Question on Fitting Performer Heads

[Jac Mac]

Dave, your roller rockers, do they have screw in studs for the heads , or are they paired shaft type or single 5/16 bolt down as per original with an adjustable pushrod cup.
Which type will decide the amount of preload you need on your hydraulic lifters---which would have been a possible cause of your 5500rpm problem, which BTW will probably not exist if your edelbrock heads have decent springs--- might just shift it up a bit

[Dave Bilyk]

jac mac, they are studs as as supplied assembled in the head. There is a threaded sleevenut with a grub screw in the thread which locks against the end of the pushrod stud.

Dave

[Jac Mac]

Originally Posted by wolodymyr

jac mac, they are studs as as supplied assembled in the head. There is a threaded sleevenut with a grub screw in the thread which locks against the end of the pushrod stud.

Dave

Right, they are what we call posi-locks. When setting your valve lash if solid lifter, or pre-load if hydraulic lifters, you turn the 'sleevenut' down until you get the reqd lash or preload, then tighten the 'grub screw' ( The Yanks wont understand us here-talking Scottish/Kiwi/English).

Going by your lifter/cam follower I am fairly sure thats a hydraulic cam, so you will want to preload the lifter. Here is the setting order for each cam/firing order depending on which you have. Set the lash on the valves on the top row when the pushrods/valves on the lower corresponding cyl are 'rocking' or on overlap, once you have done the top for in order start on the lower four while checking for 'rocking/overlap on the top row. If you bring the crank damper to TDC to start with it will be ready to set both valves on either 1 or 6, then turn the crank 1/4 turn at a time to set each remaining cylinder. Set preload by spinning the pushrod with fingers while turning the sleevenut down until you just feel the pushrod begin to drag, turn the sleevenut 1/2 turn tighter then fit grubscrew & tighten-YOUR DONE, thats it . IT probably will help to do this before fitting the intake manifold so that you can see the pushrod cup in the lifter depress slightly. Good luck & dont be ashamed if it takes a couple of goes to get right, I still do it wrong occasionally, especially if the phone goes! No excuse now since I disconnected it in the W/Shop!

1-3-7-2 .-----------or 1-5-4-2.
6-5-4-8 .-----------or 6-3-7-8.

Now for track days etc you can build in a bit of insurance by only turning the 'sleevenut' down by 1/8 of a turn after you feel the pushrod resistance, this will reduce the amount of lifter pumpup if you over rev it and decrease the chance of piston to valve contact should that happen.

[Dave Bilyk]

Thanks jacmac, I followed your instructions, its done and the rocker covers are on, rotated the engine and satisfied that there are no contacts in the rocker covers etc. Sunday I will get the exhaust and carb back on connect everything up, fill with coolant and go for a start.
I was intrigued whether the half turn on the posi-locks opened the valve at all, so at the point of zero lash, I zeroed a dial gauge on the valve and noted that it initially opened about 30 thou, then slowly, over about 30 or 40 secs returned to its fully closed position, and the pushrod again became free to rotate. So I am now beginning to understand how these hydraulic lifters work.

Dave

[Dave Bilyk]

And she makes music! Sounds really good, started first time and no tappet or other noise. Thanks guys for all your help, especially jacmac, I'm relieved I had no significant obstacles or holdups. So hopefully tomorrow I wil tidy up, put the bulkhead cover back on and go for a gentle run. then recheck head bolt torques etc.

Dave

[Dave Bilyk]

I didn't manage to go for my intended run today, I hadn't fitted the cooling fans thermostat, so spent time doing that, I then tried to warm the engine up, but had to keep blipping the throttle to keep her going. Just didn't seem to want to idle.
At first I thought hydraulic lifters, so I went through the setup again, first backing off the posi-locks to check that there was a half turn on each, there was. I then tried 1/4 turn preload, but still the same, sounds good when I blip the throttle to 3000 revs, but below 1000 doesn't seem to want to run. Float level is ok, maybe I should play with the idle mixture screws.
Checked the ignition leads and noted all were 300 to 650 ohms except no 3 which was 950, so next on the list is a new set of leads and a coil while I am at it. Also, no 8 exhaust pipe was a lot cooler than the others, so I will need to try a new plug as well.

Dave

[Jac Mac]

Sounds like an air leak- no fittings or holes in the carb or manifold you might not have plugged or a hose like brake booster or pcv not fitted. Other than that Power valve ( Holley?) which would be accompanied by black smoke & fouled/wet plugs, or just idle setting on throttle or mixture screws.

[Dave Bilyk]

Jac mac,
you got it in one! I replaced the 3 and 8 ignition leads and the no 8 plug, which just got it to 'tickover' stably at 2000 rpm, this gave me the opportunity to change the idle mixture to no significant effect (no big surprise at 2000rpm), but clearly there was still a way to go.
So next I removed the carb and spacers looking for air leaks, then I spotted soot marks each side of the manifold face, you can see in the first picture. Then, a look at the adaptor with the breather pipe shows that it overlaps the Edelbrock manifold letting air in on both sides. The face on the stock manifold is bigger and it seals ok.
So, I ditched the breather adaptor, cut some spacer tubes for the carb mounting studs, and reassembled with the tapered carb levelling spacer only. Now ticks over fine, and I will sleep well tonight! There is some tappet noise, so I will go back to the 1/2 turn preload, check torque the head bolts and box it up.


Dave

[Jac Mac]

Good one, you might find your carb has a blocked off or unused 3/8" fitting that you can use for PCV if you need it. Brake booster if fitted should source from intake runner of manifold rather than carb base.
NB. Alloy heads -retorque when cold only.