Sweet64

Hello everyone, im getting ready tackle installing new stock Elgin hydraulic lifter and s new set of stock Elgin Pushrods in my Cutlass. I had my local machine shop rebuild me a set of 1971 #7 Olds cylinder heads, and a 1970 stock 4 barrel Olds intake to set on top. With my Heads in place, im looking forward to the next hanful of steps, one being how to set lifter pre-load. Could someone reach out and give a guy a step by step layout on this procedure? Would be greatly appreciated. Thanks for all the help & guidance.


Sweet64

oldcutlass

If all valve tolerances were set correctly by your machine shop, just bolt everything together. Oldsmobile valve train is non adjustable.

Fun71

Yep, just install the rockers with the cam on the base circle and torque the bolts to 25 Ft-Lbs.

442Harv

If they are to tight, you can shim them up some. Use to able to buy a valve height checking gauge, not sure any one still sells them?

Greg Rogers

Yep as long as the base circle on your cam is the same as factory, mine wasn't. Then it is longer pushrods needed.

Sweet64

Thanks guys for taking the time out of your day to help a guy out, very much appreciated. In regards to finding the cam base circle, for each rocker install and torque down, what's your thoughts on this gentleman's way to go about it? Would love your guy's input, thanks again, have a great weekend everyone.



Sweet64

oldcutlass

It’s not that critical, just make sure both valves are closed.

Charlie Jones

Mark the distributor base at the point where each wire goes into the cap with a tire crayon. Remove the distributor cap.
Bar the engine over by hand until the point of the distributor rotor points the the mark for the number 1 spark plug wire.
Both lifters for number 1 cylinder will be on the base circle. Install pushrods and rocker arms on that cylinder.
Bar the engine over in a clockwise direction for one quarter turn until the next mark on the side of the distributor housing aligns.
This will be the firing position for number 8. Install the pushrods and rockers for that cylinder.
Keep rotating the crankshaft 1/4 turn at a time and continue through the firing order for all eight cylinders. 18436572

Oldsmaniac

I bolt down the rockers with the intake off, this way you can see how far down the lifter plunger travels down to get an idea of how much preload is there. This done with valves closed. If there is a great amount of preload you can shim the rocker stands or get shorter pushrods.

Greg Rogers

Ok maybe no one else has had the problem I did. I got a aftermarket cam that was sposta be as a stock 350 cam- no lope etc. I bought stock new pushrods. Installed cam and chain and then stock used rocker arms. Noticed about 20 thousands clearance between rockers and push rods when lifter was on base circle- no lift. I know that would have been a clattering valve train for sure. Found out the aftermarket cam was ground from a blank and had a smaller base circle, so the lift and duration was at same specs as original, but base circle is smaller, thus all the clearance. Shimming the rocker stands would just make even more clearance. I already had adjustable push rods which I didn't want to use ( as I was going back to stock-smooth idle), but I did use the adjustable ones. Later on someone on here suggested I may have actually ground the rocker pivots to make less clearance but I don't know. Well anyway I would say if you can see the pushrod go down into the lifter as you tighten it up while on the base circle you are prolly ok. If it's loose you will be able to tell.....

Charlie Jones

Do this as a check to see if the valve train has proper preload after assembly, and while the lifters are on the base circle.
Grab the pushrod between you thumb and forefinger .
Try to move the rod up and down, If you can feel up and down movement, install longer pushrods.
Try to turn the pushrod between your thumb and finger. If you can't , it's too tight.
Install shorter pushrods or shim the rocker stands.

coppercutlass

They are adjustable with shims and it's very important. Too much preload will make for a rough idle. .020 minimum .makes for a happy engine .040 imo is max ideal.

olds 307 and 403

What cam was used? I assume the stock peanut cam wasn't reused. How much were the #7 heads milled by the machine shop? What head gaskets were used? If the machine shop used the proper installed height after the valves and seats were ground, that eliminates one big variable, hopefully they did. Then with a .025" head mill, if using the .042" thick Felpro in place of the .017" thick factory shim gaskets will restore the factory distance. The other bonus, that should put you right around 9 to 1 compression if the heads weren't milled previously. The intake may need a clean up mill but might be fine with a thin gasket like the Turkey Tray. Find out all that info and you should be able to calculate where you stand before the base circle comes into play, you may already be on the upper limits. I used the 204/214 cam with thicker head gaskets on unmilled deck and heads with replacement .040" head gaskets with no ticking. Good luck.