Edelbrock 600 (1406) & 6p 13B

Jeff20B · 10-08-2008, 01:07 PM

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 · 10-08-2008, 02:09 PM

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 · 10-09-2008, 01:28 PM

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 · 10-09-2008, 01:46 PM

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 · 10-13-2008, 01:35 PM

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 · 10-29-2008, 02:27 AM

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 · 10-29-2008, 11:38 AM

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 · 10-29-2008, 02:59 PM

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

Rogue_Wulff · 10-29-2008, 03:10 PM

Quote:

Originally Posted by impulsive-RX7

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 · 10-29-2008, 03:20 PM

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

Quote:

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 · 11-04-2008, 01:23 PM

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 · 11-04-2008, 01:37 PM

Quote:

Originally Posted by 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.

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 · 11-20-2008, 01:20 AM

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 · 11-20-2008, 02:40 AM

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 · 11-20-2008, 01:37 PM

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?

10-29-2008, 11:38 AM	#22
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	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.... Last edited by Rogue_Wulff; 10-29-2008 at 11:47 AM..

11-20-2008, 01:20 AM	#28
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	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. Last edited by Jeff20B; 11-20-2008 at 01:24 AM..

10-08-2008, 01:07 PM	#16
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	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.

10-08-2008, 02:09 PM	#17
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	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.

10-09-2008, 01:28 PM	#18
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	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.

10-09-2008, 01:46 PM	#19
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	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.

10-13-2008, 01:35 PM	#20
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	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.

10-29-2008, 02:27 AM	#21
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	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?

10-29-2008, 02:59 PM	#23
impulsive-RX7 Rotary Fanatic Join Date: Feb 2008 Location: Jacksonville, NC iTrader: (0) Posts: 105 Rep Power: 17	FYI, Edelbrock does make a spring loaded float kit to solve the problem of fuel starvation in the hard corners.

11-04-2008, 01:23 PM	#26
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	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.

11-20-2008, 02:40 AM	#29
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	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.

11-20-2008, 01:37 PM	#30
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	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?