Carburetor After-Market Question

[AMC86Kid]

ok so i was wondering what after market carburetors would work for my 3.4 engine 

 

is this a good fit ?

https://www.amazon.com/Weber-Redline-Carburetor-DGES-Outlaw/dp/B00449TTOQ

 

also how can i tell if it will fit on my engine ?

any links would be nice so i can take a look at them 

[Green Mesa XJ]

That’s the right carburetor, dunno about the mounting plate adapter.

The kit for the s10 2.8 is the one I used, K490 by redline , this kit bolts to the factory intake.

 

If you wanted to piece it out just about any Weber 38 DGES or DGVS will do (as I understand it both are electric choke. DGAS I believe is supposed to either mechanical or water choke, but it seems some kits marked DGAS have the electric choke anyway)

 

The adapter plate is 99004.490 is the part number for the varijet to DGB adapter. Carbs unlimited sell them for about $90 + shipping. The air filter adapter is 99010.490 for factory air filter but you can use another type of filter as that kit at Amazon has.

 

The only other carb option I’m aware of you’d need the edelbrock intake and adapter for a Holley 390 4 barrel. AFAIK those are the only two options for the 2.8-3.4 carbureted setup.

 

 

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[AMC86Kid]

so your saying that the model K490 works on your 2.8 

then i should work on mine 

but i can't find it for sale online 

i keep finding other 38 DGES that ore other models like WK551

whats the difference ?

[AMC86Kid]

ok i think i found it so your saying you used this one

https://www.morris4x4center.com/weber-carburetor-38mm-dges-2-5l-or-2-8l-k490.html?find=jeep-cherokee-xj-1986-34

 

and since its the kit i shouldn't have to get no adaptor plate for it should i ??

[Green Mesa XJ]

Here this is the Amazon part # W0133-1815473-WEB

The search k490 jeep brings up a few kits but they are more expensive.

Everywhere else should have it was k490 redline or search for s10 2.8 Weber.

eBay has the kit lower than $400 but I can’t vouch for the sellers.

 

Edit: one guy on eBay has the kit open box said he never installed for $ 350 OBO

 

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[AMC86Kid]

the # W0133-1815473-WEB

looks like a different one then the K490 

how do i know its the K490 model for example look at this website 

http://www.redlineweber.com/carb-kits/auto/jeep/

it tells you that the K490 is for the 2.8 V6

and it tells you what vehicles are for the other models 

thats why i don't feel comfortable buying a new one if it doesn't actually say K490

[Green Mesa XJ]

ok i think i found it so your saying you used this one

https://www.morris4x4center.com/weber-carburetor-38mm-dges-2-5l-or-2-8l-k490.html?find=jeep-cherokee-xj-1986-34

 

and since its the kit i shouldn't have to get no adaptor plate for it should i ??

That link didn’t work on my phone, should be right from the description. If you get the kit you shouldn’t need the adapter plate. In some pictures of the new kits the adapter plate is already installed, the kit i bought many moons ago didn’t come like this. Keep in mind if you use the air cleaner adapter to keep the factory air cleaner you’ll need to trim to bolt because it’s too tall for MJ&XJ hoods.

That guy on ebay with the open box has the Weber air cleaner. Just search k490 jeep it’s the one for $350 OBO + shipping. I don’t know the seller but it looks like it could be legit. Only thing that looks different if the linkage adapter for throttle cable, still looks like it could be correct just different (better, cleaner) from the kit bought in the early 2000s

 

 

 

 

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[Green Mesa XJ]

the # W0133-1815473-WEB

looks like a different one then the K490 

how do i know its the K490 model for example look at this website 

http://www.redlineweber.com/carb-kits/auto/jeep/

it tells you that the K490 is for the 2.8 V6

and it tells you what vehicles are for the other models 

thats why i don't feel comfortable buying a new one if it doesn't actually say K490

Yeah I know what you mean, if you look up fitment by vehicle it does show 84-85-86 XJ. Honestly I’d try the eBay guy, he’s had it and the edelbrock intakes since early 2004. Make a best offer I’d mention you’re trying to get your mj back on the road see if you can get a little help on the price. Doesn’t hurt to try. Any best offer prices I figure is worth a shot just don’t be so low ball it’s insulting, just haggle a little.

 

Not sure if sitting for 13 years would be an issue, kind of assume not if it was stored correctly. Looks ok from the pictures.

 

BTW if you get a Weber I would not mess with the mixture unless there is a problem. Out of the box worked well at sea level and did ok at 6000-7000 feet altitude city driving.

Only problem I had is when I tried adjusting the mixture myself. At the time it was kind of gunky with old gas from sitting at my parents while I was away, screwing with the mixture was unnecessary and a pain to correct.

 

 

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[AMC86Kid]

its ok i can afford a new one 

i just need to get my engine back up and running i had a guy change the head gaskets and it looks 

like the previous shop that put the original ones on didn't torque the bolts down with enough force 

so thats why i was getting combustion leak only when it revs up 

any ways the new gaskets are in there and its bolted down tight but i can't get the old carb to start the engine

it just keeps back firing on me there must be something wrong with it

because we tore the inner gasket to it a little so I'm not surprised if i have a vacuum leak 

causing the engine to not fire correctly 

 

so now i either put on a new gasket for it and try to start it with the old carb 

or hook up a new carb and see if that makes it easier to fire, not sure 

[Jeep Driver]

2 hours ago, AMC86Kid said:

its ok i can afford a new one 

i just need to get my engine back up and running i had a guy change the head gaskets and it looks 

like the previous shop that put the original ones on didn't torque the bolts down with enough force 

so thats why i was getting combustion leak only when it revs up 

any ways the new gaskets are in there and its bolted down tight but i can't get the old carb to start the engine

it just keeps back firing on me there must be something wrong with it

because we tore the inner gasket to it a little so I'm not surprised if i have a vacuum leak 

causing the engine to not fire correctly 

 

so now i either put on a new gasket for it and try to start it with the old carb 

or hook up a new carb and see if that makes it easier to fire, not sure 

Double check your timing.

[Green Mesa XJ]

Backfiring ?
Sounds like timing, or plug wire order.
If you didn’t touch/move the distributor it would be timed where it always was, not the it is correct but you know it at least ran.

Plug wires are easy to confuse so I’d start at one and verify it.

I can’t recommend the Weber 38 highly enough, it was the biggest improvement to daily drivability.

Other thing I’d do is swap the distributor for vacuum advance, getting rid of the computer but your computer may be working correctly and advancing the timing as it should. I wouldn’t necessarily recommend replacing distributor because all the timing marks the 2.8 has are gone and there’s no way for a by the book setup. I could do it and so could a lot of others it’s just hard to describe how to do it by feel.
You may have to adjust if the rebuilder set the distributor for 0 degrees at top dead center, but you will not know that until you start trying to drive it. If they were smart ( which I doubt since they f’ed up headgasket torquing ) they would have matched the compression stroke on the 3.4 block to the 2.8, marked the position on the distributor in the 2.8 and dropped it in the 3.4, if they did that everything is good far as timing that distributor for that computer.



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[Jeep Driver]

They removed the heads.........they removed the distributor.........they changed the timing. 

[Green Mesa XJ]

Almost forgot be sure to change that oil! If you had someone working on it with you they probably already did it or recommended it. You don’t want to run that engine with radiator fluid in the oil, it will lead to premature bearing failure.

BTW did you get a peak at the pistions? I’m curious what they were marked for, usually more than stock displacement after they bore out the cylinders.


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[Green Mesa XJ]

They removed the heads.........they removed the distributor.........they changed the timing. 

Not on that motor. It’s push rod, and the cam and crank don’t have to be moved to pop off the heads kind of like the 4.0. Although Getting the valve lash set may be a trick.

It’d be good to check timing anyway but he’s got the 95 Camaro timing cover and crank pulley. It has a primitive CPS to time the engine with no timing marks on the cover. I don’t know how to describe to a novice trying to time that with a timing gun. I doubt many of the fundamentals on that engine but going back to basics like I would have done is hard to write instructions for. Probably more my limitations than anything else

 

 

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[Jeep Driver]

5 minutes ago, Green Mesa XJ said:

Not on that motor. It’s push rod, and the cam and crank don’t have to be moved to pop off the heads kind of like the 4.0. Although Getting the valve lash set may be a trick.

It’d be good to check timing anyway but he’s got the 95 Camaro timing cover and crank pulley. It has a primitive CPS to time the engine with no timing marks on the cover. I don’t know how to describe to a novice trying to time that with a timing gun. I doubt many of the fundamentals on that engine but going back to basics like I would have done is hard to write instructions for. Probably more my limitations than anything else

 

 

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Dist goes through the intake, does it not?

[Green Mesa XJ]

Dist goes through the intake, does it not?

No it’s behind all of that at the back of the motor. They shouldn’t have had to touch it other than the spark plug wires. But honestly I have no idea what has been done, if they touched it for any reason then you’re completely right and he’s got a hell of a time figuring out how to reset it ahead of him.


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[AMC86Kid]

so they took the cooling intake off 

and the two headers off 

the water pump and the timing chain area was not messed with 

the head gaskets can be replaced with out removing the timing 

and then the valve lash set was done by turning the crank shaft with a breaker bar

as each valve hit peak he tightened them down so they wouldn't wiggle 

I'm not sure why but he took the distributer cap off and then the distributer off (i though you could just take the whole thing off in one piece with the wires connected to it)

then put it back on after it was done so it might be off not sure 

and yes the oil was changed 

[AMC86Kid]

after watching this video 

https://www.youtube.com/watch?v=FHX1yXVyIMg

i believe that the timing on when the distributer fires each cylinder is most likely off 

because the crank shaft was turned to set the valves so i have to figure out how to get the timing right 

[Green Mesa XJ]

Aw $#!&. Jeep Driver was correct it’s your distributor. There was no reason to remove it it’s far enough out of the way to get the heads off without touching it.
Then the guy turned the engine and dropped it back in like it’s a Honda distributor which only goes two ways correct or 180 degrees off. Timing is way the hell off. Not terribly surprised most modern mechanics will have little experience with the old school distributors.

You need to do two things, first is find the number one mark on the distributor cap and mark the base so you can see it and take the distributor cap off. second is you need to find out if there is a mark on the crank pulley to indicate where it is, then Mark it a color you can see easily, white or yellow. Next is you need to turn the engine by hand until cylinder #1 is at the top of it stroke, like where it was when you set the valve lash. I believe the first cylinder on the passenger head is number 1.

After you have the engine set correctly you need to pull the distributor out the turn it by hand to line up with number one line you marked on its base and drop it back in so it lines up with that mark. You may have to rotate it twice to line the mark up do it’s at the beginning of the TDC and not 180 off. Just look it up for a video or better instructions on finding TDC on these old engine. You could pull the spark plug and use something like a long screwdriver to see when the piston pushes the screw driver up.


The two tricky parts are as the distributor gear starts to mesh with the cam it’s going to want to turn slightly out of alignment, you have to practice installing it so it move very little or moves to the correct mark as it’s installed.

You can see part of the gear from the cam shaft you need to mesh correctly with. The thing in the center is for turning the oil pump, nothing to do with timing.

The second tricky part is your engine needs to be off by a certain number of degrees to run correctly, 12 or 17 degrees off, what I described should take you to 0 degrees if done correctly. Normally you’d just run it loosen the bolt clamping the distributor down and turn it by hand until it’s right. But you don’t have the correct timing cover for this. So it’s got to be seat of the pants adjustments, which I’m not sure how to describe.

this is the timing cover the 2.8 should have.

This is what the harmonic balancer and timing marks should line up. Beware there can be two marks or more marks on the balancer and you have to be sure you get it correct or it will be 180 degrees off.

I’ll see if I can find a video later.



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[Green Mesa XJ]

Also at this point you need to decide if you want to go to a distributor with vacuum advance and cut the computer out of the equation.


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[Green Mesa XJ]

Here are a few links that can help.

http://www.fiero.nl/forum/Archives/Archive-000001/HTML/20130314-2-115913.html

http://www.s10forum.com/forum/#/topics/422281


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[AMC86Kid]

that guys wife is a terrible teacher 

but anyways yes i agree the timing must be off so i shouldn't try to run it no more until i know I've adjusted the timing correctly 

good so we have figured out our problem but now how do i fix it 

i can locate cylinder one yes and i do see the notch on the crankshaft pully wheel 

but i have no timing cover or bracket to show me where my degrees is 

so how should i go about this ?

[Green Mesa XJ]

You’ve got to find the compression stroke for cylinder #1. Holding a finger over the spark plug opening or putting paper there until it blows away is one technique. I didn’t watch either video all the way through.

I’m not sure how to fake the degrees you need to set it for with standard equipment. Easy enough to set to 0,
what does it say on your firewall sticker about timing?

First thing is to find where zero TDC cylinder 1 is with that crank pulley and cover, if it’s where 2.8 is maybe take a guess based on the picture of a 2.8 timing mark.
There are mechanic tools that can read the pulses from the magnetic CPS gm uses, I don’t know much about them or how to use them in this case.
Either way you’ll probably have to readjust it as you try driving it to get it responsive as it should be.

There is another trick engine builders use but it won’t work here with no timing marks to go by.

Here is another explanation of TDC

by cap269
Top dead center (TDC) occurs on every cylinder when the piston reaches the top of its bore. You can find TDC for any cylinder two ways. 1) Remove the spark plug and place a long screwdriver or piece of dowel rod through the spark plug hole so that it is resting on the face of the piston. As you rotate the engine (by hand), this will move up and down with the piston. When you see it has reached its highest point of travel, it is at TDC. 2) Remove the distributor cap after making a mental note of where the wire tower is for the cylinder you are interested in. Rotate the engine (by hand) until the distributor rotor is lined up with that position. This method is not as accurate as the first with the stick or screwdriver. If you just want to find TDC for cylinder #1, you can use the timing mark on the crankshaft pulley and line it up with the zero degree mark (some pulleys have T or TDC on them instead of 0).

Remember that TDC occurs twice during each 4-stroke cycle. Once for compression, and once for exhaust. If you're lining up the engine at TDC to do any work on the timing or distributor, you will want cylinder #1 at TDC on the compression stroke. This can be confirmed two ways. 1) Press a loosely balled piece of paper toweling into the spark plug hole, but not too far. You don't want it falling in. Then rotate the engine to TDC (by hand). If the paper blows out of the hole, that is compression stroke. You can also use a compression gauge--when pressure begins to rise you're on the compression stroke. If the engine doesn't have good compression, you'll have to use the next method. 2) With the valve cover removed, and using the screwdriver or stick/dowel method of locating TDC, rotate the engine (by hand) until the intake and exhaust valves for that cylinder are closed. You will know they are closed when there is a slight bit of play in the rocker arms (due to valve lash). If any rocker arm is too tight to move (zero clearance) then the camshaft lobe is exerting force on the rocker and the valve is not completely closed.
https://www.ericthecarguy.com/kunena/8-Service-and-Repair-Questions-Answered-Here/58908-best-method-to-find-tdc

.

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[AMC86Kid]

ok so i found the notch and i get that if i turn it i will eventually feel the air pressure shoot out of the spark plug hole 

but how do i know thats its the top dead center of the compression and not the exhaust ?

 

[Ωhm]

During compression/power cycle, both intake and exhaust valves are closed.