Weber 42 DCOE 8

[jitenshakun]

Hello,

I have triple 42 DCOE 8 on my stroker 3.0L L28.  Car starts easily and idles nicely.  The car is new to me so I can't really comment on the performance, but I can say a single cylinder seems to be running pig rich.  I'm firing black out the tailpipe and the #5 spark plug is black and wet.  Compression on the cylinders is decent (115psi-125psi) and my coolant was oil free on a recent change.  In other words, it isn't a new engine but it seems to be in decent shape.

A couple questions I'd appreciate input on:

1. Is there anything in particular to look for on servicing the carb for a single side possibly running rich?

2. What are peoples' experiences with 42 DCOE 8s on an L28?  These aren't a common carb so I'm not seeing as much information on them as compared to the 40 and 45 DCOE.

For the record, I've read Des Hammill's book and also have Haynes' manual as a reference. I'm also watching detailed videos like these.

Thank you in advance!

[jonbill]

obvious guesses are that cylinder 5 unit is different from the others. have you taken the jet stacks out and compared them? is #5 idle screw the same as the others, and screwed out the same amount?

its still a dcoe, so I dont think its different from a 40 or 45 in how it works.

 

 

[jitenshakun]

The idle screw is set about the same but I haven't compared the jets yet. 

From what I've read the 42 and 40 have many similarities. 

[Zed Head]

How about oil instead of fuel?  A bad valve seal or oil scraper ring maybe.

Are the DCOE's easy to swap?  Swap it and see if the problem stays with the barrel.

[jitenshakun]

Good diagnosis tip!

It didn't feel oily enough for oil, but the finger rub isn't exactly an exact measure. 

[jonbill]

I'd check the numbers on the jets and tubes first, that should be a 10 min job. swapping carbs around can be a fair bit of work, depending how the linkages are done.

[jitenshakun]

Any thoughts on the 42 for the L28 as a cruiser car? 

[jonbill]

sure, why not? chokes might be harder to come by than 40 or 45s, but I expect thats the only practical difference.

[jitenshakun]

I read on a Triumph page that there's a shared choke between the 40 and 42. Might not be too terrible. 

[jonbill]

I read on a Triumph page that there's a shared choke between the 40 and 42. Might not be too terrible. 

I think that says they share a design, not the part though. The body diameter is 2mm different, the choke couldnt fit.

[jitenshakun]

I've reset the idle screws and had a look inside. They carbs look pretty clean. 

I'm sorting out the fueling right now to make sure it is dialed. I'm also going to look at replacing the throttle linkage as it has some play. 

I don't want to fall into the trap of blaming carbs when it is everything but the carb. 

 

 

Edited May 28, 2020 by jitenshakun

[Zed Head]

22 hours ago, jonbill said:

I'd check the numbers on the jets and tubes first, that should be a 10 min job. swapping carbs around can be a fair bit of work, depending how the linkages are done.

Did you check the numbers?  Just curious.  You might fall in to the trap of thinking that the PO used all correct parts.

@jitenshakun