bartsscooterservice Posted April 21, 2013 Share #13 Posted April 21, 2013 L28 engine with triple SK/OER carbs, running beautifully last fall.Transplanted the engine into 1970 240z using the same ignition setup.Have not altered timing or carb adjustment. I did adjust the valves but only a couple were out.When I start the engine I have to floor it to keep it going, if I let rpms get under 4000 it dies with back firing through the carbs,new RX7 fuel pump working fine.Help please.Thanks,Chrisback firing through carb, can be running to rich or to leanignition timing offleaking valves ( but not assuming that ) Link to comment Share on other sites More sharing options...
EuroDat Posted April 21, 2013 Share #14 Posted April 21, 2013 I dont know much about SK/OER carbs, but it sounds like a mixture problem.Like Zed Head said, with no load it should get close to red line easy with a little amount of fuel.Thinking out of the box: could it be a blocked mufler? Causing exhaust backpressure. A rag of something that fell down the pipe and now blocking the mufler. Although this would probably let you idle but not rev so high.Chas Link to comment Share on other sites More sharing options...
colinc Posted April 21, 2013 Share #15 Posted April 21, 2013 L28 engine with triple SK/OER carbs, running beautifully last fall.Transplanted the engine into 1970 240z using the same ignition setup.Have not altered timing or carb adjustment. I did adjust the valves but only a couple were out.When I start the engine I have to floor it to keep it going, if I let rpms get under 4000 it dies with back firing through the carbs,new RX7 fuel pump working fine.Help please.Thanks,ChrisChris,You may be able to get some "hands on" help with this by posting on OntarioZcar. I'm sure someone with the required knowledge would be willing to stop by. Can't wait to see the car out! Link to comment Share on other sites More sharing options...
Travel'n Man Posted April 21, 2013 Share #16 Posted April 21, 2013 I would have to assume your triples have a jet set up (much like my Mikuni's).What is that setup? Link to comment Share on other sites More sharing options...
grannyknot Posted April 21, 2013 Author Share #17 Posted April 21, 2013 Well I have tried alot of things today, none of them improved the situation.Checked the muffler for obstruction, none. Took the carbs idle mixture screws back to base setting 3/4 up from the seat, set the static timing at 10*, no difference, tried the timing at 5* 8* 10* 12* 15* 18*, won't run.I re-wired the HEI an alternate way as per Blue's article GM HEI retrofit, no difference. The plugs were fouled with gas at one point so removed them, blew out the cylinders, burned off the plugs.I think I'm going to order a new HEI module & coil and start there.Zed, I can even keep the engine going at full throttle anymore just starts and dies almost immediately.Travel'n Man, idle jets are 60F8, main jets 120 (1.2mm), air jets have no markings,pump jet.40mm Thanks for the help guys, process of elimination.Chris Link to comment Share on other sites More sharing options...
Zed Head Posted April 21, 2013 Share #18 Posted April 21, 2013 I think I'm going to order a new HEI module & coil and start there.ChrisWorth a shot. Your initial wiring mistake with the extra ground might have damaged it. I damaged one when I forgot to put the one and two plug wires back on and started the engine. I turned the engine off immediately but afterward, the engine would only start with starting fluid, even when hot. I think that the module was damaged enough by stray spark or something I don't understand, to where it wouldn't generate a strong spark with the voltage available during starting. It would run just fine, it just wouldn't start. A new module and I was back to normal.Anyway, I almost mentioned it before but your symptoms were different. Who knows. Link to comment Share on other sites More sharing options...
SteveJ Posted April 21, 2013 Share #19 Posted April 21, 2013 If you have an ohmmeter, measure resistance from the positive terminal to the negative terminal and then from the center post to the negative terminal and post the results. Link to comment Share on other sites More sharing options...
grannyknot Posted April 21, 2013 Author Share #20 Posted April 21, 2013 Zed, I hope that's all it is. Link to comment Share on other sites More sharing options...
beermanpete Posted April 21, 2013 Share #21 Posted April 21, 2013 It sounds like you could have way too much fuel. Float level too high, jetting way too rich, etc. Try disabling the fuel pump and run it until the float bowls get low on fuel. If it will idle for a short time before it runs out of fuel it is from too much fuel. Link to comment Share on other sites More sharing options...
madkaw Posted April 21, 2013 Share #22 Posted April 21, 2013 Still like to know if the alternator is putting out voltage Link to comment Share on other sites More sharing options...
grannyknot Posted April 22, 2013 Author Share #23 Posted April 22, 2013 Pete, the float level hasn't been changed since since it ran like a top last fall, fuel pressure is at 3.5. But that is worth a try.Steve, as soon as I can get the engine to run more than couple of secondsI'll know if the alternator is doing it's job.Chris Link to comment Share on other sites More sharing options...
madkaw Posted April 22, 2013 Share #24 Posted April 22, 2013 You can test for exciter voltage with ignition on. Got to have 12 volts at the alternator to make voltage. Maybe your alt swap is not wired correctly Link to comment Share on other sites More sharing options...
Yarb
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now