Mike
Well-Known Member
With all due respect, starting a shotgun approach to replacing this, replacing that and bolting on a new one of these is only going to accomplish two things - it is going to require a considerable cost, in both time and money. And naught will be learned in the process.
Take the time to be sure things are working as they should, before you start replacing them. And take it one step at a time, so you will be able to keep track of the results you are producing. Make a change and see what happens. If it gets better, you know you're on the right track. If it gets worse, go back to where you were and see if you are repeating the earlier results. The go the opposite direction on your next move. Don't go changing $100 worth of parts, because you might not have any parts problems. Diagnose what is really wrong, and if it is down to a faulty part, then you are only replacing that one part. Does that make sense? OK, then let's get started.
Roll the engine around to TDC on the #1 hole and check the cap/rotor alignment. Get it as close as you can.
And remember, just because you are seeing TDC on the balancer does not mean you are at the firing stroke on #1, so pull the #1 plug and roll the motor over with your thumb over the plug hole, until compression blows your thumb off. I see more people get caught out at that. Seeing TDC on the balancer could mean #1 is about to fire, or it could be #6, so check and be sure.
Now, hook a vacuum gauge up to the engine and light it off. Let the vacuum gauge talk to you. If you cannot understand what it is saying to you, take a look at this thread for some pointers. Start jotting down some notes, so you know what you've tried and what results you saw.
With a weather eye on your vacuum gauge, close that choke blade and see if things smooth out and get better. With it having problems spitting back through the carb, keep your hands away from the top of the carb, so you don't get burned. Read that sentence <--- again, to make sure it sticks. If the gauge shows a better reading and the idle improves, then you know you have a vacuum leak, because you have just choked down what should be the engine's only source of air.
I'm completely unfamiliar with the Summit carb, but it appears they've done naught but stuck their name on an old 4010/4011 Holley design. If that is the case, you've like as not knocked the power valve out, what with the backfires. So you may have a situation where the motor is hunting and seeking, at idle, trying to deal with the additional fuel. Which will make your vacuum level readings all screwy. A quick hint for a blown power valve is a very heavy, raw gasoline smell at the headers. If you are noticing that, you might want to grab a couple of new power valves, so you can get that problem fixed before moving on to the next one. Don't get technical about it, just grab a couple of 6.5 power valves (125-65 Holley) and that way you will have a spare, if it huffs through the carb, again.
And don't go bumping timing up, unless you have already verified it is severely retarded. If it is spitting through the carb, that could be a result of overly advanced timing, as it is, so don't make the problem worse. Unhook your vacuum advance hose and cap the port it was hooked to. And after you get things sorted out, you will want that hose hooked up to timed or 'spark' vacuum, and not manifold vacuum.
If you are going to just start changing parts out for the sake of changing parts, I recommend starting with the left-front turn signal fluid and then swapping the air between the rear tires.
Take the time to be sure things are working as they should, before you start replacing them. And take it one step at a time, so you will be able to keep track of the results you are producing. Make a change and see what happens. If it gets better, you know you're on the right track. If it gets worse, go back to where you were and see if you are repeating the earlier results. The go the opposite direction on your next move. Don't go changing $100 worth of parts, because you might not have any parts problems. Diagnose what is really wrong, and if it is down to a faulty part, then you are only replacing that one part. Does that make sense? OK, then let's get started.
Roll the engine around to TDC on the #1 hole and check the cap/rotor alignment. Get it as close as you can.
And remember, just because you are seeing TDC on the balancer does not mean you are at the firing stroke on #1, so pull the #1 plug and roll the motor over with your thumb over the plug hole, until compression blows your thumb off. I see more people get caught out at that. Seeing TDC on the balancer could mean #1 is about to fire, or it could be #6, so check and be sure.
Now, hook a vacuum gauge up to the engine and light it off. Let the vacuum gauge talk to you. If you cannot understand what it is saying to you, take a look at this thread for some pointers. Start jotting down some notes, so you know what you've tried and what results you saw.
With a weather eye on your vacuum gauge, close that choke blade and see if things smooth out and get better. With it having problems spitting back through the carb, keep your hands away from the top of the carb, so you don't get burned. Read that sentence <--- again, to make sure it sticks. If the gauge shows a better reading and the idle improves, then you know you have a vacuum leak, because you have just choked down what should be the engine's only source of air.
I'm completely unfamiliar with the Summit carb, but it appears they've done naught but stuck their name on an old 4010/4011 Holley design. If that is the case, you've like as not knocked the power valve out, what with the backfires. So you may have a situation where the motor is hunting and seeking, at idle, trying to deal with the additional fuel. Which will make your vacuum level readings all screwy. A quick hint for a blown power valve is a very heavy, raw gasoline smell at the headers. If you are noticing that, you might want to grab a couple of new power valves, so you can get that problem fixed before moving on to the next one. Don't get technical about it, just grab a couple of 6.5 power valves (125-65 Holley) and that way you will have a spare, if it huffs through the carb, again.
And don't go bumping timing up, unless you have already verified it is severely retarded. If it is spitting through the carb, that could be a result of overly advanced timing, as it is, so don't make the problem worse. Unhook your vacuum advance hose and cap the port it was hooked to. And after you get things sorted out, you will want that hose hooked up to timed or 'spark' vacuum, and not manifold vacuum.
If you are going to just start changing parts out for the sake of changing parts, I recommend starting with the left-front turn signal fluid and then swapping the air between the rear tires.
It's nice when it ends up being something simple...though the road there can be pretty rocky, eh? 
