Hello, I would loke if someone knows if those two Holley 1920, can be used equally for a 1970 225 auto.

https://drive.google.com/file/d/0B8jCXW ... p=drivesdk

The old one is broken (left) , and the remanufactured one (right) has a diference in the base as you can see in the attached picture link.
This is the nearest replacement I can get from my supplier, but I can't get a smoth idle below around 900 rpm. It idles, and don't stall at 650 rpm (service manual specifications). No problem driving, good power. Starting reasoneably, but not perfect. The only problem is an rough idle. Vaccum leaks and ignition checked, valves adjusted cooectly.
I don't know if the thin covering partially the base is from factory or it's a result of resurfacing the base and then redirect the vac channel.

Thank you in advance.

_________________
You need a SL6 to smile.

for what its worth,,
I have an old Holley 1920, it is a 12R-5592B that has the same thin metal shelf at the throttle plate,, so it appears that is how the carb was originally made.
The 1920 12R-5592B mentioned above visually 100% matches the base's port opening of your carb in the right photo.

If you want to match the 1920 that you originally had,, along with the Holley 1920 moniker reference the numbers -letters that are cast in to the float bowl directly below the fuel inlet fitting

Thank you for your input.
My old carburetor is an 12R-4285B, wich I don't be able to locate a new, used neither remanufactured one.
Then, I have got this 12R-5582B, but i can't get an smoth idle below 900 rpm.
After checking all posibilities, I think this thin in the base is for redirect the flow more centered, perhaps because it would be used in a EGR intake, but...
this is only my argumentation to the no smoth idle condition.
Do you know some source to get a 12R-4285B Holley?

Thank you for your help.

_________________
You need a SL6 to smile.

try these guys, they may have a replacement or if not the parts required to repair your original carb

http://www.carburetor-parts.com/Holley- ... p_329.html

note, there is an additional number stamped into the carb on the fuel bowl side that you will need to completely identify your original carb.

Once your existing carb is fully identified
Another place to look for a complete carb is Old Car Parts Northwest, google that name their site should come up.
Or
Put an ad up here at .org in the parts wanted section

http://www.slantsix.org/forum/viewtopic ... eed#444383 The carb with tin plate is 1973 ,first year for egr.

Hi. Thank you all for your inputs.
I will try those things and post a report.
I have trying with differnt jet sizes. With 55 and 57 , it have a dead spot when initial aceleration. 59 cures this simptom. 61 no real diffence.
I will ty today the pencil test to see if in becomes better.

Thank you for your help.
Nice day.

_________________
You need a SL6 to smile.