riderosa Posted January 13, 2015 Report Share Posted January 13, 2015 I have twin weber carbs on my 76 B210 GTL race car. Is it possible for a car to run well with these two different carbs? I understand that the tops of some weber carbs are interchangeable. Is that true? Quote Link to comment
Doctor510 Posted January 14, 2015 Report Share Posted January 14, 2015 Take the carbs off the manifold and measure the throttle plate, if they are different 38/40, you could probably tune them to be happy together. FYI, the tops will fit a 45 as well. Right now, why do you think they are different? Quote Link to comment
riderosa Posted January 14, 2015 Author Report Share Posted January 14, 2015 Having trouble getting the engine to transition from idle to the main jetting Quote Link to comment
Stoffregen Motorsports Posted January 14, 2015 Report Share Posted January 14, 2015 I wouldn't run two different size carbs especially on a race engine. Have you tried changing out the emulsion tubes? Quote Link to comment
riderosa Posted January 15, 2015 Author Report Share Posted January 15, 2015 The 38DCOE25 was found to be a 40MM Carb with a 38mm carb cover plate. Quote Link to comment
Stoffregen Motorsports Posted January 15, 2015 Report Share Posted January 15, 2015 Good, that's settled, but have you done any tuning other than jet changes? Emulsion tubes? Venturis? Aux venturis? Quote Link to comment
riderosa Posted January 19, 2015 Author Report Share Posted January 19, 2015 No I have done no other tuning. I did notice that the rear two cylinders are low compression with the throttle closed in comparison to the from two. At holding the throttle wide open compression is high and uniform on all cylinders. It is believed that synchronization may be the next issue to address. The back carburetor is closed and not allowing sufficient air into the cylinders. Rich Quote Link to comment
Stoffregen Motorsports Posted January 19, 2015 Report Share Posted January 19, 2015 It may be beneficial to take the carbs and intake off the enigne and have someone look at them, to make sure things are up to spec, before you wast a bunch of time beating your head against the wall, or worse, before you blow up a motor. If they were here in my shop I would start by synching the throttle shafts, checking to make sure they are not twisted, check the throttle linkage and stops and so on before I even tried to run them on the car. Are you using soft mounts? If not, I would recommend them, especially on a race car. And a centerpull linkage. And an air cleaner backing plate to keep the carbs rigid to one another. Quote Link to comment
riderosa Posted January 19, 2015 Author Report Share Posted January 19, 2015 I have planned to do all you have suggested this week including adding the soft mount. I am pretty sure the throttle shafts are not synced based on a compression test I did with the throttle closed. The rear carb is expected to be nearly closed given I can only achieve about 60-70% of the front 2 cylinders. At open throttle that are all nearly the same. By the way, thank you for the information. I appreciate your taking the time; it is a big help to me. 1 Quote Link to comment
Stoffregen Motorsports Posted January 20, 2015 Report Share Posted January 20, 2015 No problem. Good luck. Quote Link to comment
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