One for the RV8 engine buffs.
Discussion
When rebuilding the top end it is quite well accepted that you should measure and correct the pre-load on the hydraulic lifters. The most commonly listed figures being between 20 and 60 thousands of an inch.
When required shims can be fitted under the rocker pedestals.
However I have an engine where the combination of new cam, skimmed head, cut and ground valves and some replacement valves means that some preloads are as low as .015" and others over .080". This now means I will fit adjustable pushrods.
The engine is TVR 400 with an MC1 cam so nothing extreme or race about it just a road car.
That's the preamble, now the question.
Now that I have the ability for fine adjust of the preload where should I set it?
I have read, but not fully understood, that setting it tight (.020") will improve the engines ability to rev high. The opposite being setting it loose (.060) will allow/cause the lifter to bleed down effectively acting as a rev limiter.
Your thoughts?
Steve
When required shims can be fitted under the rocker pedestals.
However I have an engine where the combination of new cam, skimmed head, cut and ground valves and some replacement valves means that some preloads are as low as .015" and others over .080". This now means I will fit adjustable pushrods.
The engine is TVR 400 with an MC1 cam so nothing extreme or race about it just a road car.
That's the preamble, now the question.
Now that I have the ability for fine adjust of the preload where should I set it?
I have read, but not fully understood, that setting it tight (.020") will improve the engines ability to rev high. The opposite being setting it loose (.060) will allow/cause the lifter to bleed down effectively acting as a rev limiter.
Your thoughts?
Steve
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff