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Egr question

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Connor strom

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Im hooking up an egr for emissions testing and have a question for the vacuum lines to make sure im doing it right. Now from my under standing i can run the lines as so...from egr into a thermal ported vacuum switch hooked into a temp senser port on the intake (next to thermo housing) and from there i can run it straight into the carb. My thinking is that the vacuum is pulled from the carb into the switch and when the switch opens it allowes vacuum flow to the egr allowing it to open and what not? Would this work or am i missing something
 
Connor strom said:
Im hooking up an egr for emissions testing and have a question for the vacuum lines to make sure im doing it right. Now from my under standing i can run the lines as so...from egr into a thermal ported vacuum switch hooked into a temp senser port on the intake (next to thermo housing) and from there i can run it straight into the carb. My thinking is that the vacuum is pulled from the carb into the switch and when the switch opens it allowes vacuum flow to the egr allowing it to open and what not? Would this work or am i missing something
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It *may* work correctly if the carburetor has a ported/timed vacuum line fitting on it. You don't want EGR at idle or under WOT, carbs designed for EGR have a vacuum port that only has vacuum applied under fairly specific throttle conditions...mainly high vacuum/low throttle opening, which is cruise.

If you ran it on a full manifold vacuum position idle would be terrible (if it would even run) so a temp switch alone won't solve the problem. You'd have to run a high vacuum/low vacuum cutoff to stop from causing issues outside of cruise, then you'd have to run a thermal switch to keep it from coming on when the engine was warming up. ECM/PCM's can do almost all this with wiring and pre-existing sensor inputs, so they are a lot cleaner than the old setups with 15 million vacuum lines.
 
What year?Most have a "catalyst" label on the radiator support. This diagram has the routing of vacuum lines,and the like ,and I think includes EGR routing,also?
 
MEANSTREAK K30 said:
What year?Most have a "catalyst" label on the radiator support. This diagram has the routing of vacuum lines,and the like ,and I think includes EGR routing,also?
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Its an 84 and it also has the sticker. Most the emissions stuff has been torn off by the previous owner so im hooking back up what needs to be there for the visual part. So im not trying to do it in oe fashion just currious if my logic is sound as to if the way i want to run it will work
 
Mine is exempt due to age. Sometimes forget a lot of you guys still have to do emissions.

Good luck with the battle
 
Yeah , here where I live , in rural Cornville, I have never had to have a vehicle inspected.....ever.My 84 pick up has had all the original emisions equipment yanked and plugged. So I geuss I can't really help with the EGR routing,except to add that the person inspecting might look at the label, and then look to see that the hoses and everything match?I know that emisions laws vary a great deal state to state.
 
Like Dyegrear stated,if the carb has a specific port for EGR,I'd use that one,as it is "timed" to only get vacuum at certain throttle openings..if you can list the model number off the carb,you might be able to find a picture of the various ports online..usually the EGR port is close to the top of the air horn,and may even be marked with letters casted into the carb body next to the nipple ..

If it doesn't have that EGR port,a ported vacuum port elsewhere on the carb could be used,but the EGR valve may open too quickly or at too low an RPM then,and cause poor driveability and performance..

The ported vacuum switch just keeps any vacuum from going to the EGR valve until the engine is fully warmed up...
 
So let me ask you guys this i went ahead and tried to run it the way i described just to see (no harm in trying i figured...haha if only id known). I got everything hooked up and started 'er up. It ran terrible couldnt keep an idle (previously it idled fine and steady at 850) so i disconected the new vacume lines and basicly reverted it to how i had it before i hooked the egr up and and it still ran like shit. Idle shoots up when you spray carb cleaner around carb spacer and bottom of intake manifold. >. < any suggestions of what might of gone wrong. Iv already tried tightening the intake and carb yet its still giving me problems
 
Also this isnt my first time with idle issues if it might add to the problem at all...its done this to me before which lead to rebuilding the carb which lead to replacing the intake manifold. Which lead to all new gaskets and hoses and the whole nine yards...haha
 
You will have to take care of those leaks to get the vacuum up. If not, the EGR will never work correctly and your idle will swing up and down, and high.
 
wheels87k5 said:
You will have to take care of those leaks to get the vacuum up. If not, the EGR will never work correctly and your idle will swing up and down, and high.
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Yea im trying to figure out where the leaks are comming from. The intake is torqued to spec and carb is on there firm no leaks at the lines nether...im at a loss
 
Connor strom said:
So let me ask you guys this i went ahead and tried to run it the way i described just to see (no harm in trying i figured...haha if only id known). I got everything hooked up and started 'er up. It ran terrible couldnt keep an idle (previously it idled fine and steady at 850) so i disconected the new vacume lines and basicly reverted it to how i had it before i hooked the egr up and and it still ran like shit. Idle shoots up when you spray carb cleaner around carb spacer and bottom of intake manifold. >. < any suggestions of what might of gone wrong. Iv already tried tightening the intake and carb yet its still giving me problems
Click to expand...
Connor strom said:
So let me ask you guys this i went ahead and tried to run it the way i described just to see (no harm in trying i figured...haha if only id known). I got everything hooked up and started 'er up. It ran terrible couldnt keep an idle (previously it idled fine and steady at 850) so i disconected the new vacume lines and basicly reverted it to how i had it before i hooked the egr up and and it still ran like shit. Idle shoots up when you spray carb cleaner around carb spacer and bottom of intake manifold. >. < any suggestions of what might of gone wrong. Iv already tried tightening the intake and carb yet its still giving me problems
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Sounds like the spacer or carb might be warped.
 
Are you using that thick insulated spacer gasket ,that has plastic inserts at the bolt holes,for a Q-jet carb ?--those only seal good once,in my experience,and tightening the carb bolts more will not help,the spacers wont crush enough to let the gasket compress more,and you'll risk cracking the carb base..

If you have a square bore carb like a Holley or Edelbrock,mounted on a spread bore intake--you can have all kinds of gasket leak issues,sometimes a special plate is needed to cover all the gasket areas on the carb and intake..
 
diesel4me said:
Are you using that thick insulated spacer gasket ,that has plastic inserts at the bolt holes,for a Q-jet carb ?--those only seal good once,in my experience,and tightening the carb bolts more will not help,the spacers wont crush enough to let the gasket compress more,and you'll risk cracking the carb base..

If you have a square bore carb like a Holley or Edelbrock,you can have all kinds of gasket leak issues,sometimes a special plate is needed to cover all the gasket areas on the carb and intake..
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Its an edelbrock 1405 series square bore carb. Its got a new edelbrock 2 inch spacer with an old but looks to be okay gasket on the bottom of the spacer and newish (came with the rebuild kit) gasket betweem the carb and spacer. Think i might need to replace?
 
Are you running a GM Q-jet intake with that carb ?...if so,you'll need the correct spread bore to square bore adapter,or a plate that will allow both to mate up and seal all the areas,you cant just put the carb on without them..if you have a square bore intake, then the carb is a direct fit in most cases..

If the gaskets are the typical flat paper type,I have re-used those without issues,but new ones are always better..if you re-use yours,dont be tempted to use RTV on them,it can get sucked up into the carb if it has vacuum ports open to the intake..
 
Its an edelbrock intake as well. As well as the paper gaskets. On the intake where the carb mounts up its not the square opening its the kind that has two ovel shapes devided by a line down the middle (cant think of the technicle term)
diesel4me said:
Are you running a GM Q-jet intake with that carb ?...if so,you'll need the correct spread bore to square bore adapter,or a plate that will allow both to mate up and seal all the areas,you cant just put the carb on without them..if you have a square bore intake, then the carb is a direct fit in most cases..

If the gaskets are the typical flat paper type,I have re-used those without issues,but new ones are always better..if you re-use yours,dont be tempted to use RTV on them,it can get sucked up into the carb if it has vacuum ports open to the intake..
Click to expand...
 
Connor strom said:
Spacer is brand new how would i check if carb is warped?
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use a straight edge, and try different thickness feeler gauges to see if any will slip between carb base and straight edge ,or use a light and see if any light shines through. Maybe double up the gaskets will fix it.What carb is it? Did you buy it new?
 
MEANSTREAK K30 said:
use a straight edge, and try different thickness feeler gauges to see if any will slip between carb base and straight edge ,or use a light and see if any light shines through. Maybe double up the gaskets will fix it.What carb is it? Did you buy it new?
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Came with the truck when i bought it but i did rebuild it didnt think to check if it was warped though...
diesel4me said:
Are you running a GM Q-jet intake with that carb ?...if so,you'll need the correct spread bore to square bore adapter,or a plate that will allow both to mate up and seal all the areas,you cant just put the carb on without them..if you have a square bore intake, then the carb is a direct fit in most cases..

If the gaskets are the typical flat paper type,I have re-used those without issues,but new ones are always better..if you re-use yours,dont be tempted to use RTV on them,it can get sucked up into the carb if it has vacuum ports open to the intake..
Click to expand...
350-3701_zpsjlkckkql.jpg
thats what my intake looks like as well my description didnt make much sense i realised
 
Connor strom said:
Came with the truck when i bought it but i did rebuild it didnt think to check if it was warped though...

350-3701_zpsjlkckkql.jpg
thats what my intake looks like as well my description didnt make much sense i realised
Click to expand...
That's a nice intake. Looks like it can use a sguare bore or spread bore carb , am I right?Why are you running a spacer?For a 4x4 application , I don't think it is needed, thought they make a few more horse on top but nothing down low. Might be wrong on that, though.
 
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