I haven't been able to find the valspring spec on the 572/620, but extrapolating based on the cam specs from Crane/Comps and other cam co's recommended valve spring for similar lift/duration cams, they have to be in the 160ish area closed. The 572 is also rated to 6000 rpm. I have confidence that we made the right choice for my application, I won't see 6000, maybe 53-5400.
After all one of the old "race" lifters decided to eat a cam and go oil pan diving after having never been over 5K rpm. Truth is it did me a favor since mains were down to copper and cranks were scored (sloppy set up)
I would have blown up this year anyway.

Let me see if I can get one from a parts guy I know at trade price.

I've had conversations with the owner of More Power Racing morepowerinc.com several times over the last 25 plus years and he continues to use cranes to this day in all his builds. Even when others seem to capture the market. He claims he's had 0 reasons to change. They do my machine work and dynoing.

They went under. Some stuff got sold off, but the company got bought by I believe S&S cycles. They dropped some products and changed some others.

Anyway, see here, they are alive and kicking: http://www.cranecams.com/

Marine Kinetics posted the spring info somwhere years back when some people where doing transplants into boats and some where breaking valves.

Same lifter used in the Merc 496's.

http://www.offshoreonly.com/forums/g...ring-load.html

Yes. Thanks for the link.

The GM# 17120060 is also AcDelco # HL121.

Well, this doesn't appear so as some of you guys pointed out this is same lifter as in 8.1's.

I just did more lifter digging for another gentleman and seemed to crack the OE dog bone lifter 'code' between GM / AcDelco / GM Performance and Merc (non blue motors).

Read thru 1st page as it took me a few posts and more time digging thru the part #'s to decipher everything.

http://www.offshoreonly.com/forums/d...i-lifters.html

Any fonal word on this story?

Okay, I have been on major lifter # searchinbg this morning.

The Crane lifters used in Merc 500EFI / 525EFI's where the Crane #16535-16 long body lifters for use in GEN VI dog bone lifter (stepnose cam) set-ups. As we know, these have been no longer available, thus why the 'soul searching.'

I just took a look at Crane's latest catalog: http://www.cranecams.com/uploads/cat...%20Catalog.pdf
and on page 122 which shows the larger HR's , shows to use Crane Lifter #26535-16 . The note letter next to the part # says "For use with standard GM alignment bars (dog bones) and having greater than stock lobe lift."

Reason was hard to find not using the current catalog is that Crane uses these as replacement hr lifters for the 8.1/496 engine and some suppliers list these as just that.
On Crane Catolog page #91 Crane states under the heading "2001–2008 8.1L (Vortec 8100) V8" that "Due to the relocated lifter oil galleries, different lifters are
required. We offer our steel billet bodied 26535-16 hydraulic roller lifters for use with the factory alignment bars to allow the use of higher than stock lift camshafts. "

Appears Crane consolidated part #'s by making these fit for GEN VI 454/502 etc with high lift cams and for the 8.1/496's.

Problem: very pricey ! But, the $$$ spread from retailers is huge.

So, with pretty good confidence, Merc #849947T01 lifters used in the Gen VI 500EFI,525EFI now uses Crane #26535-16 instead of the old Crane #16535-16.

I'm gonna try to organize all this damn lifter info I just dug up and post it up probabably on it's own thread so it can be referenced better.