454 distributer/timing problems

[rthomas]

Hello, my port side 454 has been running like crap for a bit and I've chased it down to the distributer (Tbolt V large module 1984) when I put a timing light on it its all over the place, this results in a jumpy idle and an occasional backfire at speed. is this likely the module itself or the pickup in the distributor itself?

 

[alldodge]

Being a 1984 it would be a TB4 unless its been changed

That said, I would look at the distributor cap, rotor, wires and then pick up in that order.

 

[Scott Danforth]

Look at link 21 from this sticky

MUST HAVE Technical Information for DIYers.

MUST HAVE Technical Information for DIYers. (< An @ Work Safe Search Version Of ^^^) If you have NEVER posted in this forum before, please click on How to ask a question link first. 1. How to Ask a Question .... Please Read This Before Posting A Question... 2. Miscellaneous Mercruiser...

forums.iboats.com

 

[rthomas]

thanks guys!

 

[achris]

Make sure you have the distributor body, the sensor and the module properly grounded. (with a wire, not just bolted into the engine)

 

[nola mike]

Check that the distributor doesn't have any play, worn bushings can cause erratic timing.

 

[rthomas]

well I think Ive figured it out, when I pulled the module off of the riser to find a part# (not legible) I saw that the resin filled backing had a hole in it, not sure from what. now the challenge of finding a new one, mercruiser has a kit to upgrade the module to basically a T5 (part #15248T02) but is not currently available and sierra doesnt make one either. With that in mind if I cant find a used one I might look at upgrading to a set of Davis Unified Ignition marine distributers, these are basically based on GM automotive HEI distributers, has anyone ran these?

 

[alldodge]

If your "Sure" the module is bad, then I would suggest Delco EST over the DUI

Just my opinion, others will vary

 

[Scott Danforth]

DUI is iffy. have never found where they actually tested to SAE J1171

I would go voyager over DUI. I myself am running a Mallory YLM 624 as I needed/wanted the ability to adjust my timing curve.