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Hi All,

Looking for some help. Just went through and "rebuilt" my 258, pretty much replaced all gaskets and seals including valve stem seals and rear main bearing, removed all the EGR stuff, installed a block off plate for the EGR but kept the hard tube interconnecting the exhaust manifold to my intake manifold. Installed an HEI distributor and MC2100/2150 like carb bought off Amazon, which from my understanding is really a knock off but had great reviews.

link to carb


Rewired my engine bay as well keeping only the essentials. Im having issues with all the vacuum line routings on this carb, and i think its the reason my jeep wont idle or stay on, if i were to guess i have an air/vacuum leak somewhere?

The symptoms im facing are as follows, when i go to start the engine it fires right up with two pumps of gas, goes immediately to a high idle, although my idle screw is backed all the way out, runs for about 3 seconds at high idle then stalls out. If i rev it it stays on, the minute i take my foot off the gas it stumbles and dies. btw my vacuum advance is off and plugged at the carb below the auto choke when doing this. ive set initial timing as best as i can somewhere between 4-8dbtdc while the engine off. i cant get it to continue running stable to properly set timing.

i have a PCV valve on the back of the valve cover by the firewall connected with a T to the back of the carb (biggest fitting closest to its base), and the other end of that T running down to my charcoal canister. The side port is my advance and is currently plugged until i get it running. The top fuel port is closed off for now, need a line of the appropriate size to run it down to my canister. the smaller fitting on the front by the idle quality screws is capped off. On the manifold itself ive capped off the main fitting that would run to my brake booster, i dont have it installed yet. The 4 ports on the CTO switch in the intake manifold are all running to one another in essence capped.

Thoughts on what the issue may be? Can anyone provide pictures of their setup and vacuum line routing. Im trying to keep the engine bay tidy and as minimalistic as possible.
 

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2016 JK w/ Snowplow & Trailer Hitch 7-Pin
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I think you are on the right track with vacuum leak. But don't limit yourself to the hoses and fittings.

Double check that the intake manifold is not leaking vs. the head or carb.

And check that Every Single Vacuum Port is closed off or has a hose on it.

Lastly, are you shure that the blocking plate for the EGR valve actually stops the flow of exhaust gasses? A flat plate is NOT the business end of valve assembly.
 

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Welcome to the Forum, from Cave Creek AZ.
 

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Discussion Starter #4
I think you are on the right track with vacuum leak. But don't limit yourself to the hoses and fittings.

Double check that the intake manifold is not leaking vs. the head or carb.

And check that Every Single Vacuum Port is closed off or has a hose on it.

Lastly, are you shure that the blocking plate for the EGR valve actually stops the flow of exhaust gasses? A flat plate is NOT the business end of valve assembly.
Mike thanks for the feedback, this is what i have on the intake manifold to block EGR circulation.


it didnt come with a gasket, now im wondering it thats the source of my vacuum leak... ill apply some high heat silicone around the perimeter and slap it back on see if that resolves the issue...

any other thoughts?
 

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2016 JK w/ Snowplow & Trailer Hitch 7-Pin
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Mike thanks for the feedback, this is what i have on the intake manifold to block EGR circulation.


it didnt come with a gasket, now im wondering it thats the source of my vacuum leak... ill apply some high heat silicone around the perimeter and slap it back on see if that resolves the issue...

any other thoughts?
Examine the passageways carefully. If the EGR delete is not sealing off the exhaust gasses as well as the intake passage to atmosphere, the engine won't run properly with already burnt fuel flowing into the intake manifold.
 
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