Linkert Too Rich??

[King]

Hi All

After much back and forth, procrastination, and just pain angst I have the original heads back on my 51FL with Linkert attached. I won't go into sealing the manifold but just let's say it was a good thing we did the assembly in a machine shop. Eventually, all sealed up well and I got it to start.

Now for the problem. I got it to idle well at about 960rpm but coming off idle it sputters and blows black smoke out the pipe and, when letting off on the throttle, a good foot of flame shoots out the pipe also. Dialing in the hi-speed needle does not affect anything even with the needle seated it still is acting as above. My diagnosis too rich but I might be wrong. The question is what could be causing it and how to change it? I have the float set at ¼ below the bowl lip and a #19 fixed jet (which I think is proper). Any advice deeply appreciated.

King

[steve_wood]

I know you're focused on the carb, but I would suggest that you should check to make sure your timing is correct. Are you sure you timed it to the full advance mark with the front piston on the compression stroke?

Sorry for possibly tellin you something you might already know, but you never know.

Let us know how it goes.

[Cotten]

King!

Let me begin by noting that the HS needle on a fixed jet carb will have no effect upon idle or performance under ~35mph.
And frankly, M74B HS needles are rarely sensitive even then.

Shooting flames out the pipe raises serious timing questions, as Steve suspects.
And valve adjustment as well.

Still, to have to over-enrichen to run is always an omen of vacuum leaks.
Did you thoroughly bubbletest, even the pancover screws over each intake port?
I know you did, but I am always compelled to ask!

Never does only one thing go wrong at a time,

....Cotten

[King]

Thanks Steve and Cotton

I checked timing and it was a bit retarded. The valves seem ok. I have solids so I adjust them on the tight side but still able to spin with a bit of drag.

I think a lot of my initial problem was that I was flooding on the attempt to start (too many kicks with full choke). Following advice I tried two kicks full choke/open throttle then set at ¼ choke and hot kick with the throttle just cracked. Started first kick. Adjusting the idle speed and the idle needle it now idles quite well at about 900-1000 rpm. It still acted very rich when first started but as it warmed up it got better and the throttle advance is now much smoother.

Cotton, there was a bit of fiddling to get rid of air leaks on assembly. Many years ago (long before peek seals) I got sick and tired of messing with the plumbers and brass seals so I converted to the o ring. As you have noted, an iffy proposition. Although it sealed OK, I’m still not totally comfortable with the set up. But I’m going to run it for a while and re-test. So the question is can one install the original plumbers nipples and do they come oversize if the head threads are shot??

Not saying problem solved but for now its ride and see.

King

[Cotten]

King!

I have two oversized nipples left, as one went into a '49 this spring.

A fellow forum member has the specs to produce more soon!

....Cotten

[King]

Cotten

Thanks for the reply. I haven't retested yet but some symptoms of the evil leak have manifested. I thing going back to the plumbers may be the solution. So are you willing to let go of the OS nipples?

King

[Cotten]

King!

I must keep my inventory for in-house services,
but as I posted, more are in the works.

....Cotten