Technical Edlebrock on Nailhead issues.d

It has a mechanical advance with two small springs underneath the rotor arm. Do you mean these? Or is there another set that I cant see under the base plate where the points and condenser are mounted?

 

Before you do that, with the engine not running, move the throttle wide open and check the fuel coming out of the squirters by looking down the carb throat. You should get a steady stream of fuel at both sides for the full stroke of the pump piston. Just move the throttle to wide open hold it there. If it squirts in dribbles you probably need a new pump piston seal.

 

Open it up and clean it, check the float level. Are you running a fuel pressure regulator? You need to. Set it about 5 1/2 lbs. Run a good filter as well, Edelbrocks do not like dirt or more than about 5 1/2 lbs of pressure. Also someone mentioned accelerator pump , top hole please.

 

I just looked up the manual for the 1411. The chart shows the accelerator pump in the top hole, not the middle. So something was assembled wrong or changed. If you don’t have the manual (it should have come with it), just download it. Then start checking what else isn’t right. All mentioned above, from fuel pressure to floats to jets/rods/springs.

I know some don’t like them, but I’ve never had one that wouldn’t just start, run, and drive. Generally needed some tuning, but not like you’ve got going on.

They’re simple. But read the manual until it starts making sense. Then follow it.

The first new carb I bought back in 1967 was a new 600 Holley. Big flat spot off idle, could barely drive it. The speed shop said pull it off and bring it in (real Speed Shop in those days, guys who actually worked on cars themselves). The primary jets were 10 sizes lean. They put the new ones in, problem solved. Never trusted a new carb since.

 

I'm not running a pressure regulator, do I still need to with the standard mechanical fuel pump? I am running an edlebrock in line fuel filter though. I did buy a fuel regulator about a year ago, I didnt end up fitting it because I wasnt sure it was correct. Seems to have 3 hoses. I got too confused by it and left it boxed up. Should it be mounted before the filter or after?

 

Before the rebuild, my parents drove this car every day, for 10 years, the carb was an old Holly 2bbl, that was mounted onto an adapter plate, this thing was bassically balanced on the top as the bolts on the adapter were just seated in with some electrical tape. It was fitted really bad, no fuel filter or regulator, ran like a dream. Was fast too. Hahaha.

 

Absolutely, the regular pump can make 7 lbs or more sometimes, that can be more than the Edelbrock is happy with. I use these Holley ones with a gauge. I think the part number is 12-803

 

That is the distributor Buick used from 57-66, so you have the correct one. Make sure the little rubber bushing is still there on the advance stop. As far as carburetion, all my Edelbrock's worked fine right out of the box. I would go back to the basics as far as your running issue. Are the plug wires in the right order? Points set correctly? What does a vacuum gauge show, etc. Eliminate each potential problem one at a time.

 

And as far as it being good out of the box, they're close but really not that good. I highly suggest you get the calibration kit and tune the carb. You can seat of the pants it and get closer but really I'd put it on a dyno with a sniffer in the tailpipe and go that way. Took me under two hours and three pulls to get this one dialed.

 

Wow, thats a beautiful looking car. I'm afraid I dont have access to that sort of equipment. Here in the U.K, it's hard enough trying to find a garage with a big enough set of ramps,

 

I don't own the dyno, I rent it by the hour at another shop. There are a bunch of chassis dynos in the UK. You could do it at one of those. You can also put an O2 sensor and a gauge in the car and get closer that way than seat of the pants.

 

Aah yeah, I see that. But getting the car to a garage when it will barely drive is the problem. Also money is the other problem

 

Can confirm from my past problems that with a mechanical fuel pump, you'll want a pressure regulator. My factory 401 fuel pump was pushing over 9psi. Got a regulator, set to 5.5 and she ran beautifully. Weather this solves this problem in particular, I don't know, but will be a huge benefit either way

 

I have a regulator still boxed, that I bought about a year ago..
i'm going to try it out tomorrow.
its the type that also has a return outlet on, but came with a blanking stud in case that's not needed. I've seen online that this is a better option for keeping the fuel cool. I dont want to get into the agro of trying to safely plumb another fuel line back into the tank. So will just try it dead head style first.

 

Blocking those crossovers helps a ton with reduced heat in the carb bowls. Shouldn't have anything to do with your issue. It will help a bunch starting up the car after it's hot. You still may need a carb spacer. I did on my 401.

 

In review, it seems a lot of the issues revolve around putting the 4V intake on. Going back to the basics, are the intake gaskets on the correct way? The mounting holes are slightly offset, and it is easy to put them on backwards creating a vacuum leak. How did you "block off" the exhaust crossover? The two typical ways are a thin SS shim over the square opening or plugs in the holes under the carb. If doing the former, the shim could be causing the intake gasket to not compress. Edelbrock's may not seal well on the intake creating a vacuum leak. What does a vacuum gauge show? No change when closing the idle mixture screws is indicative of a vacuum leak.

 

Pull metering rods out and look what color the spring is under the vac piston. Get one rod out and remove spring. Put rod and piston back in, this might be enough to remove the rich spot, fit the cover and try the car. If so, get springs that are weaker. There are 5 different springs available, all different colors. Once the car becomes driveable you could then buy a kit and do the fine tuning.

 

Hot4HotRods: Stick to the basics...
1. Have you checked for Wide-open-throttle?
2. Are the throttle blades clearing the bores in the intake manifold?
3. Have you tested for a vacuum leak at the carburetor base?
4. Are you using the correct carburetor base gasket designed for the intake manifold?

From all that I've read here, the carburetor adjustments are all out of wack, and the ignition timing needs to be re-verified.

 

I seem to remember buying the instake gaskets that were designed for blocking off the ports, so the port section was almost covered, except for a small hole, which was then blocked with small nut and bolt. I would have to take the manifold off to check though.

I re set the timing as to the Buick engine manual, ( it was actually advanced too much) dwell angle set at 30, timing set to 5 degree BTDC,
With the enging running I then removed the vaccum line, the timing mark position on the harmonic balancer imediately changed and moved from the 0 mark to the set 5 degree , and the engine slowed down. Also the vaccum gauge I had set up showed everything was normal.

I slowed the tick over down so that the idle mixture screws were then working, and set those to the highest possible vaccum on the gauge.

Tried to drive it. And it was actually worse. It barely pulled away before it stumbled and died.

I tried to fit a fuel regulator but couldnt get it to work. I tried swaping the inlet and outlet round. I possibly didnt have the pressure adjuster screwed down far enough, so may need to look at that.
Heres the regulator I'm using, came with no instructions as to whats the inlet and outlet. Looking online at identical types. Some info says the small nozzle is the vaccum hook up, some says thats the return to the tank. ???

 

I'm using the gasket that was supplied with the carb.

I did open up the compartments on the top for the rods. One was springing up and down freely when pushed with a finger, and one felt like it was catching on something, it sprung up when I removed the small securing plate, but wouldnt push down unless it waa wiggled around a bit.

I also did a test with the timing light, to check the centrafugal advance, with the vaccum line disconeccted. The timing mark didnt slowly move or increase as the throttle was slowly applied, it just stayed static, so that could be an indication of a problem with the mechanical advance I guess.

 

"The timing mark didnt slowly move or increase as the throttle was slowly applied, it just stayed static, so that could be an indication of a problem with the mechanical advance I guess."

Definitely.

 

Update. So I've actually got it running and driving better than its been in a long while, by changing the distributor to an HEI one. I kept the springs and bushes that it came installed with, according to the chart it comes with, sets it at 2,700rpm, which is the middle of the 3 options available with the different springs and bushes provided. I set it to 5 degree TDC on the harmonic balancer with the timing light set at 0. This is what the Buick manual says. Not sure if I am meant to set the timing light advance to 5? The issue I have is it is still running rich. I have no tacometer to set up idle speed, but when drive is engaged, the car very slowltly creeps fowards, which is how it should be I feel.
however the car is still running quite rich.
The vaccum gauge is reading in the green, but the idle mixture screws dont seem to do an awful lot, if I slow down the engine idle with the screw on the throttle plates, the vaccum then drops down into the red on the gauge that says timing too advance.

Could the issue actually be with a blockage in the carb causing the mixture screws to not opperate?

https://youtube.com/shorts/lJY5mR7o--M?si=fU15ckz1aN8I800f

 

Havent yet fitted a fuel pressure regulator. Are these types any good?

 

A few things you may want to consider:
1. It never hurts to pull out the mixture screws and shoot some carb cleaner in through the idle passages. If you have an air compressor, compressed air helps. Since you've been having problems with the carb, it may be worth just pulling it apart and giving it a good cleaning.
2. People have often complained about flat spots with the 750 Edelbrock. It's something with the design of the primary boosters, I believe.
3. Closing off the carb heat passages is probably half your problem. I have blocked crossovers on one car, and there's a slight-to-moderate hesitation until the engine is warmed up. You could probably tune that out, but the fact remains that the manifold seems to like a little heat (on a daily driver). Without the exhaust butterfly, the manifold doesn't really get that much hotter (from what I've noticed) than if the passages are blocked, but it helps.

 

You really want one with a gauge on it. and set it to around 5 1/2 lbs. I really like the Holley 12-803
https://www.summitracing.com/parts/hly-12-803 Just add a gauge.

Have you pulled the top off the carb? Checked the floats? Checked for dirt? Do you have a good filter on it as well?

Timing.
You need 30 degrees total with these engines and for best performance, you want the distributor curved so that you can set the initial between 10 and 14, and you want it to be fully advanced between 2500 and 3k. Not sure if there is anyone in the UK that can recurve the distributor. What distributor do you have in there?

 

I've ordered a seperate inline gauge and one of those dial type regulators. I'll fit those when they arrive. I've also ordered an Edlebrock calibration kit, just in case it needs re jetting.
i've got an Edlebrock filter between the carb and pump, and an H&H one between the pump and gas tank. Not pulled the top of the carb yet, but I think its something I'll do just to check for dirt.

I bought a brand new HEI one. It has vaccum and mechanical advance, with different springs and bushes to play around with..i havent touched any of that yet. It Came with coil and leads. I had to bypass the balast resitor, then it worked fine. I've no idea how to set total advance. I just followed the instructions per the Buick manual. Which says to disconect the vaccum advance on the distributor, slow the idle down to something like 400 odd rpm, and using a timing light turn the distributor so that the mark on the harmonic balancer lines up with the 5 degree TDC mark. Which is what I've done.

 

Thats a good idea. I was thinking of putting a stock gasket back on and unblocking those passages. I guess it may cause it to run richer in our moderate U.K climate if theres not effective fuel vaparization due to the manifold temprature

 

And check the float levels.

Do you know what brand it is? Some of the less expensive ones are questionable. What is the timing all in around 2500-3000 rpm ?

I've never had a positive experience unblocking them unless it's really cold out.

 

Just make sure that there's no raw exhaust blasting on the carburetor base. Any factory AFB equipped car I've seen that had heat riser holes in the intake had a stainless steel plate insulating the carb from raw exhaust.

 

You think i should leave them blocked off? The directional plate in the exhaust has been removed too, as it got jammed and caused it to overheat.


No idea what brand, but it certainly fixed the flat spot. The car now drives with plenty of poke. I uploaded a video father up a few posts back. .. just need to get the carb to run leaner ans get the idle mix screws workint. H eres a screen shot of the ebay listing I bought.