Perhaps take a reading with a timing light (so you can get back to where you started if you need to) then just mess with it to see what the max vac you can get to is.
james singleton
Well-known member
Thunderguns71, What model single barrel Holley carb do you have; just curious??? Also, I don't believe you mentioned whether you have a Load-A-Matic distributor or not?? I am curious since I have a single barrel (Holley 1940 model) with a Load-A-Matic dist., and I do not have hardly any vacuum pressure @ the dist. at idle. From what Leroy Poll said it sounds like this is normal for this set-up! Those compression #'s look a little low to me; anybody else have comments???
A
Anonymous
Guest
Yes I have the Load-O-Matic dizzy. It's all original so I'm going to assume it has the 1908 Holley. At one point I had no vaccum at the vaccum advance on the carb and now I have 9.5".
Read the stickies at the top of this section about the SCV and Load O's, not getting vacuum at the dizzy is normal for some situations.
Seems like there is a slightly different procedure for setting the timing also but I dont have my book handy at the moment so someone else will have to fill you in on the details.
Those comp numbers are not great but I would think it could still run ok. I suppose with the load o maybe low vacuum could really screws them up? Next thing I would do is fill the cyls with compressed air (many of the comp testers can come apart to hook to a compressor) and at the top of the stroke with both valves closed see where the air is leaking out. You have to be careful how much pressure you use or it will push the piston back down. You listen for where the air comes out. Oil fill means its rings (some leak is normal) Carb means an intake valve issue, tailpipe means exhaust valve. Do it on all 6 and see if there are any big differences. You may have a bad valve on that one cyl that is causing a lot of your problem. Maybe you could get lucky and only have to have the head done. With how easy the motors are to get out of these cars I would yank the whole thing and have a good look at the bottom end before I committed to doing just the head.
Seems like there is a slightly different procedure for setting the timing also but I dont have my book handy at the moment so someone else will have to fill you in on the details.
Those comp numbers are not great but I would think it could still run ok. I suppose with the load o maybe low vacuum could really screws them up? Next thing I would do is fill the cyls with compressed air (many of the comp testers can come apart to hook to a compressor) and at the top of the stroke with both valves closed see where the air is leaking out. You have to be careful how much pressure you use or it will push the piston back down. You listen for where the air comes out. Oil fill means its rings (some leak is normal) Carb means an intake valve issue, tailpipe means exhaust valve. Do it on all 6 and see if there are any big differences. You may have a bad valve on that one cyl that is causing a lot of your problem. Maybe you could get lucky and only have to have the head done. With how easy the motors are to get out of these cars I would yank the whole thing and have a good look at the bottom end before I committed to doing just the head.
A
Anonymous
Guest
The whole drive train will be overhauled when I can get the money up. I don't drive it too much, but I always wondered if I could get it running better for the time being since I never could get it to run with no choke, looks like I opened a can of worms and didn't mean to lol.
james singleton
Well-known member
Is your distributor vacuum line hooked up directly to the intake manifold or does it go to the carb spacer? You said you are getting 9.5 inches of vacuum. Is that @ idle???? I have a Holley 1940 carb with the SCV and it is hooked up to the carb spacer. I recently installed a new vacuum bisquet on my Load-A-Matic distributor and I have no vacuum @ idle and hardly any vacuum even when I rev the engine. I am not trying to steal your post here, just trying to figure out if we have similar problems??? I am not even sure if I should say I have a problem because actually my engine is running quite well and seems to respond well at all speeds. I don't particularly want to change anything with the engine running well; just trying to figure things out!???? Maybe there are others out there that have the Load-A-Matic dist. with a SCV carb and they can tell us what kind of readings, both at idle and higher RPM's, that they are getting!??? Thanks!
A
Anonymous
Guest
Mine goes into the carb. And ues that 9.5" is at idle. Before I messed with mine it ran great at about 1/4 choke, but push the choke in and it would just die instantly. Well while trying to solve that, I found my vacuum advance was bad so I replaced that. Also made sure I had no vaccum leaks. Then I noticed the timing was set to 6* so I advanced it to 10* like is specified for an automatic and put in a rotor clip also, it was missing and making the timing jump around. Done all that and it just runs like crap and since the carb and dizzy seem to work together from what I read, I don't know were to start.
pedal2themetal45
Famous Member
have you adjusted the air/fuel mixture?? on the carb....
A
Anonymous
Guest
I assume your talking about the screw at the base of the carb, if that's the case, I can run it in or take it all the way out and it doesn't have any effect. 
I dont know your carb but in general there shouldnt be any screw that does not do anything. Screws on the base would usually be idle mixture and or the base throttle/idle stop. The idle stop is easy to id because you can see the end of it where it runs into part of the throttle linkage or shaft. If the idle mixture does not do anything there is a problem. If it has to be all the way out to run its usually a sign of a vacuum leak but since you said yours does nothing there are really only 2 options. One is that there is a passage somewhere plugged so there is no idle circuit. To get the thing to run this way you would need to choke it, be dumping fuel because a the bowl is overfull, dumping fuel because of a screwed up accelerator pump, dumping fuel because of a power valve issue, or just have the throttle open far enough to run on the main circuits. The other option is that the throttle is just open far enough to run on the mains. There is a small hole in the venturi that more or less gets blocked by the throttle blade itself when this hole is blocked it makes the idle circuit work. As soon as the throttle is moved far enough to uncover the hole it basically turns off the idle circuit and you are running on the mains. If your carb has a main mixture control those would usually look like the are going into the bowl. I dont know your carb but I have not seen that many post WW2 american cars that had them.
pedal2themetal45
Famous Member
OK yes the screw in the base of the carb is the Idle fuel mixture screw. with it screwed all the way in the motor should die. If this screw does nothing then there is one of a couple things worng...
1- idle Rpm to high and past the idle curcit.. Idle should be 750 rpm in Drive with an auto matic..
2-Idle curcit pluged in the carb.
3- float to high and flooding the carb. (pull the air cleaner off, run the motor then shut it off and look down the carb and see if there is gas still running down it to the carb.. it would show up like smoke in the carb. See if gas is running out the bowl vent (thats the little pipe the stick out into the carb )
4- posability of timming be the prob as well...
With the Idle mixture screw 1 1/2 turns out from lightly seated slow the idle down by turning the idle speed screw to acheve 750 rpm in drive (the screw thats attached to the linkage.) MAYBE THAT THE PROBlume.. I think there may be two idle screws one for the choke or fast idle and one for the curb idle or idle with out the choke maybe there miss adjusted..
Once its running at idle speed 750rpm's turn the mixture screw in or out to acheve the best idle. A LITTLE GOES A LONG WAY WITH THIS SCREW.. the readjust the idle screw to reacheve the 750 rpm curb idle.
timming should be as you say 10* at 750 rpm recheck and set timming...
hope this helps
Tim
1- idle Rpm to high and past the idle curcit.. Idle should be 750 rpm in Drive with an auto matic..
2-Idle curcit pluged in the carb.
3- float to high and flooding the carb. (pull the air cleaner off, run the motor then shut it off and look down the carb and see if there is gas still running down it to the carb.. it would show up like smoke in the carb. See if gas is running out the bowl vent (thats the little pipe the stick out into the carb )
4- posability of timming be the prob as well...
With the Idle mixture screw 1 1/2 turns out from lightly seated slow the idle down by turning the idle speed screw to acheve 750 rpm in drive (the screw thats attached to the linkage.) MAYBE THAT THE PROBlume.. I think there may be two idle screws one for the choke or fast idle and one for the curb idle or idle with out the choke maybe there miss adjusted..
Once its running at idle speed 750rpm's turn the mixture screw in or out to acheve the best idle. A LITTLE GOES A LONG WAY WITH THIS SCREW.. the readjust the idle screw to reacheve the 750 rpm curb idle.
timming should be as you say 10* at 750 rpm recheck and set timming...
hope this helps
Tim
Like pedal2 said, what you need to do is set the idle speed correctly, and go back and check timing (with vac advance disconnected). If you need to re-adjust timing to get it back to 10*, do so - and then check idle speed again.
Once you get it idling at 750 rpm @ 10* timing, you should be in good shape.
Idle Mixture screw should be ~ 1.5 turns out. If it is turned all the way in and car still runs, most likely curb idle is set too high and pullling fuel off the main circuit. This is a common problem. It is possible that your idle circuit is plugged up or you have some other problem that won't allow it to idle @ the right RPM, and whoever messed w/ it before jacked the idle screw up to compensate.
Until you get the idle speed and base timing correct, you will have a hell of a time figuring anything else out.
Once you get it idling at 750 rpm @ 10* timing, you should be in good shape.
Idle Mixture screw should be ~ 1.5 turns out. If it is turned all the way in and car still runs, most likely curb idle is set too high and pullling fuel off the main circuit. This is a common problem. It is possible that your idle circuit is plugged up or you have some other problem that won't allow it to idle @ the right RPM, and whoever messed w/ it before jacked the idle screw up to compensate.
Until you get the idle speed and base timing correct, you will have a hell of a time figuring anything else out.
Do you guys really think that thats the answer ( factory specs ) I see this repeated constantly on this forum , comon guys , a good combo runs what it needs and thats hardley ever STOCK settings !!
I guess if you want your vehical to run stock ( but not to its potential ) stock is fine , me I like more and always will , keep your Falcon 6 running like an old tractor, mine will run better because I know better
But you have to have a baseline.
If it has problems at the stock settings, find and fix them there than start tuning.
If it has problems at the stock settings, find and fix them there than start tuning.
A
Anonymous
Guest
Well I'll see if I can get time this weekend and try all that is suggested. Thanks for all the help so far.
Once Baseline is met more is required ( especially if not stock ) and even then there is always more , if you dont believe me , show up at my home track and I will show you the fast way home , no offense to all here but I am beginning to believe a narrow mind of thinking is prevolent , that or every one here is under 20 years old , Ive tried to help but it seems like no one wants to learn ( or thinks they are more knowledgeable and my lack of time here gives me no creedo ) fine be that as it may , Ive seen that line of thought at other forums. Its the Internet , It really dosent matter to me one way or the other. I try to help , and sometimes I get frustrated at the lack of openness ( TFFN was one ) was hoping here was different . time will tell , Later Faron
But he's nowhere near baseline yet. He's got a major, probably carb issue and apparently some distributor issues as well. It makes no sense whatsoever to try to get a decent tune on something that is seriously out of whack. He needs to get it running properly first then start tweeking.
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