Hello everyone,

It has probably been asked before and if I missed the thread in my search I'm sure someone will probably berate me and link the appropriate thread.

Anyway, on to my question. I recently rebuilt my 460 and started the process of firing it and setting the timing. Last night we had a fiasco... When starting the truck and we were hearing a *bloop bloop* from the cylinders like liquid being suctioned. After about 5 seconds of this the truck would fire. I should also mention at this point I have to have the throttle pegged to get it running. We got the timing set to about 10* BTDC but I have to keep my foot on the accelerator to keep it running. It'll stutter at 1000 and slowly die. Then the last time we were starting it last night a rather large gout of flame shot out of the carb and the back of the engine started on fire. That was fun I tell you. So we decided to quit for the night and get some advice from friends and family.

So, any ideas? I know the timing is too advanced as I'm still getting flames out the carb. Also, I forgot to remove the vacuum hose from the distributor so that may cause some issues... Is the carb too rich? Can the mixture screws be adjusted while the carb is on the engine (Holley 4180)?

Thanks for all your help past and present.

-Jeremy

Edit: I have ground out the plugs exposing the mixture screws.

 

My 460 valve cover tag says timing should be 8 degrees BTDC. Suggestion is to check carb secondaries. Other posts here mention that if secondaries are open at idle (they should not be) it will suck/dump lots of fuel. Also might want to double check the firing order.. I'm especially interested in this, as I'll be doing first start after rebuild very soon. Keep us posted, and good luck.

 

I agree with you axman... However as I've put in a slightly more radical cam than stock I figured the timing should be a little more advanced. I think I'm getting a "false" timing reading because we've not disconnected the timing advance vacuum hose. that'll be the first thing to come off. Then I'm going to retard the timing a bit to see if that changes the fire out of the carb.

 

A couple of degrees advanced ain't gonna make the truck run like that. Issues are bigger than that.

Check for PROPER timing. TDC on #1 Spark Plug compression stroke to ensure you're not 180 degrees off on your dist install. Check firing order and ignition wire install AFTER you do that. THEN set base timing with the vacuum advance disconnected.

DO all that, in that order, and your timing will be correct.

I'm gonna have to assume that when you put the motor back together, you got the timing chain gears lined up "dot to dot" correctly...

 

That's my vote........Sounds like 180 deg. out (easy to do)

 

OK. I'll definitely check to see if I'm not 180 degrees off. Just to make sure I'm correct, the cylinders are numbered 1-4 on the passenger side from front to back and 5-8 on the drivers side front to back? Also the rotor turns counter-clockwise? The truck seems to run just fine between 1200-2000 rpms. Sounds great in fact. I can't believe it would sound that good if it was 180* off. Just my .02...

 

Kind of off topic, but where do the vacuum hoses hook up? I have removed the EGR plate and the pictures I took aren't as clear as I thought they were. I have two small ports, one in front and below the bowl and one to the left of that next to the bowl as you are looking at the carb. There is one larger to the right of the small port below the bowl. Do one of the smaller ports connect to the dash pot and the other connect to the vacuum advance of the distributor? I don't know what connects to the large port. I don't know if this has anything to do with the issue I'm having but thought I'd ask.

 

The larger port to the right of the small port below the bowl is for the PCV, which is what hooks up to the valve cover.

The small one right next to that big port hooks up to the distributor for the vacuum advance.

The small one that is pointed out at an angle out of the main body is for the EGR, if you do not have this one and you instead have one coming out of the metering block (bolted between the bowl and the main body); then this it is not a 4180 and you can disregard what I mentioned.

If it is a 4180 then the idle mixture screws are in the base plate behind tamper proof plugs which can be removed. The stock settings should make the engine idle correctly in park though.

Look down the barrels of the carb with the engine running (at an angle because you don't want the engine backfiring into your face) and see if gas is dripping into the engine, if it is then either the accelerator pump transfer tube o-rings or the powervalve is bad. It could also be incorrectly set float bowls.

As mentioned before you might want to make sure the timing isn't 180 degrees off, and make sure that you don't have any plug wires mixed up.

 

I have rebuilt the carb and everything checked out good. I'll bet that the floats are set too high. I'm going to check the wires and order later and also the distributor and make sure it's at TDC when the rotor is at one. I'll get you all an update when I have one.

 

This can happen if you're using the wrong point of reference for the timing marks, e.g.

 

Hello everyone.

Well, I seem to have the back firing issue under control. The floats were very high allowing way too much gas to flow... Also I leaned out the mixture screw. The truck still will not run after all this. There are flames now shooting out of the exhaust manifold and I have the timing set to 18 BTDC. I know this is way too advanced. The next logical step I guess would be to take off the front of the engine and check the timing dots. I don't look forward to that.

 

What happens with timing set at 8 degrees, now that you've corrected the float settings and tweaked the mixture?

 

It immediately stops running if I take my foot off the accelerator.

 

Still with timing at 8deg, it runs with you holding accelerator down. Wide open? Half? Are you having to pump it? How does it sound when it's running? Rough, or decent? Does it still output flames through the exhaust?

Sorry for apparent bozo questions, I know it seems like we're back and forth here. There's something simple that we're missing, but we'll get it.

 

Well, if it have it between 12-1600 rpm it seems to run fine, but when I let it idle at 8-900 it runs rough. It does still have fire coming out the exaust but really only when its under high rpms. I'm going to take the front off and see if the cam and crank are in fact lined up dot-to-dot.