Eddy 1405 tuning advice

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I think you're on the right track with the timing now. I do wish ONE thing though. That you'd get the horse crap outta your head about counting screw turns and just TRY the way I outlined. It's just a terrible way to box yourself in. .......and just so you know, I DO use screw counts but only on fresh rebuilds. I turn then out 3.5 turns from lightly seated. Then I adjust as I described somewhere back there ^^^^^^^ lol But you're definitely gaining on it! Keep it up!
 
Sorry Rob, I meant to mention I am using a vac gauge. Its older but I remember checking it with a mighty vac and it's pretty close.
The screw counts were an added fyi.
I got all sorts of tools lol, just learning to analyze the results lol.
Thanks
RustyRatRod said:
I think you're on the right track with the timing now. I do wish ONE thing though. That you'd get the horse crap outta your head about counting screw turns and just TRY the way I outlined. It's just a terrible way to box yourself in. .......and just so you know, I DO use screw counts but only on fresh rebuilds. I turn then out 3.5 turns from lightly seated. Then I adjust as I described somewhere back there ^^^^^^^ lol But you're definitely gaining on it! Keep it up!
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4spdragtop said:
Sorry Rob, I meant to mention I am using a vac gauge. Its older but I remember checking it with a mighty vac and it's pretty close.
The screw counts were an added fyi.
I got all sorts of tools lol, just learning to analyze the results lol.
Thanks


View attachment 1716131375
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Good! I am glad you are! That makes it SO much more accurate.
 
RRR,
I said in post #65 exactly what you said in your 'corrective' post #66, about the rod position. So I am not sure what you were correcting.
 
Hysteric.
Ignore egos. We start with yours? Rat Bastid would get a good laugh out of that...
 
Bewy said:
RRR,
I said in post #65 exactly what you said in your 'corrective' post #66, about the rod position. So I am not sure what you were correcting.
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I wasn't really correcting. Sorry if it came out that way. I was more or less reiterating.
 
Bewy said:
Hysteric.
Ignore egos. We start with yours? Rat Bastid would get a good laugh out of that...
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I haven't seen any egos. Yet. This is a good dicsussion so far. Especially if Hysterectomy stays out of it.
 
4spd,
You are on the right track: increasing idle timing. As expected, idle rpm increased. That is because the engine is making more HP from the extra timing. And your vacuum increased, indicating more efficient use of the A/F mixture. It may well need even more timing, determined by the method I described in an earlier post. A cammed up 440 that I fired up on Saturday needs about 40* for best idle. A veeeery big cammed 454 I helped with needed 55*.

With the increased idle rpm, simply back off the idle speed screw....& re-adjust the mixture screws. They work together. Adjust them together.

Once you have done this, you will have [ with the extra timing ], a smoother idle with more vacuum than what you had using less timing.
It is also ok if you have less than 040" of T slot at idle. I have never found it to cause a problem, & it leaves more of the T slot available to cover from idle to the mains cct.
I am betting your low speed cruise surging [~40 mph & under ] will be improved/cured...& you haven't touched the met rods......
 
Don't do any full throttle testing yet. Unless you know your full throttle max rpm timing and full throttle jetting are in a safe place.
 
Well I dunno if I'm losing my mind ...this morning I chk underhood and noticed that va is unhooked and plugged.....wtf?? I thought I hooked it up last night before test drive (that went great) lol
 
Bewy said:
Hysteric.
Ignore egos. We start with yours? Rat Bastid would get a good laugh out of that...
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Deal. I'll leave it to you 2 intellectual heavyweights to resolve this........
 
Well looks like spark issue? See pic of cap. Installed a new cap and replaced coil with a used one.
Test drove with surging, stumble and odd backfire. Backed out idle screw 1/8 turn and tweaked IMS screws. Still surges/stumbles.
Pulled over and removed orange 5" springs for 1 step weaker yellow 4" and surges got worse.
Cruise is when surging happens most.
Vac in park 14, in gear it bounces between 9/10.
Also heres timing check I did before noticing the arcing on cap contacts.

20230822_191218.jpg


20230822_205839.jpg
 
4spdragtop said:
Well looks like spark issue? See pic of cap. Installed a new cap and replaced coil with a used one.
Test drove with surging, stumble and odd backfire. Backed out idle screw 1/8 turn and tweaked IMS screws. Still surges/stumbles.
Pulled over and removed orange 5" springs for 1 step weaker yellow 4" and surges got worse.
Cruise is when surging happens most.
Vac in park 14, in gear it bounces between 9/10.
Also heres timing check I did before noticing the arcing on cap contacts.

View attachment 1716131812

View attachment 1716131818
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Are those numbers with VA hooked up or disconnected and capped?
 
Steve, read what you are typing here. You keep messing with the idle air screws trying to stop surging on the road. IDLE screws are not on the POWER circuit. They are on the idle circuit. They have purt near zero effect above idle. You need to set them to the highest vacuum reading at idle and LOCK them down and fuggetaboutum. You need to concentrate on the primary power circuit. The metering rods. I think you've nailed the springs. You just need to swap in some smaller rods and fatten it up.
 
Va capped and unplugged.
The reason I messed with ims was I thought I might be into the tslots with low speed cruise surging so I backed off idle screw and tried to "tune" the ins screws on the fly.
Going back to orange springs tomorrow.
Not sure if coil was an issue, but stalled twice on me today.
Noticed the cap issues after 1st test drive. maybe coil was cause of the stalling?
I compared my vac gauge to the Mityvac. Both pretty close.
I shoulda bought a strip kit lol.

20230822_233707.jpg
 
Now, this bears sayin too........Although the idle air screws don't affect anything in the power circuit, the same cannot be said about the metering rods affecting the idle circuit. They DO have some influence there. Not much, but they do, so keep that in mind. In other words, when you go to a smaller (richer) metering rod, you will likely have to readjust the idle air screws, since the metering rods have some effect at idle, believe it or not.
 
4spdragtop said:
Va capped and unplugged.
The reason I messed with ims was I thought I might be into the tslots with low speed cruise surging so I backed off idle screw and tried to "tune" the ins screws on the fly.
Going back to orange springs tomorrow.
Not sure if coil was an issue, but stalled twice on me today.
Noticed the cap issues after 1st test drive. maybe coil was cause of the stalling?
I compared my vac gauge to the Mityvac. Both pretty close.
I shoulda bought a strip kit lol.

View attachment 1716131895
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Keep messin brother. That's how we LEARN these things. Just don't get lost. Remember you can always put it back where it was, if you go off the rails, so don't get frustrated real bad with it.
 
I just wish we were local. I wouldn't come do it for you but I'd come help so you would learn it. Hell, we'd both learn something I am sure, because each one is different. You'll get there.
 
Thanks Rob, me too. Translating thru the net isnt the easiest at times.
I have a 1406 with new kit and the original 4295S with new kit that I had on the engine and running.
I dont wanna give up on 1405 as it was on last year running "decent". Everything was base calibration then. I have vc gaskets on order, once they're in I'll put all valve lash back to .022 as per Comps recommendations.
Thanks.
TT5.9mag said:
Are those numbers with VA hooked up or disconnected and capped?
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RustyRatRod said:
Steve, read what you are typing here. You keep messing with the idle air screws trying to stop surging on the road. IDLE screws are not on the POWER circuit. They are on the idle circuit. They have purt near zero effect above idle. You need to set them to the highest vacuum reading at idle and LOCK them down and fuggetaboutum. You need to concentrate on the primary power circuit. The metering rods. I think you've nailed the springs. You just need to swap in some smaller rods and fatten it up.
Click to expand...

RustyRatRod said:
I just wish we were local. I wouldn't come do it for you but I'd come help so you would learn it. Hell, we'd both learn something I am sure, because each one is different. You'll get there.
Click to expand...
 
Are you running an open hole spacer? On a dual plane manifold? If so why? Yes, an open hole spacer can help a way too small carburetor make more power at upper RPM, but it will play hell with tuning everywhere else. You're no longer trying to tune a 600 CFM carb on a 273, but more like a 1200 CFM carb on a 273. The open hole spacer literally cuts the vacuum signal at the carb in half. Ditch the spacer. the fact that adjusting the idle mix screws does in fact have an effect means that the idle circuit is in use at idle and is functioning correctly. The fact that you have to screw them in about twice as far as is typical also indicates that he vacuum signal is weak. Yes, you can make it idle, but because the signal is weak the primary circuit isn't working well at cruise. So you end up with a dead zone. The idle circuit is cut way back, but there isn't enough signal (airflow) in either primary barrel to mix the fuel correctly. You're literally between circuits.

When you say "backfiring" on trailing throttle and cruise, you mean popping from the exhaust, right?
 
The dist cap segments [ arcing ] look quite normal. Look for carbon tracking on both sides of the cap.
 
Thanks, I'm running the Edelbrock 9266 spacer, since we bought the car 12 years ago. It was put on to help stop percolation and IMO has worked fine.
I was/am unaware of how it affects the carb other than the insulating properties. Fishmen67 also mentioned it changes calibrations.
I'll look into removing it and see if that helps.
The backfire is a backfire, not a pop, altho some are worse than others lol.

Thanks Bewy, I thought it didnt look right. I had spares that I installed.
C130 Chief said:
Are you running an open hole spacer? On a dual plane manifold? If so why? Yes, an open hole spacer can help a way too small carburetor make more power at upper RPM, but it will play hell with tuning everywhere else. You're no longer trying to tune a 600 CFM carb on a 273, but more like a 1200 CFM carb on a 273. The open hole spacer literally cuts the vacuum signal at the carb in half. Ditch the spacer. the fact that adjusting the idle mix screws does in fact have an effect means that the idle circuit is in use at idle and is functioning correctly. The fact that you have to screw them in about twice as far as is typical also indicates that he vacuum signal is weak. Yes, you can make it idle, but because the signal is weak the primary circuit isn't working well at cruise. So you end up with a dead zone. The idle circuit is cut way back, but there isn't enough signal (airflow) in either primary barrel to mix the fuel correctly. You're literally between circuits.

When you say "backfiring" on trailing throttle and cruise, you mean popping from the exhaust, right?
Click to expand...
Bewy said:
The dist cap segments [ arcing ] look quite normal. Look for carbon tracking on both sides of the cap.
Click to expand...
 
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