Early 4360 FI -- cold enrichment housing index mark (scribe line)

[Peter R.]

The aluminum cold enrichment housing on my 4360 FI unit has no scribe line for indexing the thermostatic cover, so I'm not sure where to set the cover with regard to rich or lean. Maybe the mark was blasted away in a previous rebuild or maybe the housing was replaced and never scribed (if they come unscribed). Were all the index scribe lines in the same place on these housings or were they hand marked and matched to a particular FI unit? If they are all in the same place, is there any reason I shouldn't mark mine based on pictures of other housings that are marked? Even if I don't mark mine, can I set my thermostatic cover based on close-up pictures of other cold enrichment housings? If none of this will work, is there way to set the thermostatic cover without any marks based on some other factors?

[Don H.]

Re: Early 4360 FI -- cold enrichment housing index mark (scribe line)

Peter, I can't answer your main question regarding if it had index marks. Both my units (newer than yours) have them. My first question to you would be why you are wanting to adjust them? Is it not setting the choke, coming off too soon, or is it apart? The index marks could be "replicated" for adjusting with a pencil or marker. I would use pictures as a reference for a starting point but make the final setting making sure it closed the throttle valve and opens with warm up. Good luck, Don H.

[Mike M.]

Re: Early 4360 FI -- cold enrichment housing index mark (scribe line)

my 57 vet(see Restorer Fall 2010) has no scribe marks on its choke housing. this 4360 is serial # 69(it lacks the rochester ID plate on the side of the plenum like most of the first 100 rochester 4360's)Mike

[Peter R.]

Re: Early 4360 FI -- cold enrichment housing index mark (scribe line)

Don, my reason for wanting to adjust it is my desire to improve cold start-up performance and knowing that it was not set properly when I obtained the car 3 months ago. Mike, thanks for your input--it's good to know that another early unit doesn't have a scribe mark. So I won't add one. But that certainly leaves the question of how the Rochester engineers expected the cold enrichment to be adjusted without a scribe line.

[Jim L.]

Re: Early 4360 FI -- cold enrichment housing index mark (scribe line)

Don, my reason for wanting to adjust it is my desire to improve cold start-up performance .....

Try a pragmatic approach....

Loosen the three screws and rotate the Bakelite cover until the fast idle throttle stop is at approximately the mid point of the fast idle cam. Retighten the screws.

On a coolish day, start the engine.

Does it start and die? If so, rotate the Bakelite cover slightly clockwise ("richer").

Does it start and remain running? If so, note whether the engine appears to be running overly rich after a few moments. If it does, how long does it take for the cold enrichment to turn off and lean out the engine? If the engine is overly rich for more than a minute or two, rotate the cover slightly counter clockwise ("leaner").

Wait for another coolish day and try the above experiment again. There would be little point in repeating it immediately after starting the engine because, once the engine has run, no matter how briefly, its starting needs have changed. So wait until the engine is, once again, stone cold.

After two or three cold starts, you'll have the cold enrichment mechanism adjusted about as well as is possible.

Jim

[Bruce B.]

Re: Early 4360 FI -- cold enrichment housing index mark (scribe line)

Peter,

I believe Jim L. suggestion is the way to go.

I have attached 2 pictures of the cold enrichment system on my 4360 unit 136 which happens to be steel stamped on the back of the plenum and also is taged.

The small piece of tape on the housing cover is on top of the "R" in the word rich on the cover. You can also see that the cam is on the second step since it about 65 degrees in the garage. The cold enrichment system works great as long as it is adjusted properly.

I hope this helps.

[Peter R.]

Re: Early 4360 FI -- cold enrichment housing index mark (scribe line)

Jim's suggestion sounds good to me, too. I will try it. And thanks for the pictures, Bruce, and for marking the plastic with the tape line. Based on that, I think I'm at a good starting point for the experimentation.