thunder bolt IV upgrade and new engine

[garyoja]

Hello all first post on here . I am in the middle of installing a vortec 350 in my 81 hammond challenger in place of the old 260 hp 350 non vortec . couple questions i am wanting to get rid of the thunderbolt system and go to something like this 5.7L GM Delco Voyager EST marine electronic distributor kit
maybe no this exact one but somthing like this . how hard is it to swap this ?


the new engine is being done next week specs are vortec 355 4 bolt mains comp cams xm270hr 9.3:1 hypeutectic pistons wiend intake edlebrock 600 cfm machined valve guides for extra lift cam also plan on doing silent choice

boat has an alpha 1 and came from the factory with a 23 pitch cleaver ran 60 mph with stock set up on gps

 

[Don S]

Re: thunder bolt IV upgrade and new engine

Hello all first post on here . I am in the middle of installing a vortec 350 in my 81 hammond challenger in place of the old 260 hp 350 non vortec . couple questions i am wanting to get rid of the thunderbolt system and go to something like this 5.7L GM Delco Voyager EST marine electronic distributor kit
maybe no this exact one but somthing like this . how hard is it to swap this ?

Not a big deal, just need to deal with some wiring changes for the shift interrupt switch setup. Not a major problem at all.
It's actually becoming common since Merc wants more for the module than the complete EST system costs.

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

Not a big deal, just need to deal with some wiring changes for the shift interrupt switch setup. Not a major problem at all.
It's actually becoming common since Merc wants more for the module than the complete EST system costs.

is there a place on here that will point me in the right direction as far as instructions ?

mine still works i just dont trust it lol

cant wait to get her back in the water maybe go to a 26p or bigger wanting to get into the 70 mph range

 

[achris]

Re: thunder bolt IV upgrade and new engine

mine still works i just dont trust it

Why not? The Thunderbolt system is one of the best marine ignition systems ever made. IF the module fails (not very often) then, by all means, change to the EST, but if it's still working, why spend money unnecessarily? The most common problem the TB system suffers is the solder joints on the top of the sensor in the distributor become 'dry', and fail to conduct. If you're good with a soldering iron, it's a 10 minute job to fix. Or you can buy a new sensor, which has sealed circuitry, thus eliminating the solder joint problem. New sensor costs about $70... Plenty less than the EST....

JMHO

Chris.........

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

Why not? The Thunderbolt system is one of the best marine ignition systems ever made. IF the module fails (not very often) then, by all means, change to the EST, but if it's still working, why spend money unnecessarily? The most common problem the TB system suffers is the solder joints on the top of the sensor in the distributor become 'dry', and fail to conduct. If you're good with a soldering iron, it's a 10 minute job to fix. Or you can buy a new sensor, which has sealed circuitry, thus eliminating the solder joint problem. New sensor costs about $70... Plenty less than the EST....

JMHO

Chris.........

to be honest i dont know how it will work with the new engine and a way bigger cam as far as setting the timming proper . i assume it wont work proper as it was not for this new engine

 

[achris]

Re: thunder bolt IV upgrade and new engine

It will work just fine. Set the timing as per the engine suppliers spec and the ignition module will do the rest. It doesn't care WHAT cam you put in. All it does it monitor the engine speed (using the sensor in the distributor and little bit of internal math) and apply an advance accordingly.... Do you have the advance curve for the TB-IV module? and one recommended by the engine supplier?

Chris.........
EDIT: The ignition module will have some numbers on it... What are they? and I can tell you what the timing curve is.... Or what the engine serial number of the engine you're using the TB-IV dissy from.

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

It will work just fine. Set the timing as per the engine suppliers spec and the ignition module will do the rest. It doesn't care WHAT cam you put in. All it does it monitor the engine speed (using the sensor in the distributor and little bit of internal math) and apply an advance accordingly.... Do you have the advance curve for the TB-IV module? and one recommended by the engine supplier?

Chris.........

the engine supplier did not give me a base timming to start at .

and as far as an advance curve goes i have no idea what you are talking about lol sorry man the boat was 100% original with 146 hrs on it when i got it the crank went to crap do to a bad wrist pin that probably dried out from sitting in a garage for 25 years when the ladys husband passed away . and my ignorance

 

[achris]

Re: thunder bolt IV upgrade and new engine

the engine supplier did not give me a base timming to start at .

Really???? You're going to need that! Best call them and find out. (The original timing for 1981 engines was 8 degrees BTDC.)

and as far as an advance curve goes i have no idea what you are talking about lol sorry man the boat was 100% original with 146 hrs on it when i got it the crank went to crap do to a bad wrist pin that probably dried out from sitting in a garage for 25 years when the ladys husband passed away . and my ignorance

Ok.. timing curve is the graph of how the ignition timing advances as engine speed increases... For an early V8 TB-IV system it looks like this....

 

[NHGuy]

Re: thunder bolt IV upgrade and new engine

I have seen a little online chatter about the Thunderbolt IV timing curve being not perfect for highly modded motors. But I'm no hot rodder, still learning. The way it works seems right to me.
Get the cam and compression for your engine and see if it calls for a special timing curve. I wouldn't think so though til you are way into super high compression and highly radical cam profiles. You can't use too crazy of a cam in a boat motor or it will cause reversion at idle. That's what happens when there is too much overlap between the intake and exhaust valve openings, this allows a little suction after each exhaust cycle which can bring water from the exhaust into the motor. You can't have that because it will ruin your engine. Hopefully your 355 is marine cammed.
That's why the really radical boat motors are so loud, they must exhaust without adding any water til the ends of the pipes. You don't want to go that way unless you really have to go fast at all other expense.
Also take a look at the curve that's in the EST, I wouldn't be surprised if it's darn close to the TB curve.
And to answer your original question, I bet the EST instructions are available in the box and online.
There's another Hammond around the high performance forums with a built small block, take a look at his stuff, it's way out there. I think he has a 383 stroker with worked heads, special exhaust, shortened lower unit, hydraulic steering - the whole deal. Very cool, and so fast that I'm sure it takes a deft hand to manage.

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

I have seen a little online chatter about the Thunderbolt IV timing curve being not perfect for highly modded motors. But I'm no hot rodder, still learning. The way it works seems right to me.
Get the cam and compression for your engine and see if it calls for a special timing curve. I wouldn't think so though til you are way into super high compression and highly radical cam profiles. You can't use too crazy of a cam in a boat motor or it will cause reversion at idle. That's what happens when there is too much overlap between the intake and exhaust valve openings, this allows a little suction after each exhaust cycle which can bring water from the exhaust into the motor. You can't have that because it will ruin your engine. Hopefully your 355 is marine cammed .

its a comp cams extreme marine roller 270

 

[BRG25]

Re: thunder bolt IV upgrade and new engine

These guys are trying to help you determine and set the timing for your new engine based on the TB IV ignition you currently have. If achris tells you that upgrading your ignition is not needed, then listen to the guy. They have years of experience and some are even Mercruiser techs. Read carefully what they are they are telling you and answer their questions. They can provide exact specs and information about your engine and outdrive based on serial number (which no one every gives willing, it's like pulling teeth). The free, accurate advice given on iboats is extremely valuable and we are lucky to have these guys. It obvious to me you don't know S@#! about engines (no offense) and are dropping some dough on a new engine.

 

[NHGuy]

Re: thunder bolt IV upgrade and new engine

Gee a little harsh. He'll be fine.

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

These guys are trying to help you determine and set the timing for your new engine based on the TB IV ignition you currently have. If achris tells you that upgrading your ignition is not needed, then listen to the guy. They have years of experience and some are even Mercruiser techs. Read carefully what they are they are telling you and answer their questions. They can provide exact specs and information about your engine and outdrive based on serial number (which no one every gives willing, it's like pulling teeth). The free, accurate advice given on iboats is extremely valuable and we are lucky to have these guys. It obvious to me you don't know S@#! about engines (no offense) and are dropping some dough on a new engine.

The truth is i dont have all the parts sitting in front of me so i dont know what the serial numbers are untill i make it to the shop !! secuond i never said i disagreed with Chris i simply cant answer his questions right now....... IF YOU READ it says that i dont know much about marine ignition systems ......... As far as your opinion on what i know or dont know i could give two squirts (no Ofense ) the fact is i have been building cars in the garage with my dad since i was 6 and many automotive engines and i work at a high performance rod shop . we tune cars by the seat of your pants to fine tune . I simply just dont have all the info he asked for never claimed to know everything about marine stuff thats why im here .

 

[achris]

Re: thunder bolt IV upgrade and new engine

I think some confusion may have arisen because you said you didn't know what a timing curve was... (and hence the comments regarding you knowledge)

I'm sorry, but assembling engines in the garage since you were 6 is not a qualification. Knowing what a timing curve is, and how to read it and use it are pretty fundamental to understanding how an engine works. Especially if you're building up an non-standard engine... All the best will in the world, and all the best components money can buy don't make up of a lack of basic knowledge. Apart from the obvious (the cooling and exhaust system) all the fundamentals and principles of automotive engines still applies. And all the rules regarding engine building still need to be adhered to. Specific knowledge of the application of the engine to the marine environment are not that hard when you think about them. Flat torque curve (no gear shifting like in a car, so the engine needs to be producing a usable amount of torque from quite slow), not too much overlap on the cam to reduce the likelihood of water ingestion, and not so much power that the drive heads south the first time the hammer goes down....

BTW, 'seat of the pants' tuning no longer cuts it. With modern low grade fuels engine damage will occur fairly quickly if something is not set right... Particularly for an engine with a high load on it right from the get-go (like a marine engine)....

JMHO,

Chris.......

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

yes there was some confusion lol . i ment i did not know what the pre set curve was in the tb and i also miss understood when you siad addvance curve i thought you said addvanced as in has it been updated doh . i understand that a base timing is set and as engine rpm incresses the timing will advance . i am used to dealing with old cars and truck no computer just good old vaccume advance and mechanical . this little black box has my brain all messed

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

i am worried about reversion for sure . but it is my understanding that if you keep your lsa between 110 and 112 it should be good with factory exhaust ?

 

[BRG25]

Re: thunder bolt IV upgrade and new engine

Yes I was too harsh...good luck with your new engine.

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

no biggie thanks .

Yes I was too harsh...good luck with your new engine.

 

[garyoja]

Re: thunder bolt IV upgrade and new engine

We put the new engine in last night still some stuff to do before it gets flashed up . I have looked hi and low for my mercruiser manual and i am not able to find where i put it .

What i would like to know is if there is any special routine for setting base timing with the thunderbolt ?

engine came at tdc so i lined up number 1 on the cap lined up the oil pump shaft and dropped it in so it all lined up
thanks in advance Gary

 

[Don S]

Re: thunder bolt IV upgrade and new engine

No base timing for the TB4 ignition.