TB V Questions

[76SeaRay]

I read through the sticky on the TB IV and TB V but didn't find the answers to these questions. I have a TB V.

Coil -- What coil is recommended for use with the TB V?

ICM Mounting -- Should the TB V ICM have heatsink compound between it and the mounting bracket used to secure it to the Port Exh elbow?

ICM Mounting Plate to Port Exh elbow -- There are phenolic washers called out between the mounting plate and the exhaust elbow. Are these for heat insulation? They are only about 0.063 inches thick so if for heat insulation is there a better choice (ie, thicker, different material, etc.)?

 

[76SeaRay]

So, still looking for answers on these questions but most important is the coil question. I see lots of comments on the primary coil resistance. That is, Merc specs say around 0.7 ohms. However, it is not clear if a Mercruiser coil (or any other coil) with this resistance requires an external resistor as many other coils are 1.5 ohms.

 

[Scott06]

OEM merc https://www.michiganmotorz.com/mercruiser-ignition-coil-hei
Aftermarket https://www.michiganmotorz.com/thunderbolt-iv-v-hei-ignition-system-coil

call MM if yku need answers regarding external resistors

 

[Scott Danforth]

Hey @achris

 

[76SeaRay]

Thanks for the info. I will give them a call tomorrow.

 

[achris]

I read through the sticky on the TB IV and TB V but didn't find the answers to these questions. I have a TB V.

Coil -- What coil is recommended for use with the TB V?

Any coil with a 0.6Ω to 0.8Ω primary resistance and 9.4kΩ to 11.7kΩ secondary resistance.

ICM Mounting -- Should the TB V ICM have heatsink compound between it and the mounting bracket used to secure it to the Port Exh elbow?

No.

ICM Mounting Plate to Port Exh elbow -- There are phenolic washers called out between the mounting plate and the exhaust elbow. Are these for heat insulation? They are only about 0.063 inches thick so if for heat insulation is there a better choice (ie, thicker, different material, etc.)?

Use what's recommended and you won't go wrong. Trying to re-engineer things is how we make machines unreliable, and difficult to find parts for in the future.

Chris........

 

[76SeaRay]

I tried to find out from Michigan Motors if the Mercruiser coil needs an external resistor. The first guy didn't know so he transferred me to another guy's voicemail. He never called me back. I wanted to find out so I could order the resistor at the same time if it is needed.

On the phenolic washers, I found them at Grainger and they just came in.

 

[76SeaRay]

Well, I tried to order the Mercruiser coil from MM but their shopping cart tries to add back in shipping after they say free 2 day FedEX. So between the lack of response to my calls and the problem with the way their cart works, I will find somewhere else to buy the coil.

Update: Found this coil that has the correct specs it appears.

ACCEL 8145C ACCEL Ignition Coil - SuperStock - Breakerless Electronic Coil - Chrome

Excellent high performance coil for vehicles that have been converted from points to a breakerless electronic distributor or electronic ignition system, where a canister type oil filled can coil is preferred. Designed with optimized low resistance, high turns ratio windings to work specifically...

www.holley.com