17080561 / 1990 Mercruiser 5.7L

[Gmoney]

I just got Cliffs HP rebuild kit and was comparing with the idle tubes pulled from the carb.  Both the length and opening differ from those in the kit.  The new tubes are shorter with a smaller opening.  Would you recommend I get identical tubes or will these new tubes be fine?

17080561 / 1990 Mercruiser 5.7L

Thanks

[Ethan1]

I just got Cliffs HP rebuild kit and was comparing with the idle tubes pulled from the carb.  Both the length and opening differ from those in the kit.  The new tubes are shorter with a smaller opening.  Would you recommend I get identical tubes or will these new tubes be fine?

17080561 / 1990 Mercruiser 5.7L

Thanks

 I would call Cliff's shop. He would be the best to answer this.

[Shark Racer]

Were there signs that the carb had been modified by a previous rebuilder?

Cliff usually starts with an 034 idle tube size, which is going to work pretty well with a mild cam (<210dur).

What's the length difference?

[Gmoney]

Yep as it turns someone has rebuilt it before, however I don,t think the tubes were replaced. I,m thinking these are virgin tubes so to speak.  The question now is either install the new tubes as is or get larger tubes.  Any advice how to measure these?

[Gmoney]

PS the new tubes are about a 1/4 inch shorter.  I,m notsureof the best approach to measure the opening size.

[429bbf]

im not sure what kind of tools you have but i use mic. calipers and a nice big set of drill bits . i always measure my bits even if there stamped .ive got a couple different sets i think i bought them from MSC. hope this helps

[Ethan1]

PS the new tubes are about a 1/4 inch shorter.  I,m notsureof the best approach to measure the opening size.

 You can either use TIG rod or MIG wire of different sizes. I also use tip cleaner's for an Oxy-Acetylene torch. Find one that fits snug into the opening and use dial calipers to measure the O.D. of the tip used.

[Gmoney]

Guys, thanks for all the help.  I talked to Cliff today and with these marine carbs the idle tubes are smaller . . . . 0.026 range.  So I,ve got a micro drill bit set ordered and will clean the existing tubes and may oversize a couple thousandths as he recommended.  Thanks again.