heads? cam? small block stroker build
 

Building a 409 SBC forged stroker motor. What heads and cam should go on something like this. Want to run pump gas.

what kind of boat and propulsion?

what are you looking to get out of it?


Uncle Dave

25 baja force. it has an alpha one on it for now. would like to get 60 out of the boat, got 48 with a gps with the stock merc 260. was leaning to a big block, but i have most the parts for a small block.

For iron heads it is tough to beat ported DART Iron eagles

Cam i couldn't tell ya. Depends on exhaust.

My honest recommendation is to leave that boat alone, maybe change props and tune it up.

IF you really decide souping it up is for you whats your budget?

Can you do the work or will someone else do it?

Dave

Well I would be doing most of the work myself. Blew the motor up
last year. So I need to do something with it. Boat has fresh paint. took the big ugly rails off the bow and am building a new swim platform so it looks nice. I just want to go a little faster for now untill I can afford something newer. I have very little money into the boat. Hull is in excellent shape

And my budget is between 3-5 grand. Like I said I have most of the parts for another small block and would make the install easier.

Do you have a list of things in mind written down?

What do you mean blew it up? Can it be salvaged? if so o it as cheap as possible. You are going to need all the marine parts from it for sure or youll run out of money rebuying it all.

Figure out what it costs to do the shortblock est 1K
Cheap stock 2 bolt with hyper pistons are fine for the level of power you'll have. youll blow your drive before the short block goes.

Use great caution in cam selection est +500

Get an el cheapo- top end "combo" from anyone edelbrock etc, with aluminum heads/intake/ carb basically ( I have my favs but we can talk later) est 2K

Get a performance marine manifold and junk the crap your rig came with, unless it came with aftermarket stuff. est 1.5K (skip this and youll never make any power this is very important)

Do all this right and youll pick up around 100 HP or about 5 solid miles an hour from where it was when it was fresh

Of course there is a lot more to it, but thats the "recipe" Id use on that boat with that amount of dough

UD

Fixx
 

I'm running the edelbrock performer rpm heads on my donzi (355 cid)..
2.02 angle plugs 210 cc intake runners with some port work done,70 cc combustion chambers,my block is zero decked,I'm running fat top srp pistons with plasma Molly file fit rings,I'm running 6'' h beam rods and a forged 3.48 light weight crankshaft. i run a edelbrock air gap intake with some port work,a 750 pro form carburetor,camshaft is a comp cams xm270h flat tappet cam..
you could try calling bob mandara for one of his custom grind cams also,allot of people on the board here like his cams 585-654-8583..

i run 93 octane and with the timing @ 34*,,ten years and never had any issues..

if you have a factory gm 4.125 block make sure you drill the steam ports in the heads between the cyliders or your going to have some troubles..

Madera has an awesome reputation.
Teagues good at picking cams.

All the big guys will help you out if you get the right guy.

UD

Thanks for the info so far. I bought this boat and it has been kinda a nightmare so far but I like to work on things. Blew the lower first time I drove it. Rebuilt it and blew the motor second time I drove it LOL and I was taking it easy. Block had a hole in it the size of my fist but I was able to limp it back to the dock it was crazy seeing the engine run with a piston laying in the bilige. So I was thinking I have a 4 bolt bare block laying around. I was givin a set off Eddie marine small block exhaust. I also have edlebrok rpm manifold and Carb not sure what size Carb tho. Don't know how to identify. Also have a Mallory marine distributed and box. So that's where I am at. I figured since I need to build a motor might as well stroke it and the biggest kit I found all forged h beams and stuff 409. For 1399.00 it may be over kill but that's ok. Previous 48 MPH with a stainless 19 would be overjoyed to hit 60 can I do it with this build and more pitch. I got lots of nitrous laying around too if temptation persists

You will need about 400+HP to hit 60. Your budget is way too low for what you want to do. You will need Exhaust (2K) and a Roller cam (2K for the complete setup), then you still need the internals. After you do this your drive will most likly go shortly after. For your budget, put it back close stock specs and be happy with 50. Just keeping it real....

I'm all about more hp, thats a lot of boat for an alpha drive though. You start throwing more power to it and it won't last long. Rebuild it with what you have and leave it alone.

dart 200cc, vic jr, 750, 480- 230 cam hydrualic flat

You dont need forged stuff with the beans you will be putting out. Trust me just do a good balance on some good cast stuff.

If you block is useable, you should have the dough for a mellow 400HP set up at least high 3's.

You have the exhaust, all the marine stuff from your old setup

The merc stock ignition is fine.

you have a manifold

You may want a real carb, or to just tube up the one you have, Id go with a real carb here.

you are proposing a lot of work for a marginal platform and I understand why the guys are telling you to just stand down and fix what youve got- I get it, but there are times when you just cant and I get that as well.


UD

Do a search for "Reversion" you will need performance exhaust. To get 1HP per CI you will need a roller cam, a flat tappet just will not get it in the marine world. Here is what I would do. Sell the Alpha drive in the swap shop and buy a Bravo setup. Build a 502 or a 489/496 stroker engine. Or sell the boat and buy one with a 454 or 502 that already runs 60MPH. My boat came with a stock 330 454CI and ran 55MPH on GPS. After thousands of dollars worth of upgrades and hundreds of my labor hours I have the boat running 74GPS. All of the upgrades were done over a period of years and I broke many parts until I figured out what I was doing. Good luck with your project!!

Agreed on reversion, Ive built many of these combos as well

The reversion problem is why I said "use great caution" in selecting a camshaft 8 posts ago.

The poster has an EMI exhaust, these are not too bad.

Reversion is a big problem trying to get to high HP using an automotive formula of high lift and valve overlap.

Heres my latest marine small block build.
Its a 500/500 engine.

http://www.offshoreonly.com/forums/d...ent-years.html

This is my 5th small block config in 20 years. The last one lasted 10, and the 4 before that 10 combined years. I think im on a pretty good formula after all this time and money.

I finished this one a week ago and its going into the boat either next week or the week after.

I agree its a pain to get a small block to high HP levels, and if I were him Id start over with a different project.

-but he seems pretty determined.


Uncle Dave

And leave the nitrous on the shelf
-or puff it in with the boys next friday night.

DONT use it in your rig.

UD

Sorry, I missed the part where he mentioned he had aquired the EMI's. I use the EMI's with long risers and have worked very well. If he has he short risers he may want to swap them out.
I used RMbuilder for my cam and I am sure he could easily get him 400HP.

Fixx
 

i have the emi's on my donzi with the regular cast aluminum risers,the cam is choppy and haven't had any reversion problems :drink: my morot performer better (more torque) over the ss risers..
http://www.youtube.com/watch?v=dLdeNiyk0Ew

You guys are super helpful. Ill make sure to research as much as I can I'm only doing this one time. If I want to go faster ill get a different boat. If I switch from alpha to bravo do I just need the drive or everything that's mounted to my transom. Can't get a bravo untill the following year so ill have to take it super easy on the alpha. Thanks for all the input thus far I feel like such a newb with my old school baja but its my first boat and a good one to learn with

mr fixall, that little donzi sounds great! Is it a 434 and what cam and compression are you running.

Fixx
 

Thanx! BTW Sorry to steal your trend zerotosixzero :)
its a 355 cid :) compression is 10.3 and im running a comp cams xm270h.. i put it in @ 110*..i wanted a little more in the mid range and top end,,the boat come out of the hole like a scalded dog..mind you its all going through a volvo penta 280 drive, my props are volvo ultra's, 24 p L i spin up to 6200 rpms and my 26 with a heavy cup up to 5800 rpm's..

my next motor i want to build for it will be on the ls platform, im thinking a 413 cid out of a 6.0 but got to finish the formula first : )

Nice, what kind of actuation is it?
Mechanical, or hydraulic roller?

when you say 110*, are you referring to the lobe center?

UD

Fixx
 

Flat tappet hyd with hyd roller springs..110* LCA

Heres an update on my SBC project - got the engine back in.

Heading off for the lake tomorrow.


Uncle Dave

I love seeing healthy small blocks. I like the 434 for NA apps. this one liked to rev a bit but has a Ton of hours on it and is still goin strong.

I think this one will open..

You read my mind....
UD

Pretty nice....

Interestingly close to what I have as well- heads and all.

I see what you mean about rev happy- Must have sounded killer up there on the dyno!

I also see you started the pull at 4600. hows it idle?
Also I dont see the cam specs- can you share a bit more?

UD

It idles great at 800rpm, it's a custom grind hydraulic roller. That was a shortish pull because we were working on a carb issue, as you can see it's going lean up top. But, it was also the best numbers it put up so of course that's the one I'm going to post. :drink:

Im saving this thread as it has unique info for me. because our top end combos are almost identical, your build shows me what the "kill" version of my setup would approximate.

Im much more conservative on the compression, timing, and probably the cam- although 800 is a pretty good idle.

Ive got the rotating assembly to handle the HP, Im worried about CRAPPY gas. its hard to get the good stuff on the water anymore.


UD

Yes, good gas is a concern.. That one will only live on 93. I'd be happy to PM you some of the more specific details if you like. Cheers, Alex. :drink: Oh ya, those valve cover's are sweet!!