I am building a slightly modified 502 carbed with a ZZ502/502 cam and Cmi exhaust. I need to buy a new thermostat housing and circulator pump anyway should I buy them or just go with a bypass kit .I've heard bad things at the 502 really need circulation through the block and the extra pump helps but just not sure which way to go any help appreciated.

Keep circulating pumps unless you have a blower. Save yourself the headache. I run them but I also bought pumps to replace them some point in time.

Recircuating pump system.

That ZZ502 cam is less than ideal for marine use. The Crane 731 is close but more marine friendly.

agreed. Power-wise it's not bad but you need long risers with that tight lobe sep. I mean a long-distance total water mixes with the exhaust. Dry to the tip would be better yet.

not to hijack but what about in a blower application...to the OP question...454 with 250 blower

thanks

stewart

Probably 90% of the boats on the water be best off with stock circulating pump. As mentioned higher temp running engines long distance runs the majority of the time bypass is probably a good choice but even then you'd wanna use an oil stat. Many have difficulties getting consistent oil temps. So really either way you go I highly recommend oil stat. If your running a 27 poweruest I would imagine your cruising more than wot so I'd make it easy on your self and utilize stock set up. If you need to purchase put it in the wanted section. You'll likely pick stock set up cheap from another member.

i also say run the circulating pump,many don,t realize but it slows the water flow and with the thermostat it keeps the engine at a steady water temp.different story for blown or big n/a deals.

Thanks everyone for the input looks like I'll be bringing the circulator pump back in. I'll also post something in The Wanted section. I've ran that ZZ 502 cam for about a year on the previous engine with no troubles no water in the oil .I've got some pretty good CMI E top headers, it dumps the water pretty far back

first time for me not running circ pump, Im running the Whipple water pump delete serpentine belt system, so it uses a bypass