Carb issues

Beck · October 05, 2015, 10:07:27 AM

I posted on Aug 29 (I bought 2 more motors this week) about 2 motors I bought. Motor #2 in that post I have running but not well.

I have the motor running on a stand. I am using a garden hose for coolant without a thermostat. The motor won't run without some carb choke. Do you think I am keeping it too cool and not letting the engine temp come up to where the choke could be off? OR is it just carb rebuild time?

phat46 · October 05, 2015, 06:53:19 PM

Is the water coming out of the block hot? I would turn the water pressure down till it was coming out hot.

chimp koose · October 05, 2015, 11:49:59 PM

hook a garden hose up to the thermostat opening with a spray nozzle on it . hook up a water supply from house to motor elsewhere . Regulate temp by spraying the heated water with the spray nozzle to cycle coolant in and out . just don't do so much as to thermal shock the thing .

Beck · October 06, 2015, 09:57:48 AM

I can let my finger in the discharge water. It is warm, but not hot.

This motor does not have a thermostat on it. It was a boat motor that had a closed loop system. The thermostat was located on the water cooled exhaust manifold. I scrapped the heavy iron manifold so now there is no provision for the thermostat.

After I get it running well it will be used in my little pulling tractor. This one will run on gas so I plan to run a wet block circulating through an expansion tank. There will be no radiator. I have considered using a large heater core.

Weight is the enemy on this project. The tractor needs to be 1300 lb with my 250# butt on it. The back tires are 34" tall and 20" wide which = heavy. Add a 350 turbo and converter. The pounds add up quickly.

I hate to try running it without cooling circulating now. My goal was to put a little time on the motor. I have not taken it apart. It had been sitting in the boat for at least 6 years without running. The oil pan/block of the motor was full of antifreeze when I removed it. I want to see if it is useable as is. It will be swapped out when my little nasty motor is done.

wayne petty · October 07, 2015, 12:30:54 AM

which carb is on it..

at idle.. the throttle closed.. you should be idling on the fuel from the idle feed ports that are controlled by the idle mixture screw..

remove the idle mixture screw.. give the hole a shot of carb spray followed by a blast of compressed air.. another shot of carb spray.. another blast of compressed.. this may blow any corrosion or dirt out of the idle passages

when you tip into the throttle slightly.. you start to expose the idle transition slots.. at idle this slot is really not flowing as there is atmospheric air pressure above the throttle blade.. and manifold vacuum below it.. this prevents pulling much of any fuel out of it until you start to expose the idle transition slot..

the idle transition slot continues to flow when the mains start to flow and part way into the main circuit operation.. once the throttle blade is far enough open.. the entire idle transition port is in the airflow and there is not a lot of suction there to pull fuel out of in any meaningful amount..

if your idle feed restriction is partially blocked you won't have enough fuel for it to idle.. if somehow the idle air bleeds have been removed. there won't be enough suction in the idle channel to pull fuel from the float bowl ..

which carb do you have.. i might be able to point out where the idle feed restriction and the idle air bleeds are..

if you have too big a PCV .. or a vacuum leak.. same thing. you will be too lean and need choke to assist the idle and idle transition circuit..

wayne petty · October 07, 2015, 12:48:56 AM

Quote from: "wayne petty"which carb is on it..

at idle.. the throttle closed.. you should be idling on the fuel from the idle feed ports that are controlled by the idle mixture screw..

remove the idle mixture screw.. give the hole a shot of carb spray followed by a blast of compressed air.. another shot of carb spray.. another blast of compressed.. this may blow any corrosion or dirt out of the idle passages

when you tip into the throttle slightly.. you start to expose the idle transition slots.. at idle this slot is really not flowing as there is atmospheric air pressure above the throttle blade.. and manifold vacuum below it.. this prevents pulling much of any fuel out of it until you start to expose the idle transition slot..

the idle transition slot continues to flow when the mains start to flow and part way into the main circuit operation.. once the throttle blade is far enough open.. the entire idle transition port is in the airflow and there is not a lot of suction there to pull fuel out of in any meaningful amount..

if your idle feed restriction is partially blocked you won't have enough fuel for it to idle.. if somehow the idle air bleeds have been removed. there won't be enough suction in the idle channel to pull fuel from the float bowl ..

which carb do you have.. i might be able to point out where the idle feed restriction and the idle air bleeds are..

if you have too big a PCV .. or a vacuum leak.. same thing. you will be too lean and need choke to assist the idle and idle transition circuit..

here is a circuit on many but not all carbs.. the enrichment pullover especially when tractor pulling when you need as much fuel and air as possible to crank out the wide open throttle horse power.. might have to study that to see how hard it is to modify it.

i wonder of the pickup tube on digital page 6..

http://www.walkerproducts.com/_pdf/rochester2barrel.pdf

#17-116 is the same pickup tube shown above to the enrichment pullover.. so a few spares might allow you to swap or drill it larger and larger until you get more power at WOT.. it's just a thought..

might be time to use a go pro or other high speed video camera mounted above and looking forward /downward into the carb throat with a timing light hooked over the coil wire strobing the fuel pullover enrichment and perhaps the main enrichment. while noting the air fuel ratio..

Beck · October 08, 2015, 08:56:08 AM

I'm sorry for the delay in response. I have been swamped.

I am working with a Rochester 2G. I am not a carb guy, but do know where the idle screws are. I have not had a chance to address it yet.

I had another of the same carb. I have disassembled it for a rebuild. It was really full of tar. I have always had others do my carb work. This is my 1st attempt. I have not ordered the kit yet.

This motor is just to get the tractor running to work out the chassis. I am not going to get too crazy trying to get the last bit of power out of it. I will save that effort for the next motor. As long as it runs well I will be happy.

wayne petty · October 08, 2015, 06:50:09 PM

one thing i have found on 2G carbs..

when working in the float bowl after cleaning.. but before a final rinse.. working on the accelerator pump circuits.

i tend to is the accelerator pump piston bore is kinda oxidized on the surface. i will roll up some 600 wet or dry and slice a piece of fuel line and slip the wet or dry into it .. spin polish the bore. so its like glass.

i also with the T Shaped retainer and the spring it holds down with check ball out.. i usually use a phillips screw driver.. to spin lightly thru the surface of the tapered seat.. just lightly burnishing it.. and because i have thought far enough ahead.. i have NOT thrown out either used check ball.. if they are not rusted and pitted.. oh.. and i do the seat under the accelerator pump where the check ball is also.

please note.. the check ball under the Tee and the spring is a different size than the one under the accelerator pump.. they will stick hard if you get them in the wrong holes..

i take the USED check balls with a roll pin punch and Lightly with a tiny hammer i drive the used but smooth check balls into the shiny seat.. this forms the seat into a perfect curve for a better seal on the new check balls..

if you look at the used check balls. you will find that where you used a punch on them.. they will have a flat mark that ruined them. if that part falls against the seat.. you will loose pump shot .. having a random flat spot that is crazy hard to locate .. don't ask me how i know or learned that.

Beck · October 08, 2015, 09:07:50 PM

Quote from: "wayne petty"i tend to is the accelerator pump piston bore is kinda oxidized on the surface. i will roll up some 600 wet or dry and slice a piece of fuel line and slip the wet or dry into it .. spin polish the bore. so its like glass.

Ok I understand and can do that.

Quote from: "wayne petty"i also with the T Shaped retainer and the spring it holds down with check ball out.. i usually use a phillips screw driver.. to spin lightly thru the surface of the tapered seat.. just lightly burnishing it.. and because i have thought far enough ahead.. i have NOT thrown out either used check ball.. if they are not rusted and pitted.. oh.. and i do the seat under the accelerator pump where the check ball is also.

please note.. the check ball under the Tee and the spring is a different size than the one under the accelerator pump.. they will stick hard if you get them in the wrong holes.. .

My T shape retainer is still in the carb. I was unsure if I was supposed to remove it. I guess that answers that one for me. Do I just pull it out by the top of the T? The ball at the bottom of the accelerator pump is still stuck in the solids. It is soaking. I wonder if the last guy put them in the wrong holes?

Quote from: "wayne petty"i take the USED check balls with a roll pin punch and Lightly with a tiny hammer i drive the used but smooth check balls into the shiny seat.. this forms the seat into a perfect curve for a better seal on the new check balls..

I understand that also. Will do.

I think I did a no-no. I put everything but the bottom housing and float in the glass bead blaster on low pressure. It came clean. It appears all of the beads came out. The only place I have a concern is the power piston hole. Is this supposed to be removed also? It seems to have come clean. It works freely.

There are some 2G rebuild videos on the web by Mikes Carburetor Parts. I have not watched the whole series yet. I planned to buy the kit from him tonight. If this one works I am going to give my Q-Jet a try.

Thanks for the input Wayne.

wayne petty · October 08, 2015, 09:53:18 PM

quadrajets have tricks also...

if its not on a stock application. where something is different.. cam.. heads. displacement. transmission.. rear end gearing. you may want to play with the APT adjustment. 75 up carbs have a plug in the top of cover to remove and use a Double D shaped tool. you will want to make a dipstick tool if you don't already have one. it goes down the bowl vent tube or the odd shaped slot depending on what you want to measure..

http://i1207.photobucket.com/albums/bb476/waynep712/waynep712%20carb%20album/Img_121228112324_zps2eef5504.jpg

39 mm to the beginning of the metric or 1/32 scale..
http://i1207.photobucket.com/albums/bb476/waynep712/waynep712%20carb%20album/Img_121228113006_zps85ff1701.jpg

the black shaft tool is actually the proper APT tool. but they are easy to make out of some tiny tubing. if your carb has the apt thru the top.. apts in the baseplates are harder to adjust..

got a carb number??
http://i1207.photobucket.com/albums/bb476/waynep712/waynep712%20carb%20album/Img_130226154456_zpsac64069d.jpg

you need to make sure you don't use the wrong gasket.. can you find waldo in this image.. http://i1207.photobucket.com/albums/bb476/waynep712/waynep712%20carb%20album/Img_130226162336_zpsd8ae2ed3.jpg

why do i mention this.. everybody takes the apt screw out.. there is NO FIXED SETTING FOR THIS.. you don't need to remove it to clean the carb..

if its screwed up..

you will need to adjust it with the seat of your pants. and a tool..

let me describe why and how.. this is how to remove the BOG from a quadrajet.

at idle.. there is vacuum pulling the primary metering rod down against the APT stop screw.. this brings the tapered primary rods deep into the primary main jets.. so the air fuel mixture is just right when the apt is perfectly adjusted. when the APT is too low the main mixture will be too lean and you will need to tip farther into the the throttle to make it past the flat spot..

if the APT adjustment is too high.. it will be too RICH.. not just accelerating but at low speed cruise.. killing your fuel economy. .

i usually set the APT about 2 turns up from just starting to lift the primary rod holder off its lowest position.. i am holding the rod holder down with the dipstick. at this point.. i start doing 15 foot part throttle take offs.. i keep turning the adjustment 1/4 turn at a time to reduce the downward travel.. soon you will feel the carb really responding like it may have NEVER had before.. you can get it to rich by going too far up.