BBC build- Don't tell the Admiral

[Scott Danforth]

Mods, feel free to move this into the VP section if you want, however its not repair, or a problem...... its a goal for more smiles

So, been wanting to build a 383 stroker SBC for the boat for a long time (since I bought the boat)

This will be added to the links here http://forums.iboats.com/forum/owne...uisers-yachts/512516-1988-rogue-2420?t=500145

some of you may remember when I dug into the motor http://forums.iboats.com/forum/engi...o-performance-upgrades-for-an-aq271c?t=503800.

upper end of motor is ready

the added performance at the expense of fuel was a good trade off. however putting in 91+ octane to keep detonation at bay is wearing on me. so time to build the proper lower end.


the rattle can engine paint is turning out to not be the best solution to seal the motor, Boeshield has worked where it was applied, however the last time out, noted the stamped steel valve covers are rusting, some of the steel brackets are showing signs of rust, and the manifolds are at end of their life

salt air, humidity, etc can be a biotch on painted steel parts.

used the rusty metal, rust streaks and an oil leak on the outdrive to convince the admiral we need to spend a bit of $ this spring to make the boat ship-shape so to speak. She asked how much, I said about $1500-$2k :jaw: so after she picked her jaw off the floor, she said, try not to go nuts.

When I put the heat exchanger on the motor, it was originally a BBC heat exchanger (modified Mercruiser unit) about 2x the cooling I need for a half system, however was sized for a full system. going to go with aluminum EMI thunder manifolds running them on the HX. I will be making a stainless risers and exhaust diversion system at work.

This leaves a bit of $ left for the motor

Current 1988 block is still flat tappet cam. so I am going to source a roller block from either the machine shop or a u-pull it. Will try to find one for dirt cheap

Will be getting a 383 stroke crank kit, and a set of proper vortec pistons, etc.

Havent found a machine shop locally that I like, so I may have to lean on Scotty, Jake and the boys at Manitowoc Motor and Machine http://www.motormachining.com/ or Larry and the boys at Baril engine http://www.barilengine.com/ and having the motor come down with dad

will be leaning on Bondo , Tail_Gunner and a few others on the proper mix of parts.

goal is to get a good solid 383 stroker for about $1500


For those tagging along, here are a few other 383 build threads
http://forums.iboats.com/forum/engi...8632342-383-stroker-swap-into-a-201-liberator
http://forums.iboats.com/forum/engi...s/9980707-volvo-penta-5-7l-gsi-to-383-stroker
http://forums.iboats.com/forum/engi...r-to-a-vortec-5-7l-and-possibly-a-383-stroker
http://forums.iboats.com/forum/engi...-o-and-inboards/529101-building-a-383-stroker
http://forums.iboats.com/forum/engi...383-stroker-winter-project?t=524489&p=5507909

 

[GA_Boater]

[h=2]Stealthy 383 Build - Dont tell the Admiral[/h]

How much is it worth to you to keep the secret? Hello, Mrs Danforth......

Since this a build up, I think it can stay here, Scott. What you're doing isn't unique to VP, MC or OMC. It's a SBC build.

I'll ask the Admiral.

 

[keith2k455]

I like it! Congratulations on the plan. I totally agree with your justification too.

 

[Bondo]

Ayuh,.... I Like it,..... D-dish, or inverted dome pistons, set up near flush with the deck, .043" quench, 'n just barely under 10:1 compression,....



Btw,.... What's the Admiral's work phone #,..??..??

 

[Scott Danforth]

Question is, do I keep my existing block, save a bit of cash in the cam/lifter/timing chain arena or continue looking for a roller

I already have the largest wet exhaust cam that Comp allows - CL12-236, grind XM 268 H
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=99&sb=2

may have boiled this down to just a .030 overbore, new pistons, Zero deck the block, clearance the block rail for the rods spinning on the longer crank throws.

Crank - Cast is $300, Forged is $500 part of me says go forged and talk the admiral into a magnuson supercharger. Then the realist in me says, no way in heck will I talk her into that. So cast crank (will most likely be part of the rotating kit).
Rods - Stock (existing) polished and shot-peened vs buying new. labor to shot peen is about same a new set of rods - no brainer 5140 rods are dirt cheap.

Now rod length is another topic, need to discuss. 5.7 rods are stock SBC fair. hot-rodders like the 6.0. However marine motors like the shorter rod for the skirt length. then looking at the on-line catalogs, someone came out with a 5.85" long rod..... could this be the holy grail of rods? need to look more into it the cost of the rotating kits with a 5.85" rod is about $600 more.

using the on-line compression calculators
64cc vortec heads
4.03 bore
3.75 stroke
0" deck
0.041 head gasket
and a +12cc piston net a 10.22:1 CR. much lower than where I currently at.

the +16cc pistons net a 9.8:1 CR. just a tad more than the stock flat-tops and the 76cc heads the motor originally came with.

looking like one of these 3 kits so far.

http://www.summitracing.com/search/...9+4294924890+4294927933+4294880920+4294880926

need to look more into the D-shaped dome pistons they have. my guess its not the LC-Q style piston
Also need to determine if I can get the kit without the flex plate.

http://www.summitracing.com/search/...00474+332929+4294884142+4294914186+4294879783

Bondo can you find out from Ricardo where would be a better source for the LCQ piston (or does he make kits)?

 

[Bondo]

Bondo can you find out from Ricardo where would be a better source for the LCQ piston (or does he make kits)?

Ayuh,.... Rick has been postin' lately at marine engines,....

I'm pretty sure he's just a mechanic, not a parts supplier,....

 

[Scott Danforth]

Found out the 5.85" rods are generally used with the 3.875" stroker crank to build a 396 stroker. Great for a car, not that great for a marine motor.

My old non-vortec heads turn out to be 64cc heads (casting 14096217) currently have them on craigslist.

Still looking at rotating assemblies, and scouring craigslist. Looking at a set of .030 over inverted dome KB's this weekend. Price is dirt cheap

 

[Tail_Gunner]

:ranger:......................................:spy:

What hull type and drive how heavy...does she squat deep in a no wake zone???......Id stay with a scat assy by far and away...there tolerances seem to be much tighter.

 

[Tail_Gunner]

Umm that it??

 

[Scott Danforth]

yes, except mine is red faded to pink and doesnt have the center trip rails on the bow I am also missing the two filler cushions for the aft.

 

[Scott Danforth]

:ranger:......................................:spy:

What hull type and drive how heavy...does she squat deep in a no wake zone???......Id stay with a scat assy by far and away...there tolerances seem to be much tighter.

3600# dry, about 4400# with fuel, people, and beer
I can get her to squat pretty good if I have the drive up and do not compensate for us lard butts in back with the trim tabs. normally she sits pretty good in a no wake condition. the DP drive helps. Current top speed is dependent on which prop set I have on it, and whether or not they have hit something (like the submerged sail boat a while back)

Any recommendations on a SCAT assembly. and do you know of one with +12 inverted dome pistons?

 

[Tail_Gunner]

3600# dry, about 4400# with fuel, people, and beer
I can get her to squat pretty good if I have the drive up and do not compensate for us lard butts in back with the trim tabs. normally she sits pretty good in a no wake condition. the DP drive helps. Current top speed is dependent on which prop set I have on it, and whether or not they have hit something (like the submerged sail boat a while back)

Any recommendations on a SCAT assembly. and do you know of one with +12 inverted dome pistons?

Well.....now it just depend's just how transparent the budget will be and or fudge room..aka cost over runs etc etc, The hull is it at least 20 degree's of dead rise??/ 8 ft beam or 7??? LOL could it be the mythical 24x7 hull's. How far up the rpm do you want to go..5500? Do you have a intake and wet manifold i assume.

 

[Tail_Gunner]

http://autoplicity.com/173530-scat-engine-components-in-our-rotating-assemblies-department

You cam wont go past 5300 so boating on a budget that's a tough act to follow or another 400 for forged and dished.

 

[flipbro]

Wouldnt he be farther ahead to get a crank thats internaly balanced for 383 and save the cost of new harmonic and flywheel. Im also conisdering a 383 so following along.

 

[Scott Danforth]

http://autoplicity.com/173530-scat-engine-components-in-our-rotating-assemblies-department

You cam wont go past 5300 so boating on a budget that's a tough act to follow or another 400 for forged and dished.

Tail_gunner, that kit is flat top pistions with relief cuts. Looking for a reverse dome (LCQ style).

 

[Scott Danforth]

Wouldnt he be farther ahead to get a crank thats internaly balanced for 383 and save the cost of new harmonic and flywheel. Im also conisdering a 383 so following along.

Internal balancing died with the 1 piece rear seal. Your better off getting an unballanced kit and having your machine shop balance it with your flywheel and damper

 

[Scott Danforth]

Well.....now it just depend's just how transparent the budget will be and or fudge room..aka cost over runs etc etc, The hull is it at least 20 degree's of dead rise??/ 8 ft beam or 7??? LOL could it be the mythical 24x7 hull's. How far up the rpm do you want to go..5500? Do you have a intake and wet manifold i assume.

I have a complete top end ( new a few years ago). Stuck with wet exhaust, however will be making a switcheable exhaust, however that does not get me into a bigger cam. I'm good with 5200-5300 RPM limit Beam is 96", deadrise is nowhere in the literature, going to estimate 22 for now until I measure.

 

[alldodge]

You mentioned that your going to go with EMI thunder exhaust, I have the same just get the plus 3 up elbows which come with the long tubes. Only issue is if you go bigger cam you cannot go with switchable exhaust, took mine off there setting on the shelf now

 

[Scott Danforth]

Using a smart Phone level app, 23.7 degree deadrise

 

[Scott Danforth]

You mentioned that your going to go with EMI thunder exhaust, I have the same just get the plus 3 up elbows which come with the long tubes. Only issue is if you go bigger cam you cannot go with switchable exhaust, took mine off there setting on the shelf now

I agree. Problem is the admiral will want quiet operation. So switchable exhaust going in.

I used to have a great connection at CMI, thought of a set of e-tops, however my deal was still more than a set of EMI thunders off of ebay