Join Date: Apr 2010
Location: Calgary, Alberta, Canada
Morel VS GM 572/620 lifter
GM p/n is 17120060.... OR HL 121
From my gatherings this is GM heavy duty lifter, mayby someone can correct me on that. It is used on OE 454/496 GM truck applications as well all mercruiser stuff for boats. These maintain stock oil flow to valve train, it is my understanding the 502 version allow more oil to the top end. This would make sense for high rpm heavy duty applications.
There are many similarities between the too. Plunger travel basically the same, GM slightly more by 0.040. Morels at .120 total. Check ball valve slightly larger on morels with the hole which the ball seats is larger. This usually means a higher bleed down rate typically with the additional surface area. The plunger spring on the morels is softer by a lot. Morel is a 2 piece design where GM is a 1 piece. There would be more movement of the parts in Morel bodies. Axles are held in by clips vs pressed like GM. The pushrod piling system is drastically different between the 2. Morel are relying on oil squiring by the body and upper plunger into a relief hole which supplies the pushrod with oil. I am not sure if this is a means of control for oil or not. The GM ones use a disk which site under a rounded rounder head plunger, I would venture to say these really let oil get up top. Morel oiling hole online with roller, GM one is perpendicular to the wheel.
Keep in mind my morels are used but the GM ones you can’t even push the plunger in as it compresses the air in the body. The Morel plunger just collapse’s to the bottom.
Honestly I like the GM ones, id Recommend them. I paid $37US/ea. For the rebuild I will only be replacing 8, I have 12 good morels which will be broken down, cleaned, and reused.
I am thinking they should perform fine given I don’t expect to shift this new combo past 5500rpm. Valve springs will be 155-160 seat pressure, 428lbs/in rate. GM 572/620 crate motor runs 197 seat pressure.
540 BBC + 15psi Boost via Single Garrett GTX
Stock looking, and fairly stock sounding
HP and ET not determined yet!