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!

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

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.

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.

541 foot pounds of torque at 3200 rpm sounds good to me but I'm not an expert in the field.

Mine is actually twin Biii's.
Yeah, looks like a decent repower could be at considerable savings.
Was yours the HT502 or the ZZ502?

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.

Is that the cam in the ZZ502 or the HT502?

that is the 502HO cam. here is ZZ502 cam. can't run this much duration with 110 lobe sep with stock exhausts. would revert. https://paceperformance.com/i-625508...zz502-502.html

my bad. I was assuming you meant 502HO. a rectangle port 461 hp 502. the HT is a 406 hp peanut port 502. very mild cam. would work good in large boat spending it's life in the 3500 rpm range. cam specs for the HT https://www.jegs.com/i/Chevrolet-Per...52296/10002/-1

Dereknkathy you got me ta thinkin.
looked up the 502HO. Looks like alittle more hp and alittle more torque (closer to where I wanted to be) for not much more money AND still an 8.7:1 compression ratio (so still runs on cheap, easily found pump gas. Might be the compromise I'm looking for.

Might have to post this on a different thread:
Found a Ford block by ATK on the Summit Racing site with compression of 9.5:1 (pump gas?) and produces 515 horsepower for only a few hundred bucks more. Is this a viable option...better/worse than the GM? Would like to hear what you guys have to say.

https://www.summitracing.com/parts/h

Anything else out there I should look at?

Some local mechanic quoted me a price of 15k to rebuild my tired old mills or 35k for a couple of new Mercruiser 540's and not much in between so finding these crate engines is makin me real happy but scarin the hell outta Admiral Conscience. :evilb: