Offshoreonly.com - 540 BBC running poorly

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- - 540 BBC running poorly (https://www.offshoreonly.com/forums/general-q/357283-540-bbc-running-poorly.html)

ancho

10-22-2018 08:23 AM

Quote:

Originally Posted by F-2 Speedy (Post 4655391)

are these standard firing order cams ?

I don't know. Any easy way to check? Certainly a slightly incorrect firing order would explain the way the motors run.

F-2 Speedy

10-22-2018 08:28 AM

Quote:

Originally Posted by ancho (Post 4655392)

I don't know. Any easy way to check? Certainly a slightly incorrect firing order would explain the way the motors run.

I would call the engine builder......if its a 4-7 swap cylinder 7 will be 3rd to fire

payuppsucker

10-22-2018 09:33 AM

I'm gonna go with Speedy on this one.............probably has an LS firing order.

ancho

10-22-2018 09:56 AM

Spoke with the builder briefly - they said it's a standard firing order.

14 apache

10-22-2018 11:01 AM

Put new plugs in it and try again.

Baja Rooster

10-22-2018 11:47 AM

Checked fuel pressure? Pull gas cap off of the filler neck to vent the tanks? Sometimes those anti-siphon valves can stick when the gas sitting in them dries out and gets gummy. More than one tank vent has gotten clogged from sitting with spider nests and what nots.

ROB FREEMAN

10-22-2018 12:23 PM

Quote:

Originally Posted by Griff (Post 4655352)

Was anything removed from the engines or were they pulled 100% complete??
Why mess with the timing?? They should have been timed when they were removed.

First thing I would do is pull fuel filters and dump them into glass containers and check for water contamination.

Quote:

Originally Posted by 14 apache (Post 4655423)

Put new plugs in it and try again.

also Ck for cracked spark plugs from being pulled. If new should be good to go. If not hit on installation also you didn’t partially hit you’re fuel shut offs. If you have them in this whole process. Seems like fuel delivery or ignition prob to me. Good luck

ancho

10-22-2018 12:47 PM

I'm replacing all the plugs (NGK BKR5E) and both sets of plug wires first with Moroso Ultra 40, the Merc wire sets that I have now are probably from 2014 when the motors were built (or older). They ohm out OK but I have not checked for arcing at night, etc.

Griff

10-22-2018 12:52 PM

Quote:

Originally Posted by ancho (Post 4655359)

Prior to pulling the engines I removed caps, rotors, carbs, plugs/wires, and headers.

I messed with the timing because of a discrepancy in the way the 2 engines were running, both in power and water temp.

I would start by double checking everything you removed and put back on, especially firing order.
What is timing supposed to be set at?? Base and full advance?? I'm assuming full advance should be around 34*

getrdunn

10-22-2018 12:59 PM

Ground straps and all connections and including main Mercury plug all good. As mentioned possible cracked plugs. Fire it up in the dark and check for any arcing etc. just a thought. I've identified some electrical issues in the dark. I have a new DUI with plug wires if your interested in purchasing or just to try. Just pay shipping. Process of elimination. New plugs and believe it or not it wouldn't be the first time even fuel at the pump can be contaminated with water. Happened up north here and cost the station a brand new Diesel engine.

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