hi guys, this is a bit of a fuzzy question, but i've just driven my series 1 for the first time with its newly installed 13b engine, and i've come across a bit of a misfire

it'll usually drive fine for the first minute or two. then once it gets a bit of load on it, it'll start missing. that definitely seems to be the common factor, i could barely make it up a longish hill. after that the power comes off and on.

i used the coils, plugs, leads and distributor from my previous engine (which was also starting to exhibit a misfire late in its life), so they are my first suspects.

everything LOOKS ok, what would be my next step, short of "throw your wallet at it and replace everything"? i know it's an intermittent problem and so hard to diagnose, but are there any typical faults these cars have? am i barking up the wrong tree, and could it be a carb problem? would love to hear some input, cheers

 

when was the last tuneup?
what carburetor?
have you confirmed the correct timing?

 

I noticed on my car which has older wires, there was arcing from the coil output to the coil signal input when the engine was revved up, and that caused a misfire. I put dielectric grease on it until I get off my lazy butt and buy some new wires for it.

 

DerrickS: by wires, do you mean the plug leads?

diabolical1: i don't know the history of the engine, so not sure about tuneup. has a nikki 4 barrel, new needles. i've checked the float levels and theyre good. fuel right in the middle of the glass

i set the timing when i installed the distributor, but havent gone over it with a timing light (which i actually own - thanks for reminding me), but if the timing is out, wouldnt it run like crap all the time?

thanks for the replies guys

 

A bad coil can cause a high speed miss. Maybe check your coils or swap them out with another set from a friends car and see if the problem goes away. Just an idea. Ignitor problem? plugged fuel filter? clogged jet in your carb? could be lots of things.

 

I bet you you have a blockage. Take your fuel line off and into a bucket look at the flow. The take the return off and look at the flow. Mine was doing the exact same thing and it turned out to be my mesh screens. I went ahead and took off the airhorn and blew out the jets with a compressor while on the carb and off the carb. Mine would start out ok until I tried to bog the engine. To add my fuel flow was fine out of the filter but my return trickled it was sad.

 

pulled out the fuel filter and it looked about 30 years old and was full of crap, so i've hopefully found the problem there. will take it for a drive tomorrow and find out for sure

thanks for the help guys

 

see? don't stop there, just go ahead and complete a full tuneup on the thing. more often than not, you end up beating your head over the simple things. i have been guilty of this in the past as well.