HIF Throttle Disc

[PAUL161]

I need a part number for the solid throttle disc for the HIF carbs on the 72. They have the original emission valves in them causing a lazy idle back. No, I won't solder them up! PJ

 

[RickB]

I don't know the answer, though I'd like to.

When I took mine apart yesterday I noted that the rear carb had the hole in it's throttle disc soldered over and the front did not. I suppose a PO replaced something or who knows??

 

[RickB]

Would these work?

https://www.englishparts.com/products/DIS...23/370-370.html

 

[DrEntropy]

If they're of good quality machining, most likely. Screws should be renewed as well.

 

[PAUL161]

Re: HIF Throttle Disc - DOC

Doc, Moss has two throttle discs for a 72-HIF carb, 373-670 says "with/notch and 373-675 without/notch". Are they speaking of the valve or something else? I believe on the H-4, they say "without valve". I've had those thing apart and don't know what they mean by "notch", in reference to a butterfly. PJ

 

[DrEntropy]

Re: HIF Throttle Disc - DOC

Not certain, Paul. I have no HIF example here and it's been too long since one has been in my paws. But it strikes me the 'notch' may be a horizontal one, milled where the butterfly fits the shaft. Hopefully someone with more recent experience (or better gray room retention) will pipe up.

My gut says: no notch. Hopefully Hap or someone will either shoot me down or confirm. Can you not just get two of each and ship the 'wrong' ones back?

 

[Billm]

Re: HIF Throttle Disc - DOC

Has anyone asked Joe Curto?

 

[Hap Waldrop]

Re: HIF Throttle Disc - DOC

Paul, some of the HIF4 don't have the idle enrichement tube sticking up in the carb body, some are flush with the carb body and the early HS4 solid butterfly will work in them fine with no mods, just finished a set I did that to a week or so ago. Now if you have the carbs where the idle enrichment tubes sticks up, you can do one of two things, you can get the early HS4 solid butterfly and make the notch in it, or you can make the idle enrichement tube flush with the carb body like in the other HIF4s, I prefer the later of the two.

 

[PAUL161]

Re: HIF Throttle Disc - DOC

Thanks Hap, I wasn't going to pull the carbs off until I had the butterfly's in hand, but I guess I'll have to pull one just to see which ones I have. Been a while since you rebuilt them, so that's asking too much for you to remember which ones they are. Thanks a bunch for the info! PJ

 

[Hap Waldrop]

Re: HIF Throttle Disc - DOC

Thanks Hap, I wasn't going to pull the carbs off until I had the butterfly's in hand, but I guess I'll have to pull one just to see which ones I have. Been a while since you rebuilt them, so that's asking too much for you to remember which ones they are. Thanks a bunch for the info! PJ

Either way, you'll still be getting the solid early butterfly, there's only one solid butterfly for HS4s, so you can't order the wrong thing, They don't make a notched solid butterfly, you have to do that the butterfly yourself for the raised tube HIF4s. Gordon has the solid butterflies in stock, and can get them to you in a hurry, next day shipping for us, at ground prices :banana: Get a set of new split screws as well for the butterflies, use a little loctite on them.

As for the mod if needed, either notching the butterfly or flushing out the idle enrichment tube, you still have the right butterfly, anything to get rid of those pesty poppet valve butterflies.

Pay close attention to the orinetation of the butterfly, it's opposite on HIF4 than a HS4 as far the way it leans at closed postion, but the angle on the edges of the butterflies only seal one way, so look at that closely when you take yours apart.

 

[PAUL161]

Re: HIF Throttle Disc - DOC

Thanks Hap, I wasn't going to pull the carbs off until I had the butterfly's in hand, but I guess I'll have to pull one just to see which ones I have. Been a while since you rebuilt them, so that's asking too much for you to remember which ones they are. Thanks a bunch for the info! PJ

Pay close attention to the orinetation of the butterfly, it's opposite on HIF4 than a HS4 as far the way it lean on closed postion, but the angle on the edges of the butterflies only seal one way, so look closely at that.

I did that once Hap, many years ago. Good thing about that incident, you have less a tendency to forget the next one. Thanks again for your input. PJ