Kind of long and rambling, but it may be of small value to someone who might have a Edelbrock 1405/1406 Carb,
Did some tuning today on my Edelbrock 1405 (with an electric choke added). I've had some drivability issues, and the 350 really didn't feel like it was making anywhere near the power it should, and would ping from time to time at WOT, idle was inconsistent and it would surge just a little in cruise. I checked the plugs last week, and they're pure white. I'm obviously way lean.
It's funny how you just end up living with these things, because you just want to drive, and not be bothered with tuning thinking it's some kind of black art.
Bought a Edelbrock 1405 tuning kit last year #1479 and made a small stab at tuning without much luck. Ended up in worse shape. So today, to start, I changed to a needle that is the same as previous in power .052, but flows more at idle .068. Part #1448, .068x.052 (had a .070x.052 in place). Cruise mode and part throttle felt slightly smoother and more surge free. But although idle to power step off was better, it was still a little abrupt.
Went and changed metering springs from an Orange, tried Pink and finally settled on a Silver (heaviest spring). This completely cured the abrupt step off from Idle to power transition, and cruise/part throttle is now surge free.
Happy with the results so far, so I took the top off (real easy, no gas everywhere!) and went up two stages richer with the secondary jets. .101 from .095. Also cheated a bit and moved the pump shot lever from the center to the top hole. And of course, I lost the two mini clips that hold the choke and pump rod on (not down the carb, had rags in place)! Used a little loop of copper wire tied around them for now. When the top was off, I checked the float levels, up position was exactly right at 7/16". The dropped was at 2"! Supposed to be 1". Adjusted same.
Then next step is to possibly go another step richer on the secondary, or perhaps change the primary jet one step richer (.101 to .104) and see what happens. Wouldn't it be nice to just have a wideband 02 sensor setup, data logging both RPM and O2. We'll pull a plug this weekend and have a look see if they are a normal tan colour.
I'd also bought a vacuum gauge, thinking I'd set my idle screws a scientific way for a change. See a rapidly fluctuating 16-20 ". RPM up and down a little, like a vacuum leak! Doesn't look right to me. So then I think, I bet my Offshore fancy Chrome Moroso PCV valve isn't right. Pulled the line off and blocked it, vacuum stabilized. Went right down to Carquest and bought part # 76-2784. The guy knew which one my Vortec 350 needed. Plugged it in and immediately the idle smoothed out. Apparently the old one had a weak spring and would remain too far open at idle, messing up the idle vacuum. Got back to tuning, and got a max 19.5" at a steady 850 rpm. Very Nice.
PCV valve was something I really took for granted, and probably shouldn't have. It might just have been the cause of my failed fuel pump seal, and drivability issues.
So now the car really pulls seat of the pants harder all through the band. Doesn't ping, idles better and is way, way smoother. Even has a different tone to the exhaust.
The next thing to do (if the season doesn't close) is to examine and really figure out my Pertronix distributor advance and curve. Is it optimal? I've no idea, feels like it is, but there could be hidden power. The problem is, with my DIY fan shroud and fancy March brackets, I can't see the timing marks on the damper! Done all by ear so far!
Any thought or comments on your tuning experiences on the Eddy carbs or anything general?
Cheers, Mark
-- Edited by cdnpont on Wednesday 9th of October 2013 10:50:41 AM
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65 Laurentian post, 67 Grande Parisienne 4 door HT.
I think you're doing great! I'm glad you posted this.
I copied this from your post...
I've had some drivability issues, and the 350 really didn't feel like it was making anywhere near the power it should, and would ping from time to time at WOT, idle was inconsistent and it would surge just a little in cruise. I checked the plugs last week, and they're pure white. I'm obviously way lean.
It's great that you recognised that the engine was running lean and put in the time to recalibrate the carb. I see a lot of people that just decide the carb is junk when there's nothing wrong with the carb. It just needs to be set up to suit that particular engine.
Everything you need to know about tuning an Edelbrock carb is right there in the manual that comes with the carb. It's just a matter of taking the time to read and understand it, then get a tuning kit and work at it until you get it right.
You know, without actually pulling a plug, I might have thought it was rich with excessive ignition advance. The thing always gives off a good cloud of unburnt Hydrocarbon, and anyone would think "rich".
There is still more room for improvement... I just got back from a late night cruise up to Pearson airport to pick up my father in law. And it still has some (427 Northbound off the QEW after the bend) WOT pinging. Not surprising with the cold dense air tonight.
But overall it's running much better.
Absolutely Jim...The instructions Edelbrock give you are excellent, and you can taylor the carb setup to your own if you wish. I made a XL spreadsheet to track the changes I'm making.
And I can't think of why a 600 CFM Edelbrock could not be made to work half decent on a mild small block, provided the engine was in decent repair, had no vacuum leaks and had a strong well timed spark... Unless the carb was actually defective in some way.
The one thing I failed to mention was I took the vacuum reading from the "Manifold" port on the carb. Not the timed vacuum port.
I'm also running my dist vac advance off the manifold port, is this right?
Cheers'
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65 Laurentian post, 67 Grande Parisienne 4 door HT.
I'm also running my dist vac advance off the manifold port, is this right?
Yes, the manifold port is usually the way to go. There are some engines that work better with the "ported vacuum" but usually the manifold vacuum is best.
Here's a really good explanation of why manifold vacuum is usually the best way to go...
I'm certainly no expert on all this. It takes me quite a while to get an engine running well. I pretty much do exactly what you're doing, just keep plugging away until I get it right.
I purchased a 750 cfm for a 454 in my pickup and it worked flawless with very little tuning, seems to really depend on engine mods but I have seen many work very well right out of the box. the electric choke also works really good. Im happy with edelbrock carbs. I am putting a 1406 on my stock 327 in my 64 Parisienne and having some mounting issues. The carb sits on the studs right and the throttle body seems to meet the intake right. The problem is the 1406 base gasket is not correct for the stock intake,the outside base of the 1406 is bigger. So I'm going to try a 1/2 spacer and see, any ideas? Thank you
Hi Mark i read through the first post and its good you are trying to figure things out,as Jim said the info is all there its just a job sometimes trying to disect it. The eldelbrock tuning chart gives you a good base line. I dont remember your engine ...modified /camshaft/heads etc,but you need to know what kind of fuel needs the motor may want.That is the magical question. The chart does give a richer and leaner settings and then with the kit its a trial and error game,but sounds like your close. The one thing you mentioned is that the motor is still pinging. The total timing is critical and the rate it comes in at. The typical SBC likes around 34-36,but the rate or how fast it comes in is really what you need to figure out.What is the intial timing set at?.The total should be all in around 2800-3000 and if its a more radical combo then 2500 is better but its dependant of specs and the pupose.Intial+distributor = total. Im guessing its to high because you said it was pinging in the cold air which actually is the reverse, higher temps and bad air make this condition more prevelent. I wish you were closer because i have a digital light with rpm readings and its easy to get all that info with couple clicks of a button. Keep us informed,its hard to diagnose but there are couple sharp guys here that can hopefully steer u right.
I'm following the chart, and once understood, it's so simple it's funny.
My problem with the ignition timing and curve, is I cannot easily see my timing marks. That will absolutely have to change at some point. But per your suggestions, I will probably just retard it slightly. But It seems to run so nice down low and at part throttle load, my hope was at WOT I was simply lean, and that I could chase the detonation down with more fuel. Perhaps not.
Here's where I'm at so far with the Carb. I actually returned to the stock rod today (test on bottom of chart) just to see, and with the bigger secondary jet, and a silver 6" spring it runs pretty good. Some abruptness to step off, and a very slight surge at cruise, but not bad. WOT to redline not tested, so pinging is unknown.
Next on this chart will be changing rods to 1446 (.068x.042). Which will bring me to #9 on the Edelbrock graph. For the most part, 1 step richer on cruise and power. This hopefully will be exactly where I need to be. My Edelbrock 1405 tuning kit #1479 was missing both 1446 rods. So I had to order two today.
You can see my changes, and where they fit the Edlebrock graph, by the numbers under "Chart #" below. Everything after adjustment #2, the engine is running pretty good.
The Edelbrock graph is for the 1405.
-- Edited by cdnpont on Friday 11th of October 2013 04:46:13 AM
I purchased a 750 cfm for a 454 in my pickup and it worked flawless with very little tuning, seems to really depend on engine mods but I have seen many work very well right out of the box. the electric choke also works really good. Im happy with edelbrock carbs. I am putting a 1406 on my stock 327 in my 64 Parisienne and having some mounting issues. The carb sits on the studs right and the throttle body seems to meet the intake right. The problem is the 1406 base gasket is not correct for the stock intake,the outside base of the 1406 is bigger. So I'm going to try a 1/2 spacer and see, any ideas? Thank you
I have an adapter/base plate from edelbrock that I believe was meant to solve the issue you have mating an edelbrock carb to a stock intake. It is new, as I was told I would need it when installing a 600 carb on a Performer Intake. I'll dig it up and figure out it's proper application. If you are interested and it turns out to be of use you can have it for the cost of the ride to you!
I'm as good as done with the tuning on the 1405. Added the .068x.042 Primary rods today. Noticeably better mid to high WOT power. Pulls better up up the #6 cut without pinging or laying down (keeps gaining speed!).
Overall, I've really improved the tractability of my 350. Although it ran reasonably well with the 1405 out of the box, It now Idles better (even when cold). Transitions from idle to power better and pulls way stronger down low. Cruises without surging. Feels like there's more torque on tap in the mid to high rpm's and at WOT. And as an added bonus...it actually appears to get better economy, although the ignition certainly played a big part in that.
Although I have little experience tuning anything else, I can say this carb can be easily learned and tuned with decent success on any mild SBC. It just takes some patience, and a methodical approach using the Edelbrock tuning manual.
It's been fun, perhaps it might even be useful to someone...
