Cam AND ROCKER HELP NEEDED PLEASE!

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Brian Hood

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Hello Everyone,
I’ve been reading too much! I bought a Comp Cam (Flat Hyd) and some new roller rockers for a 71 LA 318. The specs for the cam are as follows. Intake 462 Exhaust 482 with a lift of Intake 275 and Exhaust 284. The roller rockers I got are 1.6:1. Will these cause problems with too much lift? Should I get a set of 1.5:1’s?

Brian
 
Need more info….what heads? Any work done to the heads? If your lift with a 1.5 rocker is 0.462/0.482 then with a 1.6 it would be 0.492/0.514…..is that too big, I can't tell you…not without knowing more about the heads.
 
From the standpoint of the camshaft size, you really don't need adjustable roller rockers. Not that they won't give you benefits nonetheless. If the heads are stock and unported, usually, 1.6s on the exhaust only, sees the biggest benefit. I certainly wouldn't worry about doing any kinda damage with the 1.6s, as long as the valve train is set up correctly. To me the biggest benefit of going to roller rockers isn't the additional power they may free up. It's the extra longevity they give the valves and guides. They all but eliminate side loading on the valve stems and guides and also stop the scrubbing action on the valve tip. In my opinion, those are far greater benefits than any additional power increase. Any power increases are just icing on the cake. Since you have the 1.6s, use them. Since they're adjustable, you'll be able to get lifter preload spot on, even with the smaller cam that will still be a good thing. They will make more power than the stockers for sure and you'll have all the other benefits to go along with them.
 
With the 1.6 rockers, you get 492 & 514 lift. I beileve, the 514 lift should clear the stock guides and seals. Anybody else on this?
 
rumblefish360 said:
With the 1.6 rockers, you get 492 & 514 lift. I beileve, the 514 lift should clear the stock guides and seals. Anybody else on this?
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I ran the 509 on stock heads so I'm sayin yeah.
 
has anyone actually checked to see if they really had .500+ lift at the valve?
just curious..
mystery rocker geometry can rob valve lift.

I say if the heads are off, take'em down to a machine shop and ask them to check/set them up for the cam.

now what pistons are you using? stock?
 
Stroker, I'm inclided to agree. Actual lift like 1w&cg was saying may not be as much as advertised. ( + the rocker ratios additional lift) But if theroretical lift is a .514, which I think would clear, but don't know for sure, I think it should be certainly checked for it.

Granted alll the cave eats of the "LA" engines unperfect valve train issues can cause less than optimal lift. Checking for it like it was perfect is the only way to go for sure and his "Have the machinest check it." is a great idea.

I myself have not been there with a stock head. I'm still with flyfish...more info would help. But in general, I think it'll work. Like yourself, the biggest cam I have run on a stock head is the Purple 292/.509.
 
Absolutely let a GOOD machine shop make the call. Also, with the hydraulic lifter itself, right there is the biggest reason not to have all the lift at the valve. That's why I love a good solid. But sometimes they're just not practical for a given project.
 
I am using stock heads with stock pistons. I found a really great deal on a 71 318 that had less than 20000 mi. The inside of this engine looks like new. Therefore, I really hate to get too deep into mods. Thats why I am keeping the stock parts. However, I am going to use your idea of a mach shop to check the set up for these heads. Thanks guys!
Brian
 
On behalf of all 3 of us, no problem.

The machinest can measure up everything on the head.
 
Good call. Although I have quite a few years as a machinist, and maybe some others here as well, there's no way for us to know what parts you have. The last thing we want is to give you advice and end up seein you break somethin. That would suck.
 
You cannot run stock 318 springs on that cam. You need to consult with a machinist. A better choice might be a smaller cam that can use a performance single spring. Then it's an easy bolt on deal. Something like the XE256H with those 1.6s could run the 911-16 springs.
 
yes, get the right springs. The matching comp springs are way cheap. Get them.
 
moper said:
You cannot run stock 318 springs on that cam. You need to consult with a machinist. A better choice might be a smaller cam that can use a performance single spring. Then it's an easy bolt on deal. Something like the XE256H with those 1.6s could run the 911-16 springs.
Click to expand...

yep, or a set of paw 340 springs or pioneer 810102, or even the mopar '847' springs. will all handle up to .520, buts thats it. all rated around 110-120 seat and 300-315 open
 
If your valve spring retainer hits the guide boss or you coil bind the springs, really bad stuff happens quick. Check to be sure. I doubt your 318 heads flow much more over .500 lift anyway. If you can trade for 1.5 rockers, it may be cheaper and easier in the long run.
 
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