Stromberg 97 Accelerator Pump Rod length

BRENT in 10-uh-C

BRENT in 10-uh-C

Well-known member
I have a customer who had a pair of 97s rebuilt by a well-known supplier for his 4 cylinder Model-A. When we finally installed them and started the engine, the engine will not idle down unless the rods are disconnected from the pump arm. The idle adjustment screws are both backed-off with an air gap. I cannot determine how to adjust it to have it idle down any further. Is there different lengths on these rods? Is there something I need to do or check??

TIA!!
 
Hmmmm . . . can't imagine why the accel pumps are causing it to not idle down . . . unless the rods are somehow holding the throttle plates open. Possibly the wrong length rods? I've never installed Stromberg 48 rods on 97's . . . but that might be the issue.

I would check and see if the throttle plate idle stop-screw is being pulled off of the stop when then the accel pumps are installed. If so, it almost has to be the wrong combination of carb bases and accel pump rods.

Do your carbs have TWO places to install the accel pump rods - one for winter and one closer to the rotational axis?
 
Bored&Stroked said:
Hmmmm . . . can't imagine why the accel pumps are causing it to not idle down . . . unless the rods are somehow holding the throttle plates open. Possibly the wrong length rods? I've never installed Stromberg 48 rods on 97's . . . but that might be the issue.

I would check and see if the throttle plate idle stop-screw is being pulled off of the stop when then the accel pumps are installed. If so, it almost has to be the wrong combination of carb bases and accel pump rods.

Do your carbs have TWO places to install the accel pump rods - one for winter and one closer to the rotational axis?
Click to expand...

Yes, the rods won't let the throttle shaft rotate enough to close the butterflies. When the rods are disconnected from the pump arms, the idle speed is tool slow of RPMs, -so it is the rods that are the issue.

And yes, there is a Summer & Winter ball setting to change that however they are on the same plane so it holds the butterflies in the same position on either ball.

Thanks everyone.
 
nickthebandit said:
It appears to be that you have Stromberg 48 throttle rods installed.
Click to expand...

I agree. Unfortunately this package came from an 'expert' rebuilder who went thru them, so the owner & I were hoping for a little better, but it is what it is, -and Speedway has a package on the way with the correct ones and a few other goodies.

Thank you for everyone that assisted with this!! :cool:
 
Stromberg also sells their own parts on their web site. With the longer rods and the idle RPM screws out you will have to screw them in to increase RPM.
 
Well, I ordered 2 new Pump Rods from Speedway. Now it appears the lengths of these are all over the place. Below are some pix of the two that were on the Carburetor and two new ones straight out of the package. The first two pics show the ones that the rebuilder installed onto the pair of 97s compared to the ones in the unopened package. The last two pix show all 4 linkages standing side by side. Thoughts....??

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I once bought those accelerator rods from Speedway and it kept poping off the ball on the bell crank link.I found that the spring loaded cap did not cover the ball link enough.Had to throw them away.
 
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