Carb ajustment or Timing

[milit73]

Ok I have a 1968 Superbee with a 383 Auto. I have replaced the Carb with and Edlebrock 650 with electric choke and just upgraded the distributor with and electric Mallroy.

The problem I am having if I punch it it falls and it face (like the engine cutting out) then the carb does a little backfire I would say and then it goes, but if I am in it a little already it will punch down with now problems. So what would you guys suggest? Also before changing out the distributor I was having this same problem oh and the timing is set at 10btc.

Oh sorry on more thing I am having another proble with not getting a higher idle at cold start-up and have adusted the choke control on the side both ways with no succes and I have checked the voltage which work fine and is fully open at normal temps. Thanks for any help.

 

[Sonny Black]

had same problem once....hot wire "to or from" coil arc on intake(just a hairline crack)... replaced it and problem solved. :icon_thumright:

I checked all ignition wires I think it maybe electrical ?

 

[RustyRatRod]

It probably does not have enough initial timing.

 

[hunt2elk]

I'm with RRR and would try advancing the timing some. How did the old carb. respond with the current timing?

 

[RustyRatRod]

One more thing. Does that distributor have a vacuum advance? If it does not, then here are two things. First, it will most certainly require more initial timing than a distributor with vacuum advance. Secondly, if you are going to drive it on the street, you are robbing yourself out of MILEAGE that a vacuum advance distributor can give you. Just food for thought.

 

[milit73]

All of the wires are new so that should be fine. This distributor does not have a vacuum advance but I had the same problem with the old distributor that did but it was worn. So how much more initial timing should I go? What would be the max I can go or should go that is? I will start at 15 BTC for now and check back later.

I know that this is not a stock cam or pistons if that makes a differance but nothing crazy as it has been so long that I bought the engine my memory is not helping me here. Oh and roller rockers also on the 906 heads. Thanks again guys

 

[RustyRatRod]

I would advance it 2* at the time until it just starts to rattle under moderate load in high gear, then back off until it stops. Really no way to tell you specifically without you trying it and adjusting it, because it's just something you have to experiment with to get right. Without knowing the exact specifics of your combo, I have no way to know where to advise you to put the initial timing, plus, even if I did have all of the details, every engine reacts differently, so your best just experimenting with it yourself. You'll learn more, plus you'll get it dead on for your combo.

Oh and with a non stock cam, you could see as much as 20* initial or more. It's just somethin you need to mess around with.

 

[Meep-Meep]

This almost sounds like the classic too much cam / not enough compression scenario, because if all was well in that department, the carb should run pretty well out of the box. If it has a lumpy idle then I may be correct and the likely cure, as Rusty pointed out, is initial timing and a lot of it. As a side note you should also have a distributor with vac advance if this is a street car. You only have so much you can do with timing so the other solution is to put bigger jets in the secondaries. After you get the timing to about 15 I and 35-38 total (all in by 2500 or so), and it still falls on it's face, then try a 4% richer sec jet. Of course all these tests should be done on an engine that is at operating temp.

The fast idle screw is on the throttle side of the carb facing down and is a bit difficult to get to. You can use a 1/4" wrench or socket to adjust it.

 

[Cranky]

And the lower your compression, the more timing you usually need. Do you know what your static compression is and how much PSI do you have on a compression test?

 

[milit73]

And the lower your compression, the more timing you usually need. Do you know what your static compression is and how much PSI do you have on a compression test?

I have no idea!!!!

 

[Photon440]

You might also need a little more initial accelerator pump shot.

 

[rsd859]

I also was thinking more pump shot, I had a dead spot on my holley the other day and I made the acc screw a little longer and presto chango no slop in the acc linkage and no sputter or dead spot.

 

[milit73]

That is set on the middle hole right now and I can move that to the lower hole but I will do one thing at a time just to make sure. I hope to try this tomorrow.

You might also need a little more initial accelerator pump shot.

 

[Meep-Meep]

You'd want to move the link closer to the pivot for a faster stroke. Do a compression test as Cranky suggests. All plugs out, engine warm, ignition disabled and throttle open. First reading should be half the total after 5 cranks.

 

[milit73]

I need to educate myself a lot better. I have no problem taking things apart and figure it out but sometimes it just gets frustrating. I appreciate all the help and I will let you know how it goes. Jim

 

[milit73]

Timing timing timing and what a different experience it is now. I really don't know what the timing is but it's on the next line below the 10tdc. My timing light is nonadjustable but it's running a lot better and no pinging. Still have some adjusting to do but being able put your foot in it and go is a great feeling.

 

[rsd859]

Good deal! Im around 13 deg on mine. Makes a huge difference.

 

[69a100]

Your going to want as much initial timing as the car will take before pinging under load. Where in VV are you? I'm in SW VV off of Marshall.

 

[Cranky]

Experimenting is what I like to do and when I go too far, it usually lets me know about it. I can't hear light ping like I could when I was younger so I have to be a bit more conservative or have my nephew ride with me to tell me if it's pinging. Sucks getting old! Anyways, an engine will usually tell you if you have too much timing by reading the plugs but with today's hot ignitions, it's not as easy to read them for being too rich etc. On advanced timing, sometimes if the carb squirter is off some, more timing will usually cover that up so if you hear some pinging and it's responding great but then gets a bit of a hesitation or sluggish when you nail it, give it a bit more shot and back the timing off a tad until the ping goes away. Keep in mind too that if you have light ping when you first nail it but goes away fast, that generally won't hurt things.....and higher rpm means less time for pinging to take place.

 

[milit73]

I am just off of Vaca Valley by Kaiser.

Your going to want as much initial timing as the car will take before pinging under load. Where in VV are you? I'm in SW VV off of Marshall.