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edelbrock 2-4 tunnelram rich out of box bbc

  
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edelbrock 2-4 tunnelram rich out of box bbc

 
jim Grover jim Grover
New User | Posts: 1 | Joined: 11/13
Posted: 11/08/13
03:22 PM

I installed edelbrocks two four t-ram with two 600cfm carbs 432 bbc pocket port
comp valves lunati 577-600 lift mech flat tappet cam 11-1 piston too rich at idle
need help already two sets of plugs fouled regulator at 5psi  

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 11/08/13
03:38 PM

Hi there,
Is there any fuel over running the squirters at hot idle?  
skyeking

wayne712222 wayne712222
User | Posts: 198 | Joined: 10/13
Posted: 11/09/13
04:55 PM

skyking is right.. use a mirror and look down the carb throats.. see if at idle. there is any fuel pouring over out of the booster nozzles.. there should NOT be at idle..  there should only be fuel coming out of the boosters when the throttle is open and the carb is operating on the main jets..above.. 1400 rpms.. if you have fuel dribble.. you might have dirt in the needle and seat.. a leaking oring on the needle and seat.. or a misadjusted float...  or even a sunk float.. anything and everything is possible...


i posted this over at cc



a few things... both carbs have to have the idle transition slots covered.. so back off the primary idle speed settings.. or flip the carb over and hold choke open and adjust throttle blades on both primaries ...

Idletransitionslottuning Zpsae2722d8

which model carbs did you get..  carb number...

once in a while.. they are equipped with a hidden idle air bypass screw under the air cleaner stud..  

look at this image... with the throttles closed...  you have to be supplying fuel only thru the idle circuit that dumps below the throttle plate..

or you will be TOO RICH...

Holley Atidle Zpsbdbaea76


below is probably whats happening with your engine...

the idle speed setting is exposing too much idle transition slot and flooding the engine..

Holley Off Idle Zps85779e58


to increase idle speed.. you will need.. depending on the carb.. to either open the idle air bypass under the air cleaner stud.. you can see that in the middle image above..  you can open the secondary throttle blades slightly.. there is a secondary idle stop screw...  you can create more of a vacuum leak with a a PCV Valve... with a filter on it..  

i mentioned on the other forum post.. about either using a fine pitch metering valve with a filter.. so you can easily control the idle air bypass and the idle speed..


as for a street tune.. hmm...

get it to idle first... without fouling the spark plugs..

next.. do you have an oxygen sensor bung in the header collector.. or room to bolt in a spacer thats threaded for an oyxgen sensor.. so you can use at the collector a 3 wire 94/95 chevy pickup 3 wire oxygen sensor and a narrow band air fuel ratio display..  or the bucks to invest in a wide band set up.. so you can see what the air fuel ratio is doing as you change the engine RPMs..

there are several circuits you are going to be dealing with .. before you start changing primary main jets...

the idle mixture screws..

the idle transition fuel restrictions..

the primary main jets..

but you will also be working with the accelerator pump cams.. and the accelerator pump shooters..

then the power valves.. that are set by what the good running vacuum is... half the manifold vacuum.. is where its usually set at..  might be slightly different for a tunnel ram...

when you come off idle slowly..  the primary throttle blades expose more of the idle transition slots and start pulling fuel from those..  via the IFR.. idle feed restriction..  this is before you have the throttle open far enough to get fuel out of the primary boosters..

there is also .. a LOT of plenum volume to enrich the fuel as you open the throttle.. so its going to be a challenge..  

larger shooters... faster accelerator pump cam opening.. again.. watching the air fuel ratio display.. to see if you are going lean or going rich...

this way . you don't have to pull the spark plugs.. and that is only how you tune the primary and secondary main jets for wide open throttle calibration..



600 CFM Four Barrel Street Carburetor
PART #: 0-1850C

1 timed (spark) port, 1 full vacuum, and 1 PCV port

hmm... PCV ports...

and 1 full vacuum port in each...

hmm...

well.. if you want to try something..  do you have access to grainger???

you could get some 90 degree elbow PCV vacuum hoses .dorman 46001 or 46002. run them into some 3/8 hose barb x 1/4NPT fittings..  and a 3/8 hose tee.. to one of these.. or one of each..

punch the part numbers into grainger..

Needle Valve,Straight,Brass,1/4 In.
Item # 6MN30
681804 300
Needle Valve, Straight, Body Material Brass, Pipe Size 1/4 In., FNPT x FNPT Connection, Stem Type Brass, Seal Material Metal, Handle Material Steel
GRAINGER APPROVED VENDOR
6MN30   $9.60


Needle Valve,Straight,Brass,1/4 In.
Item # 6MN32
Needle20valve
Needle Valve, Straight, Body Material Brass, Pipe Size 1/4 In., FNPT x MNPT Connection, Stem Type Brass, Seal Material Metal, Handle Material Steel
GRAINGER APPROVED VENDOR
6MN32 $10.17

these should allow you to adjust the idle speed and keeping your primary and secondary throttle blades as far closed as possible...

its worth a try...  if it works.. put a crankcase breather filter on the inlet..


or PCV valve on one.. and the metering valve on another.. so you have some fine tuning...

OH... and these would be for a TEST... until something clean looking could be figured out..    a hose clamp squeezing down on a  hose would do the same thing..  change the amount of air bypassing the throttle blades..  to keep the idle transition slots covered the proper amounts..


and a huge question to the other CHP forum members..

has anybody else attempted their own idle air bypass on something like this..

since holley did not install the center idle air bypass screws on most carb models..

i cannot even find which ones they did it on...

and i don't know.. of the top of my thinking cap.. if the grainger needle valve will have enough flow.. i know they have a fine pitched screw thread for tiny adjustments..
 

wayne712222 wayne712222
User | Posts: 198 | Joined: 10/13
Posted: 11/09/13
05:35 PM

this is the link to the thread i was mentioning over at the CC site..

http://forums.chevyhiperformance.com/70/9509912/chevy-high-performance-magazine/385-sbc-running-rich/

thought you might have missed it..


EDIT UPdate..

jim posted over at CC that he reset the idle mixture screws to 2.5 turns and managed to find the chokes had snapped shut... installed a wire to hold the linkage open..

all is good..  

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 11/10/13
04:01 PM

Well done OLDE Chap!!
How is is with you in L>A>??
ORL the best Pal.  
skyeking

Dave632 Dave632
Addict | Posts: 2220 | Joined: 07/08
Posted: 11/11/13
06:43 PM

Wayne that is a good idea as I never found any way to cure the excess idle transition problem except by drilling holes in my Holley carb throttle plates. I would surely give that a try if I was building an engine today.
Barry Grant carbs are the only ones I know that have that adjustment and even there the older ones did not have it.
I had the same problem the original poster had on every engine I put a wild cam in. The only way you can get the engine to idle is by opening up the idle adjustment quite a bit and therefore uncovering the idle transition slot too much.
I ran tunnel rams on most of my race motors and had the same trouble. Fouling plugs at idle and low speeds. I only found one cure and that was by modifying the throttle plates.  
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skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 11/12/13
03:52 PM

Laugh Hi Dave,
 What is teh bore and stroke of your 632 and what
 carby are you using for general purposes Confused  
skyeking

wayne712222 wayne712222
User | Posts: 198 | Joined: 10/13
Posted: 11/12/13
06:32 PM

i have been thinking of something else.. building a PCV flow testing machine.  so i will know which ones flow just how much at various vacuum rates..  this would be a huge help to people to let them use a PCV as a calibrated air bleed..

since the flow is dependent on the vacuum applied...

low flow at high vacuum   increased flow at reduced vacuum..  this could be the cure to needing to drill the throttle plates if there is no idle bypass screw.

i found a while back that at normal idle speed... that a properly sized PCV valve.. when you block the flow.. the engine should drop RPMs between 50 and 70 RPMs..

there is just NOT any reason that we cannot idle a tunnel ram engine without worrying about fouling the spark plugs..  as long as we can get enough idle air bypass going to let us keep the idle fuel coming only thru the round idle feed ports where the idle mixture screws control the idle mixture..  instead of the idle transition slots. where there is TOO Much fuel for a nice lean idle..  

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 11/13/13
09:05 PM

Hi Guys,
sorry to bust the post.,
 I don't hav e to worry about the lung tumor
 anymore as I have a duo o brain cancer tumors
 ready to have a real advanced shot at the TITLE.
 NOT Goodbye but Standby Amigos.Good Knowing U  NOEL  
skyeking

Dave632 Dave632
Addict | Posts: 2220 | Joined: 07/08
Posted: 11/13/13
09:39 PM

Icon Quoteskyeking:
Laugh Hi Dave,
 What is teh bore and stroke of your 632 and what
 carby are you using for general purposes Confused


Noel I had 2 632s both were in my last 2 race cars. The first was in my Beretta which was a Pro Mod. The second was in my 68 Camaro which was a back half car. The bore was 4.60 while the stroke was 4.75 in both. Both engines ran good, the Beretta had a sheet metal tunnel ram with two Holley 1150s on it. Ran 5.07 in the 1/8th on motor which is high 7s in the 1/4. The Camaro had a single King Demon which was rated at 1250 cfm. It was much slower but still quick at low 9s in the 1/4 on motor.
Sad to hear about your medical troubles, hope things get better for you.
Dave  
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skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 11/15/13
01:59 AM

Hi Dave,
I would not dare ask about fuel consumption for the big efforts.
Thanks for the reply..Now have 2 MAJOR battle fronts and the Alamo
 is getting closer and very real...All the very to all the guys.,  
skyeking

Dave632 Dave632
Addict | Posts: 2220 | Joined: 07/08
Posted: 11/16/13
02:44 PM

Icon Quoteskyeking:
Hi Dave,
I would not dare ask about fuel consumption for the big efforts.
Thanks for the reply..Now have 2 MAJOR battle fronts and the Alamo
 is getting closer and very real...All the very to all the guys.,


It was good on gas if you compare it to a 747. About 5 gallons to the mile at the track.
Wish you well my friend, keep fighting.  
[[SUPPORT AMERICAN CARS, STOMP A RICE CAR TODAY.]]