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I either have jinxed motor or extremely bad luck trying to run my Perry 550 with a 2100cc engine. I had the 2100 in before with twin 40 webers but it ran ragged, it idled rough and wouldn't smooth out until I hit 3500 rpms. I dropped a couple of big one and some change at the local flat-four shop but it only ran well for a couple of days. I dropped it and put my 1680 back in using the same webers with which it ran like a dream. This time I reinstalled the 2100 with a single 44 weber and it idles better but when I accelerate hard it boggs down, backfires through the exhaust and I can hear the the weber sputtering. I have an electric pump with the fuel pressure guage dialed into 3psi. I have a single pipe quiet muffler installed as I don't want to lose any more hearing. I followed most of the suggestions in my Dellorto tuning book (similar types) except for chaging the jets, on one hand they say increase them and the next time they suggest decreasing them. Since I don't have any spare jets laying around, any suggestions to point me in the right directions? Oh ya, please no crude remarks about my mutant Perry 550, I like it and only wish I could afford to build a Beck or other more exotic model.

1957 Specialty Auto-Sports(Cabriolet)

Loudon, Tennessee

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I either have jinxed motor or extremely bad luck trying to run my Perry 550 with a 2100cc engine. I had the 2100 in before with twin 40 webers but it ran ragged, it idled rough and wouldn't smooth out until I hit 3500 rpms. I dropped a couple of big one and some change at the local flat-four shop but it only ran well for a couple of days. I dropped it and put my 1680 back in using the same webers with which it ran like a dream. This time I reinstalled the 2100 with a single 44 weber and it idles better but when I accelerate hard it boggs down, backfires through the exhaust and I can hear the the weber sputtering. I have an electric pump with the fuel pressure guage dialed into 3psi. I have a single pipe quiet muffler installed as I don't want to lose any more hearing. I followed most of the suggestions in my Dellorto tuning book (similar types) except for chaging the jets, on one hand they say increase them and the next time they suggest decreasing them. Since I don't have any spare jets laying around, any suggestions to point me in the right directions? Oh ya, please no crude remarks about my mutant Perry 550, I like it and only wish I could afford to build a Beck or other more exotic model.
Nolan - I apologize in advance if this is stating the obvious, but in my garage the obvious is often overlooked.

It's been a long time since I had to do any work on engines like this, but I often found that problems like you are having aren't so much one big thing as a number of smaller things combining to cause the symptoms you describe.

In the past, when "carburetor problems" prove to be particularly vexing it has helped me to go all the way back to square one...Gap the plugs, set the timing, adjust the valves, check the distributor cap for cracks, check the distributor shaft for play, make sure the carbs are synced correctly, make sure everything in the fuel system is okay...No leaks, parts moving that shouldn't, etc.

Only then would I focus on jets, etc.

Just my opinion....Good luck.

Joe mentioned the idle jets, but I think it extends further, if the
40's were originally jetted for a smaller engine, then they won't work efficiently on a larger engine. Additionally, the accelerator pumps will need to be re-adjusted for the larger capacity engine. Also, check you distributor and make sure that it isn't hanging up when you accelerate. (remove the backing plate, clean and re-greese the weights, check the springs and make sure that no rust is present)
Hey guys, thanks for the suggestions. However, I ran into a little problem when I tried to put the clamshell back on. The single carb setup is too high and I can't get the engine cover on. Looks like I'm going to have to get another Weber 44 and go with a dual setup. While counting to 10 after struggling with the engine cover it dawned on me that with twin 40s it seemed that at least 20mm worth of fuel and air were going to each cylinder. With a single 44 only 11mm worth was going to each. Could the sputtering on acceleration be trying to tell me I was starving the engine?
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