Brand new to Thermoquads- a few questions I need help with
Good Evening, All,
I have recieved a nice rebuildable core Carb- series 9103 - a 77 400 HP application that I'd like to use on a set of 302 heads I'll be installing soon on a 273 .
I have been doing my research and I have noticed my target carb- a 1973 340 AT unit has the same Primary jet- 4098/ .098- but has a smaller secondary jet -5143/.143 existing compared to the desired 340 jet- 5137/.137 - and smaller metering rods -existing 2211- compared to the desired 340 AT metering rod 1966- so is this , if I can find the parts , a good idea ? and if so , a reasonably do-able one? What else will I need to be on the lookout for as I try to make this swap to this late model carb? I've already ordered a set of the brass floats and a shop manual , along with a rebuild kit.
does anyone know what the second set of numbers below the model number mean ? Mine has 103 S below the 1903 S on the base plate..
Thanks and Happy Holidays to All!
OK the 103 is the 103rd day of the year it was built. Means nothing for parts.
I love the ignorance about thermoquads. I have 2 of them for my 340.
You can find the correct parts if you look hard enough on ebay and online.
Here is a pdf for the manual to rebuild and tune
https://www.carburetor-parts.com › ...PDF carter-tq-manual.pdf - Mike's Carburetor Parts
You also need to reglue the transfer wells for the primaries with JB Weld Marine, there are tutorials on how to do this
I would not try to manually modify any parts since they will never be precise look for original parts.
Here is the online Bible for id's
A Carter Thermo-Quad Guide
I would start small on jetting, primaries are available. .090 and 0.127 for secondaries. Leave the rods. And only change 1 thing at a time for tuning. Go up 2 steps on primaries always 1for secondaries
Adjust rods for drivablity.
The dash pot is essential for the secondaries. It needs to pull the door tight with vacuum, the door should be 1 1/2 turns after making contact with boss in back.
Look for the secondary tool using 2 screw drivers sucks.
Use only x rings for primary seals.
The tree should be 1 /2 turns from the bottom.
They need a lot of choke to start.
Mixture screws should be 21/32 to 24/32 from base to top of screw as baseline.
Honestly i would look for something starting with a 6xxx since these are pre lean burn and are a little easier to tune. You can use parts of the one you have.
