Author Topic: 1969 z28  (Read 1535 times)

wisemanz28

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1969 z28
« on: April 18, 2012, 10:13:22 PM »
Over the winter I replaced my heads with a set that was closer to my build date, that being said I had the top end of the motor apart and when I reassembled everything the engine now runs very lean, it burns my eyes terribly. Before I took anything apart the motor ran awesome. I'm stumped any help would be very much appreciated.

67 RS Ragtop

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Re: 1969 z28
« Reply #1 on: April 18, 2012, 10:49:30 PM »
Sounds as if you either missed a vacuum hose connection, or possibly the intake gasket did not properly seal. I would use a spray can of something that would not damage your paint (WD-40 or equivilent) and spray around the gasket mating area, etc., while the engine is idling to see if you can locate the vacuum leak. Also, your ignition timing may be "off", but I assumed you have already checked your base timing, etc.. You can also hook up a vacuum gauge to see what kind of vacuum you pull at idle, but these numbers can vary a lot, depending on what your running for cam, etc.. Do all your spark plugs look the same ? This is just a starting point, but these are a couple of the obvious / possible issues. Not trying to offend, but I don't know your level of mechanical ability - so if you've already been there - just ignore me.

wisemanz28

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Re: 1969 z28
« Reply #2 on: April 18, 2012, 11:31:50 PM »
Thanks 67, I was thinking the intake didn't seal properly when it was bolted on. I used a gasket that I had not used before and wasn't comfortable using it. I sprayed wd around the intake with no change but I might try again with a can of carb cleaner or starting fluid.

wisemanz28

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Re: 1969 z28
« Reply #3 on: April 18, 2012, 11:43:53 PM »
One other thing I need to meantion, I also removed my power booster this winter and sent it to Jerry MacNeish for replating, this was also put back on along with putting the engine back together. Could something be wrong with the booster that could be causing this problem?

tmodel66

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Re: 1969 z28
« Reply #4 on: April 19, 2012, 12:34:53 AM »
Check Valve leaking on the booster?
Daniel  
'69 SS 350/4 speed  Fathom Green--POP

Mike S

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Re: 1969 z28
« Reply #5 on: April 19, 2012, 12:36:32 AM »
One other thing I need to meantion, I also removed my power booster this winter and sent it to Jerry MacNeish for replating, this was also put back on along with putting the engine back together. Could something be wrong with the booster that could be causing this problem?

A quick check would be to use a pair of vice-grips and pinch the vaccum hose closed.

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Restored

srode

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Re: 1969 z28
« Reply #6 on: April 19, 2012, 01:24:14 AM »
Just unplug the hose from the booster and cover the end - see how it runs.  Or shoot some ether around the booster and see if the idle changes.  Starting fluid (not around the distributor) is the best way to find a vacumm leak IMHO.  Short squirts here and there - in a ventilated area.  When you hit the leak it will idle right up or die if it's a monster leak.
Steve - 02D Z11 and a Plain Jane hardtop

JohnZ

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Re: 1969 z28
« Reply #7 on: April 19, 2012, 05:30:59 PM »
I had the top end of the motor apart and when I reassembled everything the engine now runs very lean, it burns my eyes terribly.

If it burns your eyes, it's running way RICH, not lean. Did you re-adjust your idle mixture screws with a vacuum gauge when you put it back together?
'69 Z/28
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L78 steve

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Re: 1969 z28
« Reply #8 on: April 19, 2012, 05:49:29 PM »
Could also be the power valve in the carb. A quick back fire in the intake will take them out. Timing may have been out during start-up.
69 Z/28 Dover White X33,ZL2,PS,M20,Std.int.04C
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C
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