Not running after porting & CAI

[CDN OpelNut]

First the good.

I finished the matching of my SSD manifold to the carb barrels as detailed in another thread.

Today I finished my cold air intake as pictured below. All good so far.

Now the bad.

The car ran when I pulled it in to the garage. Idled fine and cruised at top speed well. Low speed driving was a little jerky and I planned to change the idle jets after I finished the last two upgrades.

Now, the car started fine and idles OK, but when I give it throttle, it basically revs to about 3000 rpm and then bogs and/or dies, especially under load.

So, for you experts, could the changes I made with the porting and CAI make so dramatic a difference? I'm not talking small effect, I'm talking undrivable!

This is on my 2.4 with the DCOE45. The jets I started with are:

• Choke 32 mm
• Aux venturi 3.5
• Emulsion tubes F2
• Main jet 145
• Idle jet F8-50
• Air corrector jet 200
• Needle valve 225

I was looking forward to this drive. It's been weeks!

[GTJIM]

If you put the carb aside with fuel in it and that dried pout the emmulsion tubes may be clogged up with white powder = pull one and check the holes and the jet.

[CDN OpelNut]

Well, I pulled off the cold air intake and then set up the carb again. It seems to run OK now.

Any chance that the CAI doesn't flow enough air? Seems unlikely as a 3" intake supplies some high HP cars. Filter maybe?

I'll put the CAI back on tomorrow and then try again. I don't want to waste all that time!

BTW - The tubes and jets had no crud in them but the drilling on the tubes was pretty rough so I cleaned that up.

[Redskinsjbs]

When it revs to 3,000 and beyond, how fast are you getting there? Does it bog right away or simply when it is above that rpm? If it is right away, it is most likely the accelerator pump circuit. If it is simply when it is above that rpm, you will most likely have to re-jet to get the fuel-air mixture right in the top end.

HTH

[wrench459]

What's the A/F ratio at 3 grand?

[MICAH1]

Not any experience with a weber side draft, but what you seem to be describing along with what Jay said is fuel starvation????

The cold air intake is right on with the filter placement, and three inch airway from the carb opening and tube.

This is right up Otto's alley.... he has this setup!!!!! Talk to the MASTER!!!!!

[ggl]

Originally Posted by CDN OpelNut Well, I pulled off the cold air intake and then set up the carb again. It seems to run OK now. Any chance that the CAI doesn't flow enough air? Seems unlikely as a 3" intake supplies some high HP cars. Filter maybe? I'll put the CAI back on tomorrow and then try again. I don't want to waste all that time! BTW - The tubes and jets had no crud in them but the drilling on the tubes was pretty rough so I cleaned that up.

I'm looking at the pics of your air box and wondering if the rear port on the carb is getting much air at all

I would attach just the air box and try a quick run, then add the hose and do a quick run and finally the filter for a quick run and see when the problem comes back

[CDN OpelNut]

Originally Posted by Redskinsjbs When it revs to 3,000 and beyond, how fast are you getting there? Does it bog right away or simply when it is above that rpm? If it is right away, it is most likely the accelerator pump circuit. If it is simply when it is above that rpm, you will most likely have to re-jet to get the fuel-air mixture right in the top end.

I tried it again this morning. It is definitely worse if I go quickly to WOT. I can sneak up on the RPM with only minor hesitation. Current pump jet is a 45. I may go bigger here.

Originally Posted by Wrench459 What's the A/F ratio at 3 grand?

I wish I knew... I don't have an A/F meter and will have to rely on the plugs when I get to final tuning

Originally Posted by ggl I'm looking at the pics of your air box and wondering if the rear port on the carb is getting much air at all I would attach just the air box and try a quick run, then add the hose and do a quick run and finally the filter for a quick run and see when the problem comes back

I've tried all the combos. Doesn't seem to matter. The rear port is not ideal, but gets restricted air whether with the old filter or horns as well.

It seems to improve as it gets warm. I've the weather dries out today I'll go for a road test and see what happens.

Thanks for the replies so far. keep 'em coming.

Corey

[myopels]

Corey, You might want to get an air fuel ratio guage that works with an oxygen sensor. You have to weld a bung into your exhaust pipe and then screw in the oxy sensor and wire the rest. You could make it temporary and then take it out and screw in a regular spark plug to seal the exhaust hole. Anyway, I ave a similar set-up, and it tells you exactly how lean/rich you are at any time. Find a nice steep long hill, and you will have a poor man's dyno. Be sure to start rich and lean from there- better than burning up your motor. good luck, gerold

[CDN OpelNut]

Originally Posted by myopels Corey, You might want to get an air fuel ratio guage that works with an oxygen sensor. You have to weld a bung into your exhaust pipe and then screw in the oxy sensor and wire the rest. You could make it temporary and then take it out and screw in a regular spark plug to seal the exhaust hole. Anyway, I ave a similar set-up, and it tells you exactly how lean/rich you are at any time. Find a nice steep long hill, and you will have a poor man's dyno. Be sure to start rich and lean from there- better than burning up your motor. good luck, gerold

Thanks Gerold. I have been looking at them. Actually , I Amazon had the K&N one on special last night for $140. I went back tonight to buy one and the price had shot up $80.

I'm looking for a deal, but will get one soon so I can tune it properly. I think maybe the additional airflow may be leaning it out too much now.

Just found this quote on another site... "As a rule, no jet changes are required with just a K&N filter element, however the spark plug condition should be checked for proper mixture after the first few miles of riding. If the airbox has been modified for increased air flow, the main jet size will need to be increased to provide the proper fuel mixture."

Hmmm
C

[bigjim5551212]

it costs money, but I would have 4.5 aux venturi. otherwise, it looks ok for jetting. you didnt have the carbs apart did you? and put the auxilliary venturi in backwards?

[CDN OpelNut]

Thanks Jim,

I have a set 4.5 aux venturies that I can try. I also have the larger main jets you are sending and some idle jets to try as well. My a/f guage is on the work bench and will go in next week.

Between all of that, I should get it purring.

Corey

[wrench459]

I can't help but wonder where in the exhaust will you place the bung?
Hopefully its a wide band A/F and not a narrow band oxygen sensor.
Are you running a long tube header?

[CDN OpelNut]

Originally Posted by wrench459 I can't help but wonder where in the exhaust will you place the bung? Hopefully its a wide band A/F and not a narrow band oxygen sensor. Are you running a long tube header?

I bought an AEM wideband sensor and gauge kit. Looks quite nice and has digital display as well as the led bars.

It does not specify sensor location other than at least 18" from the exhaust ports. However, when I was looking at the K&N site, they said it should go just ater the collector on the header so that is where I am going to put it.


Cheers

[wrench459]

I like to place the wide band in the collector approx. 4-6 inches from the primary tubes. To get the sensor to live a long life mount it high. They don't like any kind of moisture at all.

[tekenaar]

Originally Posted by CDN OpelNut Thanks Jim, I have a set 4.5 aux venturies that I can try. I also have the larger main jets you are sending and some idle jets to try as well. My a/f guage is on the work bench and will go in next week. Between all of that, I should get it purring. Corey

. . . definitely go with the largest AV possible, remember each barrel has to feed two cylinders, 1,200cc in your case, so you want no mixture flow restrictions there at all!

OK, that said, I know you closely followed my CAI setup pictures I sent, but have you tried running the engine with just the slanted airbox removed from the carb adapter plate to determine if there's a restriction at the rear carb throat? Can't really tell from your pics how much of the lip you cut off when fabricating that piece to make it fit, looks OK, but . . . ?

Another observation, actually two, how are you sealing that slanted airbox to the adapter plate? . . . and, do you realize how much heat that glass fuel filter will absorb while engine is running? Small volume inside fuel filter will also exacerbate fuel heating! Better idea would be . . .

[CDN OpelNut]

Originally Posted by tekenaar . . . definitely go with the largest AV possible, remember each barrel has to feed two cylinders, 1,200cc in your case, so you want no mixture flow restrictions there at all!

I'll be methodically changing one thing at a time to get the best results. I started with the smaller AV's for bottom end grunt.

OK, that said, I know you closely followed my CAI setup pictures I sent, but have you tried running the engine with just the slanted airbox removed from the carb adapter plate to determine if there's a restriction at the rear carb throat? Can't really tell from your pics how much of the lip you cut off when fabricating that piece to make it fit, looks OK, but . . . ?

I tried running without any restriction - made no difference.

Another observation, actually two, how are you sealing that slanted airbox to the adapter plate? . . . and, do you realize how much heat that glass fuel filter will absorb while engine is running? Small volume inside fuel filter will also exacerbate fuel heating!

The plate has a good seal - self adhesive high-density foam on the plate edge.

Without the filter, my braided line from the tank isn't long enough! I'll watch it and can remove it if it boils.

Thanks Otto.

Corey

[tekenaar]

Originally Posted by CDN OpelNut I'll be methodically changing one thing at a time to get the best results. I started with the smaller AV's for bottom end grunt. I tried running without any restriction - made no difference. The plate has a good seal - self adhesive high-density foam on the plate edge. Without the filter, my braided line from the tank isn't long enough! I'll watch it and can remove it if it boils. Thanks Otto. Corey

. . . somewhat of a misconception here, Corey. AV size strictly determines maximum mixture flow volume, so you're reaching that point with the current AVs at ~3,000RPM!! . . . verified by this!

Oh, added pic of better fuel filter location to my previous post . . .