Carb Problem - Secondaries???

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   Thanks for all the help so far on the restoration of the 1967 Mustang.

I am having what I think is carburator problems.  The boat idles and runs great up to 3,000 rpms.  It does have slow acceleration however.

I think the secondaries are staying closed as while I drive I can push up on the arm back there and the boat has more of a surge.

Right now I have timing set at 6 degrees BTC at 600 rpms (I think this is right based on the manual I have).

This carburator is brand new from PCM (on a 302 engine, Interceptor) (as are plugs, fuel pump, etc.)  I originally put the old choke on as it did not have the wires on it (not sure if those are needed or not).  I was thinking the choke was adjusted wrong and was causing the secondaries to stay close.

I have since put the new choke on but it seems to be running the same.  I have not been able to test under load due to lighting conditions.  Am I missing something else?  Do the wires on the choke have to be hooked up?  Does an improperly working choke cause secondaries to not work properly.  How do I check the choke to make sure it is doing what it is suppose to?

Any help would be great.  I can provide pics if that would be of help.

Brian

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brimeg Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: September-13-2005 Location: United States Status: Offline Points: 33	Post Options Post Reply Quote brimeg Report Post Thanks(0) Quote Reply Topic: Carb Problem - Secondaries??? Posted: September-29-2005 at 11:56pm
	Thanks for all the help so far on the restoration of the 1967 Mustang. I am having what I think is carburator problems. The boat idles and runs great up to 3,000 rpms. It does have slow acceleration however. I think the secondaries are staying closed as while I drive I can push up on the arm back there and the boat has more of a surge. Right now I have timing set at 6 degrees BTC at 600 rpms (I think this is right based on the manual I have). This carburator is brand new from PCM (on a 302 engine, Interceptor) (as are plugs, fuel pump, etc.) I originally put the old choke on as it did not have the wires on it (not sure if those are needed or not). I was thinking the choke was adjusted wrong and was causing the secondaries to stay close. I have since put the new choke on but it seems to be running the same. I have not been able to test under load due to lighting conditions. Am I missing something else? Do the wires on the choke have to be hooked up? Does an improperly working choke cause secondaries to not work properly. How do I check the choke to make sure it is doing what it is suppose to? Any help would be great. I can provide pics if that would be of help. Brian

stang72 Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: July-31-2004 Location: United States Status: Offline Points: 1608	Post Options Post Reply Quote stang72 Report Post Thanks(0) Quote Reply Posted: September-30-2005 at 12:55am
	What kind of carb do you have??? Slow acceleration...could be you need to advance the timing. Do you have floatation under the floors...if so is dry?
	stang Face plants are not that funny when it's you face! The Super Air

brimeg Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: September-13-2005 Location: United States Status: Offline Points: 33	Post Options Post Reply Quote brimeg Report Post Thanks(0) Quote Reply Posted: September-30-2005 at 1:08am
	Holley 4 Barrel. . . floor is dry. If I force the secondaries to open they I do get more acceleration and top RPM's. Although I am still not at 4400 rpms. More like 3500. I am thinking something with the choke limiting fuel flow or something like that. I have no formal knowledge however so I am most likely wrong. Thanks for the help and let me know what other questions I can answer. Brian

stang72 Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: July-31-2004 Location: United States Status: Offline Points: 1608	Post Options Post Reply Quote stang72 Report Post Thanks(0) Quote Reply Posted: September-30-2005 at 1:19am
	OK..Holley! Good! Yes the two wires(neg&pos) need to be hooked up.Heat then travels to the choke spring and as it warms up the spring heats up causing less tention..and your choke plate opens!!! Here's how to ajust it. Loosen the three screws on the choke housing so you can turn the choke right or left...one direction will close the plate, the other opens it.Turn it to where it is lightly closed and has a tad bit of play...tighten screws. try starting it up...if it starts to die push it open a bit by hand (or closed a bit). It will respond to one or the other. make small adustments till you get it!You are contolling the amount of air mixture!When it warms up for a few minutes.. the choke plate will open all the way...then your ready to roll.
	stang Face plants are not that funny when it's you face! The Super Air

brimeg Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: September-13-2005 Location: United States Status: Offline Points: 33	Post Options Post Reply Quote brimeg Report Post Thanks(0) Quote Reply Posted: September-30-2005 at 1:24am
	Stang: Do you think this could cause the problem I am having? Thanks for the help! Brian

stang72 Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: July-31-2004 Location: United States Status: Offline Points: 1608	Post Options Post Reply Quote stang72 Report Post Thanks(0) Quote Reply Posted: September-30-2005 at 1:40am
	If your plate is not all the way open...yes it will cause that type of problem.Your secondaries are vacuum on a newer Holley...if your not getting to a certain point...they won't open. Also..I would think your timing should be advanced more...older engines change over time and the manual specs don't mean that much. You can do the by ear method and come pretty close.Advance your timming to the highest idle speed ( you will hear it rev higher)advance it a bit more until the engine starts to miss... at that point it's too much! head the other way and retard it until engine does not miss ...you should hear slight pinging...continue retarding it to where the pinging is gone...you are close at that point.You can do this on the lake and see if your RPMs are getting 4400+.You will need to adjust the idle back when you advance the timming! Good luck!
	stang Face plants are not that funny when it's you face! The Super Air

79nautique Members Profile Send Private Message Find Members Posts Add to Buddy List Guest	Post Options Post Reply Quote 79nautique Thanks(0) Quote Reply Posted: September-30-2005 at 11:36am
	You diffently have to fix the choke before you do anything else. You might be able to get a new wiring harness from skidim along with a new alt. Take a good look at the connector at the back of the block and make sure they match up, I'm not sure but you maybe able to tap into the coil leads for a pos, neg source for the choke. If not you might be able to remove the electic choke and replace with the older style choke stat that works off of the intake. But you are going to have to get the choke sorted out first before you worry about anything else. I would not run it until then either because you'll fowl the plugs and then you'll be chasing your tail trying to figure out what's wrong.

skyhawkflyer Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February-08-2005 Location: Zimbabwe Status: Offline Points: 275	Post Options Post Reply Quote skyhawkflyer Report Post Thanks(0) Quote Reply Posted: September-30-2005 at 12:05pm
	Stang72 is right on with your fix. Fix the choke first and then go from there. You need a positive and negative wire that's hot any time the key is on for the choke, 14 guage should work well. You should be able to find a hot wire back on the rear of the engine that will work, but it must be a "keyed" wire with the ignition switch. You can look at schematics in the reference section. Worst case, run new wires from under your dash. Now as for the older choke vs the new electrical choke. Go with electric. Go with electric even if it takes you all day to get it wired (but it won't). They are simple to adjust and work for years without trouble, can't say that at all about the older thermostatic chokes. Linkages are a hassle, and the springs corrode quickly making the choke react slowly or hang up. Let us know how it turns out or if you need some more suggestions.

Carb Problem - Secondaries???

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