ub2693v

Does anyone have any experience with Smith Bros adjustable push rods in a 324 or similar engine? My engine machinist suggested adjustable push rods since there is no adjustment from the factory, the heads have been decked, valve tips squared up and with variations in aftermarket parts/gaskets i didn't really want the clickety clack and as the engine eventually wears i can clean up some of the noise with a little adjustment and the price for 16 wasn't a lot more than a new set of standard rods. I guess my question is setting the pre-load on the lifters, do you adjust them enough so you are still able to twist the push rod with some resistance? I'm very used to overhead cam engines so this push rod business is new to me.

stan 65 cutlass

in some cases you can use an adjustable pushrod to get the initial length needed then order correct length, not sure about the 324 in particular

OLDSter Ralph

Adjustable push rod is ok for measuring, but I wouldn't use them for long term use. Just my opinion.
#1 If the heads have been milled, how much did he remove ?
#2 How do you "square up valve tips" ?
#3 Did he grind the valve stem tips to the same installed height ?
#4 If he milled the heads, you will have more "valve lifter pre-load".
#5 If he ground the valve stem tips to the same installed height, it "could" decrease "valve lifter pre-load". It would depend on how much he ground off the valve stems.
#6 I would suggest looking at "Charlie Jones engine build" on this site.

ub2693v

I guess my terminology is incorrect, he ground the valve tips because the rockers had worn into a few of them.

I don't have the sheet in front of me but If i remember correctly he removed .004" to clean up the heads.

The adjustable push-rod i guess is pretty popular with the Harley-Davidson world, Smith Bros has quite a following.

Tedd Thompson

As I remember(could be wrong on this) you have about 110 thousand lift on a stock lifter and rod, unless your machinist took a total larger than 110 thousands you should be OK. That being said, I wouldn't use a polished lifter unless no other was a viable for some reason. Then I would get one adjustable push rod for insurance, so you can measure and order a full set of push rods if needed.. Tedd

OLDSter Ralph

#1 Just for information, .004" is about the thickness of a hair. If he removed only .004" from the heads, things didn't change enough to change anything.
#2 How much did he grind from the valve stem tips ? My concern would be that if the valve stem tips had worn an indentation into them, they could be soft, and very likely do it again. If they had these identations worn in them, it would be time for valve replacement.
#3 You're asking about an Oldsmobile engine, right ? What happens in the "Harley world" can stay there. The Harley world learns from the "Automotive world", not the other way around.
#4 Smith brothers is a reputable company with good products, as far as I know.
#5 You probably have at least .050" to .060" pre-load on a hydraulic lifter. If, when the engine is running and oil is flowing, if you can't slide a .005" shim under the rocker arm while the engine is running, you have nothing to be concerned about. The most accurate way is to measure with an adjustable push rod and know exactly what you have.
I hope this helps. Others may chime in what their thoughts are.