Guys, I have a pair of B&M 250s with Holley double pumpers. We opted to use an Enderle linkage kit with the fat roller bearing bell crank that bolts to the blower. I cannot get the linkage to work right and I’m pulling my hair out at this point.

I’ve followed a pretty good article from On All Cylinders and the carbs themselves are setup okay (meaning that there appears to be no binding though it is hard to move the secondaries… I think lubricating the accelerator pump arms will help). As soon as the cable goes on it.!it’s harder to move. I feel like I got the starboard side to be acceptable,!but when I duplicated the same on the port side, I thought I might actually break something.

The cables move freely so they’re fine.

The configuration as it sits has the control cable pulling from the top (10 o’clock position on the bell crank) with the linkage rod pulling down and toward the back of the engine (2 o’clock position on the bell crank). Similar to this picture though the picture shows the bell crank at 11 and 2-ish.



I need as much travel space as possible between the linkage rod and the cable rod otherwise they bind (with the 10 and 2 setup I’ve got about 1/8 inch before they touch, maybe a little less).

The setup in my 242 was similar but used a different bottom bracket. It was smooth and easy to move - this one sucks.

Hardin Marine sells what I’m using:

https://www.hardin-marine.com/p-980-precision-roller-bearing-dual-carburetor-linkage-kit-bmholley-250.aspx

Of course no instructions are available.

Any ideas?

Tom, can you see/feel where it's binding with someone moving the controls? Disconecting 1 carb, how does it feel.

As you know, it's spherical rod ends with multi-angular movements. Are any of the rods ends binding under load?

I found the instructions here:

https://static.summitracing.com/glob...9500531-01.pdf

They operate pretty smoothly until the secondaries are opened, then it’s tight. I think that’s because the pump arms need lube at least on the starboard side. Without the cables attached they seem to be acceptable. Maybe it’s a mechanical advantage thing.

Thanks!

Wish it had some pictures though. I’ll see I can find based on the instructions.

Looked over the instructions and then looked at the setup in the boat. For the most part the assembly is the same as the instructions. I could open up the angle some between the carb bell crank and the linkage pull bell crank but leverage doesn’t seem to be an issue because it seems easy to pull until the secondaries come into play especially on the port side. Like I said, the cables are good. I could try moving the cable bracket down to the lower mounting point to give it some upward angle to pull down to.

Operating the linkage at at the splined rod bell crank works well with no binding; it’s only when the toolset bearing bell crank is added. Frustrating.

When I had a 250 blower I ran twin Holley commander 950 Efi throttle bodies with wide band o2 for great fuel control and of course timing control, plus the throttle bodies could run in line so you don’t need all that hardware, I think if you switch to one of the sniper systems they can run dual throttle bodies, works fantastic, Efi and superchargers are like peanut butter and jelly. Give it a try

Although I have seen some people on this site use the Holley sniper systems, I prefer the systems that use remote ecu, I think the heat and vibration from sitting on top of the motors can’t be good for long term reliability. I still use the commander 950 tbi and it’s almost 20 years old so it’s from Holley actually made their own stuff and their tech help was outstanding. It’s seems now a lot of their stuff not so great in either department. I am going to try aces Efi stuff that has a remote ecu and is very reasonably priced. With Efi and blowers you can get excellent idle control with idle stabilization and fuel control, when I ran carbs I had to run a lot richer to get good idle with the Efi I could lean down a fair amount, plus it liked lots of timing at idle, with the lap top I could increase timing at idle to anything I wanted it liked 18 to 20 degrees, with the timing map you just type it in on your laptop and it doesn’t effect the overall timing. Plus you can pull timing out as you go into boost especially at peak torque and then maybe add some as you go past that, it’s been extremely reliable for me, give it a try.

I believe Tom was asking about linkage binding, not dropping $10K on EFI.

I’ve thought about EFI but the boat needs so many other things right now that EFI would be something way down the list of priorities. Right now I want to go boating and this linkage thing is one of the last things holding me up.

I do agree that there is a lot you can do with EFI to make blowers work well. I might get there one day. Thanks for sharing your experience