Lack of Power after Hard Down Shift

[Oifink65]

I was on the "other" forum with this problem and now I'm looking for a second opinion. Sorry for no intro but I'm John De la Garza(catch65 on CC) and I have a 63 Spyder w/ a 140 I built a year ago. I haven't had a problem until now but It was my fault. I downshifted pretty hard and "loaded the spark plugs" is what I was told. I poured some SeaFoam in the carbs. and worked great for a few miles but then it startes to backfire, it has no power and can barely take off at a red light. I don't think I blow a piston ring or a gasket because it doesn't smoke. Maybe I should replace the plugs and wires but they only have about 500miles. Maybe I have overlooked something?

Any advice is good help, its Sunday so very one is close so I have time to figure it out, thanks in advance

[terribleted]

Start by pulling and inspecting the plugs. A compression test would not be a bad idea while the plugs are out (just in case there is a valve problem or something serious). If the plugs look bad replace them. Wires are unlikely to fail all at once. Look at the ignition and fuel systems next.

[miniman82]

Sounds like a lack of fuel...

[Scott H]

I NEVER underestimate spark plugs as a problem. I have spent many hours chasing stuff that ended up being a fouled or otherwise bad spark plug. Personally I would change all the plugs. It's not that expensive and if its not the plugs, just save them for the next tune up. Then you can move onto more serious and more involved problem solving.

[Oifink65]

I'm gonna buy a compression tester tomorrol because I still don't know whats wrong.

[MonzaDave]

Your term "hard downshift" sounds like you may have over-revved the engine. If so, you may have broken something. Start with a compression test as previously suggested.

[Oifink65]

Strange...I was taking out the new spark plugs and noticed spark plug on cylinde #2 and #4 didn't seem to fire
I'm gonna perform the compression test now but I think its gonna be a ignition problem. I hope because its the cheapest to fix