Thread: Rochester jet size ?

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Originally Posted by MelloYello

No hi-jack intended here but I did my dual Roch one barrels with fine steel wool and kept them that way with just the steel wool every now and then. I'm sure there are better ways but I'm lazy and always take a similar approach.

Those look nice!

Thats all I did was steel wool off the crust on mine......tryin not to make this project a tribute to shiney things...plus I anticipate lots and lots of dirt and mud on this rig.

Sounds like you've got the determination and are willing to do the work and that should work out fine.

meller

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This is the end result....better than it was and internally like new......this one will be covered by a huge breather anyway....I admit it was hard to resist polishing the aluminum out though.....

Now just have to drill and heat,spray and cuss and easy out the bolt from the intake carb mounting pad and I can see if it was a sucessful rebuild.


Then bend up a new fuel line from the pump...some one cut the metal one and inserted a fuel filter between the pump and carb........I will put it back in the fuel line just after the tank mounted to the frame.....I do not trust unknow rubber hose,a clear plastic fuel filter and hose clamps under the hood where if it leaks or fails fire is a sure result ...

We have sucesssssssssssss...........had to drill the bolt out,thank goodness they used what I call butter bolts.....no hardness rating,soft as butter.......drilled it out,tapped and hammered around with the screw driver and got the rest out,tapped a bolt down into it to clean the threads.

Now just have to get if fired back up and see what happens......they had the main fuse filled with aluminum foil and wire because it kept blowing,at least it had a fuse, discovered it was the loose ignition switch turning and shorting a wire out....turns out the ignition switch tumblers are bad and it makes it hard to turn,which resulted in it working loose and rotating causing a short........

Off to get fuses and a new ignition switch..........I did discover under the dash some one had installed a nice new fuse block with spade fuses...that will make cleaning the wire mess up a lot nicer as I would have done that any way.....things are looking up

Well poo.......idle screws still have to be 4.5 turns out approx to idle without my hand over the carb.......still has a flat/dead spot off of idle.

The new ignition switch works fine and instead of the 4 dollar maxi fuse as a main, I got one of the large breaker fuses for 3 dollars more...no more replacing that, since it has a good new blade fuse box under the dash I saw no need for a maxi fuse under the hood as the wire ran to the main fuse box and all wires are fused off that.


One funny thing I noticed was the cast iron carb base has 2 good sized holes running to right at the butterflies.....never seen this before on a carb...not that I have seen a ton of carbs before......but these are made into it and run at a 45 degree angle from the base plate stud holes to right at the butterfies/.....

Seems like this is a giant vac leak to me....they look factory and not cobbled in......maybe the base is for another application and just donored onto this carb.......

It runs pretty much like it did before the rebuild......idle screws over 4 turns to even idle....giant flat dead spot off of idle, really puffs black smoke after letting off.........does seem to idle cleaner now though.

Thinking I might just get a rebuilt motorcraft 2100....the carb seems to focus point of alot of issues with this jeep......black tail pipe,black plugs....was definaty wrenched on alot before I recieved it,had a busted bolt from taking the carb off before I got it. Heli coil on one of the carb screws.

Usually not a get new parts type guy......but this carb might have had some serious cobblers inside of it drilling, plugging and mix matching stuff over the years.Who knows what this carbs original application was as it old enuff to not have numbers on it, it had the metal tag that is long gone....

Not sure what to do at this point on the carb......

On a side note......right after this the starter made a little grind noise starting it for the last time,pops happened to look on the ground and ask wonder what this bolt is from......the big bolt going straight up thru the starter sheared off....

Looks like it was well on its way for a while as there was only a small shiney spot towards the middle of the shank....guess it was waiting on me to fully shear....

I'm thinking those 2 holes you describe (aimed at the butterflies) are where the needle valves go... got a picture?

If I'm right you're missing parts!

No picture, it is back on the jeep.......got the needles back in.......they are straight out the front...the holes I am talking about are at a 45 degree angle to that pointing right at the mounting bolts. same level as the needles ...they are small holes, maybe a little under a 1/8th inch....a little bigger than a 1/16th.

I am going to try a few things...it has a vac point going to the distributor that comes off right at the side of the bowl....might plug that and go straight vac to the base plate for the distributor....also will be plugging the distributor line to see if the vac advance canister is shot......that would cause a lean condition and hesitation too...I think.

You can see the vac line in my pics.......does not seem like a normal place for straght vac to come from.....might be some sort of ported vac emissions garbage port.

With it idling spray some carb cleaner on those two little holes. If it's sucking air you'll see an increase in rpm momentarily. Did your carb kit come with a decent exploded view drawing, and does it show the two holes?

http://www.hdts.vcn.com/JEEP/ROCHEST...2GC%20CARB.pdf

figure 5b shows them....I guess they are vent holes........seems pretty funny to have open holes at the base of the carb unfiltered...they are directly above the throttle blades....guess thats not my problem....seems awful wierd to me...but it shows it in the book.......

It does seem weird! And I don't remember seeing that before. It says in that book it is to help with hot re-starts, you might plug them off and see if it changes anything.?.?.?

Originally Posted by 34_40

It does seem weird! And I don't remember seeing that before. It says in that book it is to help with hot re-starts, you might plug them off and see if it changes anything.?.?.?

I think the explanation is excellent, and it specifically points out that the hot start improvement can be accomplished only with a gasket, or by the drilled holes. Being above the throttle blades the holes cannot affect idle (assuming that your throttle blades are straight and sealing in the bore properly at idle shutoff) and as you come off idle the air flow through the venturi has much less resistance so any trickle of air flow through those holes is negligible. I'd say your problem is somewhere else in that carb.

“……Well poo.......idle screws still have to be 4.5 turns out approx to idle without my hand over the carb.......still has a flat/dead spot off of idle……”


Bummer. It’s unfortunate you don’t have a carb number, but if you don’t you don’t.

First question I have is do you have an operational choke? The reason I ask is that it appears ion one picture that the fast idle cam linkage is missing. Are you bringing the engine up to full operating temperature before adjusting the idle and is that flat spot still there after it warms up? Some engines like a fair amount of choke until they warm up.

I’ve come across the bases with the holes a couple of times, it shouldn’t make a big difference. Like 34_40 I think I would probably plug them too but mainly just because I don’t like unfiltered air either.

That being said, the first thing I would check would be the carb base to intake gasket. Over the years I have come across many base gaskets that don’t effectively seal the carb to the manifold. I just ran into this on the two outboard carbs I rebuilt for the Tri-Power, the gaskets in the kits did not completely seal the front of the carb. Because I’ve run into this before I always turn the carb upside down and lay the gasket on the base to verify the proper fit. The gasket I usually use if I need one is a Car Quest G7327 (it’s an old number but hopefully it will interchange).

Although I’ve only seen the problem a couple of times another thing I would check is the PVC valve. The good one are calibrated differently. If someone threw a valve designed for say a 454 onto you engine with the smaller displacement there is a real possibility that you are pulling too much vacuum thru the valve.

While 4+ turns on the idle screws does sound a little excessive I’m not sure I’d be overly concerned about …….provided that is where they want to be after the engine is warmed up. If you turning them out to keep it running when it’s cold…..it could go back to my comments about needing the choke.

The flat spot could be a couple of things. If it happens when you mash the gas pedal it sounds like the accelerator pump shot ……verify you have a good squirt that starts as soon as the throttle starts opening. If the shot starts late you may need to drop the accelerator pump a bit which can be accomplished the straightening the external pump linkage just a bit.

If the flat spot is just off idle with a slight pedal opening, you might try backing out the idle screws just a bit more and/or adding a couple me degrees advance to the timing.

As far as the vacuum port on the front of the carb, it depends on the carburator I’ve seen them both ported and manifold in that location. Easiest way to check is pull the line and put your finger over the port. If you feel vacuum at idle it’s manifold if you don’t feel any vacuum until it reved up it’s a ported vacuum port…….the later 2Gs actually had two nipples in that location one manifold and the other ported.

Hope this helps.

.

Thanks everyone.....going to pull the starter and fixed the busted bolt...do not want to grind teeth off the flywheel.

Looks like I have some checking to do and start crossing things off the list untill it is narrowed down to whats happening.

I need to do some experiments to see where I am at on the carb.....some tunning, vac guage , choke settings etc and see what is happening,,,....very well could be the pcv valve as I have not checked it yet..........

I appreciate all the input!

Well, a part step further now......got the starter pulled and discovered why the bolt broke off.

Someone had put a 1/4 inch bolt with washers on the bottom and washers and a nut on top in a 3/8ths hole..... Seems the starter was torquing just a little bit on each start,apparent from the nice shiny witness marks, it was bending the one correct bolt back and forth each start untill it gave way.

Unfortunatly it broke off about 1/4 inch up in the hole on the bellhousing...good news is it looks good up there, no rust, so I ordered a set of heli coil left hand bolt removers to give them a try and the second good news is the hole with the incorrect bolt in it looks good, good threads.

I like it when things go good and smooth......was not easy, but it went smooth!

Drilled into the broke bolt with a set of alden industrial bolt removers and after a few rest beaks,drilling straight up over head is not easy, it backed right out of the hole........found the correct starter bolts and just finished putting it back together.

It fired right up and purred like a kitten, much much better idle after the carb rebuild..........now I can start back in on the tune process!