View Full Version : '88 318 heads, worth using?
02-20-2001, 08:13 PM
I am selling my old 318 to a friend (practically giving it away actually) and I have a set of 318 heads off a '88 Dodge van. Do these later heads flow any better than the original '69 heads? Should he use them or stick with the original '69s?
02-20-2001, 08:25 PM
If the cast number on them are '308' then I would keep them and use them. The only problem is that the '69 probably have 2.02 valves. You can install the 2.02 in the 308's and have the benefit of high flow swirl port heads. Stock 308 have 1.88 valves.
The 308's with 2.02 valves were used on the '90 - '94 Super Commando 360hp 360 Crate motor that is no longer produced.
02-20-2001, 11:39 PM
I've got the same question and have not found a satisfactory answer. In the MP Engines book they say the new (302 & 308) heads in their stock form represent a power loss when compared to the older heads, but can be made to perform as well as the earlier heads. If you look at MP's new 14 second 318 build-up recommendation, they say use the new heads. Conflicting statements? The guys at the MP hotline are not much help either. They say the new heads flow better. I was going to build a set of late model "302" heads by doing a three angle valve job and milling the head .040-.050, possibly a little home pocket port and gasket match. The thing I can't believe is they say to oversize the valves. For the expense to do that you'd be better off finding a set of 360 heads. Old heads or new heads?? I'm still confuzzled??????? :p
02-21-2001, 12:12 AM
Every thing I have heard on the "new" heads points to the swirl as being a real improvement in the head design. I have also heard the runner shape has been improved, and the chamber is smaller and more efficient. As to making the valve bigger, I dont know if it is going to hurt a street cam or not, but it couldnt hurt a bigger cam. On the street, it is the torque that puts you back in your seat, and the smaller valves and swirl design really get the gasses moving, ie. velocity. That is where you are going to get the low end grunt. On a 318, stick with the 302 head. with a 360 or built 318, may want to try the bigger valve 308 head.
02-21-2001, 03:22 AM
One thing to think about is this, how many valve jobs have been done to each, also the newer heads have hardend valve seats for the unleaded gas. The more valve jobs done, the lower the valves set. If you port and polish the newer heads they flow quite well.
02-21-2001, 05:52 AM
The 318 valves are too small for the 302 heads, switching to 360 size valves really wakes them up, and you'll still have the velocity of the small port heads which is very important for driveability. In an old Article in Hot Rod, the 302 1.88/1.60 gave a lot more power on a 318 than prepped 360 heads. And since they are closed chamber, you can take advantage of the 'quench' easier. The 308 (360) heads are open chamber heads and have bigger ports than the 318 heads; still somewhat smaller than the early 360&340 heads. In both heads the exhaust ports are totally different than that of the earlier designs. It almost looks like an exhaust port. I haev used the 308 heads about tenyears ago and the reason why I replaced my pocket ported 2.02/1.60 J-heads with them was the unleaded fuel thing. Was kind of disapointed since the heads had so small ports and a huge pushrod dogleg, anyway I bolted them on out of the box and picked a lot over the old '915' heads.
02-21-2001, 07:30 PM
I pulled the rocker shaft off one of them and did some scraping on the heads to read the casting number.
These are really well worn heads.(the van had over 200k miles on it before the 318 gave up and they didn't maintain it that well either!)
I was thinking of suggesting a strong street performer build up to the buyer. Starting with rebuilt heads and .030 overbore and KB pistons.
I don't know what the CC of the chambers on these heads are so the final compression ratio will be since KB pistions come close to the deck height when installed. I never noticed they the heads are closed chamber but wow! they are. A buildup should be interesting!
02-21-2001, 07:56 PM
Hey Dartgt66, did the 308 heads have the exhaust ports in the same location as the 915 heads (lower, higher, etc). Same shape? I thought they might be a tad higher off the block.
02-21-2001, 10:04 PM
Yeah, the "302" heads are supposed to have more port velocity. But my point again...why go to the expense of opening up the seats for bigger valves?...has anyone priced this???...I have and it is not cheap!!! People (like me) that are going to do a build up on a 318 dont have alot of cash....if you are going to dump a bunch of money into a head for porting and bigger valves, do this to a 360. Heads motor and all!! Your money wont be wasted!...no subsitute for cubic inches! Now if you bolt a "302" head with a 200 dollar clean up and valve job you might be ahead. If nothing else the chamber is smaller and you increase compression! We could all use more of that on a 318!
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