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bbogue
10-25-2015, 08:15 AM
My 61 has 66-type spacer under the 4100 freshly rebuilt carburetor. This spacer has the front 2 holes partially connected and has a vacuum connection which I currently use for my vacuum advance which helps cooling by advancing timing at idle. I have Felpro 60059 4-hole gaskets above and below the spacer. I can find no vacuum leaks. I have a low rpm misfire usually noted when cold that now seems also to be present warm as well. The misfire seems to be reduced by turning in the idle mixture screws, to a point. These are currently at 1 1/4 turns. I noticed that the gasket under the carb is slightly abraided in the center, under the balance tube area, making me wonder if the gasket is interfering with whatever these tubes do. When I took the carb off the engine the carb base gasket was noted to be a homemade single hole affair, which makes me wonder if my 4-hole gasket is incorrect. I note with interest that the base gasket for the 1960 Bird with 352 engine appears to be the single hole type and wondered if perhaps my 61 was cobbled from leftover 1960 parts. FWIW, I also noticed recently when I was adjusting float levels that sometimes the front bowl level would be correct, then not. I can find no vacuum leaks but I have fixed several, beginning with a ruptured vacuum advance. The misfire began about the time the vacuum advance ruptured. I plan to replace the spacer with the correct 61 spacer and experiment with a single hole spacer under the carb. I will also replace the carb needles in case I damaged them in setting float levels. Any advice would be appreciated.

YellowRose
10-25-2015, 08:35 AM
Bill, it was a pleasure welcoming you to the Forum! I am not qualified to comment on the problem you are troubleshooting, but we have many terrific techies on here who are. Once they start waking up, they should be commenting on the problem you are having. Thanks for the detailed report on what you are experiencing. That certainly helps. If you have not looked at the Advertisements Forum yet, you will find all the major Tbird parts houses listed there. If you need their free catalogs, you can call them or email them to ask for them. They will come in handy when chasing down parts and costs. We also have a pretty good Technical Resource Library (TRL) which link can always be found under my signature and that of John Pizzi ~ jopizz, and in the TRL forum. There is nothing that I can think of regarding the problem you are having in it though.

jopizz
10-25-2015, 11:02 AM
Bill,

I'm not sure what kind of spacer you have. A '66 spacer only has a small vacuum tube coming out of the front and is very thin. A 64-65 spacer is thicker and has a coolant port in the front and rear passenger side and a vacuum port for a pcv valve in the rear center. Can you email me a picture of your setup. A Fel-Pro 60059 four hole gasket should work fine above the spacer but in order to use the vacuum port in the rear you need a Fel-Pro 13303. However, you should be using the vacuum port in the carburetor for your vacuum advance and not the spacer. If you don't have the vacuum port in the carb plugged off that's probably why you have a misfire.

John

bbogue
10-25-2015, 02:58 PM
Bill,

I'm not sure what kind of spacer you have. A '66 spacer only has a small vacuum tube coming out of the front and is very thin. A 64-65 spacer is thicker and has a coolant port in the front and rear passenger side and a vacuum port for a pcv valve in the rear center. Can you email me a picture of your setup. A Fel-Pro 60059 four hole gasket should work fine above the spacer but in order to use the vacuum port in the rear you need a Fel-Pro 13303. However, you should be using the vacuum port in the carburetor for your vacuum advance and not the spacer. If you don't have the vacuum port in the carb plugged off that's probably why you have a misfire.

John

John, thanks for responding.
The 61 and 66 spacers are identical except for the vacuum tube which I had capped for a while until I learned from the FE engine board about how increased timing by using manifold vacuum vs ported vacuum for vacuum advance helps cooling at idle during hot weather. I tried it and it works. A little controversial but it works for me. This has no impact on my misfire as I have tried it both ways. And, I did cap the vacuum port on the carb when I changed. The 61 and 66 spacers are not heated nor is there a PCV fitting. These are much thinner than the 62-65 spacers. Phenolic vs aluminum, too. They also do not have the recessed area under the carb air balance area like the 62-65 do. There is one other difference between the 61 and 66 spacers. The 66 front 2 holes are connected for about 25% of their circumference. I really don't think my issue is the spacer but I'm going to try a 61 just to be sure. That, and a perimeter gasket vs the cloverleaf type as well. Mike of Mike's carburetors insists that the perimeter gasket is the right one. This would remove a partial obstruction in the air balance area and let the chambers "talk" better. Thanks John. I will post how my experiments go.

Bill

jopizz
10-25-2015, 03:38 PM
Your 4100 carburetor uses manifold vacuum also so it doesn't matter whether you use the spacer or carburetor. The vacuum port on the carburetor is below the throttle plates.

John

bbogue
10-25-2015, 04:01 PM
Bill,

I'm not sure what kind of spacer you have. A '66 spacer only has a small vacuum tube coming out of the front and is very thin. A 64-65 spacer is thicker and has a coolant port in the front and rear passenger side and a vacuum port for a pcv valve in the rear center. Can you email me a picture of your setup. A Fel-Pro 60059 four hole gasket should work fine above the spacer but in order to use the vacuum port in the rear you need a Fel-Pro 13303. However, you should be using the vacuum port in the carburetor for your vacuum advance and not the spacer. If you don't have the vacuum port in the carb plugged off that's probably why you have a misfire.

John

Your 4100 carburetor uses manifold vacuum also so it doesn't matter whether you use the spacer or carburetor. The vacuum port on the carburetor is below the throttle plates.

John

With great respect of your knowledge and experience, what I have read and experienced differs. Maybe there was a change in the 4100 after 61. My 61 shop manual says "At low engine speeds, or at idle, spark advance is not necessary. Because the vacuum passage opening in the carburetor is above the closed throttle plate, there is no vacuum to the diaphragm."

This seems to be confirmed by the difference in timing at idle when I switch from the carb to the spacer for vacuum to the vacuum advance. Timing doesn't change when the carb is the source but advances when the spacer is the source.

Am I mistaken?

Thanks.

Bill

jopizz
10-25-2015, 04:12 PM
If you turn your carburetor upside down and put a wire through the vacuum port you'll see it comes out below the throttle plates. Every 4100 I've worked on has it that way. If yours is different I'd like to see it. I'm not saying you're wrong. I'm just going by my own experience. Every car that I've timed that has a 4100 carburetor I've had to plug the vacuum port.

John

bbogue
10-25-2015, 04:24 PM
I will pass a wire through when I have it off next and post the results.

Thanks for trying to help.

Bill

jopizz
10-25-2015, 06:15 PM
If you find that your carburetor has ported vacuum I would definitely like to know. That would be an oddity I'd like to make note of. Thanks.

John

jopizz
10-26-2015, 12:31 PM
Bill,

I stand corrected. After digging out an old 4100 that I had laying around it appears that the vacuum port is indeed above the throttle plates which is odd because when I changed over to an Edelbrock and had the choice I set it to manifold vacuum because it seemed to me that there was vacuum at idle with the old carb. Maybe the throttle plates just weren't closed all the way. Regardless you are correct about using manifold vacuum. When I set my Edelbrock to ported vacuum the low speed performance seemed terrible. When I changed it to manifold vacuum the car seemed to take off much better.

As to your misfire issue what is the condition of your fuel tank. I've found most misfire problems are due to dirt in the idle passages of the carburetor. If you can make the condition better by adjusting the mixture screws it sounds like it is fuel related. On my '66 I used the standard Fel-Pro four hole gaskets above and below the spacer and it ran fine so I doubt the gaskets or spacer are the problem. Try removing the mixture screws and spray some carb cleaner in the holes. That's worked for me a few times.

John

bbogue
10-26-2015, 02:08 PM
Glad you cleared up the ported vs manifold vacuum question on the 4100. You had me questioning a lot I thought I had learned. Regarding the gas tank, it was new 15 years and less than 10k miles ago, installed by a PO. I replaced all the rubber lines when I got it 2 years ago as well as the fuel filter. I'm still going to replace the carb mounting gaskets and I'll try the carb cleaner in the idle screw holes. Since the first time I noticed the misfire was right after the vacuum advance failed I'm wondering if a bit of the diaphragm may have ended up in the carb. Will do some flushing and blowing while it's off. Thanks for your help.

Bill

jopizz
10-26-2015, 03:43 PM
Bill,

If the car was used regularly a 15 year old tank should be fine. If gas was allowed to sit in it for a long period of time it may have turned to varnish and rust may have started to develop. You might want to pump some gas into a container and check the condition of it. If it's not perfectly clear than you may have debris in the bottom of the tank. There's an access panel in the trunk where you can pull out the sender and look into the tank.

John

bbogue
10-27-2015, 06:24 PM
FWIW...
Noting:
1) The abrasion I have seen in the center of the cloverleaf type gasket where the air balance tubes on the bottom of the carb are located on my 61 with 4100 carb.
2) My 61 came to me with a perimeter gasket under the carb.
3) At least one vendor lists the perimeter type gasket for the 60 TBird with 352 engine which has the same type spacer as the 61.
4) At least one "expert" on another board insists the perimeter gasket is all that is necessary since there is "communication" between chambers (noted by the notches in the barrels on the underside of the 4100 carb).
5) Spacers after 61 are recessed in the center allowing "communication" between barrels.
6) It makes no sense for gaskets to be used without surfaces on both sides to bear on the gaskets. This is particularly weird on the 62 and later spacer with the hot water tube. The cloverleaf gasket in the center is suspended between the air balance chamber above and the recess in the spacer below.

My conclusions are:
1) The gasket between the carb and spacer should be only a perimeter gasket. Similar to Victor Reinz G27104. A cloverleaf type could be used with center removed. I may use a Felpro 1901 because it is thicker than most gaskets and I will remove the center. I may also cut my own from gasket material.
2) The gasket between the spacer and intake can be the perimeter type or cloverleaf type. I will use the cloverleaf type with intact center.
3) The listings by suppliers of the cloverleaf gaskets aren't necessarily wrong, there is just a better solution, for me at least.

Bill

jopizz
10-27-2015, 07:19 PM
Bill,

I've used both the perimeter gasket and the four hole gasket under the carb and I can't honestly say I've noticed any difference. 4100 rebuild kits usually come with one of each type but there's no mention of which one should be used for which application. The Ford Master Parts book only shows the four hole gasket. It doesn't show a perimeter gasket being used for any FE motor. From my experience taking apart original cars a four hole or clover leaf gasket was always used between the spacer and intake. To me a gasket is there to prevent a vacuum leak and nothing more so a thick perimeter gasket under the carburetor should be good enough.

John

bbogue
10-31-2015, 05:53 PM
I removed the carburetor, then the venturis, floats, needles, seats, jets and power valve. I flushed and blew out everything, finding nothing visible. I repaired a warped power valve cover and replaced the needles, seats and cover gasket. I previously trued the bottom of the carburetor. I reinstalled the carb with a new 61-type 4-hole spacer with a 4-hole gasket below and a single-hole gasket above, fabricated from 1/16" gasket material. I adjusted the floats. I was hopeful that the warped power valve cover leaking vacuum was the cause of my misfire but the initial trial run revealed minimal improvement, if any. Still a slight misfire, more noticeable when cold, at low rpms. The automatic choke was hanging up a bit during the trial, so I will address that and run it again.
I expect I will be making one more stab at finding this misfire. When I removed the carb for the initial rebuild a year ago, I noticed the rear throttle plates were stuck closed, no adjustment at all. I am wondering if this might not have been done on purpose, perhaps as a way to minimize vacuum leakage past the secondary shaft. I freed it during the overhaul and adjusted the secondaries but I'm wondering now if I recreated the problem. I may try adjusting the secondaries completely closed. If this works, Santa's gonna bring me a new Holley. If not, same result. I'm about done with this carb.

Bill

jopizz
10-31-2015, 06:06 PM
I've had 4100's that for whatever reason I just can't get to run correctly. That's one of the reasons I usually wind up replacing them with an Edelbrock 1406. It sounds like you've done everything possible. Just about every 4100 I've taken apart has the secondaries frozen shut. I doubt it was done on purpose.

John

Dan Leavens
10-31-2015, 07:07 PM
John I agree with your Edelbrock 1406 choice especially with all the CFM. Have it my 60 and no issues at all.:)

bbogue
10-31-2015, 09:04 PM
You guys seem to like the Edelbrock 1406. How well does it install? Works with the Cruiseomatic throttle and kickdown linkage OK? Need a hardware kit of some sort? Holley literature makes me think their 80457-S is all ready for Fords. Less so the Edelbrock info., more Shuvvy-oriented, my impression. I was leaning toward a Holley. Persuade me otherwise if you feel strongly about the choice. My 390 is only slightly modified...Comp Cams 255DEH (mild) cam, adjustable roller rockers, FPA headers with 2 1/4" dual exhausts and open-type mufflers. Stock intake and heads. My car does not sit for long periods. A weekly run, at least.

Thanks.

Bill

scumdog
10-31-2015, 09:54 PM
You guys seem to like the Edelbrock 1406. How well does it install? Works with the Cruiseomatic throttle and kickdown linkage OK? Need a hardware kit of some sort? Holley literature makes me think their 80457-S is all ready for Fords. Less so the Edelbrock info., more Shuvvy-oriented, my impression. I was leaning toward a Holley. Persuade me otherwise if you feel strongly about the choice. My 390 is only slightly modified...Comp Cams 255DEH (mild) cam, adjustable roller rockers, FPA headers with 2 1/4" dual exhausts and open-type mufflers. Stock intake and heads. My car does not sit for long periods. A weekly run, at least.

Thanks.

Bill

A vacuum secondary 600cfm Holley would really suit your 390, if you wanted
more 'grunt' you could use a 780cfm model.
The 600 would give you all the street drivability you would need and in my experience Holley carbs are pretty compatible with Ford throttle and kick-down mechanisms,I'm considering one myself to keep my '66 mobile while the 4100 is away being overhauled. The two-cents worth of a Kiwi for what it's worth. (About 1.38 U.S. Cents!)

jopizz
10-31-2015, 10:01 PM
You only need to connect the accelerator rod to the 1406 carburetor linkage. Same setup as the 4100. I just had to adjust the rod to make it slightly longer. There's no other hardware needed. I've used both Edelbrocks and Holleys and I prefer the Edelbrock.

John

bbogue
11-01-2015, 12:00 PM
I read a comment somewhere about how the Edelbrock carbs have a rear fuel inlet. How did you guys who switched from 4100's accomodate this? I'm not crazy about a fuel line laying across almost the full length of the intake then making a u-turn to the carb.

Bill

jopizz
11-01-2015, 12:20 PM
The fuel inlet is on the passenger side rear. It depends how much effort you want to put into it. You can connect a short rubber line from the existing metal fuel line into the carburetor input. I make sure it sits a few inches off of the intake. You can also fabricate a new metal line from the fuel pump into the carburetor. That's the way I prefer to do it but I've done it both ways without any issues.

John

bbogue
11-03-2015, 04:54 PM
I was more encouraged today by the engine's performance after repairing the auto choke (wouldn't open very much) and snugging the carb base nuts a bit. Backed her out of the garage with minimal misfire, warmed it a bit, then adjusted the idle mix screws using a tachometer and vacuum gauge. Tach and vacuum gauge both responded to tweaks of the mix screws which seemed best about 2 turns out, each side. Vacuum is up an inch, to 16 now, probably courtesy of the repaired power valve cover. I also set the idle speed to about 700 rpms and checked the timing. I use manifold vacuum for the vacuum advance as it helps cool the engine in hot weather. Initial timing is 16 degrees advanced. The vacuum advance is limited to 10 more degrees so I have 26 at idle. Centrifugal timing is 20 degrees and comes on fully before 2500 rpms. The test run was good, with only a little hesitation to complain about. Power was excellent but I can't say for sure if the secondaries opened. I'll check that on another run sometime. I did not notice any misfire during the run, of course the engine was warm and the issue has always been worse when cold. When I returned from the run, I let her cool for a while (to below 150) then backed her out of the garage and drove back in. Minimal, if any, misfire was noted. I plan to run it a while as is, with a few tweaks of the idle mix screws as I think necessary. Today's run was encouraging enough that I'm not going to rush to replace the carb just yet. At least I am satisfied by the improvements that the misfire issue is fuel/air related. I was becoming concerned of a head gasket leak between cylinders.

Thanks to all for their interest.

Bill

GeoffInCarlsbad
02-06-2016, 12:51 PM
Hi guys:

I am diagnosing my issues similar to Bill's on my 4100. Before I make the investment on a new Edelbrock 1406, I would like to learn how to make all these adjustments per the Ford Manual. I have not had the opportunity to use a tach and vacuum guage. I would like to get this experience.

Is there any documentation on how to use the tach? Or should I just rely on the instructions from a tach I might purchase? Same question for vacuum gauge. I then suppose that I can properly set timing better with the vacuum advance.

All advice appreciated!

~g

jopizz
02-06-2016, 08:24 PM
I would follow the instructions that you get with the tach. Most times you will hook it up to the battery and the coil. You should hook up the vacuum gauge to a port on your intake manifold. Usually I pull off the power brake hose and use that port if there's nothing else available. Here's how I adjust the carburetor. Everyone has their own method.

Attach the tach and the vacuum gauge.
Block the wheels so the car doesn't accidentally start to move.
Warm up the car until the choke is fully open.
Adjust the idle screw on the carburetor so that it reads about 800 in Park on the tach.
It's recommended that you adjust the mixture screws with the air cleaner on, however it's nearly impossible with the stock air cleaner so remove it.
Start with one mixture screw and slowly turn it clockwise until the motor starts to miss and run rough. Then as you are watching the vacuum gauge slowly turn it counter-clockwise. You will see the needle start to rise. When it gets to the point where it isn't moving any higher slowly start to turn it clockwise again. As soon as you see it start to drop turn it counter-clockwise about 1/8 turn. Reset the idle screw so it reads 800 again. Do the same thing to the other mixture screw. If turning the mixture screws have no effect on the vacuum gauge then your carburetor's idle passages are dirty and it will have to be taken apart and cleaned.

As I said everyone has their own method on how to tune a carburetor. This works for me.

John

GeoffInCarlsbad
02-08-2016, 04:46 PM
Thanks John! I will give it a shot this weekend.

I guess my question is around the tach. Is this a simple tachometer like I would mount in the cockpit or is there a meter (like a multi-meter type device)? I am guessing I can just go buy an inexpensive tach and just hook that up as instructions suggest.

jopizz
02-08-2016, 05:01 PM
You can buy just a simple analog tach that's fairly cheap. The one I have is in a multi unit that has a number of other functions. It really doesn't matter which type you use to set your idle speed.

John

GeoffInCarlsbad
02-11-2016, 01:00 AM
Hi John:

Yes, I purchased an inexpensive 3 3/8" tach from O'Reilly, hooked it up to my negative (black) and positive (red) along with a run to the neg on my coil. Worked great. Set the RPM's per the specs in the manual. Tomorrow morning it will be interesting to see if the cold-start rpms with the automatic choke adjustments per spec work.

Nice thing is tonight, after having not started her for several days, she fired right up.

Thanks for the tips! Based upon the condition I got her in, I don't think this Bird has run this well in many, many years.

Thanks for all of your help. This forum is the greatest.

jopizz
02-11-2016, 01:28 PM
Glad to see that you are getting it sorted out. Getting the choke set right can be frustrating. Small adjustments make a big difference.

John

GeoffInCarlsbad
02-11-2016, 02:41 PM
The good news is that she starts right up. But I'm still having some issues with the choke (fast idle cam).

Per the manual, I am setting the screw starting at the "step" but the picture in the figure does not necessary resemble what's on my carb.

When cold, and I hit the gas, I am getting the chronic delay, as if there is an issue with fuel delivery or the sucking of air into the carb somewhere. Last night when she was hot, it seemed fine, but today is another day! I will have to take some time to play with this when I have a few hours....but right now, yep, a little frustrated.

What puzzles me is this: The manual says, let the engine get hot, put the car in D and set the RPM to 450-475. Done. Then, to set the fast idle cam, it says to turn the fast idle screw to attain 1700 rpm at rest. That seems a little counter-intuitive to me, unless I should do that when the engine is cold? Or is there an issue with the automatic choke or the choke plate not set right?

There's always something to do, isn't there?

jopizz
02-11-2016, 03:33 PM
You really need to set the fast idle adjustment when cold. If you move the fast idle cam when it's hot the choke is going to close and it will most likely stall out. You should see a mark on the correct step of the cam. Sometimes it has an arrow and sometimes a circle. Either way it's usually the second step from the top. I would start by having the choke open 1/8" when cold. You can use a 1/8" drill bit. If you get hesitation then close it slightly. Normally hesitation is due to it being opened too much.

John

GeoffInCarlsbad
02-16-2016, 10:57 AM
Hi John:

That makes more sense. Ok, that's this week's learning experience! Thanks again.

~g