Eric at HKE, help!
09-03-2012, 11:19 PM
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Eric at HKE, help! I am pretty familiar with the ls engine family and have built quite a few but I have never seen one do this. The car is mine and here is the build:
2000 Z-28
383 stroker eagle crank and eagle h beams, wiseco -8cc pistons
243 heads p&p'd milled 52 thou, 2.02/1.575 Manley valves .650 springs
Comp cam Xr281hr, Vic jr intake, Holley 950 4150 street hp 50cc acc.pumps rear jet extensions notched float, pv plugs, 37 squirters, 84 jets all four corners, 1:1 linkage,1-3/4 headers open collectors, 6010 box initial timing 28 total 32 starting at 2000 rpm. Ngk tr6 plugs at .035 gap, th400 trans no brake, 4.10 gears, tci street fighter stall for th400 trans. Fuel cell all an fittings up to carb stays at 6.5 lbs no return line, this car has gone 12.11@114 @ 3320 lbs.
Heres the problem car will not stop popping in first gear no matter what I try with timing or fueling, thought it might be a vacuum leak changed all gaskets still pops only in first gear, ran a comp test had 180 psi in all cylinders but 1 it had 165psi but did not leak down so I don't think it's a problem but that's what I am working with any help from any one will be greatly appreciated this engine only has this season on it. I do not want to kill this thing it is this cars 4th engine!
2000 Z-28
383 stroker eagle crank and eagle h beams, wiseco -8cc pistons
243 heads p&p'd milled 52 thou, 2.02/1.575 Manley valves .650 springs
Comp cam Xr281hr, Vic jr intake, Holley 950 4150 street hp 50cc acc.pumps rear jet extensions notched float, pv plugs, 37 squirters, 84 jets all four corners, 1:1 linkage,1-3/4 headers open collectors, 6010 box initial timing 28 total 32 starting at 2000 rpm. Ngk tr6 plugs at .035 gap, th400 trans no brake, 4.10 gears, tci street fighter stall for th400 trans. Fuel cell all an fittings up to carb stays at 6.5 lbs no return line, this car has gone 12.11@114 @ 3320 lbs.
Heres the problem car will not stop popping in first gear no matter what I try with timing or fueling, thought it might be a vacuum leak changed all gaskets still pops only in first gear, ran a comp test had 180 psi in all cylinders but 1 it had 165psi but did not leak down so I don't think it's a problem but that's what I am working with any help from any one will be greatly appreciated this engine only has this season on it. I do not want to kill this thing it is this cars 4th engine!
09-04-2012, 10:01 AM
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Stall speed is 3000-3400 according to TCI, the most it stalls with a hot tire is 2800rpm, i do have a wide band in the car, with the 84 jets its pulling 12.3 in 2nd and 3rd gear. i know it can be leaned out more but i wont until i can get it to stop popping. first gear it pulls 11.3 on launch then starts the popping so i dont know exactly what its doing there, but with the pop i would think its lean? by the way the pop is before the 60ft. i switched my 6ls box out this weekend back to the edelbrock box and it was way worse so that has to eliminate the msd box i think.
09-04-2012, 10:26 AM
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tell me about it, i built this thing to go fast on motor then hit the bottle but it just doesnt want to go! its popping out of the carb. so you would think its ignition timing but i have tried everything from 18-36 initial to 22-40 total and it likes 30 initial to 35 total but still pops so i put 28 initial and 32 total and it runs like crap (8.70 1/8th mile popping all gears) but it has gone 7.79 popping in first only with the 30 int.-35 total. so i dont get it?
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09-04-2012, 01:27 PM
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tell me about it, i built this thing to go fast on motor then hit the bottle but it just doesnt want to go! its popping out of the carb. so you would think its ignition timing but i have tried everything from 18-36 initial to 22-40 total and it likes 30 initial to 35 total but still pops so i put 28 initial and 32 total and it runs like crap (8.70 1/8th mile popping all gears) but it has gone 7.79 popping in first only with the 30 int.-35 total. so i dont get it?
From a mechanical standpoint it is sticky intake valve/guide, bent valve, damaged valve seat, improper valve timing or blown head gasket.
First thing I would do is replace the needle and seat valves on the carb and reset the float levels. Then the rest of the process of elimnations.
09-04-2012, 02:01 PM
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That makes a lil sense because when i adjust the idle mixture screws the rear passenger side makes no difference unless i open it all the way up and no difference all the way closed. Just thinking out loud here but i was told the front barrels controlled out of the hole and back barrels controlled rest of run? If that is so then why would the rear passenger make a difference in run before the 60ft.? Unless its going lean out of that barrel? And now that i am thinking about it the cylinder with 165psi is on that side in fact its #6.I am no carb man, i can do LS and fuel injection all day but this carb crap is heavy.
09-04-2012, 02:25 PM
#11
That makes a lil sense because when i adjust the idle mixture screws the rear passenger side makes no difference unless i open it all the way up and no difference all the way closed. Just thinking out loud here but i was told the front barrels controlled out of the hole and back barrels controlled rest of run? If that is so then why would the rear passenger make a difference in run before the 60ft.? Unless its going lean out of that barrel? And now that i am thinking about it the cylinder with 165psi is on that side in fact its #6.I am no carb man, i can do LS and fuel injection all day but this carb crap is heavy.
However, the fact that the screw makes no difference definitely indicates some type of problem.
09-04-2012, 02:46 PM
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first thing do a leak down,its either one of three things as mentioned.1 a very lean condition .2.some thing valve train related,broken or weak exhaust spring will push the charge back through the intake.a worn camshaft lobe will do the same.3 some thing with the ign controller is off.eliminate the valtrain by doing a leak down test along with compression.also check your valve springs and rockers.i have seen pushrods cause this as well.take a vacuum reading ,should be steady at least ,im not sure what a low reading is for this cam but should be at least 12" or more no vibrations.
09-04-2012, 02:48 PM
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one more thing ,i had a holley once that sucked in pvc tape from a fitting,do not use this stuff ,gasoline degrades it and it will get in a jet.use the paste instead.does it pop in nuetral while free reving the engine?if so watch the vacuum gauge, if its starts bouncing you have a valve train problem.
09-04-2012, 02:55 PM
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plug gap seems tight for na and this ignition.off the spray ,i would say 40- 45.does it pop at initial launch?some times too much fuel on the transition will make them pop.you have a video?
09-04-2012, 03:00 PM
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nope no pop in nuetral, revs perfect and real fast. pulled valve covers and spun engine over no broke spring that i can see, but ill pull them any way just to be sure.