gsxr1216

how do i ID a used cam that is supposed to be a OEM HP500 roller cam? any specific identifying #'s on it? if so where are they located?

also, what would be the lift i should see by measuring it with calipers across the base circle then across the top of the lobe and subtracting off the base circle dimension off the lobe dimension?

thanks!

Griff

A factory HP500 cam will have some engraving on the end. I think the HP500 cam is engraved with M300 or maybe M301.

gsxr1216

well this one has MHP-300 on it on the distributor end of it, and then 16-49-98 on it below that??? i would have expected a hp500 cam not to have a 300 engraved on it!!!! it looks like it was engraved with a dremel tool is that typical???

thanks!

ckin62

When I tore down both my HP500's, they had the same markings...MHP-300 and 16-4998. Just as you described. After some research the 16-4998 number could be referenced to an old Crane Cams grind.Since the changes at Crane, not sure the reference is available as it once was. So I'd say you have a factory HP-500 cam on your hands. Like you I would have thought it would have MHP-500 on the thing, but not the case.

gsxr1216

cool thanks for the info!

at least somebody thinks like me and thought a 500 cam would be engraved 500!!!!!!!

nxfirebird

Yup, it's a carbed hp500 cam.

gsxr1216

Ok so now that i know its for sure a hp500 cam so now I have a few other questions.

first what kind of seat pressure do I need to have to run this hp500 roller cam in my otherwise stock 454 MAG it currently has the stock flat tappet cam and lifters in.

2nd will I have any reversion issues with this cam , I will be running a IMCO powerfow exhaust with the SA risers (silent choice)

Where should I set this cam up for timing?


thanks!

Griff

You might have reversion issues with the Imco's and silent choice. Merc had reversion issues with the early HP500's and switched to a taller riser with more bend.

Use some Comp cams 929 or Isky 8205 springs.

Sporl Performanc

iTrader: (1)

The Mercury carb 500 came with the MHP-300 stamped on the back , Crane part # 169611 . Specs -
222-230 @.050
576-598 @ the valve
lobe separation 110

As far as pressure goes, it mostly depends on what manufactors lifters you run. The springs that you have now will definately not work. The retainers and keepers that are in your motor are excellant and I would not change, we do have a spring that fits that retainer. You probably will have a reversion problem because the lobe separation should be around 114. We have a cam that works really well around that that is
225-230 @.050
629-629 @ the valve
lobe separation 114

Give me a call if you have any other questions !