Raising stall points tav 30 converter

#1
Tryinng to raise the engaugementbrpm of my converter. It screams off the line then hangs a good 3-4 seconds... then accelerates hard again. Do they make weaker springs for driven pulley? Can i drill the weights on the drive pulley?
 
#3
Is that the comet chart?

The problem I'm running into is the China "TAV" units aren't color coded the same and the the drive pulley "weight assy" is different. Than the "real" units. Nice that they have the weights there. I can modify mine some. But without changing the driven pulley spring is it not advisable to lighten up the drive pulley?

The Driven spring is RED as well and it does look similar.

Thank you
 
#5
what combo worked well for you? I ordered the white spring as I did not see the others. 2 tighter springs listed FS anywhere. Also didn't see any alum weight options. I drilled my zinc weight as much as I dared. But it didn't have much effect.

Mine has a RED spring on the driven. Do you want to go down on spring weight with this one?

Basically i'm trying it get it to hang the RPM out much farther before the pulley activates.

thanks
 
#6
also... do 40 series adn 30 series use the same belt? Looks like the 40 series has a bevel on both sides? They have teh 3/4 to 1" shaft adaptors. And teh $31 1" shaft 40 series driver pulleys. Was thinking of adding this to my unit? could I use the same belt?
 

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#8
I used black garter spring and aluminum weights. Red spring on driven. There is an adjustment you can make to the driven (3 holes) to make it open later
 
#9
Worked great with the green springs and adjusting the driven pully as mentioned. But the belt just can't hold the power. I jump way out in front and then get left 200 ft out or so by the quick guys. Was hoping I could adapt the cheap 40 series or 20 series driver and use my driven pulley. The driven pulley has the bevel on both sides.
 
#10
From your description of getting way out at first and then getting beaten up top, I would change the gear ratio between the driven and the rear wheel, sounds like your gear ratio might be too high?
It’s worth a try
 
#11
You want to gear it lower than you would think.
Kinda like how boosted drag cars perform better with lower gear ratios. It’s kinda counter intuitive.
What size is your rear tire?
 
#12
I was on a 64t at first. went to a 75t on a 15" tire. Maxes out around 45 and 6k. if I let it go wide open. We only race to 300ft though. And the taller gear helped me ge tout of the "hole" more quickly. If We kept going past the 300ft. I'd have smoked most of them as it went 53mph then. ALso with the MOD2 cam i feel like i need to rev it more? Shooting myself in the foot with a cam meant for 7k maybe?

thanks!
 

delray

Well-Known Member
#13
I was on a 64t at first. went to a 75t on a 15" tire. Maxes out around 45 and 6k. if I let it go wide open. We only race to 300ft though. And the taller gear helped me ge tout of the "hole" more quickly. If We kept going past the 300ft. I'd have smoked most of them as it went 53mph then. ALso with the MOD2 cam i feel like i need to rev it more? Shooting myself in the foot with a cam meant for 7k maybe?

thanks!
your not running enough gear. I ran a mod 2 cam/with 1.3 rockers last year on a 125ft drags and was pulling 7200 rpm's no problem at all. that is also done with a bunch of other stuff done to the engine to make all this work good.
now on your bike if you want more gear it almost sounds like you would have to go with a jackshaft setup and if so that would not be good in my opinion. why i think it would not be good is now your engine has to turn more stuff and thats hp lost in the drive train. if your running short drags 300ft maybe try running a good clutch with a stall of 3600 and make it pull at least 7000+ at 300ft.
one thing i have notes with a strong engine using a comet driven i tend to make the belt slip on top end(not good) haven't figure that one out yet. with the clutch, it's direct drive when lock up and it wants to push the bike hard down the track when the stall speed is correct and gearing.
 
#15
If I was running 300ft drags, I would get a Polar clutch or similar. I have a Polar setup on my 100ft drag bike.
Jr dragsters race 330ft and turn around 7800rpm at the top end, launch around 4500 rpm on a 8.90 engine.
These units can handle high HP and are much more tunable
 
#16
Think it’s an old harbor freight doodle bug clone? What I was told anyway. HF orange under the black spray paint anyway.

Non-hemi 212, mod2 cam, 160 head, .010HG, flywheel, header, jetted stock carb, wheelie bar, slick with a 75t. 12t on converter. I was worried about PTV with the 1.3 rocker and 160x head, Should I not be? Id like to run 1.3 rockers… actually have a set. Also seems to run better without the muffler. It’s a large scooter muffler 1.5” straight through design. Not sure why it seems to slow it down. Sounds great.

I honestly don’t think it’s a power issue. We are all pretty similar power wise. I believe it’s slipping. If I clean the sheaves well with alcohol it doesn’t slip near as much the first pass or 2. As the day goes on it gets worse. TONS of belt dust. Believe they are only rated for 7hp or so?

I ordered the comet clone 40 series driver pulley and dual sided belt to try. I’m just curious if it will work. I have a ¾ to 1” shaft adapter as pictured above as well. It the belt didn’t slip up top I think I’d be too far out front to catch by 300ft as it sits now. trying to keep it reasonable part wise are the polar units similar to the cheetah?

I have a new cheetah dual disc clutch sitting here. I just feel the torque converter has the advantage off the line assuming it didn’t slip up top. I know you give up some power but for a 300ft race I think it’s worth the extra off the line performance.

Thank you for the interest!
 

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#17
Also have a self-built nitrous kit using a co2 tire filler style “gun” with whipping cream nitrous cartridges. .009 jetting. Unfortunately the pressure is huge initially which usually bogs the engine. As pressure falls it actually works well and picks up about 1-2mph up top, Because it doesn’t do well at low rpm and initial bottle pressure I have pretty much eliminated using it. Need to perfect the pressure issue. Put some kind of regulator on it. Makes for some interesting conversation though!
 
#19
If I was running 300ft drags, I would get a Polar clutch or similar. I have a Polar setup on my 100ft drag bike.
Jr dragsters race 330ft and turn around 7800rpm at the top end, launch around 4500 rpm on a 8.90 engine.
These units can handle high HP and are much more tunable
When I go to the Lucas nationals the jr dragsters run 1/8 mile. Are you sure about 330 ft?
 
#20
Sorry
What I meant to say is that there is an outlaw 330 jr dragster class.
Mostly they run the 1/8 like you said.
I should have been more clear

 
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