just a quick one, i had a bowtie block bbc, and ran isky hydraulic lifters part no:3970-hyrt and now will be using a new dart big m block....will these lifters work fine ?

thanks

I'm sure the engine builders on here will answer with a 100% yes or no. But, I believe the Big M block uses a taller than stock lifter (not sure if this ISKY lifter is that piece!).

I do not know if your lifters will work, just make sure you check the lifter bore diameter and hone them to spec. If I recall they run on the small side and the lifters can seize in the bores.
Someone correct me if I'm wrong. Or was this just in conjunction with Morel lifters running on the high side compared with other lifters.

i think any bbc lifter will work in that block it, its still a bbc block basically with room for more stroke, the push rods will have to be sized properly for the correct valve train geometry and you should be good to go. keep in mind all the prostock drag racers use one guy to sleeve all their lifter bores because he has this monstrous old milling machine that is so big and heavy and over built there is like zero deflection or movement of any kind when the tooling starts cutting so they are as accurate as is humanly possible! so having any bozo at ur local machine shop ush your lifter bores might not be wise...

As Rookie said lifter to bore clearance needs to be measured and addressed appropriately for the application. You should NEVER drop any brand lifter in any brand block and call it good. This can be a recipe for a hung lifter or an egged out lifter bore. All clearances need to be carefully checked with the proper measuring tools before final assembly. Installing a lifter in a bore and wiggling it up and down side to side isn't the right way to measure clearance.

Who is it you speak of that has this magical mill?

Don Z,

The Isky 3970-HYRT is the Isky private label Morel 4603 lifter. Their sizing tends to run true to OEM.

It is .300” long, to clear the raised lifter boss, and is a direct drop in for an OEM, Bowtie, Dart, or Merlin block.

The sweet spot for lifter to boss clearance is .0013”-.0019”. Lifter to bore tolerance, bore concentricity, and taper should be checked in every application.

Bob

This is $1000's of good advice. You will save even more if you let Bob build your long block.