Are all jets the same size in a carb family?

[Guest]

Are waxstats the same size as non waxstat in the same carb family? What about b/w fixed and spring neeldes, are those jets the same?

 

[dklawson]

I know that there are .090 and .100 solid jets for SUs like HS4 and HS6. I haven't looked at what is available for WaxStat carbs. As for the needles for the two types (not sizes) of jets, the numbering is totally different. There are often identical (or nearly identical) needles in both spring and fixed configurations. However, I've never seen a list that says ABD = 5 or anything like that. Paul Tegler has a good online database of SU needles and there is a UK based site that will graphically show you various needle profiles (Google for "Mintylamb SU").

 

[Guest]

The reason I ask is I had to swap out one of my converted waxstats for a fixed needle regualr jet. I put spacer/insulators on my carbs and I needed the extra room the smaller regular jet provides.

Doug, I don't remeber if you put the dual's on your son's spit yet, but put insulators on them if you can. I did last night and the carbs run ~so~ much cooler. It is a little bit cooler this morning, but the spacers made a BIG difference. I don't think I'll be having the vapor sputter on hot start now. Going out to test soon.

 

[RickB]

Whoa - you mean you had them bolted right to the intake manifold?
Yeah, that could make them run hot. :wink:

 

[Guest]

Whoa - you mean you had them bolted right to the intake manifold?
Yeah, that could make them run hot. :wink:

That's how they came stock on the euro Spit from everything I've seen ( with the heat shield of course).

That manifold is stupid hot. I've only got about .015 clearance b/w a raised pad on the center port area of the exhast manifold and the crossover. I need to trim that down. I wish I would have noticed before I put it on.

Still sputters a bit on hot start. It was doing fine till I put the vac advance on. Apparently that raised exhaust temps quite a bit.

 

[Hap Waldrop]

Needle for HS6 .100" jet carbs are different from .090" used in HS2 and HS4. Fixed/solid needles are made totally different from biased needles, however Joe Curto makes a bushing to convert biased needle carbs to solid needles.

 

[Guest]

Not the needle Hap, I need to know if the jets are different sizes b/w waxstat spring loaded HS4's and fixed needle regular jet HS4's.

 

[Hap Waldrop]

If you got the waxstat jet, I've got plenty of HS 4 jets, what measurements do you need ID, OD, lenght of jet tube exposed, just give me a call, and I;ll give you any measurements you need for for the HS4 jet, on waxstax stuff you're on your own, that stuff is 1982-on, not what I normally work on.

 

[Guest]

Hap, I've got some fixed needle regualr HS4 jets here. What I wanted to know is if all jet ID's are the same in a carb family. Is there such thing as a rich or lean jet? (BTW, the waxstat function has been neutralized)

Right now I have one waxstat and one regualr jet in my carbs. Now I know that sounds hokey....and it is. It's a major pain to get the choke linkage to work with the stuff I have on hand. I plan on converting either this set, or the fixed needle set to F.I. I don't want to waste money buying parts for carbs that I'm not going to use for very long or waste allot of time putting the other jet in if it's the same ID as the waxstat. I had to change the rear jet because of clearance issues.

Besides the above problem, here is what I've been fighting since I put these on:

a.)Vapor lock, been boiling the crap out of fuel and running bad when hot. I have it pretty much under control, but it'll still do it upon a hot start but clears up shortly.

b.) When I adjust idle mixture, it's lean on top end. If I adjust the mixture to pull good on top end, it runs rich and poorly at idle.

I don't know if it's (problem b) because of: heat, worn needles ( which doesn't make sense to me in this case.) wrong needles, worn throttle shafts, worn jet bearings, wrong float level, flux capacitor at full capacity or alien "probe".

I have decided to get these carbs as best I can with what I have and concentrate on a F.I set up. That should correct all of the above problems and it would seem to be the best route. Drowning the car with dual webers doesn't seem like a good idea (but BOY would I love to !!!)

 

[jlaird]

Sounds a lot like a air leak to me.

 

[Guest]

I checked and everything is o.k.

 

[dklawson]

My son's Spit is currently running the single HS4 carb. I'm saving the duals for the time (if ever) when the car comes back to me. I'll keep in mind your advice on the carb insulators.

It sounds like you have already checked all the obvious things. Assuming your carbs both have the standard 0.090" jets, perhaps it is time to look at needles that go rich faster than what you are currently using. If you have the SU carb book or the Haynes SU book, they both have a list of needles and their profiles. What you may want to do is select a few needles as "best guesses" and then visit the Mintylamb web site I mentioned earlier. You can enter the needle you are currently using along with ones you'd like to try and see graphically how their profiles compare. Other people I know swear by the WinSU program for selecting new needles. I have never tried it but have only heard good things about it.

 

[Guest]

Gotta leak on the rear bowl right now where I extended the line to facilitate the bowl relocation. It was fine till I put the other jet in. The line on that one wasn't as good as the waxstat. If I would just cut the car it would be a whole lot simpler, but I'd hate to do that especially if I go to injection later. I'll play with it some more tommorrow. This thing is really wearing me out. Might go back to the DGV until I have the injection set up ready. my DGV never gave me this many problems.

 

[jlaird]

Bah, you know it is something stupid, isn't it always.

 

[Guest]

Fixed the leak, still runs like crap. I think I have trash floating around in the jet. It'll run so/so for a while, thien run like crap. You can pull the choke while it does this and sometimes it helps and sometimes it makes no difference.

Saw something weird today. Saw little bubbles comming from the bowl down the line into the jet while it was shut off. The bowl didn't feel hot enough to boil it. Will pull it down (AGAIN!) tommorrow and see. Might have the DGV back on then too. This is really wearing me out. Supposed to go to "cruisin' the coast" tommorrow. Might just wind up "walkin' th' dog".