This is my first engine build so I’d like to run the basic method I used to determine the pushrod length and get some feedback.
1. Adjusted roller tip setscrew so approx. 1 thread was exposed on underside of the roller body.
2. Mounted hydraulic lifter in bore.
3. Used adjustable pushrod (ball on both ends) to measure effective length between roller tip and lifter. I was careful during adjustment to make sure pushrod did not move plunger. Rotated engine to ensure lifter was on heel of camshaft.
4. Took measurements on 4 different valves (2 on each end of head) and arrived at 8.81”. I then added 0.040” to this measurement (provided by Lunati) and came up with a final length of 8.853”.
5. Called Smith Bros., discussed this with sales tech. and purchased a single pushrod (ball and cup) to verify length. Ordered a 5/16” dia. Rod with 0.083” wall.
6. Installed pushrod and backed off setscrew until pushrod just started to deflect lifter plunger. Setscrew now shows no exposed threads (due to 0.040” that was added to length). Rotated engined, checked pattern on valve tip.
Should I have left the setscrew with the 1 exposed thread and let the pushrod pre-load the lifter by the 0.040”? What else should I check?
I will definitely need to shim the rocker shaft (side to side) to get the roller tips centered over the valves. I will also check other head before ordering a full set of pushrods.
