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Changing from Thunderbolt to MSD..Suggestions ?

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musclecarsclassifieds

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Discussion starter · #1 ·
Currently have a 28 foot Scarab Excel.

Just installed a new 454 Gen V with Dart (Iron Eagle) heads. RPM Edelbrock Intake and a 750 Edelbrock carb.

Was sporting a Thunderbolt ignition .
Great top end. but hard starting. figured I put a little money in it so I bought the MSD 6M2 box and Marine Billet Distrib, MSD Wires. Bosch Platinum +4 Plugs.

Getting ready to drop the MSD distrib in it. But was wondering if all you gears heads had suggestions on advance timing. I heard the Thunderbolt had about a 24 degree advance. Looks like the initial timimg was set about 12 degrees. giving me a total of 36. I was pretty happy with the top end.

The MSD billet Has multiple springs for specific timing applications. It currently has 2 silver springs from factory. (slow)

Based on a little information I just provided. anyone else have the same set up or experience ? and what would be a good timing set up for my application.

thinking 2 blue springs with a blue washer ?

Thanks All !
 
#2 ·
Different TB ignitions have different advance rates depending on the module that you have . If you use the V-6 module you have more ignitial timing than the V-8 module. V-6 has 14* advance, so you set base at 22* to get 36*. V-8 has either 20 or 24 (maybe either). so you set less base timing to get to 36*

on the MSD, Go by the chart that MSD gives you either in the directions or on their web site. you want to bring the timing in quickly, and it should all be in by at least 3000 RPM. It doesn't have to all come in at once, as most boats aren't run below 3000, but faster is better. Lots of people lock it so its the same from idle up, but that can make starting hard. As long as you are not beyond 36*, and its all in by 3000 you are pretty much good to go.
 
#3 ·
Lock the distributer. Set the timing at 34-36. Dump the Bosch plugs and put some AC's in it. Change the coil to an MSD.

I am not always the brightest fool, but it works for me.
 
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#5 ·
5325user said:
I agree on the AC's.

Do you have any starting problems with the dist. locked? or kick back?
Click to expand...
No problems but I do have a high torque gear reduction starter and I use a solenoid relay on the starter wire circuit.
 
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#7 · (Edited)
Discussion starter · #8 ·
Excellent advice across the board gentleman !

I've heard Good and Bad on the MSD set up. Too late now. I own it !

Probably should of looked into DUI. MSD wires everywhere. Looks like a bowl of Spaghetti.

MSD is Proud of there stuff $$$$ better be good.

I have the MSD Billet set up with light springs and a 21 degree stop. Things should kick in at about 2800 to 3000.

I'm considering a 25 degree stop. with a 10 degree initial.
I've heard 36 is too much and 32-34 is good. But i've also heard 36 was perfect.

Rumor has it the GM 454 is unhappy with those Bosch plugs ?

General concencus seems to be with AC. This 454 H.O actually had Champion RV15YC4 which did a good job at the Top end.

But I'm removing them and putting them in my lawnmower where they belong :bigsmile:

Toss up between the 21 stop and 25 stop. lets take some Votes here !!

want to drop the distrib in Monday or Tuesday

Ciao....
Frankie


Too many jet ski's not enough time :eek:
 
Discussion starter · #9 ·
good advice. I think the TB IV I had might of been 24 degrees.

I'm looking at a stiff climb from about 1500 then the advance kicking in at 3000. still stuck on the 21 or 25 bushing. not sure how far I can push the initial ? anywhere from 8 to 12 I'm figuring. don't want to exceed 36 but don't want to leave anything on the table either.

Frankie
 
#10 ·
I have the thunderbolt IV in my boat and I ordered yesterday a DUI system it was 400.00 and that included new wires it should be here on thursday it is only a 1 wire hook-up and the tach connects to the neg. side on distributor. They asked what cam I run what rpm's it turns where it cruises and how heavy the boat is. He told me I will be surprised how it runs
 
#12 ·
I wish I had written down my set-up, but I know that my total timing was 34 degrees.

If memory serves me, initial was set at 12 with 22 degree bushing and light springs brought it in by 2400 rpm.


489 ci with Merlin heads, 10 to 1 compression.
 
#15 ·
All I can say my DUI ign is awesome what a difference going from the Merc thundervolt IV to this set up it is calibrated to 24 degrees@ 3000 rpm and a 6500rpm rev limiter. It has gained 200rpm on top. I can't wait to put my stroker kit in it and change the cam to the new firing order.
 
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5325user
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