Best Crab Cap....

[stouchton]

I need to change the Crab Caps on my 4.3GXI-E, however this will be a major pain since clearance to get to the back of the engines is nill (Monterey 282). Curious what the best cap is.... would not like to do this too often!

Thanks for an input or advice you can offer.

 

[alldodge]

Unable to say which is best, they all have issues. The biggest problem is they just stop working, (causing a miss, or misfire) and when the cap is looked at there are no visual signs or problems. The VP cap is the same as Merc so search for the VP number or
Merc 898253T23 cap
Merc 8M6001222 rotor
Merc 898253T28 cap and rotor

Should be able get one at the local auto parts store. I don't see a difference but maybe achris or Scott Danforth or Bondo can add

Distributor Cap D328A DELPHI DC20009 DC2000911B1
AIRTEX 5D1078
GM 10452458
[h=1][/h]

 

[Scott Danforth]

I need to change the Crab Caps on my 4.3GXI-E, however this will be a major pain since clearance to get to the back of the engines is nill (Monterey 282). Curious what the best cap is.... would not like to do this too often!

Thanks for an input or advice you can offer.

its a crap design. the nick-names are crap cap or cross-fire cap. the method of failure is to fire multiple cylinders simultaneously.

the connections are too close to each other and the insulation breaks down internally to the cap. about 10% of them last about 4 years, most die between 2-3 years

no choice except to change it every 2 years.

As AllDodge indicated....they work until they dont

 

[achris]

... about 10% of them last about 4 years, most die between 2-3 years...

Wow. I must be doing something wrong then. I still have the original on my engine, and it's 12 years old....

Chris....

 

[Scott Danforth]

Chris....buy a lottery ticket. That is about as rare as a rot free bayliner

 

[stouchton]

Both of mine are original, and 14 years old. Both engines seem to run well but one engine does not seem to come up to full RPM (4000 instead of 4400). Whats weird is boat speed seems correct and engines do not sound out of sync - might be a tach issue....

Fuel pressure is good, though with a little bounce from the vacuum modulator section of the pressure regulator (bounces about 2 to 3 PSI around 55psi, disconnect vacuum line and steady 55psi). Leakdown looks good after several minutes. Plugs are new, fuel pressure regulator is new. Fuel pump is newer (not original). Engine smells rich when idling, has a pretty good idle, not as smooth as other engine but very close. Got me thinking one cylinder not firing properly, though plugs all look good.

Having read about the caps, thought it might be prudent to change, and see if that also affects top RPM any and idling.

Engines have about 450 hours on them.

Just curious as to anyones thoughts...

 

[stouchton]

Answering my own question here... it was the tach. Took her out last Friday and let her run wide open - after trimming out properly hit 39.6mph with one engine at 4400 and the other reading 3000. So obviously engine was making close to 4400 rpm, not 3000. Later in the day tach decided to cooperate.

At this point I am simply going to keep a spare cap and rotor in the boat and wait for them to act up. After lasting 14 years, my guess is that they will last longer.