Anybody have any experience with Jasper marine engines. These are 350 MPI. Installed in a 28' Donzi in the Seattle area.

The are just a standard mass produced reman facility ....They do stand behind they're work ....I think its 6 months? m

I had a terrible experience with Jasper, but it was on 500HP engines. There was a Jasper guy in New England who said he could build high performance engines. First there were all kinds of problems just to get them running, then once we did the first motor popped in about 15 minutes. After bringing them to JC performance (after getting no help from the Jasper Rep) he told me the compression was so high I would have had to run over 100 Octane for the engine not to detonate. Jeff fixed them up and I never dealt with Jasper again. Just my experience. I guess if they're already in a boat and are running good they should be ok.

Find a good local Seattle shop -mechanic and have them or yourself go to GM and buy the engines as crate longblocks in the 300HP version and switch them out. Just make sure they use brass or stainless freeze plugs and use the crate long block that matches your engine years cylinder heads for intake manifold correct bolt up. You will get good new engines this way and have a GM warranty.

Best Regards,
Ray @ Raylar

Jasper Junk stay away

A few local marinas use them with very good results. I would stick with stock and low HP application only. Otherwise go to a reputable builder.

I wouldn't use them for anything HP but stock motors they do a good job and stand behind them. I repowered a few boats with them and had good luck.

Nothing but good experience with Jasper,boats and trucks.Would use them again.

I agree with magicfloat. I used them at my car repair shop for years and never had a problem. I must have installed 25-30 of them.
I used them in a formula & bertram and the same thing no problems.

Good luck