crate engines

[apollo74]

anybody know why all the gm performance crate engines say not for marine use? is there something really different in a marine engine or are they just saying that to protect their marine "partners" pricing structure? just curious, the 502 ram jet with over 500hp and 565 torque at like 3200 rpm looks like a killer jet motor.

[kevnmcd]

apollo74-There are quite a few things different between a marine application and an auto application, but probably the biggest one is the cam specs. If you are ever interested in learning the difference buy this book. It explains in detail all the differences.
http://www.amazon.com/exec/obidos/ASIN/1557882975/qid=1023943073/sr=1-4/ref=sr_1_4/104-8268102-5469514
Kevnmcd

[77charger]

marine motors have a little more clearances also.

[230Stingray]

I have over 140 hours on a 502/502 package.
I was a little nervous with the cam lobe centerline but have not had any reversion problems. GM gives it a 5800 rpm redline.
I run mine at 5200 all day long.

[gnarley]

OK really, what are the diffeences? Lets talk long block here or short block not complete auto package. So what are the differences in clearence if any? I suspect they are not different! Cam, well maybe different but would it matter that much? They don't use different blocks, cranks, pistons, rods, heads, valves, springs, oil pump or bearings. About the only thing different might be core/cam plugs needing to be brass. Are there marine head gaskets??? SO can anyone explain if & what are the differences between the crate long or short blocks and any marine, so called short blocks? And please be specific.

[230Stingray]

can't speak for all of the GM crate engines only the ZZ502 because it came in pieces and had to be partially assembled. it has brass freeze and cam plugs. The head gaskets that were supplied with the engine were stamped "marine" right on them. Hot Boat did a article several years ago on a small block crate engine conversion I will find it tonight and post what issue it was from. It wasn't a long term test but they were pleased with the immediate results. I think that the ones that are the nay sayers here are the ones that make there living in the marine business and the crate engines hit them in the pocketbook

[BBC502]

I believe they are listed for non marine use because of the use of non marine starters, ignition systems and carbueration. The short block has mentioned before is sold as a marine use unit. I have a ZZ502/502 in my 21' open bow and it runs great. I did change cams thoughand bumped the HP tp 540 @ 5400 rpm and the torque is 605 @ 4200rpm (dyno verified).

[mister460]

Gnarley's right. Brass freeze plugs. That's about it. I wouldn't buy a crate motor anyway. Never have trusted them.

[gnarley]

Originally posted by BBC502:
I have a ZZ502/502 in my 21' open bow and it runs great. I did change cams though and bumped the HP tp 540 @ 5400 rpm and the torque is 605 @ 4200rpm (dyno verified).
Sounds good to me! What hull? & what is your MPH, prop & RPM? I am thinking of putting a 502 short block under the rest of my engine in the fall. I would like around 700 after I do the head work and have the blower (small 177)tuned up. You know make it nice & reliable with power to spare. Maybe change the cam to one with a 114 degree center line and roller rockers but thats it, nothing fancy but a sleeper is what I desire.

[rjcardinal]

I bought the 502 Partial engine from GM. Its the first part number listed in the list of parts that make up the ZZ502. For less than 4K you get the block, crank, rods, oil pump, windage tray, oil pan, the ZZ502 roller cam, timing set, roller lifters, lifter retainer, and timing cover all assembled delivered to your door.
The book Big Block Marine Performance by Dennis Moore list the ZZ502 roller cam as one of the cams he recommends. To run this cam at sustained high rpm you need to have a upgraded valve train with good springs.
Ron

[BBC502]

Sorry for not answering sooner. The boat is an '86 Miller 21' open bow. I'm turning an "A" impeller at 5300 RPM. GPS was 67 mph with old(18 yrs.) pump . I just installed a new pump with droop. Feels much stronger but I haven't ran a GPS run yet. Hoping for 70-75 mph. The cam is original roller that Crower reground from .544 lift to upper .500, I think .586, The info is packed away.

[jordanpaulk]

I am considering the crate motor 502/502 for my jet boat right now. Really cant beat it as an alternative to a hopped up race motor. My question is, how much would be interchangable between the two. Say, if I got the long block package, would my rectangular port intake manifold bolt up? What about exhaust? Is it the same? Deep sump oil pan? Just trying to figure out all my options before I throw more money into the 468 I am running now.
Jordy

[230Stingray]

I think you must use the intake manifold that comes with the long block kit. The reason being is that the aluminum heads that come with this package use a port shape that is between a ovel port and a rectangle port shape. I have run this motor for three seasons now. It is a great runner for not a huge investment.

[230Stingray]

woops,
I guess I better answer the rest of your questions. Exhaust bolts right up, This is a gen 6 block so if your oil pan is for a gen 5 or 6 it will bolt right on also

[BBC502]

I think it is a great choice. You cannot use the rectangular port intake on the ZZ502. It comes with large oval port alum. heads that are port matched to the supplied GM manifold. There are plenty of after market manifolds to choose from depending on your use and rpm range. When I installed mine I had several problems. The expensive problem was the oil pan (came with the ZZ502) was too tall. I put a Moroso 9 QT. pan in, so check clearances. 2nd problem was header installation. I could not clear the head bolts so I went to the older bolt type and the headers worked. The rest of the components should bolt up with no problem.....Bill