1fastWS6

iTrader: (3)

If I do the math, my 7.400" Comp pushrods are going to be about 0.035" - .040" too long since my heads are milled.

If I get 7.350" pushrods, those will be about .010" - .015" too short which I'm afraid will cause a noisy valvetrain. Plus, it's just another $100 I have to spend on new pushrods.

As an alternative, can I just make some .030" thick shims to go under the rocker pedestals? Will this throw off the geometry of the rocker with respect to the valve?

Has anyone done this?

Thanks,

Craig

Tin Indian

Just my opinion, but you can use shims in leu of shorter pushrods.

Shims under the rockers will act just like shorter pushrods, and will decrease your lifter preload.

Just remember ... that cam you have has a .025" to .030" smaller cam centerline to lobe heel distance than your stock cam. That in itself would require a .025" -.030" [longer] pushrod.

If all you did was to mill your heads lets say .030", then you would need .030" [shorter] pushrods.

With the aftermarket cam [and] the heads milled, the lifter preload would remain the same as stock when using stock rods. It then is just "tit for tat".

Ron,

DaleMX

iTrader: (4)

Yes I did, and I still have the shims I made. I cut them out on an NC router so they fit nice. I made like 3 sets and only used one, so if you want to pay for the shipping I will be glad to send a set to you.

1fastWS6

iTrader: (3)

Sending you a PM.

Thanks,
Craig

LS1x2

iTrader: (11)

Yes you can. I used sheetmetal from lowes.

slyws6

Just keep in mind if you do this it throws off your rocker geometry a tad. Reason being it will basically make your rocker tilt forward towards the valve more when the valve is at 0 lift. So if you have a really big cam, you have the possibility of maxing out the rocker's range of motion. If you don't quite understand I can draw a diagram of what I'm talking about to fully explain it.

-Sly

LS1x2

iTrader: (11)

I see what you are saying. It would take one HUGE cam though. I'm runnig .613 lift without a problem. Shimmed them .015".

slyws6

THere is the possibility that it could affect HP way up top, could be a factor to valve float if you were getting it. Just my .02, I'm sure it'll be fine but something to keep in mind if you run into problems.

-Sly

Jabroni

So is the consensus that it's better to use .030 shims with 7.4 PR's on heads milled .030 than to use shorter PR's and not shim? I'm trying to work this out myself right now.

slyws6

No it's better to use shorter pushrods. But what they are saying is that you can use shimmed rockers, however the proper method would be to use shorter pushrods.

-Sly

Jabroni

Ok, cool. I guess I'll need those now, too! I want to do this right. Thanks!

LS1x2

iTrader: (11)

I'd use the shims and do. Matter of opinion. I belive stock pushrods are 7.38" actually. So make sure you figure that in.

DaleMX

iTrader: (4)

After the shop did a 4 angle valve job on my heads I had to use the shims (worked great) because the valves were sunk into the heads a bit more and threw my preload off. Recently went the way of Yella's and had to use the washer type shims on them instead.

Cal

iTrader: (1)

Yella Terra roller rockers come with shims that you are to use if needed, so I doubt there are any significant problems with using them.

Jabroni

I guess I'll try shimming the rockers then...as long as it's not too complicated! It doesn't sound like it is.