vavle train noise

[DAT240Z]

I have a 76 280z motor that I turboed, I install the rocker and cam of my old turbo motor in the rebuild 76-engine. I have adjusted my vavles three times and can not get the car to not sound like a tractor.I was woundering if the niose is because of I'm running hydraulic rockers in a N42 head.

[BRAAP]

Was the Turbo head that your cam and rockers came from a P-90A and did it have Hydraulic lash adjusters? You installed the cam and rockers into the Non Turbo head right?

 

If so, you can NOT use the Hydraulic cam on a non hydraulic head. The open and closing ramps of the hydraulic cam are ground for the rocker to be in contact with cam lobe, i.e. zero lash. Also, do not try to replicate the “zero lash” yourself by adjusting the rockers to zero lash either.

[DAT240Z]

Yes the cam, rockers and lash pads are from a P-90a Head installed on a N42 HEAD. Would I be better off putting the N42 lash pads and rockers back in and run the turbo cam.

Thanks

[Len]

I really don't see the benefit of using the p90a hydralic setup...no adjustability, don't know of anywhere you can buy (new)replacement hydralic lifters..and I've found they do wear out...and make noise. If I were you put back the N42 rockers so you can at least adjust the valves...and would mate up better but I haven't looked into replacement parts for the N42 head so if you were putting together a bebuild engine and the N42 parts are worn..I'd try and find a good match were you can install NOS parts...my 2cents

Also on those hydralic lifters if they were sitting you may need to prime them with oil to get the air out

[mario_82_ZXT]

You can't run that cam as it is ground for hydraulic lifters.

 

If you want a turbo cam you have to run one from a P-90 or a solid lifter P-90a. Or just upgrade to an aftermarket turbo cam.

Mario

[DAT240Z]

Len I did not use the lifters just the rockers, cam and lash pads. Looks like I need to buy new rockers and pads.

Thans guys

[BRAAP]

DAT,

The cam IS the issue, NOT the rockers or lash pads. That CAM will ONLY work with the HYDRAULIC lifters in the P-90a head. Changing the Rockers isn’t going to change or fix your issue. Also, those hydraulic lash adjusters will NOT work in a N-42 head unless you have a machine shop modify the head to accept those hydraulic adjusters, and in my opinion, that would be an exercise in futility.

 

Here are your options as I see them.

 

1) If you want a turbo cam for your set up with the N-42 head, you need a mechanical Turbo cam whether it be stock or aftermarket.

 

2) Use your N-42 cam. It is not an ideal grind for a Turbo application with its tight lobe separation, but it will run and should run quietly if the valve train is set up and adjusted properly. (I stand corrected. If the "A" grind, it is actually more ideal than the Turbo cam)!

 

3) Put the P-90a head on your short block, not only will you then have that Turbo cam, but you will also lessen the likelihood of the dreaded L-6 knock and subsequent blown head gasket and/or broken pistons. Running boost with a N-42 head on an L-28 with pump gas is like having unprotected sex with hookers… , even if you are using ARP head studs, N-42 heads, boost and pump gas are a very unstable combination.

 

 

If a customer brought this set to me in its current configuration, I would VERY strongly urge him to choose option #3.

Edited August 20, 2010 by BRAAP
A grind update.