Fast idle question OMC Holley (pics)

[a70eliminator]

1990 OMC 5.8 4bbl
It appears I'm missing my fast idle cam, does OMC omitt this piece due to the shifting? I took some pics, looks like I'm missing a spring and the lever, I was trying to set the choke qualification by the book when I noticed something just didn't seem right. The service manual shows the spring I'm missing but not a good picture of the lever that goes with it, I just can't decipher why these parts are missing everything looked original and unmolested. I don't think I really need the fast idle mechanism but I'm just the type of person that has to have everything in working condition no matter how minor it may be. Do you think the lever and spring off any 4160 would fit the bill?

 

[Benny1963]

Re: Fast idle question OMC Holley (pics)

what carb number is it you should be able to you one of several.
b1963

 

[a70eliminator]

Re: Fast idle question OMC Holley (pics)

I've been reading several threads on choke's and it seems the majority of I/O's don't use fast idle cams, there in the Cobra service manual is a picture showing the fast idle cam in the illustration of the pulloff adjustment, but no mention of fast idle adjustment, as I said mine doesn't have that cam at all, I'm just wanting to be sure I'm not missing something.

 

[wire2]

Re: Fast idle question OMC Holley (pics)

A fast idle isn't a practical item in a boat. If you put it in gear at say, 1200 rpm, it will lurch ahead (or back). Not good.

 

[a70eliminator]

Re: Fast idle question OMC Holley (pics)

Yes I agree, but my OMC has shift lock-out on the throttle so you can free rev the engine to knock the fast idle off no?

 

[wire2]

Re: Fast idle question OMC Holley (pics)

Yes I agree, but my OMC has shift lock-out on the throttle so you can free rev the engine to knock the fast idle off no?

IF it had a fast idle cam, the shift released throttle would knock it off only after some warm up. The cam is linked to the choke.

It's safer to have it return to normal idle at neutral position before engaging shift function again. It may stall if you try it too soon, that's one of the reasons for going to EFI.

 

[Don S]

Re: Fast idle question OMC Holley (pics)

Marine carbs don't have high idle cams, at all. If you want high idle, just move the throttle lever up when in neutral only position.

 

[a70eliminator]

Re: Fast idle question OMC Holley (pics)

Marine carbs don't have high idle cams, at all. If you want high idle, just move the throttle lever up when in neutral only position.

Please don't take this wrong I'm by no means trying to discredit your answer, but how do you explain this (page 4-54) in the factory Cobra Service Manual? Please I'm not trying to be a smart alec just can't figure this one out.

 

[Boomyal]

Re: Fast idle question OMC Holley (pics)

Please don't take this wrong I'm by no means trying to discredit your answer, but how do you explain this (page 4-54) in the factory Cobra Service Manual? Please I'm not trying to be a smart alec just can't figure this one out.

I've had several Holley marine carbs, both two bbls and 4 bbls. None of them ever had fast idle cams. IMHO, all for a good reason. Although I saw the text in your pic, I have no explanation for it. A fast idle cam on a marine engine, with rpm shift requirments does not make sense.

 

[a70eliminator]

Re: Fast idle question OMC Holley (pics)

Ok I can quess is that the carbs came through with these fast idle cams in place therefore the text in the manual acknowleges them Although the actual lever on the throttle plate has been omitted therefore no adjustment procedures are given. So it is safe to say my carb is actually not missing anything at all. Glad thats all cleared up. Thanks Don and all of you who replyed, I don't know what I would do without you'ns

 

[Don S]

Re: Fast idle question OMC Holley (pics)

Since most of the carbs are automotive, that part is called a fast idle cam. However, the marine version doesn't have any steps or high spots to make it an actual cam. It's all the same height. It still moves, around an axis, but there is nothing that rides on it or anything.

 

[a70eliminator]

Re: Fast idle question OMC Holley (pics)

Since most of the carbs are automotive, that part is called a fast idle cam. However, the marine version doesn't have any steps or high spots to make it an actual cam. It's all the same height. It still moves, around an axis, but there is nothing that rides on it or anything.

Exactly, Thats what I wanted to hear, I was confused reading that manual over and over again. I was really having a moment glad I didn't pis you off, I look forward to your responses especially.