69mach1377

I think this has happened before, all of the sudden the engine runs poorly. I have an electric fuel pump with a filter in front of it and had a second filter in front of the carb, Holly 750 vac. I recently removed the carb filter for more flow on track day and did not reinstall.
Could it be due to small particles in the carb or could I have just filled up with bad gas?
I inspected the needle/seat valves because last time I found stuff was keeping them open and causing flooding, but they were clean. The float level looks good thru the clear sight plugs. Don't want get into it if I don't have to.

me alot fast than u

my 1st question why remove the filter....are you using a mechanicial fuel pump?

dodgestang

Correct me if I am wrong but aren't you supposed to install the filter between the tank and the pump when you are running an electric pump to keep crap from the tank from getting into the mechanism and causing a failure?

How old is your gas tank?

If you are getting stuff all the way up at the carb through the elec pump and the first line of filtering that you would need a second filter at the carb, I would suspect a gummed up fuel pump and low pressure because of it.

69FECoupe

You may have gotten some crap in the primary metering block. It doesn't take much with a Holley. I'd take it apart and blowit out with air.

69mach1377

I think 69FECoupe did the best job of understanding my post, I will check the primary metering block.
Mealotfaster; I found that different fuel filters reduce flow by different amounts and more filters equals less flow. I changed the one before the electric pump to a higher flow version for a 25% increase in flow. I removed the one in front of the carb on track day for even more flow...
Dodgestang; I still have the filter in front of the pump. The fuel tank is original, but have not seen much gunk in the pump pre-filter, so it must be fairly clean. My fuel pressure seems normal at start up, between 7 and 8 psi. I have a guage on the carb line after the carb pre-filter.
http://img.photobucket.com/albums/v6.../enginebay.jpg

69mach1377

Well after going thru the primary block, still rough running. So decided to check valve actuation by removing valve covers and watching the rockers. They were fine so I pulled the push rods and made sure they were straight, they were. So after readjusting the rockers, pulled the carb off pulled it apart. Found some small casting flashing here and there, blew thru all the holes with carb cleaner and reassembled with some new gaskets laying around from last time. Did not do a complete 'rebuild' since it didn't look that bad...
Got tired, so there it sits on the bench for next weekend. I hope thats it...if not, then what? Ignition? It seems to start okay with partial choke, as it warms up and choke relieved is when it starts crapping out. Any other ideas if a cleaned up carb is not the answer?

69mach1377

Weekend update;
Mounted carb but still ran bad, so spent time adjusting the floats. Still ran bad so suspected bad fuel and drained it all. Replaced with some from a different station. Still ran bad...
Ignition system tests on the way. Here is where it could get expensive...

69FECoupe

Do you have or can you borrow another carb that you know is good? Did you try replacing the power valve?

69mach1377

FE,
Thanks for the response, I'm all out of good carbs right now, but was thinking my bro-in-law should have one. During one of the 3 times I had it apart, I removed and inspected the pwr valve which seemed normal. I'm thinking the carb is fine, at least for now.
Sometime this week I hope to run my MSD components thru some tests to eliminate them as a factor. The engine does not run well enough to check for spark from each wire, it bogs down and quits within a minute. I'm thinking the coil is going out, but will go thru MSDs process of elimination...they have a forum also.

Soaring

When checking for problems, first is ignition, then fuel. You should always start with ignition checks first. Since you have an MSD, I would start there. Then the coil. My 2c.
Now give me 98 cents in change.