Thunderbolt V vs Delco EST Ignition

[snowbrd84]

I bought a Delco EST ignition conversion kit (Sierra) thinking my TB V module was bad. Then found out it was mechanical issue and TB V seems to be working.

Question I have now is, is the Delco EST an upgrade? Or just keep the TB V installed? I can still return the one I bought. Or I could install and prob cover my cost selling the working TB V system.

This is on a '96 7.4 carbed Mercruiser if it matters.

 

[Scott Danforth]

flip a coin. they are comparable, however the TB V has knock control.

 

[nola mike]

Also, tb v has a dynamic advance feature based on rpm (potentially allowing more advance). I think the Delco is just a static advance map

 

[snowbrd84]

Sounds like leave it as is then and return the Delco kit.

I do have a small issue which is the timing jumps around by about 2 deg when in base timing mode. So hard to set exactly. It sounds like possibly distributor bushing? Timing chain is good. Is bushing a replaceable part and anyone have a part number? It's not on the parts diagrams.

 

[Scott06]

Sounds like leave it as is then and return the Delco kit.

I do have a small issue which is the timing jumps around by about 2 deg when in base timing mode. So hard to set exactly. It sounds like possibly distributor bushing? Timing chain is good. Is bushing a replaceable part and anyone have a part number? It's not on the parts diagrams.

YEs no advantage to the delco vs TBV except when you need to replace the module.

this parts breakdown that may or may not be for your exact engine shows dist bushings. You can put in your serial number to get an exact fit .

I would take the cap off and check the rotor for side to side play before pulling it. You have to put a lot of time on it for the bushings to wear.

https://www.marineengine.com/parts/mercruiser-sterndrive-parts/74l-bravo-gen-vi-gm-454-v8-19961997/0f800700-thru-0k999999/distributor-and-ignition-components

 

[Scott Danforth]

NAPA carries distributor bushings in stock