I was thinking of rebuilding my 1986 mercruiser 350 260hp as a 383 .. Any thoughts on what internals I should use?? Any problems running a 383. Yes it is an Alpha Drive , I have 2 complete Alpha Unitss on the shelf, was going to build one for severe duty. Is the 383 set up going to be worht my effort, or should I buy a 383 short block?? And then build that? Leaving my 260hp for a spare?? What gives??
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383 Buildup vs stock mercruiser 260hp..
- Thread starter cvx16cvx
- Start date
I was thinking of rebuilding my 1986 mercruiser 350 260hp as a 383 .. Any thoughts on what internals I should use?? Any problems running a 383. Yes it is an Alpha Drive , I have 2 complete Alpha Unitss on the shelf, was going to build one for severe duty. Is the 383 set up going to be worht my effort, or should I buy a 383 short block?? And then build that? Leaving my 260hp for a spare?? What gives??
vinny p.
Active member
383 engines are a well proven combination. You cant go wrong with it. Unfortunetly, the only thing you can use from a stock 260 Merc is the block. Personally, I wouldnt bother with using the stock Merc block. It most likely is a 2 bolt main anyway. If your going to do this, start with a good foundation and build from there.
I dont know how you plan a beefing up an Alpha. I didnt think an aftermarket companies made internals for them. The best and about the only thing you can do is get a shower and drive it smart.
I dont know how you plan a beefing up an Alpha. I didnt think an aftermarket companies made internals for them. The best and about the only thing you can do is get a shower and drive it smart.
vinny p.
Active member
Sorry Happy,
But its just not worth the cost of machining, to upgrade a 2 bolt to a 4 bolt. There is alot to it. You need new caps. the block has to be clearanced to accept the larger cap, you have to drill and tap the block, then you have to line hone. Its easier to just get a 4 bolt block.
But its just not worth the cost of machining, to upgrade a 2 bolt to a 4 bolt. There is alot to it. You need new caps. the block has to be clearanced to accept the larger cap, you have to drill and tap the block, then you have to line hone. Its easier to just get a 4 bolt block.
383 Build
I have the 1986 motor out and it is a 4 bolt main. However. I can purchase a 4 bolt main short block with all forged internals. It includes 4 bolt block balanced scatt forged crankshaft and scat rods with keith Black pistons oil pump . All for $1200
I would add aluminum heads with an airgap intake my tin and the appropriate roller cam . Also would set up a complete Msd ignition. I have a cheap machine shop nearby that would do the labor for 1/2 there fee, friend works there.
My goal would be about 350hp at the prop. I would limit the revs to 5200 looking to turn a mirage 25'.
I am pretty niave about all of this, I did find a Merc dealer with thise Mercruiser 383 reman engines, it is set up for a Bravo drive butht he dealer would strip all the bravo stuff and the exhaust manifolds to sell a complete long block. About $6k he said, then I would probably sell my complete 1986 merc 350 260 hp set up, hoping to get $1k.
Which direction should I go.
Would like to try to do it for $5k, using my cheap machine shop source. thansk Chris
I have the 1986 motor out and it is a 4 bolt main. However. I can purchase a 4 bolt main short block with all forged internals. It includes 4 bolt block balanced scatt forged crankshaft and scat rods with keith Black pistons oil pump . All for $1200
I would add aluminum heads with an airgap intake my tin and the appropriate roller cam . Also would set up a complete Msd ignition. I have a cheap machine shop nearby that would do the labor for 1/2 there fee, friend works there.
My goal would be about 350hp at the prop. I would limit the revs to 5200 looking to turn a mirage 25'.
I am pretty niave about all of this, I did find a Merc dealer with thise Mercruiser 383 reman engines, it is set up for a Bravo drive butht he dealer would strip all the bravo stuff and the exhaust manifolds to sell a complete long block. About $6k he said, then I would probably sell my complete 1986 merc 350 260 hp set up, hoping to get $1k.
Which direction should I go.
Would like to try to do it for $5k, using my cheap machine shop source. thansk Chris
vinny p.
Active member
I would recommend you build your own engine. I never trust reman engines. you never know what the hell they put in there. These guys are out to maximize their profit. They'll use cheap parts and swear they use the best.
You wont go wrong with a 383. Just make sure everything matches. take your time picking your parts, make phone calls, ask alot of questions. Post your decision before buying anything.
You wont go wrong with a 383. Just make sure everything matches. take your time picking your parts, make phone calls, ask alot of questions. Post your decision before buying anything.
Big Red
Well-known member
I would go with the 383 kit, Anytime you can gain cubic inches is a big plus. Their are alot of 383 kits out their just make sure you get one with a steel crank, forged pistons, and a good set of rods. I would recommend a pre balanced assembly, some of thease aftermarket kits are horrible trying to balance.
If your old mercruiser is still running and in the boat leave it their and find a 4 bolt block. That way you still can ride till you get your new beast built.
Big Red N.C.
If your old mercruiser is still running and in the boat leave it their and find a 4 bolt block. That way you still can ride till you get your new beast built.
Big Red N.C.
bigsbetter
Active member
I've only built 1 383. It was for a friend. He bought what was sopposed to be a 'rotating assembly'. He had it balanced at the machine shop where he bought it. During assembly, the first problem was,...well I can not really remember what problem I had first but I know there was at least 3 clearence issues. I think the first one I came into was the rod bolt nuts hit the block near where the oil pan would bolt to. No big deal...just grind some of the block away...problem solved.Then as I was installing the rods and pistons , the rods/rod bolts hit the cam lobes as you rotated this 'rotating assembly'. ( must of been a real big cam huh? OH YEA)!!! I solved that by grinding an angle on the rod bolt end to clear the cam by just a hair, maybe .010-.015". It was only maybe 2 or 3 rod bolts. Then as I rotated it a little more the pistons came to BDC and they hit the crank balance weights! I'm like "WHAT THE hECK"! So I took it back apart and sent it to the machine shop to have the pistons machined and this "rotating assembly" rebalanced. It's like here we bought this $1500.00 "rotating assembly", and all it wanted to do was NOT ROTATE!!! After it was all done, the '68 Camaro ran stronger than any other N/A smallblock I've ever seen. I can't remember what length rods was included in the assembly, I'm thinking 5.7" sounds right, but maybe wrong. I know it wasn't the short 5.5 400 rod. Any ways, It was an expierence,....Any one else have these clearence issues on a 383?
vinny p.
Active member
Charlie,
Yes, there are clearances issues with a 383 small block. I have seen all the issues you have mentioned. I have found that the higher end internals parts, IE: Callies, Lunati... dont have as much issues as the cheaper internals IE: Scat, Eagle. It also depends on the block. Some blocks have a greater core shift than others.
Most likely, your 383 had a 4" crank and 6" rods. That is the most common way to build them.
Yes, there are clearances issues with a 383 small block. I have seen all the issues you have mentioned. I have found that the higher end internals parts, IE: Callies, Lunati... dont have as much issues as the cheaper internals IE: Scat, Eagle. It also depends on the block. Some blocks have a greater core shift than others.
Most likely, your 383 had a 4" crank and 6" rods. That is the most common way to build them.
boatman4021
Well-known member
Something to remember on these sbc strokers is that small base circle cams are available to help with the rod bolt to cam problems. Vinny can probably tell you more about them, I've never had to use one. Mopar's and outboards don't have that problem!
boatman
boatman
SneakyPete
Member
If you plan on going 383, I would recomend you have some one build the short block for you if you have never done it before. I had a company build mine, its the easiest way to go. I recomend you get a piece from Scot Shafiroff out of NY. He has free shipping and a good name. I had the "complete" short block on done up for me, I sent them my cam, they added pan pump pickup and front cover, I added heads intake carb etc (by the way are you still interested?)