More Ponies for 4.3

J

John_S

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Jun 21, 2004
Messages
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Re: More Ponies for 4.3

I suspect that the 4.3L marine production vortecs, do not run with a "good" (0.040") quench. The SB V8's do not. If your bottom end is weak and needs rebuilding, or the cost/time is not a factor, go for the new pistons. It will allow for slightly higher compression, and probably some more timing advance. If not, just keep to stock vortec timing advance curves, compression, tuning, and cam. ie, make it a stock like production motor.
 
M

mtnrat

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Jul 29, 2006
Messages
419
Re: More Ponies for 4.3

imported_John_S said:
I suspect that the 4.3L marine production vortecs, do not run with a "good" (0.040") quench. The SB V8's do not. If your bottom end is weak and needs rebuilding, or the cost/time is not a factor, go for the new pistons. It will allow for slightly higher compression, and probably some more timing advance. If not, just keep to stock vortec timing advance curves, compression, tuning, and cam. ie, make it a stock like production motor.
Click to expand...
Yep and yep. I would only go to the expense of changing to these pistons if you are doing a complete rebuild etc. I just put in the picture as an illustration.
 
M

marada1

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Oct 28, 2007
Messages
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Re: More Ponies for 4.3

Yeah my engine is fresh. About 20 hrs max on a complete rebuild so I don't want to tear it back down that deep right now. When I rebuilt it 3 years or so ago I went back stock and didn't foresee doing this upgrade at the time. Really just wanted to confirm that my pistons are not too far off from what the later model vortec engines have. Looks like they are the same which is good.
Thanks
 
W

wca_tim

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Messages
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Re: More Ponies for 4.3

You should be pleased with the result of the upgrade. I picked up a boat with a lunched 4.3 2bbl version in it, and on the repower went with 4.3, edelbrock intake and carb, vortec heads, etc... after playing with jetting, props and set-up, power is great from off idle and through mid range. Top end is an honest 8-10 mph faster than what the original owner saw.

Which carb are yoin going to go with? So far I like the edelbrock, but the jet kit that they sell for use with their carb and 4.3 was way too lean. Runs great once dialed in.

Have Fun!
 
M

marada1

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Oct 28, 2007
Messages
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Re: More Ponies for 4.3

Sounds like your upgrade was exactly what I'm planning. I also am going with the Edelbrock carb (1409), and 2114 intake. Maybe you can give me some tips on dialing in the carb. It's great to hear from someone who has acually done this. Please give me more details. What kind and size is your boat? Is it OMC or Merc? Tell me about before and after performance- WOT RPMs, speed, prop size, etc.
If your engine is OMC, what did you do about the shift and throttle brackets?
Thanks
 
W

wca_tim

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May 28, 2007
Messages
1,708
Re: More Ponies for 4.3

Boat is a 1988 checkmate, ca 2500 lbs, don't have good info on previous owner specific performance. Has merc alpha 1 with 1.84 gears. Handy fellow at the local marine shop made the brackest out of sheet metal - I had a broken shoulder at the time and didn't feel like waiting until i could mess with it.

On the carb, seems best with 0.89 main jets and then two metering rod sizes richer then the ones supplied by edelbrock in the kit for 1409 use on a 4.3.

So far, performance is best with a turbo 26" that pulls great out of the hole, great mid range and once trimmed out all the way runs an honest 60+ on top end. that's with WOT around 4600. Second is 23" laser 2, 55-56 mph, 4800 at wot. numbers may be a little off (not much), going from memory right now. going to try another prop or two out tomorrow.

Hope this is helpful.

Cheers!
 
M

marada1

Petty Officer 3rd Class
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Oct 28, 2007
Messages
85
Re: More Ponies for 4.3

Hey wca tim, do you know which rods you ended up using? Looks like there are quite a few to choose from. The 4.3 kit from Edelbrock comes with the following:
2) Primary Metering Jets (.089")
2) Secondary Metering Jets (.089")
2) Metering Rods (.068" x .057")
2) Step-up Springs (pink; 7")

Sounds like you used the .089" jets. If you could tell me what size rods you used I would order them with the kit and have a good starting point maybe.

What type hull does your Checkmate have? Probably faster than my Marada. Maybe you could send a pic?
Thanks and let me know how the prop test goes.
 
180shabah

180shabah

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Joined
Mar 26, 2005
Messages
4,995
Re: More Ponies for 4.3

Edelbrock calibration kit #1485(4.3L with performer intake manifold) has the following:

Metering Jets – Primary .098, Secondary .101
Metering Rods – .068 x .047
Step-Up Spring – orange (5" Hg).
 
180shabah

180shabah

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Mar 26, 2005
Messages
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Re: More Ponies for 4.3

Dig deeper and they show two different component sets for the same calibration kit - sounds like a phone call may be in order.
 
Bondo

Bondo

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Apr 17, 2002
Messages
71,082
Re: More Ponies for 4.3

Ayuh,.......

If you want to Tune a AFB clone Carb,.........

You need the Owner's Manual to get All the Info,........

And,.......
If you buy the Strip Kit,.........
That Carb can be about Anything you want it to be..........
 
Bondo

Bondo

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Staff member
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Messages
71,082
Re: More Ponies for 4.3

Ayuh,....

That'll get you headed in the right direction,....
But,...
You'll be lackin the cast aluminum Elbow to hook up the Y-pipe....

I Really Doubt that flex-hose will work there....
 
180shabah

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: More Ponies for 4.3

Also, be sure you check the mating surfaces before assembly, there have been several cases of them being "mismatched" and causing leaks.
 
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