Rookie17

With more research done now I think you're absolutley right, its way too big.

Looking at this one: Comp XM284HR 230/236 w/112 LSA.

http://www.compcams.com/Company/CC/c...?csid=449&sb=2

Thoughts?

picklenjim

That Comp Cam would probably be just fine. Big blocks can handle more lift but you want to keep the duration down for your low end in a marine application. My preference would be either this Crane http://www.summitracing.com/parts/CRN-139011/

Or this Lunati http://www.summitracing.com/parts/LUN-60211/

MILD THUNDER

iTrader: (3)

I agree with you jim on those cam choices. That crane cam #139011 should work well with a small blower if he ever decides to bolt one on.

blue thunder

Thats exactly what I run with edelbrock al rect port heads and 9.5:1 compression. Runs like a raped ape with 5psi boost.

Rookie17

Thank you very much gentlemen. Your advice is very much appreciated.

Here's my list of parts, based on advice here and research. Presuming the cranks are ok and the rods check out, all I need to add is pistons / rings / bearings and gaskets.
And machine work as required of course.

Edelbrock Marine heads: #61559 (same as #60559) with valves, no springs or retainers: $900.00 ea MSRP
Intake Manifold: Performer RPM Air Gap type. #7562: $260.00 ea MSRP
Camshaft: Crane Hydraulic roller #139011, no lifters included: $427.00 MSRP
Lifters: Hydraulic roller, Comp Cams #249-887-16: $500.00 MSRP
Pushrods: Comp Cams #249-7154-16: $117.00 MSRP
Cam Gear Drive: JEGS #20320: $147.00 MSRP (www.jegs.com)
Valve Springs and Retainer kit: #5795: $172.00 MSRP
Roller Rocker Arms: Crane Gold Race #13750-16, 1.7 ratio: $382.00 MSRP

I'm guessing about $6k per side (at retail prices) by the time the little pieces are purchased and I find things along the way I'll want to change or fix.

Maybe I'm crazy spending $12k on a 1991 Fountain that in reality is probably only worth $30k on a good day in this economy, but I really like the boat and I'll know what I have.

And as long as I keep it a while, I can hopefully forget about engine problems during boating season for a while.

It should scoot pretty good if each of these engines make 475hp each, thats 950hp total
If I turn them to 5500 rpm, you think thats a solid 75 mph on the 28P props? Maybe I can turn them a couple hundred rpm harder than that too on short bursts as long as the hydraulic lifter stays happy. Everything else should handle it fine.

My old lady was right. She told me I wouldn't be able to leave it alone and it'd have to be better and faster before long. Seems like I'm in good company round here at least

Can't thank you guys enough! Chime in if there's anything on my list you don't like or think I'm missing.

picklenjim

In my opinion, for what it's worth ?, I would ditch the cam gear drive set up for a quality double roller billet gear set.
http://www.summitracing.com/parts/CLO-9-3610TX9/

Also I would use springs recommended by Crane to use with that cam. Make sure the push rods are the correct length for those roller lifters in a Mark lV retro set up. You have to be carefull when mix matching valve train componets.
In the heads be sure to use Inconel exhaust valves. Their expensive but deffinately worth it. Cheap compaired to dropping a valve into a piston-cracking a cylinder-trashing a head.
I thought you said you already had crane gold roller rockers. If so that should save ya $700+ there.

I don't know how many RPM it turns now, my quess is maybe 46- 4800 but with these changes I wouldn't think it's going to turn more than maybe 54-5500. 5400 would be more like upper 70's.
Here's a calculator you can play with.
http://www.marksmarineinc.com/prop_calc.aspx

wjb21ndtown

Just remember to factor in the cost of new springs and valves (and maybe retainers) into your head price, and any work that you're going to have to pay someone else to do to set them up. You could easily end up with another $1k into your "new" heads before they're ready to bolt on.

blue thunder

My cam card for the 011 cam say spring part number 99896. Set up with 150# seat pressure. I'd choose pistons to get you 9.5:1, ferrea exhuast super alloy exh valve and good ss intakes, morel lifters and cometic mls head gaskets to get you a quench of .037-.045" Remember to open up the ring end gaps substantially for a marine build. Plus if you want to throw a 177 on later you are good to go.

MILD THUNDER

iTrader: (3)

What he said.

In regards to the new heads, they do have some advantages. They are lighter, and will probably save about 150 lbs off the back of the boat. They will allow you to run a bit higher compression, on pump gas.

With that being said, I dont know if i would drop the 4k+ dollars for them on your application. I'd considering sending your current heads out to jim valako at valako race heads for a freshening, and he knows them heads all so well. Probably save you 2500 bucks or so over new heads. Out of the box the edelbrocks i really dont think are going to flow much if any better. Plus dealing with jim, he'll be able to set your heads up with proper springs and everything you'll need to bolt them on.

Ferrea makes a great valve, isky makes a great valve spring, esp the tool room series.

If you were going to go with new heads, i'd consider going with a oval port head, with smaller CC intake runners. I believe the edelbrock rect marine heads are 315CC. Maybe the #61459 Marine head with 290CC oval port heads might be a better choice.

A buddy of mine years ago made like 510HP on a 468 using merlin oval port iron heads with a solid flat tappet cam.

Rookie17

Jim, any particular reason for ditching the gear drive and going to a chain? I was thinking the chain can stretch over time and retard cam timing, but maybe I'm missing something there.
Pushrod length for correct geometry for sure, thought being to start with stock length and see where its at, unless the Edelbrock heads have a different rocker shaft height than stock. I'll mock up with the pushrods that are in it and measure from there.
As for the Crane roller rockers, I do have them already but budgeting for new sets just in case they're not perfect.

Blue Thunder, appreciate the valve spring part numbers and seat pressures. But when you say open up the ring gap 'substantially', how much is 'substantially'?
And why do you run large ring end gaps on boat engines, is it something to do with how cold they run?

As always, appreciate the opinions and advice gentlemen. I owe a few of you a cold beer or two.