I'm trying to wake up my late 70's 318 in my 72 Duster until I build a new motor. I'm getting ready to port a set of "302" closed chamber heads to boost compression a little and want to put in a new cam. Does anyone know whats the most lift I can get away with on a 318 with stock pistons without hitting the pistons. I know you can notcch the pistons but I just want to throw on some heads and cam, it .491 too much or shouls it be ok? Thanks

Butch

It has been a while since I thought about my Mopar stuff, but I would think this swap depends on whether it is a manual or auto shift car.

If it is an automatic you will definately need a stall converter with a .491 lift cam. I swapped in a .472 and it was a dog off the line and didn`t really wake up until over 3,000 rpm`s using a stock torque converter.

So, if you say you are only wanting to swap on some heads and a cam, you can use better valve springs so they won`t bind and get more lift, but you will need to deal with other area`s in the process to make it all work well together, namely, the torque converter.

If it is a manual shift car then the TQ isn`t as much a factor, you will just need a higher rpm and a little clutch fading to get it rolling without roasting the tires off every stop. That example might be a little much using your .491 lift, but it starts to get unfriendly street manners when the lift goes way up on the cam.

This should be a good topic to keep an eye on for other responses, I haven``t been here in a long while.
Guido

need to watch retainer to valve guide clearance and piston to valve clearance

i run a .485 lift roller cam in my 318 with stock untouched 360 heads,(88-360 headed 318 cop engine never been apart yet)

i swaped to comp-901-16 springs and used all stock retainers,valve seals,push rods,rockers

lunati voodoo roller cam 60710

258/264
.485/.485 lift

work great for a daily driver in a stock engine in a stepside truck

the comp springs drop on and .485 lift works great,IMHO

if it has the rotators on the exhast valve,drop those and use 8 more intake retainers and spring

the rotators make the exhast spring and clearance less in stock fourm..will not take much lift with them on the spring

on a stock 318 short dur @ 50 and as much lift as it will take works

more dur and it becomes a dog like said above

my roller cam is

258/264
207/213 @ .050

bump it up around 230 @ .050 and its a dog with out a 3000 rpm stall and gears

any thing over 230 @ .050 is not street friendly and very choppy

remember whats big for a 318 is mild on a 360

318s are vary ez to over cam and turn it to a dog

Ok, This is what I have...
72 Duster with stock rebuild 318( was done before I bought the car) and a 4 speed OD manual trans and 3:91 sure grip 8 3/4 rear. Right now the engine has an Edelbrock performer cam ( 204 duration at .050 and 420 lift)lifers and soposedly springs combined with an Edelbrock performer intake, Holley 650 carb, headers, and a Mopar Performance distributer and contol box and an MSD coil. The heads are open chamber 318 heads that appear to be untouched.

I'm going to be building a 390 stroker(because I got a great deal on a set of Diamond forged pistons and Eagle SIR rods)but its going to be a while till I piece it all together so I want to give the current 318 a little more.

Right now I have a Comp XE274 which is a 230/236 @ .050 and .488/.491 and a 110 LCA, and a Crane H-278 which is 222/234 @ .050 with .467/.494 lift and 114 LCA that I can use, and a set of Comp springs, along with a set of "302" casting 318 heads that had 1.88 intake and 1.60 exhaust valves installed.

I plan on porting the "302" heads and was thinking that the Performer cam is too small, the reason I have the Comp and Crane cams is that I was planning on building a 360 short block that I bought used that was bored .030 with forged TRW slugs untill I decieded on a stroker.

So what do you think, are both of those came too big for the 318, do you think with that lift the valves will hit the pistons? I figure with the closed chambered "302" heads and a thin .028 head gasket I should get a decent boost in compression, so I figured one of those came wouldnt bee too bad, but not ideal. So stick with the performer cam or use the Comp or Crane.

Butch

Comp 260 or 268 will wake that engine up big time. You may want to dump that performer intake. You would be better with a cast iron stock one performance wise. Assuming it is not a rpm

Yeah I know a 260 or 268 would be the much better choise, its just that I have these 2 cams already, the Comp is used but in perfect shape and the Crane is new.

And yes it is the standard Performer intake(was on it already) I am planning on getting a Performer RPM Air Gap eventually and using it on the 390 build. You really think the Performer is worse than a stock cast iron? How about the cheaper Crosswind or Summit Racing brand(probably the same thing) RPM copy intakes, I doubt there as good as the Edelbrock but are they better than a Performer? I've seen those for $150.

Butch

Mated to a 360 head, the Performer will not perform as well as the stock 360 intake. On a 318 head http://www.compcams.com/community/articles/Details.asp?ID=-409383413

The performer will be slower in the qtr then a good old fashioned sq bore intake. Since you have it make the best of it. Start with a good 4 hole 1"spacer or 2" but clearence will be a problem. The RPM is a good intake no problem. I have used the performer- the Holley street dom- strip dom-stock TQ style Mopar and sq bore Mopar cast the M1 Mopar and the LD 340 with and without a milled divider. and Offy Port o Sonic. The winner is the Milled LD and sec the standard LD TheStrip dom is hair better in the 6K + range but I dont go over 6500. I found the crutch for the low rise street dom was the spacers. The M1 dual plane is a good choice but a compromise on anything over 5,500 as it is plainly down on power by then. Just my 10 cents

herd to beat an LD340 or the LD4B for a 318 head

right up there with the airgap

night and day over a performer

Thanks guys, I quess I'll go serching for an LD 340 or LD4B. I saw a rightup were they opened up the intake port(just the opening) on the 318 "302" head to 360 size to mate with a 340/360 intake. Thats an option too.

So back to cams, Performer, Comp or Crane? What will work the best out of the 3 and what will fit without flycutting the pistons?



Butch

It is recommended not to exceed .495 lift with stock valve train. Make sure the springs you use are compatible, comp 901 should be good. Like scratchn said, the clearance between guide and retainer is crucial, don't use the rotators. Check those 302 castings, they can be prone to cracking in the valve area.

Ok the 901 Comp springs is what I have, so they should be ok. Now I understand the the clearence for the valve guide to retainer, make sure the retainer doesnt hit the top of the valve guide at full lift, correct. But what is the rotator? I just disasembled the heads and there were the standard spring, retainer and locks and under the spring was a washer, I'm guessing its a shim to get the springs to specs with the cam he was using. So what it the rotator and where is it located, sorry for the ignorance!!!

Butch

Correct on the clearance part. It is in some retainers more common to 360 heads. If your retainers are solid then your good to go. The shim was on my heads when I changed my springs and they were stock. I'm not totally sure why those are there other than a wear point for the spring against the head in case there is some rotation. Maybe someone else can chime in here and explain those shims. You might consider a spreadbore intake with a non smogger thermoquad carb. I port matched my stock 318 heads to match the intake off a 340 and rebuilt the carb. Mine runs great!

Yeah all the retainers look the same so I quess it doesnt have them. I already have a good running Holley 650 so I'm gonna stay with that. The 318 is pretty quick right now in the Duster but I just want a little more until I build the 390. I'll look for a better intake and port match to my heads, do a mild port job on the heads and maybe try out the Comp XE274 cam and see how it is.

Hey maybe someone knows, the valves are stock type with the little ramp right before the seating surface, would it be of any gain to shave the ramp off the valves? I know performance stainless valves dont have this.

Butch

Is it posible to back cut the valves at home using a bench grinder and a made up jig, or best to leave to a shop? If so any idea what it would cost?

Butch

I know the xe268 fits in a stock piston 318- I ran one for a few years, I ran it with a 2,400 stall and 3.91's.

My current 318 has the crane .467/.494 but I have KB167 pistons with valve reliefs, I have some warmed up #302's on it and a 833/4.10 rear, it makes pretty good torque, I built it for a truck and ended up sticking it in my Dart, it likes shifted around 5,400.

Years ago I ran a 557/528 lift crane in my 318's. Never any problems.