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By RossL - 2 Weeks Ago
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I have a 55 Thunderbird that has the original carburetor and distributor. The car has been upgraded to 12 volts and I was told the engine was rebuilt at "some point". I rebuilt the carb and fuel pump. The vacuum advance can was also rebuilt. I plan to spend a couple of more weeks trying to optimize what I have before I make a decision. My goal is to get the car to be more responsive, I am not looking to smoke the tires :-)
I am considering upgrading to a more modern carb and a distributor with mechanical advance. Is it worth the expense to do these upgrades?
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By 55blacktie - 2 Weeks Ago
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Define "more responsive." Does your car have a Fordomatic? Gear ratio? If you have the original 55 distributor, upgrade to a 57-up distributor. If you want to retain the mechanical tach drive, get an aftermarket CRT Tbird distributor. If you want to keep the Holley 4000 Teapot carburetor, read Ted Eaton's article (eatonbalancing.com) on modifying the Teapot carburetor for compatibility with 57-up distributors.
If you have a Fordomatic, have you tried starting out in Low by manually shifting into Low? It's more responsive than leaving it in Drive and starting out in 2nd. If you manually shift from Low to Drive and then immediately shift back to Low once it's in 2nd, it will hold 2nd gear; it's a technique that might require some practice to master.
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By Daniel Jessup - 2 Weeks Ago
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"rebuilt at some point" - I would highly suggest a compression test of each cylinder. Those readings would tell you a lot. Beyond that like blacktie says a distributor upgrade would be very helpful. Y Blocks tend to like a lot of initial advance, at times much more than what is posted in any shop manual. Blacktie is spot on for the recommendation on the Fordomatic shifting
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By RossL - 2 Weeks Ago
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55blacktie (10/4/2024)
Define "more responsive." Does your car have a Fordomatic? Gear ratio? If you have the original 55 distributor, upgrade to a 57-up distributor. If you want to retain the mechanical tach drive, get an aftermarket CRT Tbird distributor. If you want to keep the Holley 4000 Teapot carburetor, read Ted Eaton's article (eatonbalancing.com) on modifying the Teapot carburetor for compatibility with 57-up distributors.
When I say "more responsive", when I step on the gas hard, I don't feel the car pulls enough. It has a slight hesitation when starting from a full stop and I floor it. I am going to start a new post about my carb issue. I also need to check the adjustment of the transmission kickdown (I don't think this would affect starting from a full stop). When I got the car the trans kickdown didn't work at all. I got it to work by trial and error but I recently found the instructions how to do it correctly.
Yes it's an automatic. I read somewhere that it's not a good idea to start in low and push it hard (not sure if this is true). So I haven't done much with 1st gear
I've seen the article about modifying the carb for the 57 style distributor. I am still dialing in the carb and timing. I bought the car 11 months ago, but I've only been able to drive it for 3/4 weeks this year, so I'm still learning about the idiosyncrasies of the car.
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By 55blacktie - 2 Weeks Ago
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If you're looking for it to be more responsive off idle, stick with a 4-barrel carburetor with small primaries. You probably read Mark R's post on VTCI. He went from a 570 cfm Holley to a 390 cfm Holley. He's quite pleased with the performance and his mpg has improved. If you're not particularly concerned about improving the performance at higher rpm, your 55 intake with an adapter for a 57-up carburetor should do the job and save some money. However, you probably won't have enough hood clearance for an adapter and a carburetor spacer.
You could also consider having numerically higher ring & pinion gears installed, but you probably won't like them on the highway, and they won't improve mpg. The stock gear ratio behind the 55/w Fordomatic is 3.31.
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By Ted - 3 Weeks Ago
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The original Holley model 4000 carbs (Teapots) are sensitive to ethanol laden fuels. I have found that upping the primary jet sizes by two numbers helps with the hesitation issues caused by the 10% ethanol laden fuels. Also keep in mind that simply switching to the premium grade (91-93 octane) gasoline may also help as the premium grades typically have 3-5% ethanol versus the full 10% found in the 87-89 grades.
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By DANIEL TINDER - 3 Weeks Ago
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Bigger primary jets may be one of the reasons my PONY teapot performs so much better than the rebuilt original that came on the car (?). That, and the advance limiter I installed (weaker LOM spring settings) burns way more 93 octane though.
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By DryLakesRacer - 2 Weeks Ago
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Rossi… when you say you floor it from a stop it should go into low or first gear. If it doesn’t you should try what Blacktie suggests and if there is a difference, the link/rod from the carb linkage to the trans is not adjusted correctly.
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By RossL - 2 Weeks Ago
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DryLakesRacer (10/5/2024)
Rossi… when you say you floor it from a stop it should go into low or first gear. If it doesn’t you should try what Blacktie suggests and if there is a difference, the link/rod from the carb linkage to the trans is not adjusted correctly.
It seems better when I start in "Low" but still not 100%. Are you saying Starting in Drive aggressively is the problem?
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By RossL - Last Week
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Ted (10/5/2024)
The original Holley model 4000 carbs (Teapots) are sensitive to ethanol laden fuels. I have found that upping the primary jet sizes by two numbers helps with the hesitation issues caused by the 10% ethanol laden fuels. Also keep in mind that simply switching to the premium grade (91-93 octane) gasoline may also help as the premium grades typically have 3-5% ethanol versus the full 10% found in the 87-89 grades.
I tried 93 octane fuel and #54 primary jets (my carb had #52), I might have noticed a small improvement. It's very difficult to find non ethanol fuel in NJ. Any other suggestions?
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By KULTULZ - Last Week
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"I also need to check the adjustment of the transmission kickdown (I don't think this would affect starting from a full stop).
When I got the car the trans kickdown didn't work at all. I got it to work by trial and error but I recently found the instructions how to do it correctly."
The TV LINKAGE has to be adjusted with a fluid pressure gauge (see correct year WSM). There is no ands, buts, ifs or maybes.
Also correct band adjustments.
It sounds like your problem(s) is mainly the LOAD-O-MATIC and the TV LINKAGE. You need to go to a DUAL-ADVANCE DIST.
Make sure all of the TV LINKAGE is not worn and any bushings are good. Engine mounts also. If the engine moves on torque application it will negate any adjustment.
The reason(s) for the single range in those years was fuel economy (2nd gear start) and to compete with the scrub POWER-GLIDE.
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By 55blacktie - Last Week
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Common sense tells me that more fuel would be required to get a car moving from a dead stop in 2nd gear because it doesn't have the advantage of the torque multiplication of low gear. If the transmission valve body, etc. are such that a transmission will automatically shift from low to second at a low rpm, it should only remain in low just long enough to get the vehicle moving. For example, my truck has an 8-speed transmission with a 3.92 axle ratio. It always starts off in 1st/low gear. With a gentle touch on the pedal, it will be in 5th gear by the time I reach 20-25 mph. If there were an mpg advantage to starting off in 2nd, surely the transmission could have been programmed for that.
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By RossL - 7 days ago
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I found the problem causing the hesitation (after tearing into the carb a few times), fuel cap was not vented. The cap that came with the car was old, I thought it could be the original, so when I replaced the fuel tank I decided to use the old cap. I bought a new vented cap from Rockauto and the hesitation/bog is gone.
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By DryLakesRacer - 7 days ago
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 A 1955 Cadillac dual quad “bat wing” air cleaner
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