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Quote:

Originally Posted by MACDAD260 (Post 4145353)

I did a similar upgrade to my 260 Baja a few years ago. Went from the stock Gen 5 454 to a Gen 5 502 Mag. I used a Performer RPM manifold, a Holley 9022, a DUI distributor with 24* advance and 12" x3" oil cooler with a separate 5" x 2" PS cooler. Used the stock cast iron exhaust. The jetting I ended up with after much trial and error was 87p, 98s. The stock jetting in the 9022 was 72p, 87s. WAY too lean. You should be good with the dual plane that comes with engine. I would swap the water pump for amarine unit with a stainless steel impeller. My only concern would be the cam. Would want enough LSA to not get reversion with stock exhaust. I could not be happier with my swap. I have over 200 hours on it now. Really woke up the boat with a 24 pitch Bravo 1.

We did swap the water pump...put the one off my other engine on the new engine along with the larger oil pan. About to drop this thing in the boat if I can find a carb soon.

Quote:

Originally Posted by 253 (Post 4145374)

I ran mine w/ the stock exhaust and ignition, one inch spacer w/Holley 9022 Carb, did not change anything else, it topped out at 5100 rpm, it ran perfect and dependable, I did not want a hot rod engine, I wanted dependability on a low budget ,

Thats what I want...a reliable engine that will get the boat up to around 65-70 and cruise well.

Quote:

Originally Posted by ROTAX454 (Post 4145385)

What he stated about the spacer on a dual plane is correct. I support that with dyno experience. SBX if your set on using a dual plane, best one to use (as previously posted by others) is the Edlebrock Air Gap 4150 based manifold.

Take a good look at the HP950 Holley. It has a 750 throttle plate. This is really a 850 hi velocity---sorta. Again, I had dyno time on the carb too. Don't be confused with the CFM numbers or model numbers issued by Holley. Many times they do not make sense as to the true carb in the box.

Im not SET on using a dual plane, but I also dont plan to run the engine up high probably mostly around 3-4000 RPM

I will look into that HP carb

Thanks for all the help.

Quote:

Originally Posted by ROTAX454 (Post 4145388)

NOOO Use an HP Holley carb. Before you keyboard captains sound off, "now hear this". Send the carb off to a carb shop. For lunch money they will install the correct marine vent tubes. Bam, you now have an HP marine carb.

IMO, a Holley 800 marine carb from an HP500 would work well on this setup. They can usually be found in the Swap Shop for less than $300. Plenty of people are running them on OSO, so it should be easy to find someone with a baseline to get you started.

For the record, I am running one on my 489 with AFR heads and hydraulic roller, Lightning headers, etc. Yes, I could have probably made more power with a bigger carb, but it made 585 HP on the dyno, which is more than enough for my old tub. Point I'm making is that it should run fine for your application. Good luck with it, and let me know if either of those manifolds I have might help you.

Got it in the boat. Stock intake and 850 demon for now. Trying to get on the water for the 4th then will try and upgrade intake etc.

http://i19.photobucket.com/albums/b1...psgctqihzn.jpg

http://i19.photobucket.com/albums/b1...psbaniysjo.jpg

http://i19.photobucket.com/albums/b1...psakq2pkbn.jpg

Need some jetting advice on this please

Demon 850 mechanical secondaries no choke 1" AVH super sucker spacer

Where should I start on the mains primary and secondaries?

Ummmm. I see you have vacuum advanced hooked up.

Not to be an azzhole, but you need to put some marine stuff on this engine.

After this weekend the carb will be sent to Nickerson to be gone through and marinized. What distributer do I need to replace the current msd hei one with?

I would jet at 74 frt./86 rear to try it see how it runs,

You need a dist. and carb. approved for marine use, get a mechanical advance unit, set timing at 35 degree total advance, I would jet at 74 frt./86 rear to try it see how it runs, it may be a little rich.

Quote:

Originally Posted by SBX (Post 4147860)

After this weekend the carb will be sent to Nickerson to be gone through and marinized. What distributer do I need to replace the current msd hei one with?

Get a D.U.I. HEI style which is marine certified and features mechanical advance. One of the best money can buy.

This: http://m.summitracing.com/parts/dui-m12611bk

There's no need for a msd or similar box when usibg the above mentioned DUI distributor is there?