Re: 2X4 Carb Setup

jmf32 August 4th 2012, 1:29 am

Hi to all,
I wanted to let you know where I am at in this procomp 2x4 with edelbrock 600s.
The car is running fair for having some issues as of now. I do have a vacuum leak at #6 cylinder. it is not a noticeable leak by ear but it is there when sprayed with brake cleaner. I plan on changing the intake gasket ASAP.
Basically my carbs are not metering the fuel low enough at idle, so my idle (due to fuel and air) is too high in rpms to set my timing where i would like. when i try to advance the dist to a normal setting, the engine revs very high in rpms. to give you an idea of how it sounds, it sounds like a drag car at half throttle but my throttle plates are closed.now i am wondering why it is doing this. i did drive the car down the road and the engine responds well with the 2x4s. At WOT, the engine comes on strong but my overall advance is purposely set retarded for now to get an idle that is low enough for the street.that may be due to the vacuum leak. i am hoping that after the gasket change, sealing the vacuum leak will let me actually use the actual idle stop screw on the side of the carbs. thanks

jmf32 August 4th 2012, 2:09 am

Here are some pictures of the 2X4:

http://www.dropshots.com/zoom.html?large=http://media9.dropshots.com/photos/1030798/20120801/b_224355.jpg

http://www.dropshots.com/zoom.html?large=http://media11.dropshots.com/photos/1030798/20120801/b_224459.jpg

res0rli9 August 4th 2012, 6:47 am

Link No Workie

jasonf August 4th 2012, 10:36 am

Strange.I can get the links to open in a different page but I can't get them to post....

edit: figured it out. what a weird picture site.

2X4 Carb Setup - Page 2 B_224355

DFI429 August 4th 2012, 10:55 am

kim wrote:On the edelbrock carbs, the fuel mixture screw is an air bleed, the fuel flow is preset. So turning the screw in, makes it richer. To reduce the fuel your going to have to change the jet and the mixture rods.

Pretty sure the OP knows this already, but the above is COMPLETELY wrong. Edelbrock/Carter AFB carbs do not have idle air mixture screws... they are fuel-regulating. And changing the rods & jets will only affect the mixture when the throttle blades open. These aren't motorcycle carbs Rolling Eyes

http://www.edelbrock.com/automotive_new/misc/tech_center/install/1000/1405_manual.pdf

EDIT: The setup looks good, BTW Cool

rmcomprandy August 4th 2012, 12:39 pm

jmf32 wrote:hi all,
i have got the procomp 2x4 intake running today. the edelbrock carbs were each tuned in on my old torker intake over the weekend. they were dialed in so i put them on the procomp and hooked them up. my timing was already set at aprox 36 degrees. i didn't have to move the distributor. i slid the intake on from the back to the front. it bolted up fine and i started it and noticed an immediate high idle with the procomp so i backed the idle screws out and it still idled fast. sorry no rpm gauge but it was fast. in fact the idle circuits do nothing right now and the idle screws are all the way out so i retarded the timing a little to get an aproximate 1000 rpms and the car idles fine now but i need to see where the timing is at now. i am in the process of tuning the set up now but it is overall running fine. i need to see where the timing is at before i continue tuning it. so far so good. i do have the carbs to open same time. i will post back as i tune with it. note: when i retarded the timing, the manifolds now glow orange at idle but as i advance the distributor it goes away but idles too fast. it is a non vac dist but i do have a msd adjustable timing dial on the dash to control some of the timing.

IF the carbs are completely closed and it still idles to fast ... idle airflow is entering the engine from SOMEWHERE.
Find the vacuum leak source before going any further;
Carb base gaskets not sealing everywhere, an open hole(s) not noticed, leakage around the manifold ports ... SOMEWHERE. Even right through a porous casting.

jmf32 August 4th 2012, 8:57 pm

I really appreciate the replies concerning my problem.
I am waiting on a 3/8 NPT tap for the waterpump bypass hose. then i will change the intake gasket and try it.
the primary circuit on the carbs uses vacuum plungers that pull the metering rods into the jets. i did put longer metering rods in with the lightest(3" vacuum) blue springs hoping vacuum would close the jet somewhat. it didn't help it from revving. the carbs worked perfect ran as single on the torker. i mean perfect as far as adjusting then each one was put on the 2x4. it has to be the leak that i previously found at #6 cylinder and maybe another.
thanks for putting up the pics. i started thinking that it couldn't be done.
thank you

466cj August 4th 2012, 11:19 pm

The metering rods have no affect at idle. I'd suggest you put them back to what worked before. Best thing for you to do is stop messing with the engine and fix the vacuum leak. The last thing you want is to damage your engine - get the hint???

When you take the intake off check the port flange with a straight edge. I would not be surprised if it is not flat. Also lay the intake on the heads without the gaskets and make sure the angle is the same on the intake and head meaning no gap at the top or bottom. If either condition exists you will need to get the intake corrected. Yes we all know a new intake should not have these type of problems, but Pro-Comp is known for poor machine work.

jmf32 August 5th 2012, 2:38 am

I changed the intake gasket and found a hole on the intake in the cast between #6 and #7 runners. about a 1/4" long.
it looked like where it had been cast. it was large enough to see light through to the inside. i sealed the hole with silicone for now but i will probably drill it and plug it. i did put silicone on the inside of the intake also where the hole is. if you have any suggestions to fix the hole, let me know.
i did put the original known good metering rods and springs back in also.
when i started it, the engine idled down to normal so it should be good to go as far as the carbs go.
i will post back tommorow with pictures of the hole and location as it may be a problem spot on many of these intakes.
also the hole on the outside was about a 1/2" different from the hole on the inside but it is the same hole. i was able to spray brake cleaner through it with the red straw thing on the brake cleaner can.

69F100 August 5th 2012, 2:57 am

if it was me i would be sending it back and having them send me a new one

jmf32 August 5th 2012, 3:11 am

here are pictures of the hole:

http://www.dropshots.com/zoom.html?large=http://media11.dropshots.com/photos/1030798/20120804/b_225341.jpg

http://www.dropshots.com/zoom.html?large=http://media11.dropshots.com/photos/1030798/20120804/b_225245.jpg

here are the holes that i drilled and tapped for the waterpump bypass hose and heater hose

http://www.dropshots.com/zoom.html?large=http://media10.dropshots.com/photos/1030798/20120804/b_224518.jpg

here is a plug that i made on the back. i have no idea what this hole is for. i had to make a plug for it by cutting a slot in a huge coarse thread bolt. way more course thread than a NPT pipe thread plug. Does anyone know what this hole is used for?

http://www.dropshots.com/zoom.html?large=http://media11.dropshots.com/photos/1030798/20120804/b_224501.jpg

BTW only the large center plug needs plugged. the two smaller bolts do not need to be in there. the smaller bolt holes are not common with the inside plenum

jmf32 August 5th 2012, 3:16 am

here is my temporary fix. silicone inside and on the outside. do you think the silicone will be ok being where it is at? it should be as strong as a vacuum advance hose if you know what i mean. any suggestions?

http://www.dropshots.com/zoom.html?large=http://media11.dropshots.com/photos/1030798/20120804/b_230012.jpg

jmf32 August 5th 2012, 4:16 am

i also wanted to point out that i think that i had a gasket leak at the top of the #6 runner. i am not sure but on the inside of the intake, there was a dark stain that looked like air was being sucked in at the top. maybe it was my brake cleaner when i tested it. i should have took a picture of it.sorry

69F100 August 5th 2012, 6:49 am

If you going to keep it I would have someone weld it up or JB weld it the RTV will not stay your gas will eat it up and you will have a leak again.Well forget having it welded up aluminum has to be super clean before you can weld it and make it look good with the rtv in the crack it want weld up right.

dfree383 August 5th 2012, 10:03 am

Get the Blue Thunder intake and be done with it.

rmcomprandy August 5th 2012, 10:48 am

jmf32 wrote:here is my temporary fix. silicone inside and on the outside. do you think the silicone will be ok being where it is at? it should be as strong as a vacuum advance hose if you know what i mean. any suggestions?

http://www.dropshots.com/zoom.html?large=http://media11.dropshots.com/photos/1030798/20120804/b_230012.jpg

Silicone was a bad idea.
Gasoline vapor will turn it to jelly and now the aluminum manifold surface is impregnated so, epoxy probably won't adhere without a lot of preparation.

That rear hole looked to be a flanged hole with hold-down bolts above and below the hole.

466cj August 5th 2012, 1:39 pm

That is a casting defect. If you cannot get a replacement I'd grind out the silicone plus some to make sure it is all gone and have it welded.

jmf32 August 5th 2012, 4:10 pm

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. as far as the idle is concerned. the idle circuit i am guessing is still letting unwanted fuel to the engine. i would still like to lower the idle. right now it is probably 1500-1800 . i would turn it down but i can't. i do see an idle jet on the edelbrock diagram that was posted in this thread. i am going to the edelbrock link next to see if i can do anything with the idle jet. i drove the car just now and it is running as strong as i expected it too.just super fast idle. that may be normal for 2 carbs. any input?

richter69 August 5th 2012, 7:06 pm

pro comp strikes again.........

use jb quickweld on it.

466cj August 5th 2012, 7:34 pm

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. as far as the idle is concerned. the idle circuit i am guessing is still letting unwanted fuel to the engine. i would still like to lower the idle. right now it is probably 1500-1800 . i would turn it down but i can't. i do see an idle jet on the edelbrock diagram that was posted in this thread. i am going to the edelbrock link next to see if i can do anything with the idle jet. i drove the car just now and it is running as strong as i expected it too.just super fast idle. that may be normal for 2 carbs. any input?

The edelbrock carb is basically the old Carter carb. and has been around since the 1950's. I'd seriously keep looking for a vacuum leak. If not make sure the throttle plates are closed down all the way on the secondaries and adjust the idle speed on the primaries. If you put the throttle plate up to a light should be no light shining through. If there is then the plates may no be properly seated in the bores.

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.

jmf32 August 5th 2012, 8:26 pm

[/quote]

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.

[/quote]

Thank You, I will check around the intake again

jasonf August 5th 2012, 10:38 pm

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.

jmf32 August 6th 2012, 7:58 am

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

Wayne Pearce August 6th 2012, 11:11 am

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

jmf32 August 6th 2012, 11:33 am

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

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