Technical Edlebrock on Nailhead issues.d

I fit doesn't get too cold there I would.

If the fuel pressure is above 5.5-6 lbs it can push past and run rich, or if the float levels are too high. And I will tell you, I always open up a new carb off the shelf. I've found misadjusted floats and sometimes dirt in them.

 

No idea what the total timing is..i just set it up best I could with a timing light, to 5 degrees before TDC acording to the Buick manual. It cant be too far out of where it needs to be as it runs and drives . Its just too rich.

Yeah this is what I am hearing. Guess theres no point doing anything else until I can determine the fuel pressure.

 

This may sound like a stupid question, I have a dial back type timing light, when setting my intitial timing of 5 degrees before TDC, do I need the dial on the light set at 5? Or at Zero?

I am researching how to set total advance, i think for the Nailhead it needs to be 30, so guessing I dial my light to 30, then take the engine up to 2,500 -3000 rpm, do I then need that timing mark on the harmonic balancer to line up to 5 still? Or does it need to line up with the 0?

 

If you set the timing light at 0 you should see 5 on the balancer, just like if you set it at 5 you will see 0.
With the total timing bring it up to 2500 to 3000 and turn the dial until you see 0, that will be the total timing.

 

You may be able to check your actual fuel pressure with your vacuum gauge. A bit of online searching should show you the details.

With all the talk of running rich, keep an eye on your engine oil. Make sure it's not over-filled, diluted from too much gas or smells noticeably of gasoline. As a quick test I take a drop from the dipstick and place it on a dusty surface somewhere under the hood, usually someplace on the wheelhouse panel or similar.

Then watch how the oil spreads out into the surrounding surface. Good oil will spread out very slowly or not at all after a second or so. If it spreads out quickly around the drop the oil is diluted with too much fuel. You could probably do the same test on a clean paper towel and observe how quickly the oil absorbs into the fabric.

 

When upping the rpms to 3000, do I turn the dial on the light until the balancer mark lines up with 0?

 

Ooh thats a good idea. Thanks I'll give that a go..could be something in it.

 

Yes, whatever the dial is on when you see 0 is your total timing

 

So today I disconected and plugged the vaccum line, took it up to roughly 3000 rpm, until the timing mark stopped moving, then turned the dial on the timing light until the mark lined up at 0, the gun was reading 25. I heard nailheads need to be at 30. So with the vaccum still disconected, and the engine idleling at around 450/500 rpm I set the timing light at 30, and turned the distributor counter clockwise until 0 lined up with the mark on harmonic balancer. It seemed to run ok. So I switched off the engine and put the vaccum leak back on etc. When turning the engine over to start it back up, with its new timining, it sounded off, as it turned over the engine would sorta stopped suddenly with every rotation, like the timing was wrong, it took quite a few turns before it caught and fired up. I decided to just turn the distributor clockwise a fraction, maaybe 5-10mm , this seemed to sound more correct when re starting it as it fired up much easier, but I am guessing my total advance would now be at around 27?

 

If you had the light set at 30 and you brought the timing mark to Zero at idle, that means you had 30 degrees of INITIAL timing in it. No wonder it had a hard time starting. If you want 30 degrees at 3000 rpm total, set it to that and don't worry about the initial.

 

Haha yeah, It wasnt until after I posted what I had done and then had a long think about it, that I then realised I had done it wrong. This is all a learning curve for me. I've not set total timing before.

 

Your initial should be between 5-12 degrees at idle, and all in at 30 degrees at 2500 RPM. Using your timing light again, set your initial @ about 7 degrees. Run it up to 2500 RPM and check it again. Should read about 30 degrees. If way more or less, then the advance springs need to be changed.

 

Ah ok. Thanks for the info..would the springs be changed for heavier ones or lighter?
If my initial is set at 5, and the gun is reading at 25 when the balancer lines up at 0 at higher rpms, does that make my total at 30?

 

No. That makes it 25. When the timing mark is on zero, whatever the number is on the dial on the timing light, is the amount of advance. Their will be less advance at idle for Initial timing than there will be for total advance at 3000 rpm. The difference between the two readings will tell you how much mechanical advance is built into the distributor.

 

Spring choice depends on how fast you want the advance to happen. If your initial is 5 degrees, go to 1000 RPM and check it, then 1500 RPM, then 2000, then 2500. You should see the advance increase in each step, but not necessarily linear. Lighter springs will make the advance come on sooner. If you are not getting enough advance (say 25 degrees), you could change to a lighter spring if that is the problem. The advance could be hitting the stop inside distributor. I think that unit takes a silver and black spring to get the curve you want.

 

For a Dyno I've actually found that Volvo and Mercedes will typically rent Dyno time fairly cheap. And both of those dealers generally have one if they service cars they sell.

Also aside from the stumble issue your car sounds insanely like my 53 bel air with Edelbrock carb on a 350 with lakes pipes lol

 

Aaah. Nice. The stumble issue has been sorted by droping the HEI in it. There was obviously an issue with the original distributor. I was actually wondering if it would run and drive better with a full exhaust system?

 

Brilliant, thanks for all the help, i'm going to buy a d igital timing light with a tach built in. I've seen this on amazon, it displays the advance and RPM's at the same time. Once I have that I'll be able to accurately set the engine speed and make a proper job of it. I'll try setting the initial at 7 and then advance at 30, i guess setting the initial at 7 will chang3 to 5 when rotating the distributor to set the advance

 

I´ll bet you a cold one that putting in a fuel pressure regulator will fix your poor running issues. Edelbrokens hate anything abouve 5.5 psi. The HEI helped, because it has a hotter spark and has an ability to ignite a less than perfect A/F mixture, which you obviuosly have.

 

I installed a dial type regulator yesterday, and set it to 5 .5, no idea how well it works, and what the carb is now recieving. i have a gauge on order, so will fit that when it arrives.

 

Those Dial type regulators are garbage.

 

I had to adjust the floats on a new Edelbrock to stop it from flooding my 401.
Keep the exhaust passages blocked off. Is your vac advance on the correct source?

 

Next thing I'm going to do is lift the top on the carb and check for dirt, could be the reason the idle mixture screws arent doing much. Its not flooding as such, just running rich..i have an Edlebrock calibration kit on order too, I might change the rods to get it to run leaner.

The vac is connected to the passenger side port, which I believe is above the throttle blades.

 

Oh really? It did feel a bit cheap, and I couldnt really see how it worked. Nothing seemed to be mooving inside when looking into the ports and turning the dial. Think somebody mentioned using the holly ones earlier in this thread, i might get one of those. When the gauge arrives I'll see what PSI the pump is putting out and if the dial type regulator is actually doing anything

 

One thing I like about the Carter/Edelbrock AFB/AVS carbs is that there is no gasket below fuel level for a leak to develop. The only way you get fuel into the engine is via the mixture screws and the boosters. If your mixture screws aren't changing anything then you have fuel running past the boosters when it's running. If the carb plates are not open past the metering slots to compensate for a vacuum leak and barring a bad needle and seat, the two most likely reasons for this are too much fuel pressure and/or too high of a float level. That's it. Changing the metering rods and springs won't change a thing.

I have always run my carbs at 3 psi without an issue. There's really no reason for a higher pressure. As mentioned, the dial regulators are garbage.

 

The carb plates might be open too much, I would need to take the carb off and check this. If I wind the tickover adjustment screw out too far to close the plates, the tickover drops so low the engine struggles and stalls.

Vaccum gauge isnt showing a leak at all. Maybe the float level is too high? Or could be fuel pressure issue. Maybe when both of these posibilities are corrected, then the idle mixture screws will work better and then the plates can be closed off without issue.

 

A seemingly unrelated comment, but read the full thread:

I have been working on carburetors and cars since 1959. TWO of the THREE DUMBEST mistakes I have personally made on cars in the last 65 years:

(1) Blocking the heat cross-over on a street engine. The engine stalled at every stop sign / stop light for the first thirty minutes. Solution - changed to a carburetor with a manual choke and operated the choke manually for the first thirty minutes.
(2) Replacing the heat choke on my wife's older vehicle with automatic transmission with an electric because I didn't (INITIALLY) have the time to fix a burned out heat tube. Darned near cost me buying a new car until I recycled the electric choke into a million minute fragments and fixed the hot air choke.
(3) Had nothing to do with carburetors.

The O.P. has an older automatic transmission, an electric choke, and a blocked heat cross-over.

Jon

 

Aah thats interesting, I've heard lots of arguments for and against blocking off the cross overs. Might try reverting back to original. As for the auto choke it seems to work well, it does come off of choke fairly quickly, but if it stays on, it runs really bad. Last week in fact, one of the wires came off the choke, so it wasnt opperating, the car lasted about 10 minutes and then stalled and wouldnt restart for 5 minutes.

 

Keep an eye on the cheapo dial pressure regulator. I’ve read stories of them spewing fuel.

 

This post is concerned with a 1950's car, with auto transmission, for street use:

Electric chokes have been around since at least the early 1930's. The car manufacturers did NOT use them; WHY?

The older automatic transmissions REQUIRE a richer than normal mixture due to the extra load placed on the engine by the automatic / torque converter until the fluid is hot.

The cause to open with an electric choke is electricity. The chokes are set to go off in a given time (I understand this issue may be corrected by installing a reostat to control the electric voltage, thus adjusting the time. I have not personally tried this "fix"). Without the "fix" they open entirely too quickly for the older automatics.

The cause to open with a conventional hot air choke is the heat of the engine. Thus the choke is going to partially open as the engine (and transmission fluid) warms, an continue to open as the engine warms.

When the OP's choke failed, the choke butterfly would not have opened past what would be accomplished via the internal choke pull-off; so the engine would have been pig rich as the engine warmed, and would have stalled within a few minutes.

The inline dial type fuel pressure regulators regulate pressure by regulating volume. These regulator have a volume rating (if you can find it), normally 10~15 GPH. If the engine is operating at an RPM that uses the rated volume, whatever it is, then the regulator will function to a point. If the engine is at idle using only minimal fuel, then the output pressure will be virtually identical to the inlet pressure. Finally, the numbers on these regulators are NOT calibrated in psig, rather the numbers are a linear scale (so if the numbers run from 1 to 5, then a 2 would be 40 percent of the inlet pressure IF the engine was using the rated volume, a 3 60 percent, etc.). These regulators are still quite useful IF one has a strong right (or left) arm, and a rabbit problem in one's garden!

Jon