the cam to match them if the base circle is different...then throw in the fact you'll need shorter pushrods to offset the longer lifters. For a stock engine, that's really a little much...you'd be better off buying a running magnum if you want the roller cam that bad.

And as 66fs said, the hp ratings differ due to hp measurement methods. The only thing different between a '69 and a '74 2bbl 318 is the pistons in the '69 are like .020" taller, which give it a smidge more compression. But, 68-74 all used 675 heads unless someone swapped them. If your 75 ran significantly different than your '70, the '75 does use different head casting and probably has a smog pump on it...little different setup.
 
thank you everybody for the info and tips. I am just going to use the 74 because it is a complete setup all together and ready to drop in and if i was going to build a motor for my car it would not be a 318
 
You must log in or register to reply here.
-

Back
Top