2X4 Carb Setup

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As for the idle mixture screws turn them all the way in (clockwise) and back them off 1/4 turn and adjust from there. I'd also make sure your timing is set correctly. If the idle screws do not respond you still have a vacuum leak. Personally I think you still have a leak someplace.

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Thank You, I will check around the intake again

jmf32 wrote:Thank You for the replies.
I will clean it up there at the hole with a die grinder and weld a small bead across the hole.

Why would you waste time fixing a new intake. The item is clearly a POS. Send it back now before you grind on it and void any warranty you might have chance of getting.

Why would you waste time fixing a new intake. The item is clearly a POS. Send it back now before you grind on it and void any warranty you might have chance of getting.

Thanks for the suggestion. I would have sent it back for warranty but I have also drilled and tapped it for my heater hose and waterpump bypass hose. Warranty is already void. The hole isn't an issue anymore. it is sealed. A small tack weld is all that the intake needs to be permanently fixed. The machine surfaces on the intake appear to be as good as any that I have seen. The casting is not the best for sure but the manifold is working fine on the car except for a super fast idle that i cannot lower other than retarding the distributor. Today I am going to check very thoroughly for any small vacuum leaks that I can find. If there aren"t any leaks then my fast idle problem is in the carbs. BTW, I was able to advance the distributor at idle last night. It is at 10 degrees BTC at idle.I will post back later today with more detailed information.Thank You

I can't help wondering if one or more of those "mystery" bolt holes has been drilled on the upper side of that manifold has opened up an intake port? Worth a check, put a piece of tape on each one of them, see if it makes a difference.

Wayne (SAWDOFF) Pearce

Thank You
On top of the manifold, there is another complete set of carb stud holes for each carb but they are plugged at the bottom.
I will plug them to be sure.
I am plugged at the back of the intake. New soft carb gaskets. No leaks on the carbs. The carbs are plugged front and rear. I will spray the intake runners with brake cleaner and be back here shortly.
Thank You

Hi,
I am back from checking the intake for leaks. I had leaks at every runner this time due to a port mismatch. The intake was leaking badly at the corners of the square ports on the intake. The gasket intake holes are round so obviously the corners leaked. Actually this problem had occurred since I had found the casting hole earlier. If you read back where this thread started, I had originally reused my old intake gasket with permatex and it did seal but I had a hole in the intake. This time I did not use permatex and used a stock 460 manifold gasket.The standard gasket cannot seal properly due to the high square ports on the ProComp manifold. The only solution to remedy this was with a Cobrajet intake manifold gasket with the large openings. I found one on the shelf and I have just put it on. I have to return to work so I will post my results soon. Thank You

Well, no more vacuum leak and the car is finally idling at a lower rpm now. It is still idling fast for my liking. I did find that my throttle plates were slightly open. There was another idle screw underneath the linkage that I never saw until now. i turned the screw out on each carb. it helped a little but i cannot believe that i cannot make the engine stall by adjusting carbs. if i retard the timing it will stall. There is no vacuum leak. I can spray the brake cleaner heavily on the ports and all is good there. why a super fast idle? the "0" white timing mark on my balancer is aprox 1" from the pointer at idle.

You have two things for setting the idle. The idle screw which opens/closes the primary throtle plates and the two idle mixture screws in the front that control the idle mixture. If you turn the idle mixture screws all the way in you should be able to stall the engine by making it too lean unless the primary throttle plates are open too far and getting into the transfer slots. I seem to recall you tied the primary throttle plates together. Try disconnecting the linkage, but leave the returns springs on and turn out the throttle plate idle screw on each carb. Keep in mind you have double the "air leak" area so is to be expected will need to close 'em down some.

As for the timing, Disconnect the vac. adv. for the moment and put a timing light on there and set the idle at 10 deg. BTDC. at about 700 RPM.

466cj wrote:You have two things for setting the idle. The idle screw which opens/closes the primary throtle plates and the two idle mixture screws in the front that control the idle mixture. If you turn the idle mixture screws all the way in you should be able to stall the engine by making it too lean unless the primary throttle plates are open too far and getting into the transfer slots. I seem to recall you tied the primary throttle plates together. Try disconnecting the linkage, but leave the returns springs on and turn out the throttle plate idle screw on each carb. Keep in mind you have double the "air leak" area so is to be expected will need to close 'em down some.

As for the timing, Disconnect the vac. adv. for the moment and put a timing light on there and set the idle at 10 deg. BTDC. at about 700 RPM.

As of right now, the throttle plates are covering the transfer slots leaving none of the slot exposed. I even double checked after that I found the other idle screw underneath the linkage. I backed that screw out all the way to the point that the plates start actually rubbing into the throttle bore of the carb. I tried stalling the engine by turning the idle mixture screws all the way in. No Luck. I think that each carb is treating the other carb as a vacuum leak if you know what i am trying to say. Thank you

So how low an idle speed can you achieve? What I can say is each carb now needs to meter 1/2 the air and fuel it had to before, but something still just don't seem right here.

Hi, I found the reason for the high idle. On the 2nd carb, the primary throttle plate linkage was actually hitting the intake manifold. I can't believe that I did not see it earlier but it just wasn't really noticeable.The linkage appeared to be closed at a glance. I raised the 2nd(rear) carb up with a Moroso 1" spacer to fix that. The front carb does not hit the intake anywhere, just the back one will hit the carb mounting pad.The car is idling at 950rpms now. Fully adjustable.Idle mixture is set to the highest possible vacuum at idle which is around 12". Timing is cinched down at 36 degrees total. The 2X4 intake with the edelbrock 600s really makes the engine run better everywhere in the powercurve compared to a single 750 edelbrock . It is very smooth off idle with power all the way through. I noticed a big difference in lowend torque and just more power at any speed. I am very satisfied with the power. Thank You

Glad your got it working have fun

Good see you got it sorted out. Sometimes is like peeling away the layers of an onion. I am a bit surprised it runs that good considering it is such a short runner open plenum intake. May just be worth taking a closer look! Steve

A couple of things threw me off. The casting hole right off the bat. Then replacing my original intake gasket with a standard 460 type was next.Then the throttle linkage hitting at idle on the rear carb. I haven't changed the jets or metering rods from stock. I did adjust both carbs accelerator pumps to maximum setting which is the hole closest to the carb. I know that I can make the carbs richer now for more power but it is making more power than I ever had with a single 4150 type carb. The engine sounds better, it is smoother, and it idles the same as before also. it is just moving more air. I did invest in some good quality linkage when I bought the parts and I am glad that I did so that I can adjust it. I found that to be a real time saver plus it is safe as you know how much damage can be done when the throttle is stuck wide open. I used the 1/4" NPT hole in the back of each carb to install the meth/water fittings and tapped the bottom side of each carb(1/8") to install the nozzles so that the 2 nozzles are spraying into the plenum. I use the meth/water to prevent detonation on pump gas. It does work.My timing has ended up at 32 degrees with a non vac distributor but I am not dead set on leaving it there.I want to be at 36 degrees once the meth/water vacuum switch is set properly.

What linkage did you use? I plan on running two Carters on a tunnel ram and still need to pick up the linkage.

Jess

I bought the linkage from Eelco. It is high quality for around $75.00. The kit had every part that I needed.
Here is a link. I bought mine on Ebay along with the carbs and manifold. All separately. I have $650 total in my 2X4.

http://www.eelcoequipped.com/index.php?cPath=24_28_57&osCsid=p578ng8nrghuv801ad276u29f7

BTW: click on carbuetor linkage

UPDATE ON PRO COMP 2X4 INTAKE. I WENT TO INSTALL A 1/2" PIPE PLUG IN THE REAR OF THE MANIFOLD,WOULDN WORK ! I HAVE TO GET MY 1/2" NPT TAP OUT AND THREAD IT. THE THREADS INSIDE FROM THE FACTORY ARE JUST ROUGHED IN AND FAR SHORT OF BEING ENOUGH FOR A PLUG-FITTING ETC. WONDER WHATS NEXT TO DISCOVER ?

I threaded that hole in the back with a bolt type tap. i want to say that it was 7/8" course thread. I then cut a piece of bolt
aprox. 1" long and cut a slot in it so that I could tighten it. I used liquid tape(from walmart auto/electrical section) on the threads to keep it tight.
It has not moved. I am not recommending this but this is what I did to seal that hole and it did work.

it may have been a 3/4" bolt. can't remember exact size.