Someone, please, the equation for determining the diameter of a bellcrank to be used on a Weber 40 setup. Standard 914 accelerator cable length/throw (full close/full open) and standard Weber 40 butterfly. Also, anyone know of a source for such a bellcrank? Hope not to have to farbricate one myself. No lathe so will have to be with an electric drill for turning power. Extremely primitive.

The absolute best bellcrank I've seen is this one from CSP.

It's extremely rugged. Really, really well built. And even uses ball bearings for the rotation. Such a great product and worth every penny.

I have the one Mark pointed out and I like it. It's easy to adjust and will even work if you install it incorrectly...ask me how I know:/

do you have any pics of it installed?

I sure do!

So in this setup, it appears that both rods link to the carbs at the BACK of the carbs. My carbs are absolutly identical, which means the rod attachments are at the front of one carb, the back of the other. My bell crank is homebrew and designed to accommodate this. I have a hunch that it does not pull equally on both carbs. anyone care to comment on the viability of my set up? Don't hate on the general condition of the rest of the engine bay, I have cleaned it up since i took the pic.


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do you think this is a better setup than the hex linkage from cb performance?

I had a type 1, full race 1776 that I used to drag race. I had the hex linkage come off many times due to wheel hop. Always at the pivot points. I've never tried this bell crank but I have made my own in the past. I would lean to the bell crank over the hex.

seams like i had a single 4o idf setup on a center mount type 1 offroad car. the carb i had had the throttle pull on the wrong side. FAT performance had the arm to allow me to put it on the other side of the carb so i could use it. but if your linkage is working well, it might not be worth the change.

reread your post. its not working well. call FAT. if i remember right, the arm is different, so you cant move it front to back. but check to make sure. maybe it was the arm on MY carb that wouldnt work.

Just switch the attachment on one of your carbs so they both attach in the rear ...

Is this what I should be using for my Jenvey's Mr. McMark?

it looks like the parts in the csp link comes with the arms for the carbs so you may not need anything extra

Looks VERY nice!

CSP's web-site says the linkage fits Weber IDFs, but no word on Dellorto DRLAs. I'm thinking that if CB Performance hex linkage fits both, then the CSP should too. Anyone using this on Dell's?

Thanks!

Steve A-

Let me see if I can remember how I did mine. If I recall, the sweep of the IDF's butterfly is 78 degrees. I measured mine. Then I measured the amount of cable taken up by the gas pedal (with the adjuster at about the mid-way point). The circumference of a pulley needed to pull the right amount of cable is the length of the cable throw divided by (78/360). The radius of the bellcrank or in my case, the pulley is the circumference divided by 2*pi.

So if the gas pedal took up 2 inches of cable, then the circumference is 2/(78/360)=9.2 inches. The radius of the pulley=9.2/2*pi=1.47 inches. So the diameter would be 2.94 inches.

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Unequal pulling/pushing is unacceptable. You should be able to adjust your carbs so that they hit WOT at the same time and flow the same volume of air at idle. I'm a fan of home built stuff, but you gotta be 100% accurate with this type of thing or you're engine may not run smoothly or you may be tossing money away in wasted fuel. A carb linkage should have ZERO slop or wobble. It should move both carbs equally, and it should be simple.


100% better. I will NEVER recommend hex linkages again. They are all horrible.


I think so.


It looks like they'll work.

Take a look at the Sidewinder bell crank designed for the Type IV engine. I use this on my Jenvey throttle bodies works perfect. every time all the time Yes I make them and sell them. Check the vendors section.

@mcmark In the example pic you provided it appears the angle of the T-cable comes from the front of the engine rather than the R side like OE?
Did you find its necessary to reroute due to cable length or bracket placement?

Source for the CSP Mark mentioned...

https://www2.cip1.com/ProductDetails.asp?Pr...129%2D941%2D400

out of stock at the moment but they get more all the time.

Yes.

I heard they are no longer being made in the 914 application .
Been searching for a customer for sometime,plenty in the UK but the shipping is mental for me.

I didn't think it was a 914 application, just a Type 4 application. I bought Mark's bracket and took the cable up through the front engine seal. I also lengthened the rods so they would line up with the carbs better.

Type 4 with pancake fan I believe is the application description.

@Tbrown4x4 Thanks Todd that s info I was seeking How did you lengthen as the rods are L+R hand threaded, coupling nuts, weld?

Wow, old thread.

I used the CSP bell crank linkage on my 2056, and it worked great.

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Got it from Pierside Parts in Huntington Beach ... they had the best price ... https://www.piersideparts.net/CSP129941400.html

Coupling nuts and threaded rod with jam nuts. I'm pretty sure ACE hardware had everything. It was only temporary until I could get a left hand tap and make longer stainless rods. That was 2 years ago!

@mikey914 As a side note, I'm testing 914rubber's throttle cable. It needs to be about 4 inches longer to be routed through the tins like OE.

@Tbrown4x4 thanks for this info. So I am clear, this would be about 4 inches longer than stock cable length for OE routing through the tin to connect with CSP linkage? I'm assuming Mark's cable is stock length. Also, this would be 4" longer for both cable and sheath, correct?

Yes, 4 inches overall. That left a nice radius following the stock routing. I haven't reached out to Mark for a while, but I thought he already had a "carb length" cable ready. He was going to send me another to try out, but I think he's changing how the pedal end is swaged onto the cable.

I just thought of something: my car never had the "yellow" fabric cable retainer that goes on the ECM bracket. That could affect total length if someone had that on their car.

Currently out of necessity building one from a chinese copy set up ,has no roller bearings in the bellcrack,and came with cup joints as per carbed VW/Porsche 911.
I have replaced the cup joints with mini CB Performance rose joints and set the geometry and it really works well and its so simple but you need to setup right IMO easier than a crossbar and less parts to wear.
Frankly McMark put me on to this and when you play with them you see why as compared to crossbar ,cheers man.
My CB Performance crossbar is up for sale no question,take it the way you want but bellcrank setup works.
[attachmentid=712046

Speedworks (?) have one but its a front mount that means not on bellhousing bolts,wouldn't work for me with short manifolds,looks like a fine piece however.

IMO any setup @ the flywheel end of the motor is better and the one I showed is that,finished setting up and its not easy but it works great .
Full throttle achieved and no 'tip in issues',hardest part is getting linkages the same length...fine tuning.
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It works very well and The Dellorto's have great throttle return springs so no third spring needed.
Ready for a flaming .