Ignition Module / Distributor Replace or Upgrade?
 

Had an aluminum intake fail on my Carb'd 454 Merc a few weeks and watered down the compartment pretty good. I replaced the intake and cleaned down everything. Started engine and engine sounds great was setting timing and noticed it was all over the place and had no advance. Went through the diagnostics and started to inspect Ignition Module which I have the 848821-2 HP500 Carb module (engine is mildly built). I shook the module and discovered it was full of water.

That being said ans the fact the module has been discontinued and superceded to what looks like a Delco module that I am not sure of the spark curve led to me to see all options available. Should I just replace the module with either "New old stock", used, the superceded Merc 840130A05 or is there a better option to upgrade or replace the Thunderbolt V system as a whole?

Some concerns I have and that is making my decision a little more complicated was if I replace the Ignition Module, what if the Knock Module also needs replacing? I see plenty of complaints with the aftermarket companies that I question reliability from the old Merc system.

So any voice of reasoning out there that can clear up what route would be the most logical route to take.

There is one in the swap shop right now. Hurry and snag it. Same one as yours.

Btw to answer your question regarding aftermarket replacement I wouldn't do it unless you just purchased a marine DUI but no knock sensor etc. just a marine version distributor of what GM used for many years. Simple and trouble free for under 300.00.

First off thanks for sharing input! I have messaged the guy, with no response. I also have a lead to New Old Stock on ebay. What brand do you suggest? I am a Holley/MSD dealer so I can grab their marine drop in ready unit but it has a mechanical advance. I figured I was going backwards from the electronic setup now? As everyone else I am aiming for reliability and do not want to upgrade to a headache lol.

I see people switch to the Delco however the timing curve is different from what I have now. I do not have a chance to put the engine back on a dyno to test to see if I am at the same power which would in a sense always leave me a sense of wonder.

I suppose maybe I am overlooking into this?

The advantage of centrifugal Advance is it's old school. You want to change the timing curve change the timing curve. Lighter weights comes in later heavier weights comes in sooner. Same with the Springs only backwards. You can file off the inside edges of the weights to increase the total amount of timing advance or get different weights with more restriction to reduce the total amount of advance.

The advantage of centrifugal Advance is it's old school. You want to change the timing curve change the timing curve. Lighter weights comes in later hevier weights comes in sooner. Same with the Springs only backwards. You can file off the edges of the weights to change the total amount of timing advance or get different weights with more restriction to reduce the total amount of advance.

Now, here's my question. How much different-better is that DUI unit than a junkyard large-cap HEI? Or a $50 Chinese version off eBay? It's not like we're running these things at 7,000 RPM. The vacuum advance block off plate is available for 12 bucks or so. Some even advertise with the hardened steel gear which cost as much as the whole distributor if you were to buy it by itself.

I see your point and my first response is when I get pulled over for a potential ruiteen inspection or way over the decibel limit I want nothing to do with non marine components under the hatch. All I want is yes sir, no sir and be on my way and get back into my case of beer I had stashed rather than leading to a trip to jail for the night. Now back to the performance probably minimal when comparing to the GM hei that's been around for years. I would trust the inners and most importantly the gear than that of the Chinese ones on eBay. I've got a couple of flame throwers and they are well built and supposedly much more marine friendly dealing with the harsh marine environments and water resistant. They supposedly don't corrode etc etc.

in regards to any additional voltage I doubt much if any but can't support that cause I've never tested. If I had to guess I would say nearly identical. I would imagine there's a ton of GM and Chinese ones on the water running around with zero issues. No matter what HEI one was to go with they sure eliminate many ignition problems. Simple, effective and trouble free. Although mercs tbolts treated me well over the years also. .

I wouldnt consider a non-marine part for my boat to save a few bucks. The only way I would see something that comes from an auto is if I was in a pinch.

Anyways that being said.... I ordered a D.U.I. Distributor. I am going to transfer my original Merc Dist Gear over to the D.U.I. because I have a roller engine and the D.U.I.s come with cast gears and the tech I spoke with recommended to use a melonized gear. Hopefully we will be running solid for the weekend.

as long as your gear is in good shape nothing wrong with reusing it. A matter a fact I'd prefer to.