Edelbrock 600 (1406) & 6p 13B

[Rogue_Wulff]

Anyone running this combo?
I'm mainly looking to see if anyone has had to retune the carb, or if the outta the box setup worked good for them. I can get a good idle, and it will snap to attention when the the throttle is at WOT, but it has a major bog in the lower RPM range. I'm thinking the step up springs may be a bit too heavy.

So, anyone got a baseline tuning setting for this carb?

EDIT: Typo in title, should read 1405.....

[Jeff20B]

My Edelbrock experience is limited to use on a Camden but what I can tell you is your springs may be too soft. If they were stronger they would lift the meetering rods sooner adding more power sooner. They are held down with vacuum signal. The stronger the springs, the sooner they lift as you accelerate/the less vacuum it takes to lift them.

[impulsive-RX7]

I doubt it will do well out of the box. They are calibrated for a v8 application. You will at least need to change metering rods and jets. I'll see what I have on my 1405, It's seems to be tuned pretty well... I have a 12A, but it should give you a base line.

[Rogue_Wulff]

My Edelbrock experience is limited to use on a Camden but what I can tell you is your springs may be too soft. If they were stronger they would lift the meetering rods sooner adding more power sooner. They are held down with vacuum signal. The stronger the springs, the sooner they lift as you accelerate/the less vacuum it takes to lift them.
Actually, I think I have the opposite problem. Just above idle, it starts crapping out. When it starts crapping out, fuel is dribbling from the boosters. I *think* the springs are too strong, and lifting the rods too soon. Once I raise the RPM enough to get past the crappy spot, it rocks. Getting it above 3K is the problem, from 3K till BEEEEEEEEEEEEEEEP!!!! is great.
I'm going to pull the springs out, to test my theory. If that works, it's time to make a 30 mile trek into town, for the $9 spring kit and a set of fresh plugs.
I don't care about the road-drivability aspect, as this car will likely only see autox/track use for a while.
While I'm at the speed shop, i'm gonna inquire about solid floats. I have access to a stock S4 turbo manifold and turbo. I just might go blow thru on the 1405......

[impulsive-RX7]

Which springs are in it right now? I have the pink springs in mine.

[Rogue_Wulff]

I've got the factory orange springs. As far as I know, the carb is still sporting the factory setup. It was bought, installed, and never worked right. It had a metering rod retainer clip that was on wrong, causing that rod to hang in the raised position, and the dizzy was way off.
I still haven't determined if the timing is quite where it needs to be, seems my timing light went MIA. Playing with the dizzy, I got part of the bog out, but I'm sure the carb still needs fine tuning.

[impulsive-RX7]

Nevermind, I think I have the orange springs in too. I tried the pink springs but went back to the orange ones.

[Rogue_Wulff]

I'm guessing very few have ever attempted to use this combo. I have the car at a point that it is ready to hit the road, aside from being tagged. I'll look into the cost of tagging it this coming week. I'm kinda curious how it's gonna run. I have been very tempted to swap the plate off my 83, and go for a back road run. There are advantages and disadvantages to living across the street from the police chief, in a small town. My stuff is rather safe, but it would be difficult to hide the plate swap........

[Rogue_Wulff]

Well, I tagged the car, and went for a run. Aside from ignition/timing issues, it runs quite well. It's being a pain though. When the timing was off, it idled great. Now that I am getting the timing closer, the idle is getting crappy. The crappier the idle gets, the harder the damn thing pulls........

[FC Zach]

How are you checking/setting the timing? I check/set mine at 5K RPM. 8 deg BTC on trailing and 23 deg BTC on leading. This setting works just fine for the higher RPMs. Works well enough for around town too.

[Rogue_Wulff]

I'm using my ears and the butt dyno, since my timing light is MIA. The pulley is also not installed correctly, which further complicates things....

[FC Zach]

Doesn't the pulley only go on one way? I honestly don't remember, I thought the holes were offset and the pulley could only go on one way. Or do you have another problem? If so I guess you could just put it on TDC and make yourself some new marks w/ a protractor and a compass and a little creativity.

[Rogue_Wulff]

Pulley can go on any of 4 different ways. Perhaps newer engines only allow for one way to install the pulley, but this is an '84 6P 13B.
The RB intake blocks access to one of the bolts holding the inspection cover, so I can't line it up using the flat spot on the flywheel. I've got it very close to being timed right. Once I get it in the ball park, I can reset the pulley, so I can fine tune it with a timing light.

[FC Zach]

Good luck man, it took me forever to get mine just right. Sometimes help from a friend can be a great thing. Especially if your setting it the timing, holding the light, and holding the throttle at the same time. Your using the vac. advances on the distributor?

[Rogue_Wulff]

Yeah, I have the vac advances hooked up.

[Jeff20B]

Are they hooked to the correct nipple on the carb? I ask because I'm having a similar low RPM bog from a Nikki with vac advance hooked to one of the nipples on the spacer. Perhaps the wrong nipple. High RPM is fine.

[Rogue_Wulff]

I have them hooked to the "Timed" port, as Edelbrock calls it (I've always refered to it as "Venturi vacuum", since it comes from the air flowing thru the venturi). I currently have the manifold vacuum port, and PCV ports capped.
I don't have any kind of bog, just an occassional ignition breakup at high RPM. This is most likely timing related, as it has gone from 3K to 6500+ before breaking up, due to playing with the timing. The car has the DIY direct fire ignition using 3 GM modules and 3 MSD blaster coils. The previous owner never got the car to run correctly after installing the ignition system, likely due to the pulley being misaligned.

[Jeff20B]

Timed should be correct. Speaking of timed, good luck on finding tdc.

As for my Nikki setup, I discovered somebody had adjusted trailing timing for a 25 degree split. I changed it to 10 and the difference was huge. No more low end bog, no more wanting to die at idle, massively improved driveability etc. This car is now ready to serve daily driver status for someone. :)

Strangely, the vacuum advance hose didn't pull a vacuum at any RPM... so I pulled it. It was probably on the wrong nipple but the car runs so much better now I didn't bother trying to hook it to any others.

[Rogue_Wulff]

LOL. This will have you scratching your head, or laughing.....
I *finally* got the timing dialed in good enough to make it run. I think the mechanical advance is frozen, so I have to run excessive initial timing to make it pull hard on the upper end, and this causes a poor idle quality. Once I got the leading dialed in, I hooked the trailing back up. This induced massive misfiring, so I swapped the trailing plug wires, which cured it. With leading going coil to plug with the direct fire, the trailing is now running thru the leading holes of the dizzy cap. L1 goes to T2, and L2 to T1. I know it's totally wrong, but it works. I don't want go thru the whole proceedure again, just to get the trailing set "correctly" at the cap.
I'll do that once I get the pulley set right and free up the mechanical advance.

As for the Nikki setup, normally, the "Timed" port is usually found on the spacer under the carb, 2nd from front. However, most carb base gaskets supplied with carb overhaul kits block the passage between the carb base and spacer, rendering this port useless. I have made several 12A's run better, and get improved MPG, by simply removing the carb, and either removing the gasket, or cutting a hole in it where the passage is blocked.

[Rogue_Wulff]

Well, it appears the float level needs to be lowered for autox use. Left hand turns were great, but the fire went out completely in the right handers. I suspect the float level is too high, since edelbrock addresses the flooding/stalling under hard braking as too high float level. A right hand turn in a rotary powered vehicle would place the same fuel slosh load as a V8 under hard braking, and a left would be the same as hard acceleration.
I'm not sure yet if the cutting out under hard acceleration was fuel or ignition related. Could have been either, considering all the other ignition issues I've had to sort out. (DLIDFIS)
I don't have those issues on the road, so I'm guessing most of the track problems are fuel sloshing related.

[Jeff20B]

Wulff, grab the rotor and see if the upper shaft with the reluctor will rotate and spring back. If not, yous gots a problem! Time to do a lube job.

Hey, what's the update on your Edlebrock situation? I really want to use one in NA form on a ported 4 port 13B but I'm a little hesitant because it's currently my daily. Is your intake manifold a Racing Beat 6 port version? Did you add a carb spacer?

I have a seperate runner 4 port Hitachi manifold and an old Hayes Rotary holley adaptor plate. It has a channel connecting both primary runners. The manifold has seperate runners. The carb adaptor is about 1" tall. Will the connected primary runners in the carb adaptor be enough for the Edelbrock to have an acceptable vacuum signal on a rotary? What did you do on yours to get it to want to idle and all that?

[Rogue_Wulff]

Jeff, the mechanical advance is working correctly. I had already confirmed it by using the method you suggested. Turned out the wires between the GM ignitors and the magnetic pickups were reversed.
As for my setup, it is the RB 6 port 13B holley intake, with a 1" 4 hole spacer. The spacer was required to make the carb linkage clear the water outlet, the one under the fuel inlet, to operate the secondaries.
I don't know how much difference it would make having a spacer with the channels connecting the runners. Since mine seems to run great with all 4 runners isolated, I have left it that way. It seems to have a good vacuum signal the way it is.
The only carb issue I have, is I need to lower the floats. I ran the car at an autox a couple weeks back, and it suffered from having no power during right hand corners. Likely caused by fuel slosh. I cannot replicate this issue on the street, without driving in a manner that I do not approve of. Since this occured before I found the wiring problem, it could have been related to that.
The carb is still tuned to factory specs, and seems to be doing fine. Once I found the wiring problem in the DLIDFIS, and corrected it, it will idle smoothly at 700 RPM, and pulls hard all the way to 8K. I have a small issue with the ignition still, that causes an occasional misfire above ~6500 RPM. I'm still not sure what is causing that. Perhaps it is related to the condensor on the side of the dizzy not being hooked up. I also need to get a timing light on it, but mine seems to have grown legs and wandered off....

[impulsive-RX7]

FYI, Edelbrock does make a spring loaded float kit to solve the problem of fuel starvation in the hard corners.

[Rogue_Wulff]

FYI, Edelbrock does make a spring loaded float kit to solve the problem of fuel starvation in the hard corners.
I am aware of the spring loaded needle and seat assembly. I will try that, if lowering the floats does not help. I haven't seen anything about spring loaded floats. If this is something other than the spring loaded needle and seat assembly, please post a link to the item, Thanks!
I don't think it is a fuel starvation problem, as it only occurs during hard right hand turns. By hard, I mean harder than anyone would "reasonably" see during street driving. Hard left turns are no problem. I could induce power oversteer at will during left turns, but hard right turns was like the key was turned off.
I believe the problem to be related to the floats being a tad too high. The Edelbrock carb is not often used in applications that would have the fuel sloshing towards the "front" of the carb, while attempting to accelerate. Normally, this carb would only see this fuel slosh condition under hard braking, where the throttle is fully closed.
Having 200K+ miles on the stock springs also allows the car to lean quite a bit, which likely adds to the problem.

[impulsive-RX7]

Well I knew it was spring loaded something.

You are correct, if it was right hand turns it might be fuel starvation, but lefties.... I don't know.

From the Edelbrock website


Q: I have a Performer Series carburetor and my engine stalls when I come to a stop or a sharp turn, what will fix this problem?

A: An incorrect float level can cause this to occur. Make sure that the float levels are set properly at 7/16” per the owner’s manual (download here). Excessive fuel pressure can also contribute to this condition.

[Jeff20B]

Ah, so it seems to have a good vacuum signal with all for holes seperate. Hmm, I wonder how mine will be with both primaries joined.

[Rogue_Wulff]

Ah, so it seems to have a good vacuum signal with all for holes seperate. Hmm, I wonder how mine will be with both primaries joined.
Kinda hard to really guess. The SE 6P has rather small primary ports, even compared to stock ports on a 12A or 4P 13B. With the small size of the primary ports, one would think the 6P 13B would have a more pronounced pulsing action, especially at lower RPM, with the runners seperated. Of course, the edelbrock carb does have the PCV port in the front, which would tend to allow for a certain amount of cross flow between the primaries, especially at idle, to keep a stronger vacuum signal.

[Jeff20B]

Wulff, I swapped from a 5" SC to a 7" today and I seem to have a stalling problem under braking now. It was very slight before with the 5" but is quite pronounced with the 7". I lowered the fuel pressure from 5 to 4.5 then to 4 and still the same.

It behaves like it's getting too much fuel because it bogs and stalls. To get it started back up I have to floor it as in a typical deflooding proceedure. Then it blows a bit of smoke which is also typical of having been flooded (washes all the oil off the internals).

The engine has lots more power and accelerates better than before but as soon as I slow down or make a panic stop, it dies/floods. Corners are less of a problem since lowering fuel pressure. Only stops cause problems now.

[Rogue_Wulff]

Jeff, is the carb mounted sideways, as would be typical on a rotary, or in the standard V8 manner with the primaries towards the front of the car?
That is sorta an important item, to give a good idea where to start troubleshooting.
If the carb is mounted with the primaries facing the front like a typical SC application, try lowering the floats. Edelbrock suggested I lower mine to 1/2", and if that didn't solve my problem, try the "Off road" needle/seat assemblies with the springs.

[Jeff20B]

It is mounted sideways.

Back when this carb was in the RX-4 on the 5", my brother swapped the meetering springs and rods attmpting to tune the carb. I bet if I swapped back to stock it would correct things because the carb currently takes a while to return to idle on the 7", as if the rods arn't lowing back into the jets fast enough. Thoughts?

[Rogue_Wulff]

Sounds plausable. If the rods are not getting pulled down quickly enough, excess fuel will drip into the venturi. I'd also check to insure the rod plungers move freely. I had a problem with one that didn't, and it dribbled fuel constantly into one venturi.
As for not returning to idle quickly enough, that could be from a vacuum leak, or weak return spring/binding linkage.

[Jeff20B]

Could be binding linkage. I recall I snugged it, perhaps too snug.

I suspected a vacuum leak too but I made sure the new brake hose was secure. Maybe it's the carb gasket. It's old so I should just swap it out to eliminate it. Thanks.

[Jeff20B]

I had some success today. The way I attatched the cable to the carb linkage was with two pieces of steel with a hole at each end 1" apart. I secured them to the carb with a small bolt and two nuts counter-tightened to allow slack in the linkage and not come loose. It works well. I had the nuts a little too tight so that's fixed now.

The other weird part that I haven't figured out yet is that the carb linkage is actually getting stuck internally. It slows the return to idle and makes the gas pedal stiff at first. Is there any place I should lube? Maybe run premix? Or plumb the OMP into the carb float bowl like a Holley?

[Rogue_Wulff]

My cable is hooked in a similar manner. 2 ~1/4" X 1.5" strips of metal, with 3 holes. One end has holes big enough for the cable end, and the other 2 are just big enough for a screw to fit thru. The center screw holds everything together, and the end screw attaches it to the linkage. Lock nuts are used on both. The screws are only snugged enough to keep the cable from falling out, and allows for free movement at the carb.

As for the linkage binding, perhaps the AP linkage is in a bind, or the primary-secondary linkage at the other side is interfering with the water outlet or binding. Other than those 2 spots, only place I could imagine any binding, would either be inside the AP, or the throttle shaft itself. I mean, these are very simple (but effective) carbs.