View Full Version : bolt airflow mod

08-04-2006, 05:45 PM
Hello all,

I'm not new to pb gun mods but I am new to Spyder's.

I have done the remove the venturi thing and polished the rough edges on the stock bolt and I have begun filing the inlet on the bolt, removing the square edges and opening the inner portion of the opening, basically making the inside portion larger than the outside part of the inlet.

In the past I performed a bolt efficiency test, using several bolts for the Impulse. The WAS Equalizer bolt performed the best. The main difference is the construction of the inlet of the EQ bolt which is smooth, ramped and larger than the other bolts tested.

Does anyone have any comments on the following-
I'd like to elongate the inlet on a stock spyder bolt slightly. My theory is that as the bolt moves away from the valve it "should" allow some extra air to flow thru the bolt thus increasing efficiency.

Also. Any comments on drilling the threads for the venturi larger for more volume?


08-05-2006, 04:15 AM
yup, you can elongate the entrance hole of the bolt. but you would also need to some how make the transition not a sharp 90* on the inside wall. with the sharp transition, you would/do have turbulance.

the AKA Lightening bolt is made in the way you described, and with a nicer transition. also, there are other bolts that are made in such a way. like the insane pain sports bolt. at this moment, these are the only two aftermarket bolts that i would suggest that are current on the markets. the others i did not mention are not so good.

but back to your question, yes, it will allow for slightly more efficiency. even if you do not lessen the inside transition.

and welcome to the forum!

08-05-2006, 08:30 PM
thanks for the response.

In your article reguarding removing the venturi you state that you do not have to do anything with the threads after removal. Would I be better off filling the threads with jb weld if I don't slope the inlet?

As far as chamfering the tip of the bolt face, is it okay to infringe into the "ball detent relief pocket" =) with the addition of more cup to the face?

The bolt has a step in the milling approx. 1" from the face of the bolt. It's slightly wider twards the tip. Is this normal?

I plan on more internal mods but I'm taking it one step at a time. I've got to say I'm totally impressed with this Victor all things considered.

Thanks alot

08-05-2006, 08:46 PM
im not sure what you mean from the step being wider at the tip, but is it the part where it drops between the front of the bolt, and where the orings are? it it is, it's wider cause the inside of the bolt is drilled out. adding cup to the face will help it be more gentle with balls, it's actually one of the mods mentioned in the bolt mod guide.

08-05-2006, 09:22 PM
On the outer part of the bolt , near the face of the bolt where there's approx 1 1/2" that makes contact with the bore, there's a small step that is hardly measurable but you can see it. It looks like a miiling flaw but it could be to make a tighter fit.

Just wondering if I should polish it out.

If I cup the face of the bolt more than stock, the cup will begin to enter the cutout for the detent. It seems like it would create a very sharp edge.

The bolt is a stock Victor bolt.

08-05-2006, 10:02 PM
well what i did to the face, was i took some sandpaper, and pushed my index finger into the bolt, and twisted it a ton, till it was nice and rounded and very smooth. i now know what you mean by the step. I kept mine when i polished it. i never noticed it, but you can barly feel the step if you rub your fingers on it.

08-06-2006, 03:12 AM
about filling in the threaded hole where the venturi used to be, there really is not a need to fill that in.

08-06-2006, 02:59 PM
just JB weld in a peice of metal and put it in 45*. It'll compensate for that full 90* turn very well. I'v seen a few autococker bolts that way.

08-06-2006, 04:33 PM
For final polishing of the exterior of the bolt I plan on getting a long bolt and threading it into the venturi threads. Then I'll probably clamp a drill and attach the bolt to the drill. Ghetto lathe.

One idea I had to create a slope for the inlet is to set the bolt so the tip is higher than the rear of the bolt and then lay some JB Weld in there. If you can't visualize and have a loose bolt around, hold the bolt with the front higher than the back with the inlet facing up. I'd probably do it in 2 phases. Fisrt fill the threads then build the ramp.

Or maybe I could index the veturi, cut the tip off and rig a ramp on that. Thanks for the idea ooglie.

Befor all of that happens I'll probably just get a delrin bolt.