Holley carb on 250 six

Hi,

We have a 72 Comet with the 250 six and a Carter RBS carb. Were able to score an Offy 3 carb manifold and some 1904/1908 Holley 1 barrel carbs. I want to rebuild and try out each carb individually on the original head. That way when we do the conversion we can at least start out with "good" carbs before fighting the multiple carb linkage and calibration adjustments.

The Holley carb will bolt on to the intake but the throttle linkage is a problem. The cable from the as pedal is a "pull" for full throttle and a "push" for idle. The lever on the Holley is set up for a "push" for open and a "pull" for closed. Has anybody done a Holley conversion for this setup? I know the Holleys were used on earlier cars but don't know what the linkage looks like.

Thanks,

John in Kalifornia

congrats on scoring the Offy intake and Holleys they're one of my favorite looking 3x1V setups with the Glass Bowels! All you will need to do is to use a Bell Crank connected t the linkage to change the direction of the pull. Good luck and post some pictures when you can

Here is a simplified diagram of the carb arms and the direction of throw. You can see that the Holley goes "up and down" and the Carter goes "left and right." The Carter has a one fourth inch ball stud where the Holley just has holes. I'm trying to use the KISS principle and avoid complicated monkey motion linkage. That will come when I try go get the triple carbs set up.

John in Kalifornia

That shouldn't be a problem, it looks like they 'throw' in the same direction. It just changes the geometry some. Are they on the same side of the carb? Are you using solid linkage or cable? From above or below? White brain stems and cells are growing through your prefrontal cortex as we speak, you'll figure it out

Back again.

What I have are two small Falcon 144 type carbs and a couple larger ones, like off a 170.

Rebuilt one of the small carbs with new parts from a Walker kit, even though the carb looked good. No way of telling of the old rubber would be compatible with Kalifornia EPA gas. When we rebuilt the Carter RBS with a NOS carb kit it only lasted about a week then the rubber parts inside went bad. I replaced the rubber parts with Walker items and carb is still good after 3 years. Mike’s carb parts on the '"Net has some good videos on rebuilding the one barrel carbs.

I pumped all the old gas out of the car by running the original Carter RBS carb off a funnel hung from the hood latch. The fuel line was disconnected at the carb then fed into a gas can. I let the fuel pump empty the tank. I want to start with fresh gas when I try the Holley carb out. As soon as I make an extension arm with a ball on it for the carb I'll connect it to the throttle cable. Then put some gas in the tank and see what happens.

BTW, there are lots of junk carbs out there. One of the larger Holleys was completely butchered up and unusable. Easy to go with those replacement new Daytona carbs from Argentina but at 300 bucks each I will try the Holleys.

John in Kalifornia

biggyr":3q70fvfz said:

Back again.

What I have are two small Falcon 144 type carbs and a couple larger ones, like off a 170.

Rebuilt one of the small carbs with new parts from a Walker kit, even though the carb looked good. No way of telling of the old rubber would be compatible with Kalifornia EPA gas. When we rebuilt the Carter RBS with a NOS carb kit it only lasted about a week then the rubber parts inside went bad. I replaced the rubber parts with Walker items and carb is still good after 3 years. Mike’s carb parts on the '"Net has some good videos on rebuilding the one barrel carbs.

I pumped all the old gas out of the car by running the original Carter RBS carb off a funnel hung from the hood latch. The fuel line was disconnected at the carb then fed into a gas can. I let the fuel pump empty the tank. I want to start with fresh gas when I try the Holley carb out. As soon as I make an extension arm with a ball on it for the carb I'll connect it to the throttle cable. Then put some gas in the tank and see what happens.

BTW, there are lots of junk carbs out there. One of the larger Holleys was completely butchered up and unusable. Easy to go with those replacement new Daytona carbs from Argentina but at 300 bucks each I will try the Holleys.

John in Kalifornia

Click to expand...

Hi John, Yes unfortunately the old Carb kits just are not compatible with todays fuel blends. Glad to hear you are making some progress. I used to pull out the fuel tanks and either have them boil out at the locale radiator shop or take them to Chem Strip to have them cleaned. The ones I had cleaned at Chem Strip I would then use the Aircraft Slushing Solution to coat the inside after that they stayed very clean and rust free. Too bad the other 170 Holley is bad those would make nice end carb's on your Tri Powered 250 along with a Cater YF for the center or another big Holley. Good luck

We have a 72 Comet with the 250 six ... able to score an Offy 3 carb manifold and some 1904/1908 Holley 1 barrel carbs. I want to rebuild and try out each carb individually on the original head. That way when we do the conversion we can at least start out with "good" carbs before fighting the multiple carb linkage and calibration adjustments.

... good idea, each old carb has a signature operating condition and usualy a bit of throttle shaft shaft leakage, a set of solid thin metal gaskets under outer carbs can help getting carbs setup.

The Holley carb will bolt on to the intake but the throttle linkage is a problem. The cable from the as pedal is a "pull" for full throttle and a "push" for idle. The lever on the Holley is set up for a "push" for open and a "pull" for closed. Has anybody done a Holley conversion for this setup? I know the Holleys were used on earlier cars but don't know what the linkage looks like.

The Offy linkage is made for a side push setup on a bellcrank to provide variable progressive-to-synchronous outer carb options. Converting to a pull cable can be simple with Offy original linkage retained. With Offy - Holley linkage, the center carb throttle position controls the outers. Adding a throw arm across the original linkage reverses it's operation and provides the needed Maverick or other cable PULL action. also the center carb works fine with outer linkage disconnected for tuning.











. .

I commend your ambition of forging a built 250 with Offy Tri-Power - equipped with Holley 1904's. It will offer many hours of fun tuning each carb individually and then getting them to work together.
have fun

Thanks for the pics of the tripower setup. I will study them. I also looked at the pics on the link you gave out. You sure have a lot of carbs!

I didn't get anything done on the carbs today but I did make some progress. I had an Innovate air fuel meter kit laying around, never used. It consists of the meter, a wideband ox sensor and a bung to weld on to the exhaust. The cable supplied is 8 feet long. You are supposed to connect it to the car battery through a switched voltage. I made up my own standalone system by putting the meter in a box with a battery and a switch. I used a 2200mah 3S Lipo from my electric model airplanes. It puts out about 11 volts under load. The cable runs through a grommet on the side of the box to the ox sensor. There is no connection to the car except of course the ox sensor. No worries about grounding, ignition interference, etc. I also have an Innovate exhaust clamp that fits in the tailpipe.

First I calibrated the gauge. It read 22.x in free air, which is correct. I tried the system out on my late model vehicle. The readings were what chemists would call stoichiometric, an ideal 14.7 or close to it. It did not seem to matter if it was idling, steady state or accelerating, nothing much changed. It did go lean when coming down from high speed, which one would expect as the injectors go to a minimal duty cycle when you let off the gas. Then the "duh" Homer Simpson light came on. This was AFTER the catalytic convertor. The truck just passed smog this week so I would expect it to run clean.

Tested the wideband on the Comet. The exhaust clamp didn’t go in all the way because the tailpipe was curved down but I don’t think it mattered. It worked! The cable was long enough so that I could read it from under the hood. Now this is a vehicle that is pre smog, nothing except a pcv valve for emissions.

Reading at idle was adjustable with mixture screw from 13.5 to 17, rich to lean. At higher throttle opening the reading was 12, too rich?

I adjusted the idle to 14.7 then played with the pcv valve. When I removed if from the valve cover and just had it sucking outside air the idle went lean, up to 16. When I put my thumb over the pcv valve it went slightly lean to 14.3. I would expect the reading to be richer when the pcv was connected to the motor as there is considerable blowby due to bad rings on number six cylinder.

I think the wideband will be useful in checking out the Holley carbs. The engine has good throttle response with the old carb. Should be able to get some kind of idea if the other carbs are good or not. I should look for my glass spark plug (Colortune) maybe that will tell us something.

It’s easier to futz with carbs than FI.

Tomorrow hope to get the bracket made for the Holley carb so I can try it on the car.

John in Kalifornia

nice job building your portable exhaust gas analyzer!

Well now.That`s just slicker than black ice.
Good luck.Have fun.Be safe.
Leo

OK, I hooked up one of the Holleys to the car today. It took all day chasing around to find fittings, nuts and bolts, etc. It is a smaller one, like from a 144 Falcon. I removed the choke assembly.

Here are some pics.

I went to button head Allen bolts to hold the carb adapter to the head. Also I had to do some grinding to clear the linkage.

Made up a couple of 1/8 aluminum pieces. One is a stop for the idle speed adjustment. The choke linkage was removed so there was no place for the idle screw to rest up against. The other part is the adapter to change the up and down motion of the throttle to a left/right. I added a ball to fit onto the stock throttle cable. The side view shows the spacers added to clear the body of the carb.

Here it is on the car. One pic shows the idle position, the other full throttle.

How did it work? Not so well. The idle mixture was rich, and then as it warmed up went to about 15. The idle mixture screw had very little effect. As soon as I gave it the gas it went dead lean and would not pick up. IF is opened the throttle very slowly I was able to get it to speed up but the meter showed a very lean mixture.

On the bright side, the throttle linkage worked well. The float bowl did not leak. I’m using a cork gasket. I didn’t catch anything on fire.

I think I need to modify a spare float bowl cover with a sight glass so I can see where the fuel level is.

Next step is to try another carb.

John in Kalifornia

Rebuilt another carb for the Comet. Let's call this one the "170" Holley, as opposed to the small "144" carbs. This time it worked out fine. Drove the car around the block to make sure it worked My home made air/fuel standalone tester verified it actually mixes the fuel somewhat correctly. Gee, maybe I should go into the smog test business, I have the sniffer.

Now to rebuild the other "144" carb.

John in Kalifornia

G R E A T work!

Y not the RBS on ur 250?

Getting cars ready for a Smog Test in California can be a big job not only does it have to test good at the pipe it has to have all the correct parts to pass the visual test. There can be some good money in it though sometimes finding all the correct parts is time consuming. congrats on getting a good 170 carb to use now you just need two more that match it.

Hi Again,

I started to rebuild the last “144” carb. While doing this I noticed something different with the linkage. Sho ‘nuf, on the “bad” carb I had put the nylon accelerator pump cam on backwards. When the throttle was advanced it sucked gas out of the bowl instead of pumping gas through the discharge nozzle. That may be a problem!

I’m going to finish the rebuild of the last carb then go back and figure out the “bad” one. Spent a lot of time squirting brake cleaner and canned air through all the various passages to figure out what they all do. Then I made some drawings on the white board to ‘splain it all. These things ain’t that complicated.

BTW, I tried the antifreeze in a crock pot carb cleaning method. I think I will stick with regular carb cleaner.

Aside from warped bodies and bowls from over tightening the bowl screws I think the main problem lies in the metering blocks. There is an economizer poppet valve that may go bad and lots of tiny passages you just can’t get to. I ordered a NOS metering block from EBay, picked one that looked pretty much the same as what I have, just for a spare. Lots cheaper than another junk carb. The metering block is the heart of the carb, other stuff is easy to check out with carb cleaner sprays.

Mix and match will eventually get some good carbs if I don’t run out of patience.

John in Kalifornia