Mods for 502???

[jbone]

I'm considering some off season modification to my Indmar carberated 502.
I'm considering a cam, intake, and gear drive. It has a 750 Holley and according to the builder it is putting out about 415 hp.
Are there any recommendations on the cam and intake I should use, and if there is something else I should do while I'm in there.
The engine will only have about 45 hours on it at the end of the season, and is a simple crate engine at this point.
Thanks,
J

[ECeptor]

Here's a post I copied and archived from a while ago. I'm not sure who wrote it, but maybe someone here will recognize it.
"This combo was designed for the boater with a 502 engine that didn't want to spend the big $$$ for a an HP500 upgrade. The engine builder wanted:
Smooth Power
Good Idle Characteristics
Could be used with stock type exhaust / silent choice
Max power for a stock bravo unit
Cost effective
I did some "consulting" and designed the cam around an engine to turn a max of 5500 rpm. Here is the results:
502cid - 100% stock short block other than min. deck cut to make flat
8.8 compression. Did not zero deck - pistons .012" down + .040" headgasket
850 Sea Demon 82P 90S
HVH 1" Super Sucker
HV/Brodix 2000 Intake
Canfield 310 heads / CNC Chamber / No Port Work
Cam - custom Hyd Roller Just under 225 at .050 I w/112LSA around .600" lift
2" Primary Schoenfield Headers - dyno mufflers
Will test Gill Exhaust again when done testing in this state
Belt driven Sea Water pump working - cross over - alternator working - no PS pump.
89 octane fuel - yep, Winter Blend right from the gas pump.
35 Degrees total timing - HEI external coil distributor ( yes, the computer one) with Jacobs amplifier/coil
RPM HP Torque
2100 194.3 483.8
2200 206.6 495.67
2300 217.5 498.52
2400 231.0 505.70
2500 243.9 512.60
2600 256.8 519.00
2700 269.2 523.36
2800 279.9 524.64
2900 288.2 521.78
3000 295.2 516.70
3100 302.8 513.17
3200 312.2 512.08
3300 323.2 514.40
3400 336.7 519.97
3500 351.9 527.69
3600 374.4 542.69
3700 387.9 550.14
3800 406.6 562.41
3900 424.7 572.21
4000 440.7 578.35
4100 457.4 584.13
4200 468.2 586.44
4300 480.3 586.50
4400 490.9 585.93
4500 500.4 583.75
4600 508.8 580.29
4700 515.1 576.90
4800 526.3 575.77
4900 531.4 569.77
5000 536.0 563.20
5100 540.2 556.26
5200 540.9 546.34
That bullet will move any 4Klbs boat very nicely."

[cstraub]

That person would be me.
Chris

[ECeptor]

That person would be me.
Chris
I hope you don't mind me quoting you. If so, let me know and I'll delete it.
With that said, I don't save the details of a lot of people's builds so consider it a complement!

[cstraub]

No, I don't mind. That build was designed for a guy wanting HP500 power, that had an existing 502 sitting in his, did not want to spend a ton of money, and wanted to do it his self.
Chris

[jbone]

Thanks for the input.
My current factory setup limits me to 4800 rpm. I am currently only getting about 57 MPH wot at 4700 (gps). It has the AT "A" impellor.
I was hoping with some minor mods, I could safely get to around 5000 rpm without harming the engine.
The boat is a 21' open bow. It is pretty heavy. I would like to get 60+.
Is a cam and intake upgrade something that could get me there? If not, I'm open to suggestions.
I'd like to keep cost around 1K for parts.
J

[ECeptor]

What is your head's casting number?
I would think a 502 should push a 21'er well over 60mph.

[jbone]

What is your head's casting number?
I would think a 502 should push a 21'er well over 60mph.
Without taking the covers off, the only number i see is M 14097043.
As far as the speed, this is not bad for 3000+ lb boat.
Most in this class are at about 53-55 top speed.
J

[nodigg]

I think you should buy my Whipple set up I am taking off my 502...it should be newly replaced under warranty by Oct-Nov 2005. Taking offers now.

[Krumbsnatcher]

I think you should buy my Whipple set up I am taking off my 502...it should be newly replaced under warranty by Oct-Nov 2005. Taking offers now.
pics please

[nodigg]

pics please
Hmmm, don't have any but it is a 2300R, polished with the whole kit for installation included.

[jbone]

I think you should buy my Whipple set up I am taking off my 502...it should be newly replaced under warranty by Oct-Nov 2005. Taking offers now.
This may be a stupid question, but will it work on the carb 502?
How much$$$
J

[ECeptor]

Without taking the covers off, the only number i see is M 14097043.
As far as the speed, this is not bad for 3000+ lb boat.
Most in this class are at about 53-55 top speed.
J
My boat is a 24' deep V that weighs nearly 4000lbs loaded up and runs nearly 60 mph with a bone stock Merc 330hp 454.
So unless I'm missing something, it sounds like your engine is not putting out the +400hp that it should. The reason I say this is I bought my boat a year ago and I just learned a few weeks ago that the ignition advance module was not functioning from the time I bought it. A new module, new coil and new plugs completely transformed my boat.
Go step by step through your tune up procedure from the service manual. I did this last winter, but skipped a few steps (like checking timing and timing advance!)...wish I had taken the time then!
3000# 21' boat + stock 502 should = +65mph

[jbone]

My boat is a 24' deep V that weighs nearly 4000lbs loaded up and runs nearly 60 mph with a bone stock Merc 330hp 454.
So unless I'm missing something, it sounds like your engine is not putting out the +400hp that it should. The reason I say this is I bought my boat a year ago and I just learned a few weeks ago that the ignition advance module was not functioning from the time I bought it. A new module, new coil and new plugs completely transformed my boat.
Go step by step through your tune up procedure from the service manual. I did this last winter, but skipped a few steps (like checking timing and timing advance!)...wish I had taken the time then!
3000# 21' boat + stock 502 should = +65mph
Didn't I say jet??? :idea:
Yours is most likely a prop to get that kind of speed with that boat.
Much different.
Believe me, 60 mph is not easy to attain with a heavy 21 and a jet.
J

[ECeptor]

Didn't I say jet??? :idea:
Yours is most likely a prop to get that kind of speed with that boat.
Much different.
Believe me, 60 mph is not easy to attain with a heavy 21 and a jet.
J
Ahhh, sorry, I missed the jet part! :messedup:
So, what you need is a 330hp 454 with a Bravo 1! :idea:

[jbone]

I go to the lower river (Martinez Lake) so the jet works out really nice. Hitting sand bars with 2 little girls on board isn't nice.
With the jet I can go over about 1' on plane. Plus I get to throw out a huge rooster. That's cool.
J

[Wally_Gator]

Someone correct me, but isn't 4800 rpms towards the upper limit of an A Impeller?
If you do improve upon your HP numbers it might be a good idea to have your impeller cut to something like an A/B.
You may also need to look at how your boat rides. Is it running really wet?

[jbone]

Someone correct me, but isn't 4800 rpms towards the upper limit of an A Impeller?
If you do improve upon your HP numbers it might be a good idea to have your impeller cut to something like an A/B.
You may also need to look at how your boat rides. Is it running really wet?
I am aware of the impellor and will adress this issue if needed.
As far as running too wet. I've been messing with the settup all season. I think it is about diaoled in as I can get it. My avatar pic was taken at or close to wot.
J

[jbone]

Why are quotes coming out different colors?

[cstraub]

This is a combination that I cammed for Leo Mahlow for a 23ft Stingray:
1. Chevy 502 4.47 X 4.00 2:Jets: 82 Front 90 Rear
3:Timing:38 4: 850 Marine Demon Dual Plane Intake
5: 110 Octane Fuel 6:Lash N/A
7:Shop Headersw 2" 8:MSD Distributor
9:Compression estimated at 9 to 1
Heads: Canfield 310's out of the box.
Camshaft: 230/620 lift Hyd roller with Morels
FileName : MAHLO502.D10
RPM // C_TQ //C_HP // BSFC// Oil Temp.//Water Temp
3700//549//386.7//.405//201//191
3800//553.1//400.2//.414
3900//555.5//412.5//.409
4000//560.2//426.7//.406
4100//561.5//438.3//.399
4200//565.5//452.2//.397
4300//566.7//464//.393
4400//571.7//478.9//.392
4500//572.5//490.5//.391
4600//571.1//500.2//.391
4700//570.6//510.7//.392
4800//571.8//522.6//.395
4900//572.4//534//.4
5000//572.7//545.2//.408
5100//570//553.5//.415
5200//565.5//559.9//.419
5300//562//567.1//.425
5400//558.8//574.6//.429
5500//551.3//577.3//.433
5600//543//579//.442
5700//534.3//579.8//.451
D.T.S. 4000 dyno