89 Smog 318

[68satellite]

I need some advise on building a 300+ HP 318 motor for my 81 Trailduster. I have an 89 318 with only 20k miles from a donor Diplomat. I know the heads have to go due to air pump ports. I plan on swapping the heads with the ones in the truck now. Any suggestions on cams, carbs & ignition would be greatly appreciated. I have a cast iron high rise manifold for it but dont know what cfm carb to put on it. I need more horsepower to turn the swampers. 318's are good little motors, but need more POWER!! Thanks

[rumblefish360]

The pump ports are not bad heads. Just plug the holes via a tap and allen head set screw. The newwer heads are better for this use anyway. (someone correct me if I'm wrong...swirl ports, right?)
I have used a Crane cam speced @ 272-284, .454-.480 advertised duration with good results. Use it with a 9.0-1 - 9.5-1 compresion. A good cfm carb would be 600. Holley or carter. Your choice. Use the 1.88-1.60 valves from a 360. Get'em new. There cheap enuff. The 2.02 will kill the low end torque. The head should have a 3 angle valve job done. A good idea is to Pocket port the head for added power.
Ignition. The MoPar orange box is a good start. An MSD is the standard.
Use headers with a 2 1/4 to 2 1/2 exhaust max.

[tsteiner61]

I was originally going to build up a 318 for my 73 van to about the same specs as what you describe. Here are a few pieces of advice I got in the process.

Best heads: '302' heads (given the year, it probably has those now), also called swirl port like Rumblefish360 said. with a porting job will outperform most other heads according to the guys at MPP. Plug the holes and keep those heads...
CR: 9+. You won't get to 300HP with a bump there.
Carb: I was going to use a 600cfm Holley list # 0-1850.

As I write this, I'm finding myself very much in agreeance with Rumblefish360 on all counts.

Good to see someone from the Lehigh Valley on the board. I was born and raised in Allentown. Graduated from Dieruff High in 88. Sure do miss those battles we used to have with EHS in football every year. Don't miss getting killed in wrestling, though.

[5thAve]

Those 302 swirl port heads are the best 318 heads to use. They actually offer good performance on 360s aswell. Make sure they aren't cracked because they're prone for that between valves.

Also make sure that the oil passages are completely unclogged because later 80s 318s had oiling problems to the top end.

For a carb you could go with a TQ... they offer good performance and gas mileage and can be set up to run great under almost any situation.

[Crank]

get the swirl polish stainless valves their cheeper than a 3-angle valve job and flow better but other than that the rest sounds great to me guy's.

[5thAve]

I did a 5 angle valve job on mine, then again I had nothing better to do at the time (and figured that's better then doing nothing and I can use the heads in the future) and had access to the machine.

I started with a bad set of heads (not knowing the 1 was bad at the time). The machined surface of the burnt valve does a great job in brining out the 3 flat spots

[rumblefish360]

Crank;

Your off base a bit. Getting better valves are only the start. Once your past the valve, you have a stock path for the air to flow. While not bad for the target HP, a 3 angle job is a good idea since the head is already there and can really help out. Saving money in this area is penny wise, dollor foolish. Or HP foolish.
Why not spiff up the area while your there. $$$? If its money, your only short changing yourself. (and I see 5th ave had some time to kill )
I would recomend a little porting to insure that a 300+ HP goal is meet. Not alot is needed. The right head won't. The non-perfect head will.
Without the porting, power would be near or at lets say 285 HP. Porting the bowls will add another 30 or so HP. Now insureing that 300 HP. (numbers pulled out of the air but not unreasonable)

ALSO..tsteiner61 and all readers;
You said "You won't get to 300HP with a bump there." Just incase you mean the bump in the floor of the exhaust port....(Granted, there not the greatest head out there but)...
The bump on the floor of the ports will actually help flow. As opposed to hurt it. It helps direct air flow up and away, out of the port as where taking it out will cause turbulence. (sp)
A little proof? Go to Huges.com and take a look at the higher cfm rated heads. Notice the "J" heads only get to stage 1. And the "X" gets to only stage 2. The 596 head with the air ports and bump get to a stage 3 port level with air flow around 300cfm.
It's sayin a little something about the older heads without this bump. The X & J heads floor is concave. A little pocket in the corner. bad, very bad for high flow. Not a smooth exit.

[tsteiner61]

Actually, I meant a bump upward in his compression ratio. He'll be hard pressed to make 300+hp without at least 9:1, IMO...

[rumblefish360]

Agreed. 9.0-1 would be a min. 9.5-1 is where I would start.

[bbaspense]

If you are swapping small blocks anyways...why not use a 360....more cubes, more torque, fits the same...

[Bodie Jr]

Hey all. My 90 W-150 has a 318 also. Does mine have the same type heads as ya'll are describing? Where are the pump ports located? I will be doing some work to my heads in the future also. Maybe putting a slightly better cam in it . Comparable to the comp cams 468 grind at the max, but using a Hughes cam or Mopar,

[5thAve]

Yep, you probably have the 302 heads on the 90. They used them until the magnum engine came out (and while you can swap heads between magnum and regular engines it requres some machine work).

The ports are behid the exhaust manifolds under the exhaust passages into the heads, the air pump connects to the back of each manifold with a pipe that tends to rot out at the bends overtime.

[Bodie Jr]

Thanks 5th ave and everyone. I didn't think these heads were worth fooling with. Ya'll have saved me a bunch of money. Thanks again.

[5thAve]

I said something useful?? WOW!

The only cost I have in those heads is the $$ I paid a buddy for them when I was getting other parts and the time for the valve job. I still have that burnt valve kicking around somewhere, it was a conversation piece for a while, and something to take up room on a shelf

[goldduster]

That engine will have a roller cam in the block, which is probably (correct me if i'm wrong) not compatable with the hydrolic cams used in pre-'85 318's. This is why you may not want to use that block

[5thAve]

I'm pretty sure you can use a regular cam in there but don't quote me on that one because I'm not 100% sure.

I also seem to rememebr that the main reason you can't use the roller cam in older 318s is because you don't have the tapped holes along the top to hold the lock plate inplace that holds the metal strips in place to stop the lifters from turning.

[cageman]

I was reading all the prior posts and I was thinking hey that is a roller cam motor, then goldduster beat me to the punch. I read somewhere where they get 325 horsies out of the same 318 with those heads with a 460 something cam with 9.25:1 comp ratio. That is about 100 hp more with new cam pistons and a shave here and there. These are commonly looked ver as a performance engine. As for those heads that everyone assumes they are SMOG, send them my way and I will bolt 30-40 hp on with them over my J heads.

[Fred]

38satellite check out
http://www.geocities.com/alwest_83/318.html

Fred..

[Crank]

rumblifish360 the reason i said to use the stainless valves is because all the flow numbers i have seen the biggest gains were with the swirl polished valves usually around 30% in flow .i think it's cheeper in the long run if you go to the 360 size .unless you do it yourself.but i have seen them go for as little as 5-bucks appiece not manley but stainless is stainless no matter who's name is on the box. cageman you can use the magnum heads on a older block and is suppose to be the best heads you can get .the problem is oiling because their is no pasages on the older blocks..So the solution to this problem is simple ,use the lifters off the old AMC engines they have a oiling hole in the top of the lifter to push oil threw the pushrods the lifters are .904 the same as 318/360 and the exaust manifolds and headers are the same bolt pattern.you need a magnum intake though .

[Pro74PW]

Were the 302 heads around in 76, I have a set of heads on my 360 that I had some ports plugged below the exhaust. Thanks

[goldduster]

302 Heads are found around '85-'91 on 318's only, though any head put on a small block with the air pump has the holes that you describe.

[68satellite]

You guys are the best! You saved me lots of trouble with the heads. The knowledge on this board is awesome. Thanks again