carb vs cam help needed

[forango]

I am whaving a major problem with a newish engine I bought.....these are the spcs on the engine:

306
underdrive pulleys
Holley red fuel pump(regulated at 6.5-8psi)
new internals/polished crank
Edelbrock performer RPM instake
Edelbrock performaer plus #3722 cam dur 282, lift .498 ( i think it is basically an E303 style cam)
FMS valve springs and pushrods
Powerfire MSD style distributor(no vacuum advance)
Mated to a C6 with higher stall converter

When I boguht the engine originally it has an Edelbrock 500 cfm carb on it...I have since replaced that iwth a Holley 4160C(600cfm)

My original issue was that when I would put it in gear the engine would keep stalling immediatyely in R and in D unless I was holing some gas to it. After speaking with trans shop kind of figured it was due to potential vacuum leak and high idle so I started working on getting it turned correctly and that when I ran into more problems...I found the timing was set at 18 degrees inital timing and I could not get the idle screw to lower rpms at all(revving at about 1550rpms)...so I brought timing down to 10 and then 14 degress and at those as soon as I start bringing the idle down anywhere past 1200 rpm the engine just stalls out again.

My hope is that the cam is needing something more from the carburetor. I am wondering if there is something i should be doing to properly setup the Holley to give the engine more gas maybe or air at idle?

Any help is greatly appreciated...I have been trying to figure this out for 2 weeks and am out of my depth at this point , LOL

 

[General karthief]

Hook a vacuum gauge to it, when you're working with a carb'd setup you are basically the computer, you need to verify the base timing and advance setting, is the carb new? No matter, I suspect you have a vacuum leak, is there a spacer under the carb? Using the correct gaskets between the carb and manifold and/or spacer.
Verify, I have to write things down, Yeah I'm easily confused and dealing with a carb'd setup can get, lets say daunting?
You should check float level even if it's new, get a manual for the carb, you're gonna need it,
Give us a shot of the carb installed on the engine.

 

[forango]

Attached are pics of both sides of carb..one downside of this carb is there are no sights on the sides of the float bowls..It is a fairley new carb, I had it on my old engine untouched..the only parts I have tried adjusting are the idle screw and the red spring that attaches tot he throttle, but set that back where I started.

I do have a spacer under the carb, I replaced the gaskets it came with higher waulity gaskets...the 3rd picture is the gasket that was under the Edelbrock the engine came with...Maybe I should go with a Holley version of that?

 

[forango]

Hook a vacuum gauge to it, when you're working with a carb'd setup you are basically the computer, you need to verify the base timing and advance setting, is the carb new? No matter, I suspect you have a vacuum leak, is there a spacer under the carb? Using the correct gaskets between the carb and manifold and/or spacer.
Verify, I have to write things down, Yeah I'm easily confused and dealing with a carb'd setup can get, lets say daunting?
You should check float level even if it's new, get a manual for the carb, you're gonna need it,
Give us a shot of the carb installed on the engine.

As far as setting idle and timing, so far the only timing the engine has run at "properly" is 18 degress...that is a bit extreme right? Just not sure if that much timing could hurt anything

 

[limp]

You need to get your idle down to set your timing...
Spray some wd40 around the gasket base and any other possible vacuum leak sources, that includes your power brake lines and the vacuum tree if you have them..... If the idle changes you have found your vacuum leak..
Why did you change your Carb? Was this doing this before the carb change? I would like to see the fuel pressure below 6 lbs maximum....

What are your plans for the car?? Street or strip?

 

[forango]

You need to get your idle down to set your timing...
Spray some wd40 around the gasket base and any other possible vacuum leak sources, that includes your power brake lines and the vacuum tree if you have them..... If the idle changes you have found your vacuum leak..
Why did you change your Carb? Was this doing this before the carb change? I would like to see the fuel pressure below 6 lbs maximum....

What are your plans for the car?? Street or strip?

I tried spraying some carb cleaner in those areas, but with the idle roaring at 1500 rpms it was hard to hear any real difference.

The carb that was on the engine was old and I had just bought the Holley so it seamed like the logical choice to change it out..I have neve rhad much luck with Edelbrocks also...Whether it was doing this before the change it is hard to say.,..when I bought the engine I saw it run on a stand for a short time but not sure what the rpm idle was or any of that....I also changed stuff like the fuel pump etc.

As for plans it will just be a street vehicle but I will definitely be having som e"fun" with it. It is actually in my 78 F100 truck...I am currently in between Mustangs...but the engine is from an '89 fox coupe.

 

[limp]

Well, you need to get that idle down somehow....
If you try to idle it down and it won't, that usually is a vacuum leak or possibly a too big a cam that will not idle down?
No experience here with this cam? Anyone else have any??

Can you remove and plug or cap all vacuum sources from the intake manifold? This should eliminate any other items besides the engine..

Try removing the throttle linkage.. Keep the return spring on though.... Something might be hanging up in the linkage...

As the General said, are the floats adjusted? Is the holly new? have you taken off the float bowls and blown out the orifices and made sure its clean?
Too high a fuel pressure can by pass the needles causing too much fuel to by pass, same with incorrect float height.... If I " recall" max fuel pressure is 6 lbs... Try to adjust it below that...

Is the carb coming off of fast idle? The fast idle cam is a bit sneaky on Holleys..... Mine is under the choke... Looks like your choke is hooked up to power... Is it full 12 volts? Most newer carbs want a full 12 volts, the wire from the alternator that heated my original carb choke is 7-8 volts from what I have read..

Do you run a PCV valve? Do you have a vent in the opposite valve cover? Have you pulled out the PCV valve when its running?

Just tossing out things here...... If nothing seems to work, you might see if someone put the cam in retarded or advanced?

 

[forango]

Well, you need to get that idle down somehow....
If you try to idle it down and it won't, that usually is a vacuum leak or possibly a too big a cam that will not idle down?
No experience here with this cam? Anyone else have any??

Can you remove and plug or cap all vacuum sources from the intake manifold? This should eliminate any other items besides the engine..

Try removing the throttle linkage.. Keep the return spring on though.... Something might be hanging up in the linkage...

As the General said, are the floats adjusted? Is the holly new? have you taken off the float bowls and blown out the orifices and made sure its clean?
Too high a fuel pressure can by pass the needles causing too much fuel to by pass, same with incorrect float height.... If I " recall" max fuel pressure is 6 lbs... Try to adjust it below that...

Is the carb coming off of fast idle? The fast idle cam is a bit sneaky on Holleys..... Mine is under the choke... Looks like your choke is hooked up to power... Is it full 12 volts? Most newer carbs want a full 12 volts, the wire from the alternator that heated my original carb choke is 7-8 volts from what I have read..

Just tossing out things here...... If nothing seems to work, you might see if someone put the cam in retarded or advanced?

I will try that with the throttle linkage and leaving on the return spring..but without being able to give it a little gas i am not sure it will fire easily.

As faar as the cam being too big to idle..I am not sure what that means exactly, from what I have seen this cam is comparible to a Ford E303

Maybe the fuel pressure is too high, i figured it might be too low...I will try bringing that down also...as far as the float bowls, there is no sights on the side so I will look into adjusting that...I will also look into that choke voltage, but it shoudl be 12 volts when key ON witht eh wiring I used.

What does that last part mean with the cam being put in retarded or advanced? I know a professional engine shop did the work so I would hope it is installed correctly.

I truly appreciate all the information you guys are tossing out...Where I live I don't have anyone to swing by and help me out liek I used to in these type situations

 

[limp]

I know what you mean... Left all of my gearhead friends I grew up with back in Oregon when I moved to Florida.. I met some people at car shows here when I had my dodge at some shows who wanted me to join their clubs and I just didn't want to get involved with any clubs.... Probably my mistake.

large cams will not idle down very low. I do not think yours is too large, but I honestly don't know.... Again just tossing things out here...

Do you see those large head screws with the slot in them on the sides of your float covers? You remove those ( one at a time) and adjust it so the fuel is at the bottom of those holes.... You need to " blip the throttle" when you do this in between adjusting the floats to get the fuel level correct...
Do the primarys first, then the secondaries next.... When you " blip" the throttle on the secondaries, do not use the throttle but move the secondary butterflies with the linkage or by the lever...... Your raising and lowering the fuel level a few times doing this to make sure its correctly adjusted...

The screw/nut assembly on the top of each float bowl is how you adjust them... The screw is a keeper while the nut is how you adjust float height up and down.. don't be in a hurry here, fuel lever in these float bowls is very important...

Your thinking fuel injection pressure, not carb fuel pressure... All your doing here is filling and keep the bowls full of gasoline, your not pressurizing injectors... 2 or 3 pounds of fuel pressure will pump all the fuel you will need in a 5/16"fuel line.....

I would try the other carb on your engine.... If it solves your idle problem, you know what the problem is.....

Can you start your car then get out and pull off the throttle linkage? Or remove the linkage, pump the throttle by hand twice, then get in and start it before you move back to the engine compartment?

We all make mistakes, and the cam might be installed wrong or you might have an adjustable cam gear that was installed with too much advance...
This is not an easy check, so this is just something to consider....

 

[forango]

2 other things i was just thinking...

#1--this engine was originally mated to a manual trans...don;t think that would have bearing on my problem but wanted to toos it out there

#2--When I installed my vacuum tree into this engines manifold I did so using thread tape assuming that is good enough, but is there maybe a specific type of thread tape I should have used that helps to elimnate vacuum leaks?

 

[forango]

I know what you mean... Left all of my gearhead friends I grew up with back in Oregon when I moved to Florida.. I met some people at car shows here when I had my dodge at some shows who wanted me to join their clubs and I just didn't want to get involved with any clubs.... Probably my mistake.

large cams will not idle down very low. I do not think yours is too large, but I honestly don't know.... Again just tossing things out here...

Can you start your car then get out and pull off the throttle linkage? Or remove the linkage, pump the throttle by hand twice, then get in and start it before you move back to the engine compartment?

We all make mistakes, and the cam might be installed wrong or you might have an adjustable cam gear that was installed with too much advance...
This is not an easy check, so this is just something to consider....

I am in New Smyrna Beach, FL myself...It has been so long since I have tinkered with any carb'd engine that has cam and whatnot installed since I've been driving FI cars for a very logn time now. LOL...and my buddy that could figure this problem out in minutes moved and I lost contact..sucks

 

[limp]

2 other things i was just thinking...

#1--this engine was originally mated to a manual trans...don;t think that would have bearing on my problem but wanted to toos it out there

#2--When I installed my vacuum tree into this engines manifold I did so using thread tape assuming that is good enough, but is there maybe a specific type of thread tape I should have used that helps to elimnate vacuum leaks?

remove this hose and plug it at the intake manifold....

 

[forango]

One more thing I am not sure I mentioned is that before I wloered the timing, the engine idled fine at 18 degress timing...it idled high, but still sounded good and revved fine, it would just die when going into gear.

 

[forango]

remove this hose and plug it at the intake manifold....

It isn't a hose it is the actual vacuum tree...liek an old schoolo metal one..i will get a picture of it

 

[forango]

vacuum tree

 

[limp]

vacuum tree

Hard to tell what that is... Is the brass part installed into the intake... Is this picture sideways?
Remove that entire thing and plug it off... You need to eliminate each area one by one....

 

[limp]

Here is the back of my intake manifold outlet for vacuum to my tree... Its shown open and capped for first start..
The more I " think " about it I think you have a vacuum leak, so baby steps here taking everything out of the vacuum system that could leak from this fitting..
What year is your car? Mine is an 83 and the correct vacuum tree is not made anymore, although I think this newer one would work.. If that was my car I would install a fitting like mine and run a vacuum line to a vacuum tree....

Notice the two black plugs in the lower part of my picture plugging up two vacuum ports... Do you have any open on your intake??

 

[limp]

Here are 3 vacuum ports on the front of my Carb... Do you have them plugged? Mine are capped with a rubber cap.. The second picture shows the small port/capped to the right of the larger port/capped..... Your carb might be different, but you should have at least 2 ports in this area...

 

[General karthief]

Nothing wrong with your vacuum port, everything is limps' post is good, let be add that I believe this issue prolly is a miss-match at the carb base, limps' carb is a different style but same principle, I would start at the carb, 600 cfm is a good size and will work just fine with some 'tuning'. Get gaskets that match your carb, next make sure that spacer is compatible with the carb base, now it's time to flip it over, check the blades are set to the idle slots correctly, the blade should barely expose the slot, with the carb off set the floats, take a straw and blow air through any holes you can, you'd be surprised what todays fuel leaves behind when dried up
With matching gaskets and spacer you can bolt the carb back on.
Now we work on this timing issue, that may or may not be THE issue, pull the left (passenger side) valve cover, spin the engine over to TDC of compression on the #1 cyl, balancer on zero, both valves on that cyl closed, rotor at #1 spark plug tower.
Get this far and you're ready to crank the engine.
You need toast for 'tun-a-fish' you need a vacuum gauge to 'tun-a-carb.
Get it to idle, set the timing, now the 'fun' begins.
This eliminates 2 unknowns.

 

[forango]

Here is the back of my intake manifold outlet for vacuum to my tree... Its shown open and capped for first start..
The more I " think " about it I think you have a vacuum leak, so baby steps here taking everything out of the vacuum system that could leak from this fitting..
What year is your car? Mine is an 83 and the correct vacuum tree is not made anymore, although I think this newer one would work.. If that was my car I would install a fitting like mine and run a vacuum line to a vacuum tree....

Notice the two black plugs in the lower part of my picture plugging up two vacuum ports... Do you have any open on your intake??

So I am pretty sure all my intake openings are capped off, However it appears that you used something other than tape to seal yours...What did you use to seal your fittings?

I will also look into a better vacuum tree like that....Mine is literally from 1978 LOL