318 and 360 head question

[Donahue72]

anyone know if the magnum heads off the new 318 and 3602 will work with the older blocks. I have a 71 318 and was just wondering if i could throw a set of new 318 magnum heads on it say from a 99 ram 1500

 

[rumblefish360]

Yes, you can swap them on, but, you'll need hollow pushrods for rocker oiling. And do remember to recalculate the new 1.6 rocker ratio into what will be the new lift at the valve from the old 1.5 ratio.

 

[Cranky]

Isn't the head bolt holes drilled at a slightly different angle too?

 

[YY1]

I think it's the intake bolt holes that are at a different angle. Straight down vs parallel with block deck on non-Magnum.

 

[rumblefish360]

Isn't the head bolt holes drilled at a slightly different angle too?

I think it's the intake bolt holes that are at a different angle. Straight down vs parallel with block deck on non-Magnum.

Correct, then again, he didn't ask. My extra 2 cents about the pushrods I thought was needed, not a compete write up on head swap cave eats. ;)

 

[Supershafts]

Just mill your la heads and bring the comp up... the mag heads aren't great...
You need a intake also, different lifters and pushrods...

When all you could do is mill your heads, and get better perf

 

[YY1]

I don't know. The 1.6 rockers will be like getting a new cam, and the mag heads have the flow to handle it, plus the have quench and better all around efficiency. Might be woth the minor extra expense and trouble if you were going to go with a 4 barrel anyway, the mag and non-mag intake I was looking at are almost the same price.

Apparently the stock bore, stock stroke 318 is capable of 400 HP, ie, it's all in the top end.

I've heard the mag heads crack easy, but I have 117,000 on my 2000 Dak, and it runs like the day I bought it.

 

[66 coronet]

The mopar performance book for the la engines says not to use the magnum heads they will bolt on the older blocks but the top end will not oil.

 

[rumblefish360]

You need an updated book.

 

[Donahue72]

I don't know. The 1.6 rockers will be like getting a new cam, and the mag heads have the flow to handle it, plus the have quench and better all around efficiency. Might be woth the minor extra expense and trouble if you were going to go with a 4 barrel anyway, the mag and non-mag intake I was looking at are almost the same price.

Apparently the stock bore, stock stroke 318 is capable of 400 HP, ie, it's all in the top end.

I've heard the mag heads crack easy, but I have 117,000 on my 2000 Dak, and it runs like the day I bought it.

i would like to keep the 318 that came with the car but i want to get some decent power out of it. which heads would be a better upgrade thats off a different engine. im on a tight budget here so i dont want to buy aftermarket heads. i was going to bore the block out 30 over and i have a 220 lift 426 duration purple shaft cam that i got for free.

 

[David]

http://www.dippy.org/forum2/index.php/topic,295.0.html This site has alot of info about swapping magnum heads onto an LA block. I've thought about doing the same. It also lists all of the other parts you will need to get to use the magnum heads on the LA block

 

[Coronet 500]

Try and find a pair of "swirl port" casting last three numbers 302. Years 85-91 maybe a Fifth Ave. found mine on a 87 1500 ram pick-up. They have closed chambers of 56-65cc's and can raise your compression up to one point. When you look at them they don't look like much, but they have the new design port that works real good. Some guys hog them out and add big valves because the small combustion chambers are very desirable. With that cam, these ports and smallish vales keep the velocity up for great trottle responce. A nice dual plane manifold, a 600cfm vacum secondary Holley and headers and you'll have a nice tire peeler that still gets decent gas mileage.

 

[Cranky]

Does the teen need to be bored? What's the main use for the car? The biggest bang for the buck is a gear swap. And even with a head swap and cam, the teen isn't going to respond all that well unless you do go with a lower gear. You'll feel the difference but it's going to be somewhat sluggish on the low end. A buddy and I took a 72 Demon with a 318 and threw on some 360 pocket ported heads (yeah, lowered the compression), .480 lift cam, Torker intake, 600 DP, headers and lots of gear and it runs 13.51 @ 102 but the 60' is only 2.2 due mainly to a stock converter but once it hits 3000 rpm, it hauls butt.

 

[Donahue72]

the car is going to be my toy. Mainly a street car and weekend track warrior. for now i want to put the 318 back in just so i can get the car back on the road to enjoy it. meanwhile i want to get a 360-440 to build up and make it a street/track monster.
there is a guy running around my area in a 74 dart with a 318. car moves really good and all he has is a cam, intake,carb and headers.

 

[YY1]

The reason I haven't done a ton more research on the mag swap is that my 318 currently has the swirl heads. I want to see how those work with a new cam and carb before I tear more into the motor. I do have a 5.9 with a spun bearing, ie still has good heads. I was thinking about that comp 268 cam, or maybe a 270. I figure that might get me 50 or so more HP without overflowing the heads. The mag heads might get me 50 more. that would put me close to my target.

318's used to be rated around 230 Gross HP, but dipped way down to 145 net in the mid 70s. The swirl head 9.5:1 got back to 175 net, and the magnum got to 240ish NET.

There's more than one online buildup of 400 HP 318's. I'd like to stay a little tamer, ie not spending thousands on head work or AL heads, but I'd like to see the other side of 300 HP so I can at least keep up with the new V6 Mustangs. All the aritcles I found were stock bore and stroke. One was even a 200,000 mile bottom end.

You can get 600 HP out of a 360/408 stroker if you have 6 grand.

I have about 500 bucks and a good running 318 that doesn't need rebuilt.

 

[Coronet 500]

I love talking about 318's. The set up I suggested to Donahue72 is what we have in a truck but with a Comps XE 256 H and with thier camquest program shows 280 hp 360 tq,that cam you have sounds like one of the small RV cams. I ran some 260-280 duration cams and they top out at 300-310 hp 350 tq, showing how those valves restrict the combination. If you go to a larger valve and some pocket porting you'll see 350 no problem. Those new LA X heads will take you to 400+ with good compression, carb and manifold. It's all in the heads, velocity to make torque down low and thats it or rev the small stroke with converter and rear gear to make bigger horsepower.

 

[YY1]

I say don't overbore unless it NEEDS to be bored. If it has good static compression, I wouldn't even open the bottom end up, except maybe to check the oil pickup and for sludge. Spend that machine shop money on other things. If nothing else the LA bottom end is durable.

The comp 268 is a very modern dual profile, and the exhaust side is more like 280.
It's the largest the reccomend with a stock converter. For the record, I'm also looking at that 256 grind. I checked the 270 and it's single profile old school. EDIT (Hmm maybe I was thinking 265)

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=627&sb=0

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=635&sb=0



I have a line on a $50 performer intake, which I'll probably get and use a 600/625/650 CFM carb. I really want the air gap intake. That cam should be right on the line and work with either.

I don't remember the casting on the late non-mag heads, but they are a more efficient design than earlier LA style. The main drawback is valve size. I'm not sure if the heads themselves raise the compression by the full difference or just part of it. Not a bad head for bolt on added comp and unleaded friendlieness, as long as you don't overflow them.

I still say I gan get over 300 HP for under $500 (not counting the original engine purchase).