I have a 326 in my 1967 firebird that I put an Edelbrock cam, intake, and carburetor, and headers, 3:56 posi, and 2 1/4" duel exhaust . I am having a very hard time trying to figure out what my initial timing should be set at with all my changes. Once I get the timing set right then I might figure out this Edelbrock carburetor. I know factory setting is 6 degrees btc. But the motor almost wants to die. I have had it at 10, 12,14, and now 16 degrees btc which it starts good and runs but I can't get any power taking off the line, runs better after 3,000 rpm. Anybody have the same set-up out there?
I went through this last year, I use the ported vacuum off the carb.(passenger side port) to my vacuum advance I set the timing at 12deg BTC and I saw a lot of power then, had to set the mixtures too. Do you have a dial timing light? I am running a Comp Cams camshaft with a Eddy 1406 carb. Crane cams XR700 electronic ignition set the plugs to standard gap .035
Yes I have a digital light, just bought. It is hooked up to the ported vacuum. What metering rods and springs and jets are you using on your 1406? I have 98 in front 95 in rear, pink springs with 7342 rods
What is you max timing without vacuum advance connected? If the heads are original 1967, those like 41 degrees total. Be sure to check it up to 4500rpm to make sure you find where it tops out.
I have original heads #140 and original point distributor. Where do you want me to start the initial timing at ? I am at 16 now and will go out in the garage to test the total up to 4,500 rpm
Actually I'm using yellow springs with 7547 rods and Jets .098 and .095 in my 1406. 7342 rods are a little rich. That's your flat spot your rods. Now set your timing with the advance disconnected to 12 deg no more than 14 deg BTC. Again put the vac advance back on the ported side and run it again. You shouldn't have your idle mixtures out more than 3 turns maybe another half turn at the most. Are you running points or a conversion kit in your dizzy?
Ok went to the garage and started with 15 deg of initial timing at idle 800 rpm. Turned up rpm to 2500 and had timing mark at 27 degrees not including the initial 15. Turned up rpm to 4500 rpm and the timing mark moved to 41 degrees not including the initial 15. So what does this mean? Neighbors are getting a little restless when I got up that high of rpm, should have done this earlier
I have been going back and forth on 7547 and 7342 rods as well as springs. How come you use such a light spring-yellow? I have a point distributor original
think about it, At idle my springs are pulled down all the way and when I come of idle through the idle transition circuit I'm using a light spring so it doesn't pop up as fast as a orange or pink and keeps it lean til the engine responds. If I went with either of the other 2 springs they would pull the rods out of the jets to quick and may cause it to lag.
The original Carter AFB that came on the 326 HO was the 4246S It had front jets .090 and rear jets .083 and .065x.052 rods with the orange springs but the Venturis were set up for this carb. The eddy 1406 is a universal carb. fits many engines, we have to start with the base and go from there. It's all trial and error when you start playing with the rods and springs.
Maybe I'm expecting to much but I was able to spin the tires before and now I can't get any power out of the hole. Your set up got me closer but not spinning rear tires yet This is what I have,
Acc pump top hole 7342 rods Yellow springs Screws turned out to 3 turns Vacuum at 900 rpm is 13 in hg Timing initial at 13 btc
did you try the 7547 rods? heres a test, disconnect the throttle from the pump and see if you get the lag still? PM me your email address and I'll send you some pamplets on CarterAFB/Edelbrocks and how to make them work for you like you want it too.
To be clear, are you're saying you started at 15 degrees then it added 41 degrees on top of that? So the total of the two would be 56 degrees? If so, that's way too much! Your total timing should be 41 degrees BTDC regardless of the initial.
Thing is I can't imagine your distributor would add 41 more degrees to the initial unless someone put in the wrong weights, or (on a points distributor) the limiter bushings were worn or missing.
By the way, you don't have to limit yourself to 12-14 degrees initial. Ideal initial timing depends mostly on fuel octane, static compression, cylinderhead design, and camshaft. To a lesser extent, bore size, intake design, engine operating temperature, and spark plug heat range also play a factor. If you put in a camshaft more overlap, then you're engine may run better with more initial.
If it doesn't sound like your starter is struggling during cranking (check this when engine has been up to full temperature), and doesn't run-on with up to 16 degrees, indicates that your setup wants more. Just make sure you're total is not too much or coming in to quickly.
Maybe I'm expecting to much but I was able to spin the tires before and now I can't get any power out of the hole. Your set up got me closer but not spinning rear tires yet This is what I have,
Acc pump top hole 7342 rods Yellow springs Screws turned out to 3 turns Vacuum at 900 rpm is 13 in hg Timing initial at 13 btc
Anything else I should be looking at?
Ah, I just noticed your vacuum level at rpm is on the low side here. That also tells me (assuming you dialed in the air/fuel ratio to best rpm already) that you need more initial timing.
Also don't forget, once the timing is all dialed in, you have to readjust your a/f mixtures. The ignition timing will affect a/f ratio.
Would have to agree with FirebirdMike, I didnt quite understand the 41 degrees not including the initial timing. If your timing shows 41 degrees at 3000 rpm with the vacuum disconnected, that is your total timing...IE.. 15 degrees initial and the rest is your mechanical timing. I normally run my car up to 3000 rpm and set timing to 34-36 timing and then the initial is what ever it bottoms out at and set my idle to around 800 or 850 where ever it needs to be set at with an auto tranny in park(vacuum disconnected). But car dependant and what it likes, but you have to make sure your mechanical advance is working right and giving you about 18-20 degrees advance. You cant set both, you either set initial and go with what results in the total or you set total and accept what the initial comes out to. Obviously, if it doesnt run right then you have to adjust the initial down or up dependent on your engine and what it likes...just my opinion
Good point. All this should be done with vacuum disconnected and car port plugged. Thanks, I forgot to mention that.
The closed chamber factory heads typically like 40-41 max. The open chamber 35-36 max. Usually all in by 2600 to 3000 rpm works well. Bring it in much faster and you may find yourself having to dial it back a degree or two which means you're shorting yourself in the upper rpms.
As far as your timing is concerned: you will want it to be around 14-16 deg at idle and 32-36 max advance. (16-20 deg advance curve limit) The vacuum advance needs to be dialed in to. 15 deg limit and 8-12 deg vac advance comin in at highway cruise speeds. Is your distributor stock? No recurve kit, has it been rebuilt? Is the advance stock or a aftermarket? I know it's still points all these settings are for a recurving the dizzy, the limits are different for a stock dizzy.
Ragu brings up a good point for limits on the stock dizzy. Not trying to hijack the tread, but if you have an HEI dizzy, what are the typical limits on that. Does having an HEI dizzy mean your total timing will be as high as 41-44 degs at 3000 rpm? I am no expert but I was always taught 34-36 for total, and would have thought that 41-44 is a little too high? Please educate me, cause I always need more knowledge...lol
Ragu brings up a good point for limits on the stock dizzy. Not trying to hijack the tread, but if you have an HEI dizzy, what are the typical limits on that. Does having an HEI dizzy mean your total timing will be as high as 41-44 degs at 3000 rpm? I am no expert but I was always taught 34-36 for total, and would have thought that 41-44 is a little too high? Please educate me, cause I always need more knowledge...lol
As far as what the total should be (without vacuum), look up at my earlier post. Assuming you're using the correct octane for your static compression ratio and cylinderhead material, and you haven't made it come in too early, it depends on the combustion chamber design.
Older heads that are closed chamber like a little more than the open chamber Pontiac heads. KRE heads have a heart chamber design and improved spark plug location that mimics the modern GM LS1 chambers, and therefore work best with about 32 degrees.
HEI versus points seems to make very little difference. Maybe a degree or something.
These are guidelines, and you need to optimize what works best for your combination.
Setting the vacuum advance should be done after you have your initial and centrifugal dialed in first.
The original Carter AFB that came on the 326 HO was the 4246S It had front jets .090 and rear jets .083 and .065x.052 rods with the orange springs but the Venturis were set up for this carb. The eddy 1406 is a universal carb. fits many engines, we have to start with the base and go from there. It's all trial and error when you start playing with the rods and springs.
Great topic.
I just happen to have a 326 with a 1406 Edelbrock carb in my 64 Tempest. I think the carb is stock out of the box. I have found that my car seems to like 16 to 18 deg advance, but is not even close to having a good tune with the carb..
The more initial advance, the more off idle torq. I'm guessing that backing off the timing to 13 is why you can no longer spin the tires.
Setting timing is such a black art. I don't pretend to have all the answers. The more I read the more tricks I learn. Tip in procedure, pulling a vacuum hose and listening to the idle speed, listening for ping.
Really only a dyno or 1/4 mile testing is going to help you figure out what the best total timing your motor likes, and a out of tune carb will not help you achieve a goal of getting it all working right. Initial should be increased until you have a stumble or have trouble starting the car. Need to make sure you don't have timing coming in on idle with week springs. I really want to buy a Air/Fuel meter and work on carb setup.
I wonder if the 326 AFB specs can be used in the Edelbrocks? I see in the Edelbrock manual the stock set up is (.098")(.075" x .047")
If you don't have the latest HPP magazine they have a Rocky write up about a points distributor that you should check out. If you want more initial without more total you will need to limit the mechanical advance.
Rohrt the only thing I know is the venturi's were setup for the engine the carb was to be installed on back when Carter's were used. I have a 4246 326 HO carb installed, it's a tricky carb to work with, it has 2 idle mixtures and air screw. I have my 1406 packed away for now. But the settings may work in an eddy 1406, doesn't hurt to try.
I may try that on my 1406 Eddy and see if I can get it to run smoothly, It should workout good just the venturi's and it's idle bleeds are a little bigger on the Eddy than the original Carter. I am wondering if the air bleeds be too big for the smaller jets and rods? Doesn't hurt to try. Just a wasted gasket
If you can get ahold of an air/fuel ratio set you could change and monitor them until you get the correct fuel ratio. When I had mine on the dyno we had to change the rods and jets a few times until I got the ratio close. I don't think I would have gotten it near correct if it wasn't for the fuel/air gauge set. A couple of guys I know have them mounted on the dash permanent. Mine is an Edelbrock 800. I thought I would need to have more fuel with the increase in displacement and compression ratio but I had to lean a lot.
If you can get ahold of an air/fuel ratio set you could change and monitor them until you get the correct fuel ratio. When I had mine on the dyno we had to change the rods and jets a few times until I got the ratio close. I don't think I would have gotten it near correct if it wasn't for the fuel/air gauge set. A couple of guys I know have them mounted on the dash permanent. Mine is an Edelbrock 800. I thought I would need to have more fuel with the increase in displacement and compression ratio but I had to lean a lot.
The A/F gauge is exactly what I would like to do. Ragu keep us updated on your testing.
Summit sells a few kits for around $200. Sensor, weld in bung, wiring and gauge. There are some hand held units and some that work with I pads, I phones etc. I don't have either. A hand held one could be cost shared by a few and used to tune multiple cars. Unfortunately I'm the only one I know on this island that's even remotely interested.
I think I will be going with the AED due to price and feedback. Should be all I need to get a close dial in and see if I go way rich or lean when I transition from off idle.
Right now til I get back into it, I'm running the HO carb. it was ment to run on a 326 HO engine, I don't have to tune it, Just set idle mixtures and the air screw. I plan on setting a 1406 up like a original 326 carb and testing it soon, just gotta get through this month, been tough one.
I agree with USMC, I set my total timing to get the best HP, torque etc. at higher rpm then set the idle screw to 700rpm. I started with 43 total [on dyno]put it up one and power went down. I kept lowering it and making pulls, I got the best power at 39 total, that's where I left it. 39 total gave me 9 at idle, I started with 12 at idle.
Maybe the reason your tires don't spin off the line is the new cam. Bigger cams need more rpm before they start to perform. I settled on the smaller of the two I was leaning towards. The larger would have gotten me a lot more HP but I would have to rev it to 7000+ rpm to get it and it wouldn't start to perform until 3500. The one I put in gets me all the power it's going to by 5000 and I have a lot of torque at low rpm.
I sent him a bunch of info on the edelbrock/carter carb's and how to tune them in, he was running too rich, the carb he has needs to be leaned out some for his engine, I am running a similar setup. I run my timing at 12-14 deg, with ported advance. I have leaned out the carb. I've tested them and found several setups that work. 1405 .100 jets and rods 075x047 work great with this engine, I spent last summer testing out Edelbrocks and Carter AFB's from 3649SA, 3721sa, 9635sa, 3895s, 4242s, 4246s, 9635s, and found
The 4242 ran good but had a rich lag off the line.
4246 ran good had good idle and was good off the line but no top end.
9635sa ran the 1405 setup and she was quick off the line and burned up the tires.
3721sa ran a little rich, but she idled good, same as 9635 but no top end.
3649 & 3895 both ran rich, idle was rough, but was lagging off the line.
1406 stock, great idle, ok off line, no top end needs to be dialed in.
4028sa ran good at idle, good throttle response off the line, seem to run good at top end too. didn't like the fuel location.
9635s it's like the 1406 but richer, great throttle response and good off line, top end seem good too.
This summer I am working on some Q jets, I am building a jig to straighten the air horn and bodies out and I want to see if they are better. I am getting fuel leaks and erratic idles with them.
I agree with USMC, I set my total timing to get the best HP, torque etc. at higher rpm then set the idle screw to 700rpm. I started with 43 total [on dyno]put it up one and power went down. I kept lowering it and making pulls, I got the best power at 39 total, that's where I left it. 39 total gave me 9 at idle, I started with 12 at idle.
Maybe the reason your tires don't spin off the line is the new cam. Bigger cams need more rpm before they start to perform. I settled on the smaller of the two I was leaning towards. The larger would have gotten me a lot more HP but I would have to rev it to 7000+ rpm to get it and it wouldn't start to perform until 3500. The one I put in gets me all the power it's going to by 5000 and I have a lot of torque at low rpm.
A Dyno is the bast way in the world to find the totle timing. Then your half way there. Assuming your numbers are with the vacumm can disconted it sounds like you have 30 deg mechanical. I would play around with the initial advance to see what the car likes. I would guess that magice number of around 12 to 14 would give you better off idle performance.
Once you get that number then you can modify your mechanical. If it HEI then there is a Rocky Rotella sheet out their that has a nuber of weights and center plates you can use. If its a Points distributor you would have to limit the advance movement with either a bushing, brazing or a set screw.
On my firebird with the old motor I Had some ping issues. If I backed it off to 34 total it put me around 10 initial. One day while messing with it I put it at 18 initial and took it for a drive. It was like a different car. I could stomp on the gas at a 15mph roll and light up the tires. I couldn't do that the timing at 10.
Interesting, I have very good off idle performance with nine degrees, but I will try some more just to see, as long as I limit my total to 39. If more initial will get me better of line power why not? If I stomp the gas at 15mph now I'd be going sideways, more off the line and DOT slicks maybe.
Sorry, another brain malfunction, I have 29 degrees total not 39. The heart shaped SD combustion chambers allow for a few degrees less timing but mine was quite a few less. The guys running the dyno were surprised but that's what got us the best power. So the mechanical advance is only 20 degrees. With my number 48 iron heads I ran 41` total and 12 initial for 29 degrees mechanical and vacuum. I have a different distributor than I had with the iron heads and have yet to measure with the vacuum attached.
rohrt I had my timing set to around 20BTC last year and the samething was going on but at cruise I was pinging had to dail back to 12BTC, gains are not as much, but it isn't pinging.
I just had an Edelbrock technician rebuild my carb , every little piece, everything. Ran better but still no low end power. He suggested an hei distributor when I came back after the test run, so I decided to put in a Petronix igniter to keep stock appearance. I am at 13 or 14 degree initial timing with 13 inches of vacuum, stock distributor with vacuum advance. One power spot higher than stock set up on the 1406, #2. My problem which has been the Same for two years now is that I am using a lot of gas. When car is turned off I can smell gas. I just put a 200 r4 in the car but still getting bad mpg.. The car stumbles on take off but wants to run strong from 55 mph on up to 100+.
Are you still using Pink springs? I use yellow or lighter because the cam has low vacuum. 13-15"hg How far out do you have the mixtures turned out?
Start your engine up and remove the accel. rod from the pump. Then rev the engine and see if the stunble is gone or worse? If it's responsive and better then you are running rich or if it's worse then you have a lean condition. Might have the wrong pump Squirter(nozzle) Just a little test you can try
I forgot one thing we haven't thought of, we both went from 2" exhaust to 2-1/4" exhaust, we now have more flow out of the engine, less back pressure, of course we are gonna use more gas than before. Just a thought I was thinking of.