Ladeef Posted September 5, 2014 Report Share Posted September 5, 2014 I've been trying to tackle an exhaust leak between the header and the collector. I went out driving yesterday and had some weird behavior. Any throttle input past %50 would stutter and spit, and I couldn't rev past 3k. Changing gears helped and lower rpm seemed to work better. Could this be the result of the carbs sucking in the burnt exhaust gases? or something different. The problem seemed to happen randomly, I had been driving with the exhaust leak for a few weeks and top end performance was a little iffy, but never this bad. Quote Link to comment
datzenmike Posted September 5, 2014 Report Share Posted September 5, 2014 Exhaust leak is unrelated to your problem. What makes you think there is an exhaust leak??? Quote Link to comment
Ladeef Posted September 6, 2014 Author Report Share Posted September 6, 2014 Heavy exhaust smell in the cabin and when I reach my hand down by the collector, exhaust is shooting out of there pretty hard :) Quote Link to comment
datzenmike Posted September 6, 2014 Report Share Posted September 6, 2014 I bet you have one of those little blue filters on the valve cover breather... right? Put a new collector gasket on and use stainless steel bolts, nuts and lock washers. Quote Link to comment
banzai510(hainz) Posted September 6, 2014 Report Share Posted September 6, 2014 maybe the exhaust leak is causeing soem lose of power. But I say maybe . I think more like timming is out,or you have a point distributor and your condensor or dizzy bushing is worn out cause a issue. point bouce will cause a back fire cut out.. fuel filter plugged(get new one and cut old one up and see how much rust in there) or main jet partial plugged. Or you put a extra HOT coil in there and finally the points are arching(add another ballast resisitor. just last week my 521 was having a gas smell leaking right on exhause manifold. Found out the accel pump diaphrame had a hole. Now truck runs 50% better Quote Link to comment
Ladeef Posted September 7, 2014 Author Report Share Posted September 7, 2014 Just an update, I patched up the exhaust leak, and it runs WAY better, no more stumbling and it idles smooth, even takes full throttle inputs well. Still has a problem hot starting, but it levels out. Now the idle is at about 1500rpm which is a bit high for me. I searched the Chilton manual for idle adjustment on the SU Hitachis but didn't locate the idle screws. Any help? THanks! Quote Link to comment
datzenmike Posted September 8, 2014 Report Share Posted September 8, 2014 Any exhaust leak wouldn't have caused this. If you changed the exhaust gasket on the side of the head you also fixed a leaking intake gasket and this did the trick. 510s didn't come with SUs in N America so there will be no manual with that info. The early 240z had similar SUs and so did the Roadster before that. Some adjustments could be found there. The biggest thing is getting the two carbs sync'd so one isn't doing more work than the other. The go to guy for this is probably Sealik http://community.ratsun.net/user/2344-sealik/ Quote Link to comment
Ladeef Posted September 8, 2014 Author Report Share Posted September 8, 2014 Thanks for the replies, I found the "throttle stop screw" which is essentially the idle screws from what I gather. Quote Link to comment
datzenmike Posted September 9, 2014 Report Share Posted September 9, 2014 There is the idle speed and the idle mixture screws. Turn the mixture in until the idle begins to drop then turn the other way. It may even raise the idle speed. Keep going until the idle drops. Go back and forth and stop roughly in the middle where the idle is fastest and smoothest. Turn the idle speed down. Start over, finding the smoothest fastest idle position, then turn the idle speed down. Keep doing this back and forth until you cannot improve the idle quality and the idle speed is 750-850 ish. Your idle mixture is set. The idle mixture setting has no effect on any running above idle. Best if the valves and the timing are set properly first before adjusting the mixture. Quote Link to comment
blackwolf Posted September 15, 2014 Report Share Posted September 15, 2014 hey i have a similar issue my collector seem to be cracked on the engine side pretty bad form the sound of it anyone know where i can get a new or good used one or would it be easier to just make one i have a '84 z24 720 btw Quote Link to comment
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