I understand that a choke pulloff controls the ability of the secondaries to open, and that stock the choke pulloff takes a few seconds to open them, causing a delay.... Now, I wanted to drill out my choke pulloff so it'll open faster (the desired 3/4s)...
Can I ONLY modify the plastic style? I've never seen one of those before... Can I modify the stock steel type? I've heard this is "harder", can it be done?

Thanks -J

 

Nobody knows? huh, i'm shocked... I thought this was a fairly important common upgrade...

 

I've heard it discussed, but never had to need to try it. From what I recall, it only works if the restricting orifice is at the end of the hose nipple. If the end of the nipple is wide open, the orifice is at the back of the nipple, and inaccessible.

 

hmm, that's what i've heard... I've also heard the only ones to modify are plastic housed ones, but i've never seen one in real life... The opening on mine is quite small, and I think it'd be the restriction, I guess it can't hurt to try drilling it, if it's not the restriction it won't make any difference...

I thought this would be a first modification... doesn't this promote the ability to open the secondary air valve without a 3 second vacuum drop delay? I'm not sure if it's my imagination, but when I kick it down, it seems to start kicking out bigger power after a few second delay.... maybe it's just getting the rpms up high enough...

 

Cam/intake powerband and secondary opening are easy to confuse.

 

I guess this isn't "real life", but at least you can see what it looks like http://www.carburetion.com/pull.asp .

 

I've drilled out the metal ones. You will need some super tiny drill bits from a hobby shop. I think if the hole goes over .025" it is then too big (will have to verify this in my old carb book). The tricky part is drilling through the case of the pulloff inline with the small hole inside, and then sealing it afterwards. I will post some pics of one I modded later tonite.

 

Thanks Lo-tec!
I'm not crystal clear about what you are referring to with drilling the case and inline, perhaps a picture will clear it up for me... Do you thinks its a worthwhile mod?
I have an incredible assortment of drilling abilities at my new job, so I figured this is something I should try....along with many other q-jet drilling modifications recommended by Doug Roe, but that's for another thread...

 

Here is a pic of one I actually cut open to figure out where to drill. The hole that needs to be enlarged is directly behind this one, maybe a 1/4" back. I used a small screw with an o-ring on it to seal the hole when done. I didn't have time to research my q-jet book, but I'm pretty sure over .025" is too much. This one was marked .0225, and I think the one I ended up with that worked the best was .019". You might want to search around, I thought someone sold an adjustable one years ago when I was messing with this.

 

ok, so the gist is to drill in that spot, say .2 (#7) or something large, and then I can see the smaller hole on the inside, or use a tiny drill bit to feel for the hole, then drill into the small inner hole, until the choke pulloff takes around 3/4" second to fully open? I guess I can plug the big hole I drilled, with my finger to test opening speed.. Then plug the big hole with a sheet metal screw and o-ring or other method... perhaps some epoxy and... I dunno, some flat piece of metal....
That sound right?

 

Correct. I just used a short screw with a wide head for the oring to seal. You could just goop the screw once you get it right and aren't going to drill anymore. You can see the small hole inside, just hard to take a pic of it. Be careful drilling it, the bits are easy to break. I used a small hand held pin drill? (manual tool to put the bits in and spin by hand).

 

If that equipment includes something that drills around corners, you can avoid that extra hole entirely...

 

ha! Yes, and the ability to drill with my mind...

I have wire drill sizes.... but no pin vice.... I have no idea how anyone else uses these, and so far I haven't found anyone who has used them before.. and they seem to short...?
I'll pick up a pin vice and give it a try.




on a side note, would it be worth while to drill out my idle mixture screw holes to around .090"? I figured i'll probably need it sooner or later, and it can't hurt since I can just turn in my screws further... right?

 

I'd do it later rather than sooner. Nothing like making modifications for their own sake to screw things up.