Spark plug wire set for 7.4L Bravo

[jet_pilot]

Brand new to the forum and pretty new to boating over all. I have a 91' SeaRay 270Da with a 91 rebuilt 7.4L V8 and a Bravo 2 leg. I was going to replace the spark plug wires and came across a deal on a set from Sierra, part number 18-8802 which I bought . In looking around it seems to me that I have a choice 18-8802 ( the ones I bought) or 18-8804 for thunderbolt ignition... Whats the difference? What If I got the wrong ones? Does it matter?

Will get some pics of the boat and engine up in a week or so for future questions, I am sure I will have lots.

Thanks for the help!!

B

 

[HT32BSX115]

Re: Spark plug wire set for 7.4L Bravo

Brand new to the forum and pretty new to boating over all. I have a 91' SeaRay 270Da with a 91 rebuilt 7.4L V8 and a Bravo 2 leg. I was going to replace the spark plug wires and came across a deal on a set from Sierra, part number 18-8802 which I bought . In looking around it seems to me that I have a choice 18-8802 ( the ones I bought) or 18-8804 for thunderbolt ignition... Whats the difference? What If I got the wrong ones? Does it matter?

Will get some pics of the boat and engine up in a week or so for future questions, I am sure I will have lots.






Thanks for the help!!

B

Howdy,


Welcome to iBoats!!


The Thunderbolt ignition is a high energy ignition system compared to a points/coil type system. higher voltage probably.....

I believe yours is a coil type with an electronic (non-points) type system.....possibly similar to a Pertronix system.

Since Mercruiser uses serial number ranges to determine parts requirements, it's helpful if you post those.




What kind of Jet do you pilot?


Regards,


Rick

 

[jet_pilot]

Re: Spark plug wire set for 7.4L Bravo

Thanks Rick, here are the serial numbers from the engine OD611781, outdrive OD634523 and Part numbers for the distributor cap 805759T-2 (replaced in 96') and rotor assembly 13524T-1 (replaced 96').


Fly a LearJet 31A


Thanks,
Barret

 

[Bondo]

Re: Spark plug wire set for 7.4L Bravo

with a 91 rebuilt 7.4L V8

Ayuh,... Welcome Aboard,...

I donno what you bought, but a 91 is possibly a T-Bolt IV, or more likely T-Bolt V igntion...

 

[HT32BSX115]

Re: Spark plug wire set for 7.4L Bravo

Ayuh,... Welcome Aboard,...

I donno what you bought, but a 91 is possibly a T-Bolt IV, or more likely T-Bolt V igntion...

Yeah. It might be a IV.

OD611781 according to Doug Russell refers to the diagram below.

0D603118 THRU 0F800699

Is the above a IV? Mine is a V

According to your serial number it could be a TB IV or V. you'll have to check the link below.

Your serial number according to the following link could be a 92 model.

http://www.dougrussell.com/partscat...N. V) GM 454 V-8 1992-1996&index=1621

Fly a LearJet 31A

Cool jet. keep that oxy mask close above 410!!!


Cheers,


Rick

 

[jet_pilot]

Re: Spark plug wire set for 7.4L Bravo

I know I cringe above 410, I have been as high as 470 never light enough to see her reach the 510 advertised...


Anyway is it a problem if I put on spark plug wires that were intended for a non thunderbolt ignition?


Barret

 

[HT32BSX115]

Re: Spark plug wire set for 7.4L Bravo

I know I cringe above 410, I have been as high as 470 never light enough to see her reach the 510 advertised...


Anyway is it a problem if I put on spark plug wires that were intended for a non thunderbolt ignition?


Barret

I had a T-38 to 470 once. Go above 500 and the USAF would consider you an Astronaut!! I actually thought I saw curvature of the earth! I also thought the sky seemed darker in the middle of the day! Now I don't ever go above 410 That's scary enough!


Those plug wires will probably be ok. Most wiring sets nowadays will handle all the newer electronic high energy systems.

If you could take them back, I would get the "right" ones though.

In the worst case, you could have arc-through if the insulation wasn't good enough to handle the higher voltage. That would be a problem.

 

[Bondo]

Re: Spark plug wire set for 7.4L Bravo

Anyway is it a problem if I put on spark plug wires that were intended for a non thunderbolt ignition?

Ayuh,... My Guess is, the cap ends might be Innys, instead of Outys...
I kinda doubt there's much difference in the actual cables...

 

[jet_pilot]

Re: Spark plug wire set for 7.4L Bravo

Thanks guys, I will give them a try one at a time see if the cylinders are still working fine since I can't take them back. If it works great if not not a big loss.

And yah the sky is definately darker more of a black blue at 470!

Barret

 

[HT32BSX115]

Re: Spark plug wire set for 7.4L Bravo

They'll probably work just fine.