HT 502 marine application?
08-30-2018, 10:35 PM
#1
HT 502 marine application?
Just saw an HT 502 engine (as opposed to the zz502) advertised on a website. It looks to produce less hp, more torque, and have a heavy duty block...BUT...the fine print says not for marine use.
How could it be that much different from any other engine? Would someone please enlighten me!
How could it be that much different from any other engine? Would someone please enlighten me!
08-31-2018, 06:26 AM
#2
Registered
looked at that engine before as well, the issue is GM does not sell any engine for marine use, they only supply engines and/or componants to be assembled off site that are then sold to marineizers. All warranty is thru whoever does the marineizing. I think this engine would be great in a bigger heavy boat..wanted to run 2 of these when I repowered my Gibson few years back...wish I had known enough to reverse rotate one. In order to get warranty on these engines you need a vin # of a heaver truck/RV etc that would have had a 454 in, not impossible...hope this helps...Rob
08-31-2018, 09:02 AM
#3
Thanks for the reply Rob. Yes, it does help.
these engines would go in a Formula 34PC, so it would be a heavy boat. It had a couple of very tired, probably original 454's. Wanted to put bigger engines in it because I will be using the boat around Cape Cod and I want it to be able to get out of it's own way on occasion.
Good to know about the warranty. Guess none of them will have a warranty if they are used in a boat instead of a car. Sounds like a rip-off.
these engines would go in a Formula 34PC, so it would be a heavy boat. It had a couple of very tired, probably original 454's. Wanted to put bigger engines in it because I will be using the boat around Cape Cod and I want it to be able to get out of it's own way on occasion.
Good to know about the warranty. Guess none of them will have a warranty if they are used in a boat instead of a car. Sounds like a rip-off.
08-31-2018, 11:04 AM
#4
Registered
The HT502 had same shortblock all the other GM Performance 502's have. Same short block as Merc's 502MPI also.It just has tiny heads with tiny valves with tiny valvesprings with tiny camshaft. 
LOL.
Was made for an emissions legal replacement for the 454TBI engines,more than it was for anything else really. GM had a kit with computer chip.exhaust/and etc to make the retrofit 50 state legal. GM probably sold some to some industrial applications too I'm sure.
LOL.Was made for an emissions legal replacement for the 454TBI engines,more than it was for anything else really. GM had a kit with computer chip.exhaust/and etc to make the retrofit 50 state legal. GM probably sold some to some industrial applications too I'm sure.
08-31-2018, 04:29 PM
#7
Registered
Does your boat have one or two? Looks like a V drive, or at least not a bravo?
In my experience with my ZZ502 I would switch out the bearings to H series which give you an extra half thousandths of clearance and make sure that cam is good for marine. Mine wasn’t.
Only mercruiser offers a warrantee for marine use that i know of and you could probably buy two engines for that, and the warrantee is good for what, a year or two?
The H502 has iron heads so that’s good. Check the cam, switch out the freeze plugs, put your accessories on it and you have what Merc sells for half the cost.
In my experience with my ZZ502 I would switch out the bearings to H series which give you an extra half thousandths of clearance and make sure that cam is good for marine. Mine wasn’t.
Only mercruiser offers a warrantee for marine use that i know of and you could probably buy two engines for that, and the warrantee is good for what, a year or two?
The H502 has iron heads so that’s good. Check the cam, switch out the freeze plugs, put your accessories on it and you have what Merc sells for half the cost.
08-31-2018, 07:04 PM
#9
Registered
Here is the cam. Specs a little down the page. About a mag grind. Little less lobe sep.https://paceperformance.com/i-625492...oller-cam.html. Iron rectangle heads.
