500 caddy power

Automotive powered airboat discussion.
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BigEddieEST
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500 caddy power

Postby BigEddieEST » Mon May 09, 2016 8:04 pm

Hello fellow swamp lovers I have a 1975 500 caddy elderbrock intake, 500 holly carb, and swinging a 74 water walker. I'm looking to get a little more power out of the boat motor inside is stock. Who knows about these motors for airboat application? I can run the hill with me an another but my boat seats 5 I would love to run dry with my boat fully loaded
13 Diamondback hull
500 Caddy
74 water walker

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Deano
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Re: 500 caddy power

Postby Deano » Mon May 09, 2016 8:31 pm

Buddy Branch has a DD cam kit for your engine that I believe includes a timing set.
That would be the easiest single upgrade you could make without getting involved w/rebuilding it, imo.

Naturally, your engine needs to be in a healthy condition to do a cam swap.
He is among the most knowledgeable Caddy people there are and is easy to talk to.
I believe his number is (352) 797-9910.

Additionally, there are volumes of Caddy info here to be had.
The [Search] feature on this board works real well.
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but it is not the path to knowledge; it has no place in the endeavor of science."
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Pumpkin74
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Re: 500 caddy power

Postby Pumpkin74 » Mon May 09, 2016 8:49 pm

Gearbox!
500 caddy stinger 1.73 2 blade maximus

Bdriller
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Re: 500 caddy power

Postby Bdriller » Tue May 10, 2016 12:18 am

As far as dollars per lb of torque at prop , probably gears and prop, however if u have a small boat and u want to wake it up a little go with the buddy branch recomendation

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BigEddieEST
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Re: 500 caddy power

Postby BigEddieEST » Tue May 10, 2016 1:49 pm

Thanks for the info I'm calling buddy tonight and I'm going to get the cam and anything else he suggests I don't want a gearbox I love being able to only spend 20 and ride all day with the dd
13 Diamondback hull
500 Caddy
74 water walker

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Ricky Bobby
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Re: 500 caddy power

Postby Ricky Bobby » Tue May 10, 2016 4:29 pm

If you change your mind shoot me a pm I've got a 2-1 ch3 belt box off a caddy fixin to be for sale in the next few days
"Criminal Mischief " 13-7'6 hamant gso 480 ,contenental injection , 78" 9 blade Razor X, water-methanol injection

One Eyed Gator
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Re: 500 caddy power

Postby One Eyed Gator » Wed May 11, 2016 10:45 am

A few things that can be done.
If you have aluminum intake weld up the exhaust crossover and the divide plenum. The plenum is divided but does come up to plane of the carb mounting surface.
If you have the cast pulley set find a stamped set ( check TDC to make sure it reads correctly) or get an Aluminum set.
Get a light weight high torque starter
Make sure you have High output coil and good wires
Tune your carb with an O2 meter.
Have heads redone with good valve job and correct springs for your cam.
Good set of long tube headers with 2.5" collector and mufflers

In a DD it is all the little things that add up to make you DD get noticed in a crowd of high HP gearbox box and aircraft boats.

tom favreau
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Re: 500 caddy power

Postby tom favreau » Sat Aug 12, 2017 6:06 pm

I put a thumper ca in my 472 it made a difference and didn,t notice gas usage at all watch out on timing them they are cam timed to # 2 tdc then distriburer timed to tdc on #1 piston it make a big different on power. just saying.

SWAMPHUNTER45
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Re: 500 caddy power

Postby SWAMPHUNTER45 » Sat Aug 12, 2017 9:12 pm

Can't buy a better direct drive cam shaft than the one Mr Branch offers. Don't waste your time buying a catalog book cam or the so called airboat cam from California.
Over the past 20 years Buddy has done airboat R&D and perfected his product. My suggestion would be to buy the kit he puts together that comes complete with the timing set. He degrees the cam and gear assembly and sends a special aircraft drill bit and instruction on pinning the gear.

His price is very fair for what you get and they work.

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Deano
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Re: 500 caddy power

Postby Deano » Sat Aug 12, 2017 11:13 pm

This thread is over a year old, Swamp. I'd hope BigEddie already has a season on his Branch cam.
tom favreau wrote:I put a thumper ca in my 472 . . .
watch out on timing them they are cam timed to # 2 tdc then distriburer timed to tdc on #1 piston . . .

As much as I hope your intent was to help others, this is a really bad recommendation. The 'Thumper' grinds were developed by cam companies for a different engine family and the masses who wanted the 'sound' of an upgraded cam. Evidently, they have done less R&D with these engines than we have. The originator of the 'Thumper' series doesn't even seem to know the correct rocker arm ratio, as they still publish the wrong numbers for their entire Caddy line. :roll: Whether this is genuine ignorance, lack of concern for your results, a marketing ploy, or all of the above, I would have thought they would have corrected it in the following 40 years, however, they have not. That in and of itself should speak volumes about what you don't want.

The Caddy heads do not need, and will not benefit from having an exhaust side bias ground into the cam. In fact, quite the opposite. The intake port (and the associated runner) is what is lacking in this case, and comparatively speaking, the exhaust port actually breathes pretty well already. If a man wanted real performance instead of 'the sound' of performance, he may well be better off to grind the bias into the intake side.

You may not realize this, but you already proved all this to be true when you said in the other thread that you have a 425 that will outrun your 472. That didn't make sense to me when I read it, although it does now. If you still don't believe it, do a cam swap and change nothing else, you will see where that lack of power is originating.

I suspect I know what you are attempting to convey about cam timing, but you really didn't even come close.
#2 has nothing to do with anything, unless it is in conversation and there is small child or big kid and a local taco stand involved.
Last edited by Deano on Sun Aug 13, 2017 5:49 pm, edited 1 time in total.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

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kwanjangnihm
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Re: 500 caddy power

Postby kwanjangnihm » Sun Aug 13, 2017 4:49 pm

Deano wrote: #2 has nothing to do with anything

Deano I usually agree with you, but I have to admit I enjoy a good #2 :toothy7:
(sometimes 2 or 3 after stopping at a local taco stand) :cheers:
" I don't care who you are back in the world, you give away our position one more time, I'll bleed ya, real quiet. Leave ya here. Got that? "

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kwanjangnihm
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Re: 500 caddy power

Postby kwanjangnihm » Sun Aug 13, 2017 4:52 pm

SWAMPHUNTER45 wrote: sends a special aircraft drill bit and instructions

once again us AC guys are helping out you caddy guys!! :stirpot:
" I don't care who you are back in the world, you give away our position one more time, I'll bleed ya, real quiet. Leave ya here. Got that? "

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Deano
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Re: 500 caddy power

Postby Deano » Sun Aug 13, 2017 6:04 pm

Kwan . . . I edited my post to reflect the previously overlooked reality. :lol: Thank you for the assist. :thumbleft:
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan


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