After finally getting our car on the road, I’ve been working some of the kinks out. We’re running a flatty with 3 new Stromberg 97’s on straight linkage. After some initial runs with the car I noticed that the rpm’s weren’t dropping off at idle and I was having to pull the spoon pedal back with my foot at stoplights. We’re using the Stromberg Snapback springs. The builder used the springs on the outboard carb only so I added one to the center carb as well. It didn’t seem to help much so I started digging deeper. I could see the center carb wasn’t returning back to the idle screw completely. I pulled it off the car and, after popping the acc. pump rod off, I found there are two rough spots in the pump actuation. The throttle shaft is super smooth. I don’t have a gasket set yet so I’m hesitant to pull the top off yet (have an appointment to get the exhaust pipes squared away in the morning). What should I look for when I do and what could possibly be causing the issue? It’s definitely internal. The motor only has about 20 hours on it. The other two carbs snap back just fine, although one definitely does so with more authority than the other. Sent from my iPhone using The H.A.M.B. mobile app
Are your carbs new 97s or originals? you have to push the acc pumps pretty straight to work them. Pull the top and check the acc bore. Good luck, Gary
These are new 97’s I was just playing with the linkage after swapping the problem child with the forward carb and now for some reason the back carb acc pump is stuck. What the hell?!? I hadn’t even messed with it other than popping the pump rod off of the throttle. The pump was ok but it did have a very small rough spot. Put all the linkage back together on all 3 carbs and it was locked up. Started checking and found the back carb acc pump locked up. Don’t want to force it of course but what the hell would cause that? It was fine and now...$&%#!! Sent from my iPhone using The H.A.M.B. mobile app
I have that same problem right now, Their getting caught on something. Any thoughts on this subject. Thanks Joe
I have two brand new 97's from England. The problem I am having is the accelerator pump sticks. Any ideas what the problem is? Thanks! Rich
I have three 97's from Clive on my roadster and I installed snap back springs on all 3 (heaviest in the center). I still encountered the fast idle issue. I ended up using a Stromberg block pin, in lieu of the ball/spring in the fast idle/choke mechanism on the fore and aft carbs since only the center one is choked. That helped as my blower was sucking the blades open at WOT on the outer carbs. The issue remained however, and I added a return spring to pull the carbs closed. To be specific I found that pulling the center carb closed with the additional spring, dragged the other two closed with it. I think it is more to do with my progressive linkage than the carbs themselves. It works fine now and has for a couple of years. I stretched the spring to ease the throttle pedal tension and it drives with little effort on the loud pedal. I am not crazy about the look of the spring, even though I fancied up the forward bracket, so I am paying attention to your fix. Regardless of the looks, no more 1200 RPM stop lights. I see in this older pic I used 2 springs originally, that was overkill, I now run only the outer (larger) spring.
I was going to say the same thing about the accelerator pump cup being rolled over on its self. They use leather cups like the original and not susceptible to the alcohol like synthetic. They roll over easy on themselves though. That's what the problem sounds like. I finally chamfered the top of the accelerator pump bore to aid in loading the pump to help as you've probably going to have the top on and off to get the power valve right. Good luck...you will like them after you get them set up.
The Jalopy Journal
