Won't run right - argghh
Burning Brakes
Joined: Jul 2005
Posts: 787
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Originally Posted by DSchaefe
It was the original 6239 Holley - I switched because the Holley was worn out - leaked fuel through the linkage, float continually getting stuck even after a rebuild, etc. It would run good for a week until the float stuck and then it would flood terribly. I had it thoroughly restored (took 6 weeks) so now it should be usable. I have heard they are very difficult to use/tune properly so I have left it off. Also I was going to hold it until I was able to rebuild/restore the whole engine.
Putting it back on involved changing out all of the fuel line to the pump as well. I may try it this weekend.
Putting it back on involved changing out all of the fuel line to the pump as well. I may try it this weekend.
If the carb was original to the motor and an original spec cam is in it or close, the holley should be tuned very well for it.
The float problem isn't some insurmountable problem....either crappy float valves not made by a good company ( holley or maybe quick fuel are good choices IMO) were installed, or the floats were fuel soaked or somehow hanging up. Ive used holleys on daily drivers with almost no hiccups.
Thread Starter
Pro
Joined: Nov 2001
Posts: 534
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From: Cave Creek AZ
I just finished re-installing the old/new Holley and new lines to the fuel pump. The stumble is gone - hooray. It fired right up, I adjusted the idle mix to go a little leaner - still at max vacuum - 17-18, and adjusted the idle speed to +-800. I left the tiiming as-is at 9 initial and 32 with mechanical. Test drove it and got it real warm (had it up to 95 on Pecos Rd - oops did I say that...) and still no stumble. it is still running on but I think that is a malady specific to the MSD - it is known to cause run-on in these old Chevys - need a diode in the voltage regulator line out of the alternator to kill the power to the MSD when the key is off.
The real test will be if this carb maintains it's float levels - prior to the restoration the seconday float would stick high and flood terribly.
Thanks for all of the input - if nothing else I am learning more about this car every day.
I guess I'll store the edelbrock for a backup.
The real test will be if this carb maintains it's float levels - prior to the restoration the seconday float would stick high and flood terribly.
Thanks for all of the input - if nothing else I am learning more about this car every day.
I guess I'll store the edelbrock for a backup.
Burning Brakes
Joined: Jul 2005
Posts: 787
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Oh, BTW.....there is a lot of folks that say these days that every engine needs it's advance all in by 2500-3000
As if one size fits all. Not.
The mechanical advance can enhance the power at mid to upper rpms and compliment the camshaft installed in the engine by bringing up the cylinder pressure AS NEEDED.
If the cam is near stock, it isnt needed much. period. The stock curve from the factory is probably the best curve the engine ever responded to.
At the other end, a cam with 230 degrees or NET duration or more probably could probably stand to have it's mechanical advance all in by AROUND 3000 or in a really light car less rpm than that.....but the car had better have a good bit of gear and never be lugged around in fourth cruising.
So whats the solution? The proper solution is to set the mechanical advance to make the engine produce measurable results, such as improvements in dyno readings or drag times (or maybe one of those G-tech sensors).
But just cranking the mechanical advance up when the motor is basically stock or just blindly doing it is somewhat counterproductive.
As if one size fits all. Not.
The mechanical advance can enhance the power at mid to upper rpms and compliment the camshaft installed in the engine by bringing up the cylinder pressure AS NEEDED.
If the cam is near stock, it isnt needed much. period. The stock curve from the factory is probably the best curve the engine ever responded to.
At the other end, a cam with 230 degrees or NET duration or more probably could probably stand to have it's mechanical advance all in by AROUND 3000 or in a really light car less rpm than that.....but the car had better have a good bit of gear and never be lugged around in fourth cruising.
So whats the solution? The proper solution is to set the mechanical advance to make the engine produce measurable results, such as improvements in dyno readings or drag times (or maybe one of those G-tech sensors).
But just cranking the mechanical advance up when the motor is basically stock or just blindly doing it is somewhat counterproductive.
