wrist pins

broken wrist pin or piston pin hole
brad 5 4.467x4.250
6300 2step lean out @6.8 gallon on 2 step
20% over superman 42lbs at 9400rpm
i had tapered wrist pins 1.094 and the ends are broken off
and it pulled #1 piston apart then #2 rod broke
what wrist pins should i be using ,how much do they weigh,
and were should i buy them
i dont want this again

thanks
duane rister
618-781-4703

 

If you haven't done so already, get the system flowed & set up by a good fuel system guy. The damage was likely not the fault of the wrist pin, more likely you had serious detonation. The Superman blowers keep putting out air, my opinion is that you don't have to lean it out, in fact you need to be putting more fuel in.

 

everyone has an opinion....so here's mine....more fuel....throw 2 step in nearest trash can. bottom line....when it starts "2 steppin" you are going to break stuff....especially with a blower. i know...this guy runs one and so does that other guy. we all fall into that trap....i would dump it. just my 2 cents
Darren

 

fuel system has been flowed and 2 step helps
me drive
wrist pin is 3.250 long and aprox .225 thick with
tapered ends 1.094 4.467 bore x 4.250 stroke
what size should i be running
taper
no taper
seems thin to me
thanks
duane rister

 

I just went through the wrist pin sizing thing not long ago. After all the smoke cleared, the best pins to use were straight wall and around .250" wall no less. I made about 20 phone calls to various rod/piston/pin builders and this was the configuration they suggested more times than not.

Hope this helps
Corey

 

When I used to work at JE, I told everybody the same thing. Taper wall pins have no use in a blown motor. If they weren't bent, you had to beat the hell out of them to get them out because the ends were egg shaped. I proved it all too many times. We used to blow up all the time, but the pins would slide out like butter. I used to buy H13, .250" straight wall from Stetson. I think he got them from Hoffman.

 

2 step

Darren, I am not being a smart ass but, Carl Speiring did my fuel system, and he told me to run one, leave around 3500 . It is a DMPE Kebelco with converter., If I didn't think he was real good, I wouldn't of driven to Canada twice. Just another thought. Don

 

I agree whole heartedly with no taper wrist pins on a blower motor.

As far as the two step goes there is another middle ground, particularly with a converter (of course since you are leaving at 6500 this does not apply to your stuff). Thats to run an air throttle and if you want to leave at 3500 and that requires a blade opening of 15% go ahead and set it to 25% and use the 2 step to hold it at exactly 3500. This will give you several advantages, one as the air changes the engine will be the same speed, two the throttle will be at a point where you pickup RPM instantly as it comes off the two step as well as less time to reach wide open throttle, three it will be a lot easier on the engine than banging away at WOT. I wanted to try this on the last car I tuned but the elder crew chief keboshed it

So many things to try so few people with cars to experiment on

 

This is exactly how we run or throttle. I'm glad to see someone else with this idea. We are using the 8973 box to set or limit to 3500 and adjust the air throttle just beyond that. It works great.

 

Hey Duane
I had the tapered pins in my motor at ZMAX and bent 2 of them. I have since replaced them with straight wall and have not had anymore problems.
I don't like the WOT 2 step. You ought to try the air throttle. Once we got it figured out, it really works good and you don't have to dump all that fuel when you're on the 2 step.
Kenny Keller

 

Same box 8973 on the car I wrenched. If you have a powerglide with a probrake did you figure out how to have your air throttle deactivated while backing up? If not and the airthrottle is activated while backing up and there is any kind of malfunction it could be ugly if the throttle snaps open . When we bought the air throttle the help desk at Dedenbear was no help at all, they told the car owner how to wire it and the way they described it would be activated while the car was backing up

If you are using that setup and need a system to activate it only when the car is on the brake send me a pm with your e-mail address and I can send you a PDF with instructions and a crude drawing.


Richard Gavle

 

We run a Lenco Drive. no affect on the throttle.

 

I was thinking of running an air throttle, but I have heard some horror stories of people basically getting run down if the solenoid fails. I would imagine if the solenoid fails, it should fail safe? Has anybody heard of any issues using this setup?

Corey

 

Hello Comax Racing,

This is exactly what I was referring to the possibility of occuring. The way some people have them connected (and this is the way some of the cylinder manufacturers are instructing that they be installed) they are used to either open the throttle with air (dangerous as hell) or they are installed so that when they are activated the air cylinder is retracted (as it should be) anytime the transbrake is applied, also dangerous as hell since you back up a glide equipped car by activating the brake when the car is in reverse.

The way the system should be used is that when the system is not in use the throttle acts normally, only when the system is in use (car in 1st transbrake on) does the air cylinder retract (whatever amount you have preset the cylinder) so that when the throttle is matted the injector blades only open a preset amount and when the transbrake is released the air cylinder is deactivated and the internal spring in the air throttle extends opening the injector blade fully.

Anyone who wants the diagram to wire there car this way can contact me by PM and I can send a PDF with instructions and diagram to configure.


Richard Gavle

 

My air throttle has air on it at all times acking like a regular throttle.When the trans brake is applied, it dumps the air from the cylinder. The thorttle opening is adjusted with washers to determine your starting line rpm.
I don't see how this could be dangerous. If the solenoid failed, the motor would go to WOT with the trans brake on and that could tear up some stuff. The only time it is activated is in low gear with the trans brake on.
This is the only system I've seen or used and I really like it.

 

Ours is installed the exact same way as Kenny Keller....and a Lencodrive trans.....we have a switch on the steering wheel that Sean activates just before staging....so the throttle air cylinder is fully extended (we have setup as a pusher) and acts as a regular cable until the driver flips the switch..and for safety measures he only activates the throttle controller a few feet from the beams...we also use 1/4" AN washers to set the staging RPM....so that we do not disturb the WOT stop under the pedal....the throttle is fully functional during the startup - burnout - backup - etc....just turned on for staging only....hope this helps...

 

Mine is installed and used exactly like Scott's. I never activate the switch until I am just ready to enter the beams for my run. This also switches my rev limit chip from the burnout chip to the run chip.