'86 Mercruiser 200 Thunderbolt ignition

[baw3510maverick]

Background:
I bought an '86 Chris Craft 2 years ago, and have continued to try to run down a couple of problems. After rebuilding the carb, the engine was still bogging down at full throttle, and would intermittently sputter and backfire.
Last year, I threw my hands up and had a guy look at it. He diagnosed "no advance signal, bad distributor and ignition modual"-i've now duly noted the mispelling of module.
He removed the thunderbolt ignition amplifier, replaced the OEM distributor with an HEI distributor (not sure what kind of pickup--still getting schooled on ignition systems) and somehow wired it straight into the wiring harness.
The boat was run 1 time after the repair, and I had to run it in circles for about 30 minutes, and it finally evened out and ran for a couple of hours, but wasn't quite right. Thought it was coincidentally bad gas.
This year--March I drug my boat from home in Alabama, to Maryland, where I'm stationed in the Marines, and began getting it prepared for the season.
After de-winterizing, I cranked her up and ran her at idle for a good hour. Shut her down--no problems. The next day I was going to take her to the water, and I could not get it to start, finally got it started but couldnt keep it running.

Found another "marine mechanic" to come have a look. He got the boat to crank and run some, then it would not start again. He determined it was jumping time, needed a new timing chain; then we could not get the motor to stay running at all. I said great, never heard from the guy again.

Got a mechanic buddy from work that "knows boats" to have a look, and to my disbelief, it cranked right up. Remember the last time it was being cranked--it wouldn't run. He adjusted the distributor, and we kept it idling, but it had major backfire when gouging the throttle. It also was missing really bad. All new plugs and wires, fire on all. We found that there was no advance on the timing, and it did not seem to be jumping time. We determined that without the amplifier, there could be no advance.
We then found out Mercruiser does not manufacture the amplifier any longer.
I orderd an MSD iginition kit, under the impression from talking to the tech, that this would solve my problem and replace the OEM system.
Upon receiving the kit, I found the wiring diagram calls for the ignition control module to be plugged into the OEM Ignition Amplifier!
Back to square one!

1986 Merc 200 Alpha I, SN A482092
Ignition Amplifier, P/N 390-7804A3, is not available from Mercruiser or any used parts dealer I could find.

Finally the question:
1- If this part is unavailable what is the work around? Mercruiser couldn't tell me. I was astounded there was no superceding part or a fix.

2- Does anyone have any idea where to find an aftermarket or used amplifier?

This issue has had to have been experienced by others. I've read all the Thunderbolt and Mercruiser threads till I cried, but couldn't find anyone specifically addressing the parts problem.

Final note: I apologize for the length of the post, but after reading about 100 the past week, I've seen quite a bit of chastisement from you guys on people not providing enough info. So hopefully the overkill doesn't kill you.

Thanks,

Brett

 

[Bondo]

Re: '86 Mercruiser 200 Thunderbolt ignition

1- If this part is unavailable what is the work around? Mercruiser couldn't tell me. I was astounded there was no superceding part or a fix.

Ayuh,....

Update it with a New or Used Igntion system.....

It shouldn't be too hard to find 1 on ebay for a 305 Merc....

 

[Maclin]

Re: '86 Mercruiser 200 Thunderbolt ignition

Just speaking to the switchover to HEI that the first guy did, it does not need an external amplifier and should have mechanical advance built into it. That is if it is a full functional GM HEI distributor. I really think he was trying to get you going as cheaply as possible and still have a good ignition without having to run down parts that are no longer available. He may have been a little quick to come up with his diagnosis, but then again maybe he was spot on.

The HEI advance mechanism is right at the top inside the distributor and you can see the weights and springs. You can move the rotor some and watch the weights move and pull the springs out and then let go and it all snaps back. I would have the distributor looked at to see if all that works.

There should really be no need for external MSD type units, the HEI system gives good spark and is simple enough to hook in as it is all inside the distributor, even the coil.

Having typed all of that in, there are other wiring issues as now the external coil is not part of the system, and other components may not get wired back in correctly. I am sure there is a scheme to an HEI conversion that the first guy followed.

I did help a friend with an HEI car once, it would run sometimes but not start at other times. They were trying to leave work and it would not start so they called. I removed the distributor cap and noticed that the wires to the coil (actually looks like a transformer on those) were not tight, the nuts had only been hand threaded down like their brother (who had rebuilt then installed the engine for them) had meant to get back to that and did not. I tightened those nuts down and vrooom, no problems after that.

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

Guys, appreciate the timely response.

Bond-O, appreciated the reply, but you really didn't tell me anything. I know I need to fix it, the question is how.....what works, what doesn't?.......

Maclin,
You're steering me well. You were on target with him getting me going cheaply; he and I actually had that discussion.
I don't believe the distributor is mechanical; I'm thinking it's electronic from what I remember my buddy saying. He was schooling me on the difference. I will verify to rule that out.
Another note; the4 original mech did remove the original cannister type coil and replace with another one that looks like a small transformer, so there IS an external coil in the scheme. And there is a module? on the dist. that plugs into the coil.

So--sounds like my next step is to pull the dist. and verify what it is exactly. Where can I cross-reference a part number if I can find one?

if my comments above gave you any more insight into what I'm dealing with, Please advise.

Again, thanks for the response and your time.

 

[JustJason]

Re: '86 Mercruiser 200 Thunderbolt ignition

i understand your doing this, that, and the other thing to your carb and ignition system... but i have to ask, what are your compression numbers?

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

Great question. Haven't checked. My mech buddy is back home in Mich, and we were going to check that when he got back just to rule it out before we actually did anything else. Meanwhile, I'm trying to figure out what I can figure out on the ignition...........
I've seen the compression testing brought up in several threads and the manual.
I may invest the $40 and go get one now. I was supposed to have her running for the fourth
Thanks for bringing that up.

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

Mentors,

Attached are some photos, maybe can shed some light.

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

couple more pix.

If anyone can provide a comment on what you can glean form the pix on the wiring, please advise.

Semper boating.

Remember tomorow, all who have served and sacrificed for our freedom to do things like boating.

 

[Don S]

Re: '86 Mercruiser 200 Thunderbolt ignition

Well, it looks like they used a Delco EST distributor and coil. Not a problem, Volvo used them for V8 and V6 engines, and Mercruiser used them for the 3.0L engines and still do.
They do work with the shift interrupt system,
Since you have it, might as well make the best use of it. The ignition amplifier for the thunderbolt IV ignition is still available, the part number was changed to 15248A1 and it now costs about $375 and you DO NOT need it with the EST ignition system.
One thing about the EST, is you can not set the timing and make it run right without first putting it in base timing mode. It locks out the advance so it doesn't move around while you try to set it.
I can find the timing setting for a V8 (which has nothing to do with actual timing BTW) and the wiring diagram to get it working if you want to stick with the EST, or if you go with the Thunderbolt, you need to use the new Amp and the original distributor.
You DO NOT use the ignition amplifier with the EST distributor.
You must have some real hacks back there that want to use the amp with an EST.
I doubt you need a timing chain, just someone that actully knows something about the ignition systems and how to install and service them.

 

[Maclin]

Re: '86 Mercruiser 200 Thunderbolt ignition

Hey bawmav,

If you still want some advice, if I were in your deck shoes I would take Don S up on his offer and stick with the EST, it is "free"...

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

Roger that
Two things:


1- when the "marine mechanic" came by and diagnosed the timing chain. He did reset the distributor at the __deg mark at TDC, and it would run then jump out.
this was what made him think the timing chain. Not sure what else that would mean, even though it did not happen again when my buddy came by and we got it idling. Thinking maybe this is what you're referring to as the base timing, maybe not. Please correct me, and explain a little bit. I'm likely to attempt this myself.
I'm getting tired of depending on others, I'm an electrician by trade, and can read and understand. I get tired of being too busy to work on my own stuff and getting screwed. And nobody EVER does it like I would.
Anyways.....

2-The MSD system kit I still have-- The MSD guys said I can wire this in without the amplifier with the Magnetic pickup distributor diagram with the kit.
Is this Delco distributor a magnetic pickup? I was telling him the dist was an HEI. So the dist is not an HEI? You can tell by the pictures I guess?
If so, in you guy's opinion, is the high pro MSD system worth the $800 bucks to stick on an original stock '86 with no other mods. Of course, the tech guy was trying to sell his product and keep me from returning it, going on and on about performance, fuel economy, prolonging the life of the engine...yadayada yada.
Is it worth it?


Just want to discuss a little further so I can weigh options.

Don S, appreciate the generous offer. Pending response to the above, I may surely take you up on it.

Thanks again guys.

Happy fourth, I'll be thinking about my brothers in the sandbox.

 

[Don S]

Re: '86 Mercruiser 200 Thunderbolt ignition

1- when the "marine mechanic" came by and diagnosed the timing chain. He did reset the distributor at the __deg mark at TDC, and it would run then jump out.

A broken shear pin in the distributor gear will do the same thing. If it did the same thing on 2 distributors, yea, timing chain. But that is just not seen on marine engines very often. But, if the distributor can be reset the second time and it runs again for a while. The timing chain is NOT the problem. It will not jump back in time to make the second distributor work.

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

roger. Same dist jumped out. The Delco.
Mystery is it hasn't "jumped" since.

Personal opinion on the MSD mentioned above???
Other comments on questions in line 2?

Sorry to keep bothering you man, but I'm going to FedEx you some brotherly hugh for all your help!

 

[Don S]

Re: '86 Mercruiser 200 Thunderbolt ignition

I've never worked on or used an MSD system, so I can't say one way or the other.
If the roll pin is sheared, it may be binding and now holding for a bit till the next time it slips.
Just pull the distributor out, and try to remove the pin, if you can drive it out, it's probably sheared and off set. Then just pull the gear off the distributor and put in a new pin.

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

Don S,

I can find the timing setting for a V8 (which has nothing to do with actual timing BTW) and the wiring diagram to get it working if you want to stick with the EST, or if you go with the Thunderbolt, you need to use the new Amp and the original distributor.
----------------------------------

I'd kindly take you up on your offer. I'm going to pull the dist to check the pin and connections. But since we've adjusted this thing and have no advance, we'll still have to start over. If you have the wiring diagram (with possibly an elementary diagram to trouble shoot with showing the contact positions) and setting for the base timing, I'd be much obliged.

B

 

[Don S]

Re: '86 Mercruiser 200 Thunderbolt ignition

Here is a link to the Merc 3.0L service manual. On page 4E-12, you will find a wiring diagram to show you how to wire the system for use with the shift interrupt system
Then on page 4B-25 you will find the procedure for putting the distributor into base timing mode in order to set timing.
I'll have to find the timing setting degrees for an engine like yours since Merc didn't use the EST on any carbed engines other than the 3.0L

You will set the timing at 10? BTDC while in base timing mode and around 6-700 rpm. Then once you come out of base, you will see approximatly the folloing values.

Initial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10?
600 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19?
800 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22?
1200 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25?
1600 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26?
2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27?
2400 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28?
2800 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28?
4000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28?
4800 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28?

 

[Maclin]

Re: '86 Mercruiser 200 Thunderbolt ignition

BawMav,

I personally would not go to the trouble of putting the MSD unit in on a stock engine. On a high compression, over-cammed and finnicky high-horse engine maybe. The stock EST puts out good spark for the rpm range and conditions your boat engine will experience. Just get the EST wired in correctly and the advance tested/working, then make sure you have the proper spark plugs and you should be in top tune.

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

Roger Don, didn't get the link to the wiring diagram.

Maclin, thanks for the input. I'll take the advice. thanks.

 

[Don S]

Re: '86 Mercruiser 200 Thunderbolt ignition

Don't believe I forgot the link, sorry about that.

http://www-alt.mercurymarine.com/mnetdata/SERVICE/CRUISER/Servmanl/13/13covr2.pdf

 

[baw3510maverick]

Re: '86 Mercruiser 200 Thunderbolt ignition

It won't let me go to the link. Maybe you have some kind of membership or something so you can look at online manuals.
Maybe you could download and email?

I'd hate to have to order the whole manual just for the ignition.......

If you can think of something else, let me know. I'll still be digging and checking the pin, compression, and other stuff.

thanks again for the help