Tony Posted December 1, 2013 Share Posted December 1, 2013 My Super Sprint engine has been running like a charm until lately. Now it misses/backfires during acceleration towards higher RPMs. Cruising slowly in higher gears, there also seems to be regular subtle missing. Only things that have changed are cold weather (low 30's), running straight Turbo Blue to flush old gas out of the tank before winter storage and some white smoke on start up. Gut feeling says coil is acting up but would appreciate any insights anyone might have. Also wondering if condensation in the distrib cap might be a possibility. Going to check the wiring/connections in a minute and head out for a 40 degree blat....... Thanks, Tony Link to comment Share on other sites More sharing options...
ihckb2 Posted December 1, 2013 Share Posted December 1, 2013 Check for pitting on the inside of the distributor cap posts. My experience is that caps with aluminum colored posts are bad for this. Try to find caps that have brass colored posts. Your rotor should also be brass on the tip. Even if you clean them up and then try to see if it still misses, it will at least eliminate if that is the cause of missfire. Link to comment Share on other sites More sharing options...
Tony Posted December 1, 2013 Author Share Posted December 1, 2013 Cleaned all of the connections, some were greasy, but no improvement. During the test drive, found that it ran well in second gear from 2K up to around 5k when it started missing a bit at the top. In third, missing started much lower and was much more prevalent at the higher rpms. Will look into a new distrib cap and rotor. Still surprised at how it went from running smoothly to missing in two short weeks between two blats..... Any chance that the higher octane fuel might have a bearing? On the previous blat when it was running well, it really went like a rocket. My last three gallons of Turbo blue came from the bottom of the 50gal drum at the supplier. Wondering if moisture might be the culprit. Thanks, Tony Link to comment Share on other sites More sharing options...
TheDingo8MyBaby Posted December 1, 2013 Share Posted December 1, 2013 Check that one of your venturi's hasn't come loose. This is a common problem with 40 DCOE 151's that caterham used on the super sprint. Can you pull off the carb covers to try to determine which cylinder is missing? Link to comment Share on other sites More sharing options...
Tony Posted December 1, 2013 Author Share Posted December 1, 2013 Not sure about that. Can you be more specific as to pulling off the carb covers to determine which cylinder may be missing. The webers are new carbs to me..... I'll pull out Tony Weale's Seven book and read up. Thanks, Tony Link to comment Share on other sites More sharing options...
jlumba81 Posted December 1, 2013 Share Posted December 1, 2013 Also check your electrical grounds. Link to comment Share on other sites More sharing options...
twobone Posted December 2, 2013 Share Posted December 2, 2013 I had the similar experiences with my super sprint last spring. I had put gas stabilizer in the tank over the winter. Perhaps I put to much in? Anyways, until I had run a tank or two thru, she ran like a pig. As a second check, after you have run thru with clean gas, check your float bowl hights. Good luck!! Link to comment Share on other sites More sharing options...
Kitcat Posted December 2, 2013 Share Posted December 2, 2013 I suspect you have a petronix elec distributor, or some variation, not mechanical/vacuum. If not, it's a common upgrade. How new are the ignition wires? That's an easy replacement item that sometimes causes issues. Link to comment Share on other sites More sharing options...
Dave W Posted December 2, 2013 Share Posted December 2, 2013 If the float level is correct and the bowl is clean, next check the fuel filter. Dave W Link to comment Share on other sites More sharing options...
scannon Posted December 2, 2013 Share Posted December 2, 2013 White smoke on start up usually means water is getting into the combustion chambers. Have a look at your plugs in the morning before start up and see if there is moisture on them. Could be you need a new head gasket or have a crack in the head or cylinder wall. Link to comment Share on other sites More sharing options...
Tony Posted December 3, 2013 Author Share Posted December 3, 2013 Thanks for all of these suggestions. I pulled off the air cleaners and found backfire/misfire residue (slightly thick brown fluid) around each carb intake except for cylinder #4. Think I'll pull the plugs soon and get new spark plug wires as well. I do have a mechanical distributor and may take a look at it as well. Any suggestions for finding replacement parts? Are they easily available or need to be ordered through Caterham? Again, thanks much.... Tony Link to comment Share on other sites More sharing options...
TheDingo8MyBaby Posted December 4, 2013 Share Posted December 4, 2013 The white/blue smoke on start up is a symptom of oil leaking past the valve stem seals - a common problem on crossflows and likely not related to your problem. Rather than replacing your plug wires - why not check the resistance first? There's no sense replacing something if it doesn't need replacing Assuming it's a later super sprint, it should have the aldon dizzy which is pretty reliable. Otherwise points and condenser is a good place to start. The pertronix have also been known to go bad. Interesting about the lack of residue on #4 - but this could just be a symptom of your carb turning. I agree with others to check your float bowl height. Also check to make sure your floats aren't cracked. One thing you may want to do is run it for a few seconds at the RPM's it generally misses and then pull the plugs. See if any of them are overly wet. Again - it also may help to pull the carb cleaners off and run the engine at the RPM it generally misses at and listen for the cylinder(s) that are missing. Link to comment Share on other sites More sharing options...
bball7754 Posted December 4, 2013 Share Posted December 4, 2013 I had my Aldon distributor re-curved (as well as other general maintenance), but did not replace the Pertronix ignitor (http://www.pertronix.com/prod/ig/ignitor/default.aspx). After reinstalling, I had a miss, stumbling, and general erratic running. I replaced the ignitor, and all the issues vanished. Steve Link to comment Share on other sites More sharing options...
yellowss7 Posted December 4, 2013 Share Posted December 4, 2013 Hey Steve, :seeya: Have you got your engine back together? Is everything working properly now? Tom Link to comment Share on other sites More sharing options...
bball7754 Posted December 4, 2013 Share Posted December 4, 2013 Tom - It is. He rebuilt the engine, and the only real change was he used a thicker head gasket to lower the CR from 10.5 to 9.9. It ended up producing almost the exact same HP on the dyno. He only charged for parts, but since I needed another set of pistons, it was still not exactly cheap. I also took his advice and for track days have been using a mix of race and regular gas, to get the Octane up to the upper 90's. Seems like the prudent thing to do, and certainly cheaper than another engine rebuild. I've done two trackdays (one a 2 day, the other a 1 day), and no real issues - except for it spitting coolant out into the catch tank. Sound familiar? Think I've solved that also. He had removed the thermostat, so put that back in (new one), and I also think I underfilled the coolant amount. Also replaced the pressure cap. Anyway, since I've made those changes it seems to be fine. Should be good to go for NJMP next June. Steve Link to comment Share on other sites More sharing options...
Tony Posted December 8, 2013 Author Share Posted December 8, 2013 Thanks all for the suggestions. Worked through many to no avail, so I emptied what Turbo blue I could from the tank and refilled with new pump gas. That seemed to make a big difference..... Still can't believe I got a batch of bad Turbo blue.... at $10. gallon. Did learn how to read spark plugs, still learning, but found cyl. #1 was a medium tan, cy. #2 was black & sooty, cyl. # 3 was a light tan and cyl. #4 was grey. Think my Webers need some attention. Going to start collecting parts for a Spring tune up. When I filled up on pump gas, noticed the filler tube? was leaking onto the ground. Aaargh. One more thing to fix before Spring. Trip to the gas station today was sunny and 24 degrees. When the fingers started to work again, I checked the plugs. All part of the fun of owning a Seven and well worth it..... Link to comment Share on other sites More sharing options...
Kitcat Posted December 8, 2013 Share Posted December 8, 2013 Tony: My filer tube leaked too. Just tighten the hose clamps w/screwdriver. Link to comment Share on other sites More sharing options...
ultraslow Posted January 4, 2014 Share Posted January 4, 2014 Check to see if plug leads to dizzy are in correct pews and that rotor is oriented correctly. Both this caught me out. ultraslow Link to comment Share on other sites More sharing options...
ultraslow Posted January 19, 2014 Share Posted January 19, 2014 Breaker points? Could be the dwell , at higher rpm's. Ultraslow Link to comment Share on other sites More sharing options...
Tony Posted January 19, 2014 Author Share Posted January 19, 2014 Just pulled the carbs off for rebuild, opened up the distributor and...... no points. Just the original Caterham electronic ignition set up with rotor that has slotted skirts. Unfortunately, the metal slotted skirts part is loose and needs to be fastened securely back to the rotor disk. Went back through 10 years of blatchat and found that it could be ? epoxied in place. Now trying to determine what approach to use. How to epoxy it in an exactly concentric location so that it won't come loose. They mentioned using Alardite/Aldarite epoxy, but not sure what an alternate might be. Really don't want to replace the distributor at this point....... Anyone else been this route of repair? Thanks all for the many great insights, learning the ropes slowly.... Tony Link to comment Share on other sites More sharing options...
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