Carb has too much idle hole drilled?

[crazypete]

Hey folks, I just got a hold of a 0-80540-1 holley double pumper 600 cfm carb with the 4 corner idle. It was an ebay item but it is so clean, you could eat off it. Only problem is...

It came with the butterflies drilled, I assume for a wild cam of some sort. The thing is, I cant get it to idle any more than a really lopey 500 rpms or a shaking the car 1200 with the pedal in.

Is this way too much for a stock cam or should I be able to compensate with idle screws? The A/F guage reads full rich but it is never accurate anyway..

I DID fog the cylinders (Pour oil in them) after removing the heads and scraping the carbon off the stock pistons. How much should that interfere?

[Rev]

Originally posted by crazypete
Hey folks, I just got a hold of a 0-80540-1 holley double pumper 600 cfm carb with the 4 corner idle. It was an ebay item but it is so clean, you could eat off it. Only problem is...

It came with the butterflies drilled, I assume for a wild cam of some sort. The thing is, I cant get it to idle any more than a really lopey 500 rpms or a shaking the car 1200 with the pedal in.

Is this way too much for a stock cam or should I be able to compensate with idle screws? The A/F guage reads full rich but it is never accurate anyway..

I DID fog the cylinders (Pour oil in them) after removing the heads and scraping the carbon off the stock pistons. How much should that interfere?

What happened to your 670 Avenger? You might try putting it back on to see how it idles. You might also do a temporary repair of JB weld on the holes in the butterflies just to see if that will fix the idle problem with the other carb. Just a couple of thoughts.

Rev

[Dark_5.0]

This isnt quite the same thing but I bought my throttle body used and it had to big of a hole drilled in the butterfly and idled high. I repaired the hole with some epoxy and havent had any trouble since.

[crazypete]

My poor avenger...

Well here is what happened. I was redoing heads and intake so I decided to disassemble and clean the holley. I took it apart until I had 2 blocks, the base and the body free of any small parts. I dropped these into a tub of gasoline and carb cleaner. I tossed in some fast orange and let it sit for a few days, sloshing it up every once in a while. I take it out and I see a little white residue. No problem, I blast hot water at it and reassemble. I put it all together and reinstall and start the car. It is not a happy car!

I think it barfed a cup of gas up through the carb first thing. This burst into flames so that was fun to put out. Then when running, I here the hiss of the intake and I here this kinda "puck puck puck" sound. I go up front and look down into the carb and see one booster like....you know when you have a faucet just barely open it spews water sideways and in circles then dribbles and so forth. Yeah. 3 dead boosters and 1 coughing up gas. I figured that white residue was in the booster channels. I disassemble and lo and behold.. all the boosters are fouled with white mold looking stuff. Like dried sugar.

Soaked in just laquer thinner. No change. I boiled in water and detergent. Even worse white residue. Boiled in just water. No change. Water and silver polish. Now it's really bad.

Aiiieeeee! How can I clean this carb?

Somewhere halfway through this, that wonderful double pumper caught my eye and I went for it!

So should I be able to idle with those holes or am I having another problem? The AF _does_ read really low then really high after a few turns on all four idle screws. Stinks like all hell. Burning oil I think. Thick black smoke. I almost choked on the fumes. The burnt oil behind the car continued to stink for hours afterward so bad I needed to put a boxfan on it so it didnt stink up the whole house.

Could I have insta-fouled all my plugs?

[~The Jester~]

Insta fouled the plugs, and NASTY rich on the carb. What jets are in it? First place I would look. The extra holes in the throttle plates are the next thing to address. JB might work for a temporary "diagnosis" type fix, but we gotta keep things smooth in there. Also check to make sure the secondaries aren't getting sucked open from a weak diaphragm. Or if it's mechanical, make sure the linkage isn't bent. Primaries should open quite a bit before the secondaries start to move. Check the choke linkage for a weak spring, crud, etc etc it might be pulling the choke closed on you too.

Keep us posted bro!

[crazypete]

I super checked the ebay carb since it was...well....a used ebay carb. The secondary mechanical linkage looks really good with a roller bearing. This is a chokeless carb so thats one less variable to worry about. I've always ran without a choke. The secondaries were 72's and primaries 70's but the metering block was stuck with an especially sticky gasket so I figured that the heat and gasoline would loosen it up and I'd check the power valve next week.

For filling the holes, I'm going to use some of the round topped metal screws with the stems cut off (identical to the ones that hold the butterflies on the throttle shaft).

I've heard someone say that you can pour 1/2 a quart of oil down the intake of a running engine to stall it right before storing it for the winter to keep rust off. I figure I did this in effect.

How does one "de-fog" an engine properly and get the oil out other than throttle blipping till it starts running properly?

Any ideas on how to clean the backup avenger?

[crazypete]

Something's still not right.....

I poured gas down the spark plug holes then into the carb-less intake, starter spun it to wash the oil and carbon out, cleaned the plugs, plugged the 4 holes in the carb's butterflies and reseated the carb. I got some gt-40p headers and got the driver's side in definitively but the passenger side is shorter by a 1/4 inch so I have some bashing to do.

Now, I go to start her up and she wont idle....again...sigh.

I pull the idle screws till they are sticking way out of the block and the A/F guage (it got coated in oil earlier so I dont even know if it still works) refuses to even register midline values. The car barely idles at a very sickly 300-500 lopey rpm with the idle screw in to the point where the transfer slot is almost uncovered (The secondary side...the transfer slots are there but not actually cut out...is this normal?). It REEKS of gas so I'm going to have to disagree with the A/F guage.

I checked all 8 wires with a timing light and all 8 are sparking and the timing is 10 degrees.

I checked the vacuum and it is a sickly 2-8 hg's heavily wobbling. I went in and definitively sealed the carb to the intake with rtv.

No change.

I sealed the top of the intake where the heads and intake meet (the front and back are already rtv'ed) with oodles of RTV.

No change

I DO remember when I first put the 1.7 roller rockers in and turned it over the first time, there was a huge bang/whack/pop sound from the passenger side. But that didnt happen at all afterward. I figured the rocker wasnt seated and it snapped into place or the double valvesprings were a bit intertwined and they snapped into place. If I had wacked a valve into the piston, it would have broken off and would continue to make noise as the debris would bounce around inside the cylinder, right?

I think I undershimmed the rockers and have them hanging open slightly. I didnt really adjust them, I just blasted them into place nice and tight and that was that.

Any ideas, guys?

[PKRWUD]

First off, NEVER put RTV silicone anywhere near a carburetor. If you need it to seal the base gasket, you have a much bigger problem that needs to be addressed. There is never a good reason to use silicone on a carb, but there are dozens of reasons not to.

What do you mean 'the secondary transfer slots are there, but aren't cut out?

Forget the A/F gauge, all you need is a vacuum gauge.

Check the compression and see if the valves are closing all the way. If they are, get a can of Brakleen (green can, NOT the red can!), remove the idle mixture screws, and spray the Brakleen into the openings where the mixture screws go. Then spray it into the air bleeds above the boosters. Reinstall the mixture screws, turning them all the way in until they seat, and then back them out two and a half turns. Back the idle speed screw out all the way, and make sure the butterflies are seated. Turn the screw back in until the butterflies start to open, then turn it in two more turns. Remove the sight plugs from the sides of the bowls. Make sure every vacuum port on the carb is capped. Attach your vacuum gauge to the intake. Start it up. Watch the sight plug holes on the sides of the bowls, and make sure the floats are set correctly, then put the plugs back in. Turn the idle speed screw until the rpms are around 800. While watching the vacuum gauge, turn the idle mixture screws, evenly in quarter-turn increments, so that the vacuum gauge goes up. When the gauge will no longer go up, back the idle back down to 800 rpms with the idle speed screw. Then, work the mixture screws again, trying to get the vacuum gauge to go up. When it will no longer go up, and the idle speed is around 800 rpms, turn each idle mixture screw in 1/8th of a turn.

That should take care of everything, assuming your valves are adjusted properly, and your ignition timing is correct.

[crazypete]

I just picked up a compression guage but I'm still at work. What's a ballpark compression reading that I should get?

Brakleen is a an autoparts store item, right? (brake cleaner?)

Luckily the 80540 has no vacuum passages in it's base, just the crossover in the middle and 2 small crossovers on the ends. I flattened the silicone by hand so it wont bulge up when pressed down. Problem is I have a stripped carb base bolt (ds front) so sealing otherwise is impossible.

I can see the little transfer slot "pockets" in the secondary side base when I had the base off. But the slots themselves are not cut out of the pockets on the secondary side.

By the way, PKRWUD, you are _the man_.

[crazypete]

Ok, I finally got outside with a compression tester and I discovered 3 things:

1. Dont touch an engergized coil wire. That wasnt fun, especially with a nice aftermarket coil. Cleared my sinuses

2. I had the right mixture some time ago and am well past it. The plugs were cleaned and reinstalled with the carb when I plugged the idle holes. Now they're black with soot after maybe 3-4 minutes of combined engine running! Absurd rich

3. Compression is consistent though the numbers look a bit low 105-115 psi. The cylinders all hold pressure for minutes (and probably more but I got bored)
1: 115 psi
2: 105 psi
3: 110 psi
4: 110 psi
5: 112 psi
6: 113 psi
7: 110 psi
8: 115 psi
This means the rockers are adjusted otherwise they wouldnt hold pressure (right?)

This has to be an intake leak..... Only reason left for 3-8 vacuum reading. 1 header is aslo disconnected but it wouldnt cause THAT much of a problem, right? I know my car runs like *** when the exhaust is loose but it should idle somewhat!

[PKRWUD]

Originally Posted by crazypete

I discovered 3 things:

1. Dont touch an engergized coil wire. That wasnt fun, especially with a nice aftermarket coil. Cleared my sinuses

I'll have to write that one down so I don't forget.

Originally Posted by crazypete

This has to be an intake leak..... Only reason left for 3-8 vacuum reading. 1 header is aslo disconnected but it wouldnt cause THAT much of a problem, right? I know my car runs like *** when the exhaust is loose but it should idle somewhat!

Your compression is pretty low, but it's consistant. Could be a sloppy timing chain. The waivering vacuum gauge is because the mixture is so bad, but it's still pretty low. What is your ignition timing set to?

As far as your stripped bolt, they can be replaced. You really should fix it.

Try doing the things I described above, and tell me what happens.

[crazypete]

The timing was confirmed at 10 degrees while cranking. I have no vacuum advance. I attached the timing light to each wire and they all produce flashes so all 8 cylinders are firing.

I'll do the brakleen tonight. If that fails, I'll put one pair of stamped rockers back on and check compression on that cylinder. If that fails, I'll pull the intake and reseat it (I removed the intake without removing the distributor)

The compression might be lower because I relieved the valves and smoothed the flash completely off the combustion chambers (and the runners: heads+intake). I probably added a few CC's. Shouldnt that just offset the smaller CC's on the gt-40p's and put me back where I started?

Hey, this carb has screw in air bleeds (they look like jets). Maybe someone messed with the bleeds.

[PKRWUD]

I'll tell you what I think. I think part of your problem is the stripped bolt for the carb. Even if you seal around the edges with silicone, you still aren't sealing between the idle passages in the bottom of the throttle plate, which will screw everything up, and create a vacuum leak. Stripped bolts can be fixed. I suspect you're gonna have problems until you fix yours. I also suspect that the carb may need to be rebuilt, but we won't know until you solve the mounting/stripped bolt issue.

There is a test to find out if the intake gasket is leaking, and it's much easier than removing the intake. I would have sworn I already typed it out for you in one of your threads. If I didn't, let me know, and I'll fill you in.

[crazypete]

I'll go in tonight and pull the carb and threadloc the stripped bolts' tap. It still has threads in it, but you can see the stud rise as the bolt is tightened so they dont hold much. The thread-loc had worked before to hold it down and allow pretty good tighening to take place but I pulled/replaced the carb so much in the last 2 weeks that it came loose again.

I swapped my stamped rockers on cylinder #1 to see what would happen and I was shocked. The compression dropped from 115 to about 102!! This is with carb propped open and no other plugs. I _think_ this is telling me that the ports in the head and intake are too big and I'm having velocity problems.

Quick question for tonight's tuning session: Can a 4 corner idle carb be run like a 2 corner idle carb (put the 2 rear screws in and adjust from the front).

I found an old post with the intake trick. 3-7 psi vacuum while cranking with throttle blades shut. Will do.

[PKRWUD]

Originally Posted by crazypete

I'll go in tonight and pull the carb and threadloc the stripped bolts' tap. It still has threads in it, but you can see the stud rise as the bolt is tightened so they dont hold much. The thread-loc had worked before to hold it down and allow pretty good tighening to take place but I pulled/replaced the carb so much in the last 2 weeks that it came loose again.

Dude. What you need to do is fix it right the first time. Either drill it out and put in a heli-coil, or get an oversized stud. Heli-coil would be my choice.

Originally Posted by crazypete

Quick question for tonight's tuning session: Can a 4 corner idle carb be run like a 2 corner idle carb (put the 2 rear screws in and adjust from the front).

Sure. 4 corner idle is just for fine-tuning engines with a lot of cam. After you get it set with the front, you can back out the back ones in small increments until the vacuum gauge stops rising, and then turn them in 1/8th of a turn. Then reset the idle speed.

Originally Posted by crazypete

I found an old post with the intake trick. 3-7 psi vacuum while cranking with throttle blades shut. Will do.

Make sure you block off every vacuum line going to the intake.

[crazypete]

AHA!

I did the intake test and I got a flickering 0-1 psi(?). There is one and only one vacuum stem and that had the guage on it (slid onto a hose with a clamp) so I guess it is the intake. It must be an intenal leak because I rtv'ed around the intake top earlier and rtv'ed the carb base so it was not leaking from there either. The carb was fully closed.

As long as I will be pulling the intake, I'll heli-coil that annoying stripped thread. Well, at least I know I did the head/intake port correctly and the rockers were a good purchase. That low cylinder pressure still bugs me but well let the "seat of the pants" decide how this project turned out.

[88fivepointoh]

OK, One question, The casing is aluminum, water will cause it to corrode quickly especially if boiled. I did this on my 87 Camaro once to clean it and destryed the Carb.. Was a great excuse for a new one however.. hehehe.. Also RTV, BAD!!! on carbs, clogs everything up. I am leary on putting expoxy on the Throttle Blades. it it falls down there and makes its way in the cylinder, you could cause danmages. weld them closed would be best and grind them down smooth...

[crazypete]

I'm not sure about the corrosion thing since the carb is aluminum after all BUT after cleaning step number 2, there was white powdery stuff on everything which could have been corroded aluminum. But, being a stubborn SOB, I refuse to write off the avenger since it was my first carb. I will boil and soak and do whatever necessary to clean her out. It was probably fine seeing how my intake probably has an internal leak.

The bolt threads are loc-tited (is that epoxy? Sure doesnt look like it). In all honesty, the screws could hold themselves in without extra help but it seemed like quick and dirty insurance so I dont have little screw heads in the intake.

I will de-rtv the carb when putting the intake back on.

[Rev]

Pretty sure that JB Weld is gas proof. Soldering the holes closed would probably work well too and could be smoothed off pretty easily. Actual welding might warp the butterflies with the heat and that would cause all kinds of problems.

Rev

[crazypete]

Victory!

Got it! It was the intake. I pulled it and got some good felpro gaskets and RTV'ed like crazy and torqued the intake down to specs.....then I saw that the stupid cork end gaskets had been ejected so I RTV'ed the ends shut and WHAM! It started up! What a difference.

I was using 5-6 full turns of all four idle screws to try and get it to idle.... now, I am using 1.5 turns of each of the 2 fronts only and it idles like a charm! It can actually idle lean! The avenger never was able to idle less than med rich. That black smoke mentioned before was actually burning oil from the cylinders I fogged. I know cause there's a pool of grey burnt oil behind the car.

I ran it for 30 mins to clear out the cylinders and the exhaust and apart from a header that refuses to accept it's pipe, I'm done.

Only one quick question left.... The idle screw. When I had it backed out, it was coughing along at 400 rpms or so and I had to put the screw in to slightly and sudenly hear a hissing sound and it then started to idle regularly. I thought there was supposed to be a small amount of air coming in even with the blades 100% closed....oh well

IT RUNS!!! WOOPEE!

Thanks to everyone for helping out!