ConcoursMustang Forums
1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1964 1/2 - 1965 => Topic started by: markb0729 on January 17, 2017, 01:21:24 PM
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I've been trying to track down an engine miss that starts to occur at 1200 RPM and above. I've worked out a few issues with the ignition system and think that it's in good working order. I've already looked for external vacuum leaks around the carburetor and intake manifold and found none. I'm using FelPro 60059 gaskets for the carb to spacer and spacer to manifold connections. I took a second look at this gasket and it does not seem right. It looks like there will be a lot of leakage around the bores of the carburetor and it barely covers covers the perimeter base of the carburetor. Is this what the stock factory gaskets look like? I would think the gasket should seal around the carburetor bores? Does anybody make an exact duplicate of the factory gasket? Worse case I could make my own but i'd like to know what the original gasket looked like.
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Wow - not even close - yes the gasket should cover up to the inner edge of each those "bores"
If you can't find the one you need. They are out there just have to find the source and a good number
If you need to you could use that gasket as a pattern for the outer shape then transfer the four cutouts to the pattern. If you go this route always make 3 or 4 while your at it.
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Hi there,
I had a very good experience with gaskets sourced at Mike's Carburetor Parts. He also stocks nice brass floats too. I can't vouch for the bottom gasket. I purchased a float bowl gasket from them and some brass floats and was very happy with the results.
Gaskets - http://www.carburetor-parts.com/Autolite-4100-Gaskets_c_588.html
All his Autolite carb parts - http://www.carburetor-parts.com/search.asp?keyword=autolite&search=search
Ron
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I reused the old carburetor to spacer gasket when I rebuilt the 4100 on my 65 GT last year. The one in the kit just didn't "look" right. Everything else in the kit was OK though.
Jim
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Hi there,
I had a very good experience with gaskets sourced at Mike's Carburetor Parts. He also stocks nice brass floats too. I can't vouch for the bottom gasket. I purchased a float bowl gasket from them and some brass floats and was very happy with the results.
Gaskets - http://www.carburetor-parts.com/Autolite-4100-Gaskets_c_588.html
All his Autolite carb parts - http://www.carburetor-parts.com/search.asp?keyword=autolite&search=search
Ron
Thanks Ron. I clicked on the link for the carburetor gasket and was surprised to see that the website was recommending the use of the square bore gasket over the gasket with the 4 holes (See pic from website below). I've read that people use the square gasket with aftermarket intake manifolds but my intake manifold is a stock cast iron 4 barrel Ford intake. The description of the gasket from the Mike's Carburetor Parts website states...
"Autolite 4100, 4 barrel flange gasket. Fits all 4100 series carburetors. Some of the old gaskets had individual holes for each bore. These are the replacement and open style."
Their is no mention of stock vs aftermarket intakes. Does anybody know if this type of gasket be used along with a stock intake manifold and spacer? Does anybody have any experiences using 2 square carburetor mounting gaskets in a stock application?
I reused the old carburetor to spacer gasket when I rebuilt the 4100 on my 65 GT last year. The one in the kit just didn't "look" right. Everything else in the kit was OK though.
Jim
Was the kit from Mike's Carburetor Parts or another vendor?
I'm surprised no one knows of a vendor that sells the correct fitting carburetor mounting gasket. You would think there would be more complaints of poorly running engines.
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Hello Mark.....I've read your story on the VMF about your problem. I have more or less the same issue: a slight miss at idle up to about 2000 rpm. Tried and checked everything. Vacuum leaks, compression, timing, points instead of pertronix, coil, other 4100 carb AND gaskets!
I've cut my own from 1 mm thick gasket material but this had no effect at all!
(http://i1304.photobucket.com/albums/s522/Dakloos1963/P1050026_zpsxez1ndbm.jpg)
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Was the kit from Mike's Carburetor Parts or another vendor?
The rebuilt kit's brand was Walker.
Every once in a while, the power valve does not seat well. If you have the old valve, stick it back in for a sanity check. It's gasket is another overlooked area too.
I notice you have the "adapter fitting" on the choke housing for the steel line routed from the exhaust manifold. The cover looks stamped vs. cast. Just a "notice".
Jim
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Hello Mark.....I've read your story on the VMF about your problem. I have more or less the same issue: a slight miss at idle up to about 2000 rpm. Tried and checked everything. Vacuum leaks, compression, timing, points instead of pertronix, coil, other 4100 carb AND gaskets!
I've cut my own from 1 mm thick gasket material but this had no effect at all!
Your miss seems to mostly happen in the RPM range where I don't have a miss. A random miss on my engine starts around 1200 RPM and continues through the upper RPM range. I did have a miss at idle and the engine would occasionally "stumble" at idle. Through troubleshooting, I found out my new after market yellow top coil had a bad resistance reading in the secondary circuit. For testing purposes, I bought a coil at the local auto parts store and the miss and stumble at idle went away. I also had an occasional miss in the timing light strobe at all RPMs on all cylinders with a Pertronix 1 installed. I replaced the Pertronix 1 with points/condenser and the timing light strobe miss was not evident anymore. The engine is running much better with the new coil and points/condenser installed but the random miss starting at around 1200 RPM persists. Here is the link to the VMF site if others are interested in mys engine miss saga:
http://forums.vintage-mustang.com/vintage-mustang-forum/1023937-troubleshooting-engine-miss-66-289-a.html (http://forums.vintage-mustang.com/vintage-mustang-forum/1023937-troubleshooting-engine-miss-66-289-a.html)
I believe the ignition system is up to snuff so I'm taking another look at the carburetor and air intake system hence why I'm looking at the carburetor and spacer mounting gaskets. With the engine at idle and a vacuum gauge hooked to the intake manifold there is slow movement in the vacuum from about 17.5 Hg to almost 18.5 Hg. I feel this may be an indication of a slight vacuum leak or a carburetor tuning problem. It's discouraging that you made a correct fitting carburetor mounting gasket and that did not help with your problem. Did you make 2 gaskets; one for the carburetor to spacer and another for the spacer to manifold? We have been down almost the exact same troubleshooting path with no luck. Whats your next move?
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The rebuilt kit's brand was Walker.
Every once in a while, the power valve does not seat well. If you have the old valve, stick it back in for a sanity check. It's gasket is another overlooked area too.
I notice you have the "adapter fitting" on the choke housing for the steel line routed from the exhaust manifold. The cover looks stamped vs. cast. Just a "notice".
Jim
Unfortunately, I had the carburetor rebuilt and don't have the original power valve. I told the rebuilder that the carburetor was going on a stock build so I'm assuming he installed a power valve somewhere in the 7.5 to 8.5 Hg range. I could take a peek and try to get some numbers. Do you think the power valve could cause my problem? I'm not sure when the installed power valve "kicks in" but the vacuum gauge is not in the 7.5 to 8.5 Hg range when the engine is missing. I've been doing all my testing with the car in Park (not a road test).
I was just looking at a Walker parts list for the 4100 and it also lists the square bore carburetor mounting gasket as also listed on the Mike's Carburetor Part's site. The guy that rebuilt my 4100 sent 2 square bore carburetor mounting gaskets back with the rebuilt carburetor and said "Use the mounting gaskets I send you when you install the carb." I looked at the gaskets he sent and figured he must be wrong and installed the horrible fitting FelPro 60059 gaskets shown above. That's 3 different sources saying to use the square bore gasket. Is the square bore gasket a better solution to the original 4 hole gasket supplied by Ford? This is a stock Autolite 4100 carburetor, 1 " spacer with PCV port and cast iron Ford intake manifold. I know the square bore gasket is not concours correct but I just want to get my engine running correctly.
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Without reading through 3 pages over at the VMF site and since it has not been mentioned here yet, has anyone put an analog dwell meter on either of these examples? Points gap combined with correct dwell angle is a MUST to dial these cars in. The dwell angle has to be within specs & should not change as the engine accelerates or decelerates.
(This detail on vintage cars OTHER THAN GM's with the slide-up window distributor cap, is hard to get it perfect ~that slide-up cap design was one of the best things about vintage GM's ~now only if they would have put the darn thing up front of the engine like a Ford!)
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Yea, I hear ya on the little door in the distributor to adjust dwell, great concept. I wouldn't be surprised if it was a bean counter thing where not having the little door would save a nickle in manufacturing. ::)
I replaced the Pertronix 1 with a NOS Motorcraft points and condenser. Set the initial point Gap to .017 and checked the dwell with an analog dwell meter. IIRC with an initial point gap of .017 the dwell reading was 25 at idle. I closed up the point gap ever so slightly and the dwell is now set to around 27.5 at idle with no variation. I do get a maximum dip in the dwell angle of about 1 degree (dwell reads about 26.5) when opening the throttle above idle and running the engine in the higher RPM range (lets say 2000+). The dwell angle does not vary back and forth when holding at a specific RPM or revving up and down in the higher RPM range, it sits at 26.5. With the engine at idle and a vacuum gauge hooked to the intake manifold there is slow constant movement in the vacuum from about 17.5 Hg to almost 18.5 Hg. I also noted a vacuum variation at 1600 RPM with manifold vacuum at 21 Hg with a very slight variation (no more than .5 Hg) above and below 21 Hg. The engine still has a random miss above 1200 RPM with these readings. The vacuum gauge readings are why I'm back to looking at the carburetor and intake for adjustment or vacuum leak issues.
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If you have access to one, I would try another carb (brand doesn't matter) to see if the problem remains
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If you have access to one, I would try another carb (brand doesn't matter) to see if the problem remains
not a bad idea...
Another option is if you know of a local company who has a gas analyzer (emission) tester. Even better with a dyno...Might be worth the bux to save a few migraines!
Like in many situations (not just car work) we'll often spend 3-4 times as much to"do it yourself" rather than pay some "crooked" shop just dying to stay alive in such a business.
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If you have access to one, I would try another carb (brand doesn't matter) to see if the problem remains
I have 3 Autolite 4100 carburetors. I had 2 rebuilt by 2 different rebuilders. The second carburetor is installed now and was bench tested by the rebuilder. The first one I installed definitely has a clog somewhere in the idle circuit on the drivers side. I can turn the drivers side idle mixture screw in and out with virtually no affect on the engine. I may order a premium carburetor rebuild kit from Mikes Carburetor Parts and rebuild the second (or third) carburetor myself so at least I know where I stand. I considered buying a new Summit M2008 Series Carburetor number SUM-M08500VS (https://www.summitracing.com/parts/sum-m08500vs/overview/ (https://www.summitracing.com/parts/sum-m08500vs/overview/)) but I'm hesitant on spending $300 on a carburetor I would only be using as a test. Ugh!
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Another option is if you know of a local company who has a gas analyzer (emission) tester. Even better with a dyno...Might be worth the bux to save a few migraines!
Like in many situations (not just car work) we'll often spend 3-4 times as much to"do it yourself" rather than pay some "crooked" shop just dying to stay alive in such a business.
Yes, I'm starting to get agita over this problem! I would be more than happy to work with a local company that could help me figure this out. I live in Burlington county New Jersey. Does anybody have a suggestion or can point me in the right direction in finding one?
The rebuilder of the my engine is known as a Ford mechanic and builds his own hot rods for racing. He seems to know his way around a wrench. Anyway, he returned to me an engine with lots of little issues to work out. I'm really hesitant to return to him.
Last fall, I took the Mustang to a supposedly reputable classic car shop specializing in Fords and for my trouble I got a big bill and a car that ran "a little" better. This shop supposed rebuilt the first 4100 for a second time and it has a clogged idle circuit! I was very disappointed to say the least. My faith in finding competent rebuilders and mechanics who can help figure out the problem has been significantly diminished hence why I'm spending a lot of my own time trying to figure this out. I'd like to work with a local shop if I can find a competent one.
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... I'd like to work with a local shop if I can find a competent one.
They are out there, probably about 65 years old, guys who cut their teeth on these old carbon-tuners. I agree, there are too many kids who only learned on fuel injected cars who really cannot tune the older beasts...but I bet some of their Daddy's can ;) Smog shops that certify for the State (wherever you might live) ought to know of somebody nearby I would think.
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I recommend getting the Standard Motor Products kit p/n 361D. RockAuto has it for $19.75 using the 5% discount code you can find on the web.
The Standard Motor Products (Hygrade) kit, Mike's kit, the $50 "High Grade" kits on eBay, Etc. Etc. are ALL rebranded Walker Product parts in one form or another. What I mean by that is the Ebay kits are dumped out of SMP (Hygrade) boxes with $20 markup. SMP purchases individual components from Walker and makes up their own kits. Yes, I've verified this with SMP.
Thanks for the recommendation on the rebuild kit. It looks decent. I'm going to pick one up. It looks like a power valve is included in the kit. Would you happen to know what size?
The Fel-Pro 1901 mounting gaskets are not concours correct by any means, but are extra thick and seal.
I'll give this gasket a shot.
A big cause of "stumbles" I have found are from primary jetting too low. For example on the C5ZF-C the #49 primary jets do not cut it with modern fuel and a mild cam (262/270 duration). You really need to be at #50 minimum or #51. It is even more of a problem if you're running the generic 7.5 Hg. power valves from the rebuild kits. Ford used a stock 8.5 Hg power valve (on the '65 1.08 and 1.12 HiPo) that came in sooner (when vacuum drops to 8.5 Hg, versus 7.5 Hg). I was buying 8.5 Hg. power valves from Quadrajetparts, but they phased out the kind that I liked that fit well (snout had good clearance in hole) and now they appear to just be selling the Holley brand with snout that cuts it damn close to hole wall.
Now we're talking, just the sort of info I was looking for. The carburetor currently installed is a C5ZF-D. Primary jets are #49. Secondary jets are #58. I'll pick up a couple of #50 and #51 primary jets and a 8.5 Hg power valve if not the size included in the SMP rebuild kit. Do you think the #58 jets are good for the secondary jets? I have a pair of #59 secondary jets I can install if need be.
I have a really mild Comp Cam P/N 31-215-2 installed in the engine. The duration is 252/252 The full specs for the installed cam are in the attached picture. Let me know if you think this cam would change anything with respect to the jetting you mentioned above.
As far as what runs best...
The C5ZF-C, Change Level C (5EC dated) I'm selling was the best running 64/65 1.08 out of about twelve C5ZF-C/-E carbs I experimented with. Next best was another Change Level C, Next best was a -E Change Level B (5CB dated). So what I can confidently tell you is the later the revision generally speaking the better the carb. will run!
For 1.08 C5ZF carbs missing original tags, if you look at the base mold dates (on very bottom) I've found the "9-1-64" mold dates generally always run better than the "7-17-64" and "7-27-64" mold dates. I've seen the 7-64 dated bases with tags up to 1965 Change Level B; I've never seen an original tagged 1965 Change Level C with the 7-64 base mold, just 9-64. Therefore I like the 9-64 bases better from a run standpoint.
I have never researched this in depth (and have no plans to), however I suspect the big or small numbers (one or other) on the bottom of the booster venturi may also indicate booster revision since the boosters out of a 1969 HiPo service replacement C6ZF-C seemed to be higher than the '64/'65/'66 factory assembly line HiPo carb boosters I looked at the bottom of. Just a suspicion.
Both of the rebuilt Autolite 4100 carburetors I have tried are the C5ZF-D model (car has an automatic transmission). Tags are missing on both carburetors so I don't know the date codes or change levels. I don't see a date stamped on the foot of the first carburetor (picture below), that seems odd. It does have the hot idle compensator in the air horn. Wasn't the hot idle compensator phased out on later revisions? The second carburetor, which is installed on the car now, has 9-1-64 stamped on the foot so based on what you said, I'll focus on tuning this Carburetor.
Everyones help is much appreciated! Thank you.
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Looks like the first carburetor may be a bit of a Frankencarb. I'll put that one aside for the moment. Anyway, I took the air horn off the Frankencarb and noticed that there is a brass clip installed on each opening of the pathway that connects the primary and secondary fuel bowls. The clips appear to act as a baffle to prevent a sudden transfer of fuel between the primary and secondary fuel bowls. I can post a pic tonight. The 4100 that's installed now on the engine with the date of 9-1-64 on the foot did not have these clips. Should I put them on?
I'll gather up all the parts I need, set up the carburetor and see if I can get it dialed in. Hopefully it will take care of the miss. I suspected it was running a bit lean. Hope this works. If not I'll still have learned a bunch!
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They're baffles, and they're required. A lot (two words) of 4100 seem to lose them in rebuilds.
Jim
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Thanks for the recommendation on the rebuild kit. It looks decent. I'm going to pick one up. It looks like a power valve is included in the kit.
What's not included in 4100 rebuild kits is the secondary vacuum actuator diaphragm. Be advised that there are two types. I think the change over date is around the intro of the 65 model year. Another thing to be careful about is the check ball in the secondary vacuum activation circuit. It's 0.125 in dia, located in the passage at the top of the secondary vacuum chamber that angles down.
Jim
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The 361D kit does have the secondary vacuum diaphragm along with replacement plastic arm/clip.
What's not included in 4100 rebuild kits is the secondary vacuum actuator diaphragm.
Then let me rephrase my statement - "Some 4100 rebuild kits do not have the secondary vacuum actuator diaphragm".
The 361D kit does have the secondary vacuum diaphragm along with replacement plastic arm/clip.
Most of the metal arms have been switched out to the plastic arms and corresponding diaphragms (bottom picture) that you find in the 361D kits.
This would be considered non-concourse by some.
Jim
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Thanks guys good info! I'll be ordering carburetor parts this weekend.
Edit: Oh yea, I called Standard Motor Products to find out what size power valve was in the 361D carburetor kit and the guy said it was 6.5Hg to 9.5Hg? I questioned this and said it should be a single value and he repeated himself. He seemed to be annoyed that I was questioning him so I left it at that.
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I just called SMP (718)392-0200 to get a straight answer and they verified it as a 7.50 Hg.
Thanks for calling SMP. It sounds like you may have spoke with the right person. I'll order an 8.5Hg power valve.