One friend of mine ran a 406SBC in a 20 Rinker for a number of years. Another ran triple 406's in a Magnum. No probs. in either case. Both made lots of power and ran very well.

 

Wow.... talk about cubic inches. I think that TR7 fuel tank would make a good primer ball for those triplets!
RK

 

Have a friend whose brother uses a 400 sbc for his boat.It flys.

 

I would suggest making the 350's 383's. You already have the blocks. Just get 2 rotating kits and add the inches to what you have. 400 blocks are very scarce these days.

 

350's ??

New to boats, 18' 1973 Kona jet boat, hardcore drag racer/motorhead (blown alky)20+ years.
Depends on $$$ and time. 3 things I always write down before I start a project.
1 Planning, who to do what, get what where
2 Objectives to accomplish
3 Budget
I realize I'm new here and on the lower end of things $ wise,BUT I hope I can bring some good imput to the board.
Ok!! What I would do is this.....350 ,s !!
You own them, the cylinder walls are thicker than the stock block 400.s, If the 350's are marine motors they came with 4 bolt mains, forged crank and pistons. the 400 does not and gets into $$$ real quick!!
They are an excellent plat form to start with. I wouldn't touch the short block! Talk to a REPUTABLE engine builder. ( not always the most expensive) Cylder heads and a cam that is for the application!!! Superchargers are great also. The most important part is that the parts
cannot be bought willy nilly! They must be a combination that will work together!!! With the supercharger, to keep costs down, I would look at the Snow Performance boost coolers.
I hope this helps.
AA/Paul

 

AA/Paul,

You are misinformed on the factory GM 350's internals (no worries... a lot of people are)... they are all cast. Cast cranks, cast pistons. Basically, they are the same engine that you would have in the 1/2 to 1-Ton truck line. They are nothing special.

For the cost of a good performance rebuild I would build 383's.

 

Oops... forgot!


Welcome to Speedwake!!

 

I think that TR7 fuel tank would make a good primer ball for those triplets!
RK

Can you say Fiero? as in Pontiac

 

I would suggest making the 350's 383's. You already have the blocks. Just get 2 rotating kits and add the inches to what you have. 400 blocks are very scarce these days.

I pretty much agree with Cstraub. 400 blocks in good condition with no cracks and a standard bore are scarce and they cost in the $500+ range most of the time. They all should be magnafluxed for cracks before buying. Don't get one that needs bored more than .040" as the walls are pretty thin. Some can go .060" depending on core shift but a sonic test is in order to confirm. 400's commonly crack in the deck area around the steam holes. If you have the coin you go for a World aftermarket SBC at $1800 a pop. You can go up to 434-454ci with these.

Since you allready have the 350's I would turn them into 383's or 396ci's. I'm going to build a 396ci for mine over the winter out of a 350 block. It will require a tad more clearancing of the block than the 383. You will have to run a small base circle cam if you don't opt for ARP 2000 rodlbolts.

Eagle 4340 rotating assembly's for 383's and 396's run in the $1500-1700 range. Doug Herbert has good deals right now on Scat 4340 383 kits for $1300.

The 383's and 396's will be cheaper and more reliable than the 400's IMO.

 

I have run 400s in my ski boat for over 35years from center mounts to race boats and your claim that a stroked 350 is more reliable then a 400 is somewhat unjustified. my lastest engine is a stroked 434 and it has a lot of balls and have never had an engine with so much torque and reliable, I can run away from any 350 stroked or not. remember there is no substitute for cubic inches

 

Thanks for the info.
I've bought 2 of them over the years and they were all forged. I got lucky I guess. I'll double check next time!!!
I believe they were Mercruzers.?? It's been a few yrs.

 

I have no experience with the 400 blocks, but I seem to remember reading something about the way the water holes in the block are not optimum for use in a marine environment.

 

I have no experience with the 400 blocks, but I seem to remember reading something about the way the water holes in the block are not optimum for use in a marine environment.

That's a misconception from back in the days where, 1) the 400 was susceptible to overheating because of plugged up cooling systems and poor emission controls (very lean tune), and 2) people not drilling the proper steam holes when using non-400-based (performance) heads.

The 400 is a great foundation for a powerful small block. You can't beat the increased displacement! I bartered/traded for the 383 build that's going into the Stinger, but she came with a 406 that needed to be put back together that I plan to use at some point.... in what I do not know yet!

 

Also. in the marine engine you run a cooler temp (around 140 degrees as apposed to 180+ like a car.

I have a 400 (eagle rotating) in my 18 Donzi >> best upgrade I ever did; and I played with a lot of combinations. Torque is the game in boats and CI are the safest and least costly road. 383 would be the next best and slightly cheaper since you already have the blocks. That extra `1/4" stroke will definately help.

 

I still want to do something with my 406 but I got the 383 and over 500 horse for no money (bartering services is always good).

I think my 406 plus a B&M 250 will work just fine!!

 

Can you say Fiero? as in Pontiac

Opps your right. I knew that didn't sound right.

re- original thread....... sounds like the 350's I have would be a better bet with a vortec upgrade. Thanks for all the input.
RK

 

That's a misconception from back in the days where, 1) the 400 was susceptible to overheating because of plugged up cooling systems and poor emission controls (very lean tune), and 2) people not drilling the proper steam holes when using non-400-based (performance) heads.

if i remember right there is casting numbers to look for that was a better casting I think they were "817" and "511" for some reason when a 400 was bored .30 over they would crack under stress. My uncle had a "509" casting that did not last. HIs engine builder told him it wouldn't but he ran the dayum thing anyway :laugher:

 

I pretty much agree with Cstraub. 400 blocks in good condition with no cracks and a standard bore are scarce and they cost in the $500+ range most of the time. They all should be magnafluxed for cracks before buying. Don't get one that needs bored more than .040" as the walls are pretty thin. Some can go .060" depending on core shift but a sonic test is in order to confirm. 400's commonly crack in the deck area around the steam holes. If you have the coin you go for a World aftermarket SBC at $1800 a pop. You can go up to 434-454ci with these.

Yup a pair of 430 SB would be the cats azz in my book.

 

Opps your right. I knew that didn't sound right.

re- original thread....... sounds like the 350's I have would be a better bet with a vortec upgrade. Thanks for all the input.
RK

RK,

Here's what you need....

http://store.summitracing.com/partdetail.asp?part=ESP-B12010030&autoview=sku

This is the same kit that I'm running in my 383. Under $2K for a complete forged and balanced bottom end.

I have always been a fan of Vortec heads (the 383 in my 4Winns has'em), but I think there are much better alternatives when you consider the preparation involved. Granted if you're going for a stock-type rebuild, the Vortecs will do great (they will work better with the proper D-shaped dish piston), but if you're looking for a good amount of power, then I wouldn't go this way due to the work involved to make them perform.

 

if i remember right there is casting numbers to look for that was a better casting I think they were "817" and "511" for some reason when a 400 was bored .30 over they would crack under stress. My uncle had a "509" casting that did not last. HIs engine builder told him it wouldn't but he ran the dayum thing anyway :laugher:

There are two casting numbers....

Two 509s and one 511. Both are available with a 4-bolt main but the 2-bolt is a better block. Add splayed main caps and they are very solid!!

 

Very true Tomz!!! With the Factory 4 bolters #7 cyl is thin!! I've built both 350 and 400 combos and been happy.

 

There are two casting numbers....

Two 509s and one 511. Both are available with a 4-bolt main but the 2-bolt is a better block. Add splayed main caps and they are very solid!!

Yup i forgot about that Good call. The 509 he ran was an orig 4 bolt block.

 

RK,

Here's what you need....

http://store.summitracing.com/partdetail.asp?part=ESP-B12010030&autoview=sku

This is the same kit that I'm running in my 383. Under $2K for a complete forged and balanced bottom end.

I have always been a fan of Vortec heads (the 383 in my 4Winns has'em), but I think there are much better alternatives when you consider the preparation involved. Granted if you're going for a stock-type rebuild, the Vortecs will do great (they will work better with the proper D-shaped dish piston), but if you're looking for a good amount of power, then I wouldn't go this way due to the work involved to make them perform.

Thanks I will check it out!
RK

 

We Just built a 406 and put in My Dad 230 Chris Craft Scorpion ,Runs Great ,et its first set of Bevel gears in two weekends. Hole shots are a no nne thing we ran into is there were no straight across bolt hole for the starter so we had to run a large flywheel. Luckily we found that out early on so we had the right one balanced. We are still trying to fing the best prop. It has 22% slip with about any three blade 21p. So we are looking for a 23. It did go from 39 MPH to 54 (GPS) with only a motor change.