Hello,

I've been reading this forum for a few months as well as some other marine/engine forums and I need some help with my build. I'm restoring a 1976 Regatta Jet Boat, with 305 OMC & 12YJ Jacuzzi pump. The boat was parked due to shearing the PTO to crank bolts and the PO never had time to go and fix it. The boat has been sitting for 11yr, but water has slowly been making it way in. I'm going to replace the stringers and the floor, and upon closer inspection of the 305, the water has been making it way in it. There was a lot of rust in the intake manifold, as well as the head. The cylinders had some rust as well.






The PO had a 350 that he was going to put into it instead, and I just picked that up. That engine has been sitting for 10yr in a warehouse on a pallet and developed some rust in the cylinders as well. I figured since I have to rebuild an engine, might as well rebuild the 350 and drop that in there. However, the heads on the 350 have some chipping on the fire rings, so I think those heads are junk. My plan with the 350 was to have the block hot tanked, decked and most likely bored over if necessary. The quote I got for that was around $200 to hot dip, $200 to deck it, 50$ to magnaflux it. So the machining work is adding up a lot. Since the heads are junk, I can either wire wheel the 305 heads and put those on, or find a used set of vortec heads or regular heads, or get those ebay vortex style no name heads. I was planning on using ARP bolts on everything as well as an MLS head gasket. I'm going to use all brass freeze plugs as well as installing a marine camshaft. I've read about tapping out galley plugs and drilling a small hole to lubricate the chain. I've also seen videos of drilling out all the oil galleys, but I would need to use a high volume oil pump as far as I understand. I don't mind doing mods which can improve the longevity of the engine and are easy to do.

This is meant to be a very budget build and I'm not looking to make power runs or race the boat. It's very light as is and I'm looking for reliability/bang for the buck. I want to run regular 87 pump gas as well.

What is the most budget bang for the buck thing I can do? Can I reuse the springs&cam from the 305 in the 350? Is it worth to deck the block or get vortec heads? I was going to use a flat-tappet cam as they're $200 versus converting to a roller cam which is exponentially more. Should I not have any machining work done at all and just hone it at home and re-ring? For the pistons, should I get the dished pistons like I keep seeing in marine engines or the flat top?

Thank you

It looks like I can't post any pictures until I have 10 posts so I can't upload any pictures.

Not sure what you mean by chipping on the fire ring. Make 7 more quick posts and then you can put the pictures up

And to be honest with you on a 350 Chevy engine it is pretty hard to build one for what you can buy one for. Its what i do for a living and lately its a losing cause unless you want something really different. The only way to go on cylinder heads is new.

Where are you located.

Here are the pictures of the 350. You can see its casting number as well as the chipping. One of the pistons has some wear on the top, maybe from detonation?

Yeah the whole point is I like the mechanicals and want to learn along the way. It seemed to that whole rebuild kit was like $400 and so I thought it would be affordable to do the work myself.

Located around Sacramento, CA

Here are the pistons:

How many bolt mains you have?

id for sure have that block checked out. Overbore pistons and all new looks like a given. Line honed, decked, new heads, new bearings, connecting rods, cam, lifters, rocker arms, pushrods. I’d look at doing a 383…maybe a 396. Skip white has excellent parts kits. Lots of head options out there.

intake manifold
carb will be a choice depending on what route you go.

all comes down to budget and power requirements. Not just about doing this work…which is very doable if you have skills, tools, and manual. But do you know how to make all this work together that’s the art.., cam, heads, piston, carb etc.

Tough call.

The 305 block actually looks a lot better than the 350. The 350 looks like it has a ton of corrosion in the water jackets. Heads dont look any better

You cant put the 305 heads on the 350. It bumps the compression up too high.

Depending on how fast you want to be I would freshen up the 305 and put it back together. Just do the bare minimum. You can probably do that relatively cheap compared to doing the 350. Get the boat done and see how it is with the 305 in it. You can then decide if you want to upgrade the power. At least with a jet its fairly easy to swap the engine

Hone the bore first to see what you have , whatever one cleans up the best is the one you use . I wouldn’t spend the money on ARP bolts for a stock build.