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View Full Version : Mercruiser Ignition 454 vs. 502??



powerplay230
08-15-2001, 03:27 PM
Hello,
Just finishing up a repower project on my 23' Powerplay. I replaced an older Mark IV 330 Horse 454 with a new 450 Hs/502 longblock. Among the things I changed were intake (used Merlins) and went with Edelbrocks marine carb'. The item I need help with is the Mercruiser ignition, is it ok to use the setup off the 454? The 454 box has 32 degrees total advance compared to the 502's 28 degrees, not sure how much different the curve is or if it matters. Also does the Thunderbolt ignition have a built in rev limiter. Appreciate anyone's input who has been there before, my mechanic isn't as worried as my wallet is.. don't want to melt a motor yet.
Thanks in advance,
Rich

rivercrazy
08-15-2001, 03:49 PM
If I were you I invest in an Marine MSD ignition.

Racing Ray
08-15-2001, 04:11 PM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

powerplay230
08-20-2001, 02:57 PM
Ray,
Couple of questions that I think you could answer-
If sticking with the Thunderbolt could I just replace the ignition module with one from a 502 Mag'. You switched to the entire MSD system are you happy with it, much of a difference with it?
Last question- if not using F.I. what carburator are you using. I'm not real happy with the Edelbrock version of Weber....
Thanks for all your help!

Racing Ray
08-20-2001, 04:15 PM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

powerplay230
08-20-2001, 04:28 PM
I set it up on a Merlin single plane intake (one of the only ones I found with bronze linings) and used a 1" spacer that was recomended from the builder I bought intake from. Boat is pretty hard to start and has a very bad stumble if I accelerate hard from an idle. From 1500 or up its fine all the way to 4600 where the ignition dies off. I think it has a bad accelerator pump as its stream is pretty weak compared to the Holleys I've had in the past. Very interested to see how it runs once I get the rev limiter raised and carb right as it is already 150% better than the 454 was.

Racing Ray
08-20-2001, 04:44 PM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

powerplay230
08-20-2001, 06:45 PM
Thanks Ray appreciate the ideas. Look forward to sneaking out of work early to give it a try.

powerplay230
08-20-2001, 07:03 PM
Ray just checked out your HP'Car site...Nice. Nice looking Chevelle, knew you had to be a good guy especially if you race a BB Chevy. 71 SS454 Owner here.... http://free.***boat.net/ubb/smile.gif

Racing Ray
08-20-2001, 07:27 PM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

powerplay230
08-20-2001, 08:34 PM
The "little" powerplant that runs it to 9.004s thats too funny http://free.***boat.net/ubb/smile.gif.Mine is just a lil toy, all stock on outside but motor runs pretty good for what it is. Best time it has run is 11.20 on street tires and no gas well maybe when this boat project has me temporarily satisfied I can go back to the street toy. Just here in Fla summer heat is a killer. How did you put your pictures on to site here.
Thks,
Rich

Havasu Hangin'
08-20-2001, 08:57 PM
Hey Ray,
Is Super Gas a 9.90 "heads up"?

Racing Ray
08-21-2001, 02:16 AM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

powerplay230
09-15-2001, 03:48 PM
Racing Ray,
Thanks for the tips, have gotten motor to behave much better. Still a little hard to start but a little adjusting makes a big difference.
thanks again,
Rich

Racing Ray
09-15-2001, 04:24 PM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

phillyray
09-17-2001, 06:29 PM
Hey racing Ray...what made you go with MSD VS. Crane or some of the others?

Racing Ray
09-18-2001, 02:25 AM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

Hustler
09-18-2001, 10:15 AM
Hey ray, I take it your one of the magnificent 7, I have a buddy that runs SG in div.7, Personaly I am one of the crew members on the PeenRite FMD Dragster( we must be politacly correct here)Are you going to be in vegas?
Hustler

Racing Ray
09-18-2001, 02:42 PM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

Hustler
09-18-2001, 03:08 PM
we will definetly be at the division race, I'de come look for you but hell theres gonna be about 300 of you there, I work on Darren Nicholson's car so stop by if you have a chance. My buddy that runs SG is Doug Spencer this is his first year, he also runs the socal SG assoc. hope to see you out there. are you going to make it to OP6?
Hustler