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Discussion Starter #1
I have a 267 in a 79 El Camino that is giving me some weird issues. I had it apart to replace some leaking gaskets. While I had it apart I added a Summit Racing cam, new timing chain, factory quadajet intake and a Q-Jet. It also has true dual exhaust with headers leading into 2.5 inch pipe. My problem is that I can’t get it idle below 1000 -1400 RPM. Also it won’t rev up past 2500 RPM. I changed the fuel pump, but that didn’t do anything at all. Same problem at the same time. Any ideas on what it could be?
 

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Rebuild

Check for the proper accelerator linkage travel and the torque on the carb bolts.
 

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Sounds like an intake leak or air leak at carb maybe even verify cam timing or something with distributor timing.Also are the valves adj correct
 

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Discussion Starter #7
I've checked the intake for leaks, as well as making sure that the carb is tightened down. I triple checked that I had the cam in correctly before I tried to start it. I had talked to a few people and they thought it might be a fuel pressure or volume problem. I had no idea how old the pump was so I just replaced it with a new one. I have a inline filter between the pump and the carb, as well as a filter in the carb. I'm starting to think that maybe it's either ignition or fuel pressure. I have checked the distributer placement, but that doesn't mean that I'm not off by a tooth or something silly like that.
One thing that I was thinking about at lunch time. I received two gaskets with the carb when I bought it from Summit, both gaskets are a open design, but the intake isn't. It has the traditional four holes design (one for each barrel). see below for what i mean------ O O
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Would that small open gap between the base of the carb, and the intake cause a problem? I wouldn't think that it would, but maybe it causes some weird venturi effect or some nonsense.
 

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I've checked the intake for leaks, as well as making sure that the carb is tightened down. I triple checked that I had the cam in correctly before I tried to start it. I had talked to a few people and they thought it might be a fuel pressure or volume problem. I had no idea how old the pump was so I just replaced it with a new one. I have a inline filter between the pump and the carb, as well as a filter in the carb. I'm starting to think that maybe it's either ignition or fuel pressure. I have checked the distributer placement, but that doesn't mean that I'm not off by a tooth or something silly like that.
One thing that I was thinking about at lunch time. I received two gaskets with the carb when I bought it from Summit, both gaskets are a open design, but the intake isn't. It has the traditional four holes design (one for each barrel). see below for what i mean------ O O
0 0
Would that small open gap between the base of the carb, and the intake cause a problem? I wouldn't think that it would, but maybe it causes some weird venturi effect or some nonsense.
I'm just off a little the way my engine is running and I got the same gasket could it be wrong? Maybe a better 4-hole gasket? Could solve my problem to. Glad I saw your thread. Seems always to be something stupid.:dontknow:
 

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There is a THICK gasket that should be used between the carb and the intake. It does sound like you have a linkage problem. Check the pedal for travel/hangup on carpet.
 

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Having a summit carb and converting to that from a Quadrajet, I can tell you I had to mess with the linkage adjustment for a couple weeks before i got it right. It appears to me that your throttle pedal is stopping before the carburetor is ready to go wide open. I needed to physically pull another 1 inch or so of cable out of the linkage and forward toward the front of the engine. This allowed 2 things: The engine to run at wide open throttle; and The gas pedal was now closer to me instead of closer to the floor. Obviously, when it's closer to the driver, you're going to have more "pedal mashing" area, therefore the linkage pulls the throttle plates farther open (full throttle).

If that's not the problem then I just wasted alot of hot air :yell:

The thick gasket they come with is FINE. It seals up great and provides at least a minimal amount of heat dissipation. Don't use a thinner paper gasket as some of these carburetors are not machined flat on the bottom. How do I know?? I chased a vacuum leak for weeks before realizing it wasn't my 1" spacer that was leaking...it was the CARB!! It would not seal up to the paper gaskets. Had to remove my spacer and RE-install thick gasket. My engine now idles happily at 750rpm.
 

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Discussion Starter #12
Okay, let me go over what it is, and what i've done to it. It was a two barrel
(Rochestor Dual Jet) carb 267 V-8 originally. I replaced some leaking gaskets (Oil pan/timing cover and valve cover gaskets) and while I had the pan and cover off I went ahead and put in a small cam from Summit. I also bought a quadrajet from Summit and put it on a factory cast iron intake. It has the HEI distributer that it came with when I bought the Camino.
I have checked to make sure that the throttle opens all the way, the blades do when I manually move the linkage. But not when I give it full throttle with it running, as it isn't making enough vacuum to open the bores up.....it's only a 267 after all. lol
I've tried this driving and with me under the hood in the driveway, and it still does the same sputter/choke out around 2500RPM. With me working the throttle at the carb, or at the pedal.
I can't check the timing at idle since it's not really idling, but it was at roughly 25 degrees on the timing marks yesterday, with the advance capped off. I put a vacuum gauge on it, and it was pulling a steady 18 pounds at the fast "idle" that is has right now. Drops down to zero when you open up the throttle.
I didn't think that the open gasket would make a big diffence, but thought i should mention it. I don't like, or use the paper gaskets either. I like the thick ones, so the 4 hole one is the same thickness as the others.
I'm starting to get frustrated with this vehicle, and have thought a couple times about just shooting it to get it out of my misery! lol, just kidding. It is frustrating though! :dontknow:
 

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There are 'lock-outs' on the secondary system. It will not open until those lock-outs will allow it. The first one is on the choke side. Until the choke is completely off, there is a brass pivot lever that will prevent the secondaries from operating.

That lever has a notch at the bottom which engages a pin. Once that lever is 'off' of the pin, the secondaries are operational. Also, the secondary throttle plates will only begin to operate near the very end of travel on the throttle cable; it's that last little bit of travel that opens them to 'full open' very quickly. So, you have to be off of the choke and you have to get full throttle action from the accelerator cable for the secondary air valve to work.

The secondary air valve will not work with you revving the engine in your driveway, I've never seen it happen.

There is a tricky little adjustment on the secondary air valve damper spring that determines the rate at which that valve opens; and it should be adjusted to meet your engine's needs. If the spring is too tight, the valve won't open quickly enough and the engine power will be weak. If that spring is too loose, the valve will open too quickly and the engine will "bog down" when WOT is executed.
 

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There are 'lock-outs' on the secondary system. It will not open until those lock-outs will allow it. The first one is on the choke side. Until the choke is completely off, there is a brass pivot lever that will prevent the secondaries from operating.

That lever has a notch at the bottom which engages a pin. Once that lever is 'off' of the pin, the secondaries are operational. Also, the secondary throttle plates will only begin to operate near the very end of travel on the throttle cable; it's that last little bit of travel that opens them to 'full open' very quickly. So, you have to be off of the choke and you have to get full throttle action from the accelerator cable for the secondary air valve to work.

The secondary air valve will not work with you revving the engine in your driveway, I've never seen it happen.

There is a tricky little adjustment on the secondary air valve damper spring that determines the rate at which that valve opens; and it should be adjusted to meet your engine's needs. If the spring is too tight, the valve won't open quickly enough and the engine power will be weak. If that spring is too loose, the valve will open too quickly and the engine will "bog down" when WOT is executed.
Are you suggesting that the engine is not reving past 2500 rpm because the secondaries are not opening?

Umm, No..
 

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I'm just off a little the way my engine is running and I got the same gasket could it be wrong? Maybe a better 4-hole gasket? Could solve my problem to. Glad I saw your thread. Seems always to be something stupid.:dontknow:
So, you have the same gasket and instake as John? But, yours idles fine and revs past 2500 rpm?

So, that's obviously not the problem with John's motor.
 

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Okay, let me go over what it is, and what i've done to it. It was a two barrel
(Rochestor Dual Jet) carb 267 V-8 originally. I replaced some leaking gaskets (Oil pan/timing cover and valve cover gaskets) and while I had the pan and cover off I went ahead and put in a small cam from Summit. I also bought a quadrajet from Summit and put it on a factory cast iron intake. It has the HEI distributer that it came with when I bought the Camino.
I have checked to make sure that the throttle opens all the way, the blades do when I manually move the linkage. But not when I give it full throttle with it running, as it isn't making enough vacuum to open the bores up.....it's only a 267 after all. lol
I've tried this driving and with me under the hood in the driveway, and it still does the same sputter/choke out around 2500RPM. With me working the throttle at the carb, or at the pedal.
I can't check the timing at idle since it's not really idling, but it was at roughly 25 degrees on the timing marks yesterday, with the advance capped off. I put a vacuum gauge on it, and it was pulling a steady 18 pounds at the fast "idle" that is has right now. Drops down to zero when you open up the throttle.
I didn't think that the open gasket would make a big diffence, but thought i should mention it. I don't like, or use the paper gaskets either. I like the thick ones, so the 4 hole one is the same thickness as the others.
I'm starting to get frustrated with this vehicle, and have thought a couple times about just shooting it to get it out of my misery! lol, just kidding. It is frustrating though! :dontknow:
You can check the timing, put 36 degrees in it at 2000 rpm. I don't think that's the problem, but it couldnt hurt for now.
 

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Discussion Starter #17
There are 'lock-outs' on the secondary system. It will not open until those lock-outs will allow it. The first one is on the choke side. Until the choke is completely off, there is a brass pivot lever that will prevent the secondaries from operating.

That lever has a notch at the bottom which engages a pin. Once that lever is 'off' of the pin, the secondaries are operational. Also, the secondary throttle plates will only begin to operate near the very end of travel on the throttle cable; it's that last little bit of travel that opens them to 'full open' very quickly. So, you have to be off of the choke and you have to get full throttle action from the accelerator cable for the secondary air valve to work.

The secondary air valve will not work with you revving the engine in your driveway, I've never seen it happen.

There is a tricky little adjustment on the secondary air valve damper spring that determines the rate at which that valve opens; and it should be adjusted to meet your engine's needs. If the spring is too tight, the valve won't open quickly enough and the engine power will be weak. If that spring is too loose, the valve will open too quickly and the engine will "bog down" when WOT is executed.
I have let it run long enough to allow the temp gauge to show 190 - 200 degrees. Gotta love the hot and oh so humid Georgia summers! I don't think that the spring is opening to tightly. Its doing the same thing when I drive the car or am sitting in the driveway. What spring is it? I can see how it might be opening too quickly and that might be causing all or most of my problems. I don't understand how the air valve won't work when if i'm in my driveway. If I'm opening it up all the way, why wouldn't it work?
Thank you everyone for your help so far. It's been a while since I messed with cars, and this was/is my reintroduction back into hot rodding. I truly appreciate everyone's input and assistance
 

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hang in there John
make sure all the vacuum ports on the carb and intake are plugged
and sometimes re-torqing the intake is needed, after a few heat cycles..
if it has a egr valve?? check it,, it will act like a big vacuum leak..:texas:
 

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Discussion Starter #19
hang in there John
make sure all the vacuum ports on the carb and intake are plugged
and sometimes re-torqing the intake is needed, after a few heat cycles..
if it has a egr valve?? check it,, it will act like a big vacuum leak..:texas:
I've double checked everything to make sure that it was plugged at least twice. I've checked the intake bolts, but i'll check all of that again tomorrow. The EGR was blocked off with a plate. if that was leaking, i can understand the idle problem, but would that contribute to the cutting out around 2500?
 

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no, not with a blockoff plate..

as said? are the valves/rockers adjusted right?? :dontknow:

also if you have the metal vacuum line to the trans, behind the carb on the intake,,
check that its still connected at the trans..
:texas:
 
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