what did I do wrong???

jeff81 · 07-02-2005, 10:24:00 AM

I can't get my timing set right. Put the distributor in after determining #1, etc, she fired right up and runs good.

I've got the idle screw almost all the way in and at 800 rpms when I pull the vacuum line to time it, she barely runs.

If I advance the timing enough to get it to idle without vacuum, it shows about 25-30* advance with the light.

I hooked up the vacuum and set the distributor by "ear" and the engine runs good.

What is going on to cause this??? Any ideas????

I did move all the wires on the cap one position counter-clockwise to get better clearance for my air cleaner, but I dropped the distributor in accordingly.

When the light is on it, the timing mark on the damper is about straight up when vacuum is hooked up. Without vacuum, it's about 1 1/2 inches past the top of the timing tab.

It does seem to run good (sitting) at this setting, but something isn't right and I can't figure it out.

HELP

[This message has been edited by jeff81 (edited July 02, 2005).]

[This message has been edited by jeff81 (edited July 02, 2005).]

Camaroz · 07-02-2005, 11:34:00 AM

Have you checked your distributor? The advance weights may be stuck or? Sounds like your advance is comming in way to early.

Just a thought,
Steve

jeff81 · 07-02-2005, 01:48:00 PM

Checked distributor. All is well there. I have this issue posted in the "Troubleshooting & Diagnosis" section also, and noted that I did change my carb base gasket type. Has a 4-holer (Q-Jet) now. Before I had the "open bottom" type. No problem setting timing with that one.

I'm thinking maybe the motor is starving for fuel at idle. Maybe that's why she won't run with vacuum off. Could be messing up my ported vacuum too.

I realigned the engine at 12* on the damper and the rotor is right on the spot for #1 plug wire on the distributor.

I'm off to the parts store for a different carb gasket. Let me know what you guys think. I'll report back later. Thanks.

[This message has been edited by jeff81 (edited July 02, 2005).]

onovakind67 · 07-02-2005, 01:55:00 PM

Set the initial and total timing with the vacuum advance disconnected and plugged. If it won't run with the VA disconnected, advance it until it does.

Gary S · 07-02-2005, 01:59:00 PM

Nothing is wrong. It is supposed to work this way. Taking away vacuum advance will cause the engine to idle down. If it tries to idle too slow, it dies. It is the way engines are supposed to work.

jeff81 · 07-02-2005, 04:00:00 PM

I gotcha onofakind67 & Gary. I did that. Problem is it won't idle (with vac disconnected) until the mark on damper is waaaayyy past the scale.

That's why I'm thinking it's a fuel problem. I think the 4-holer base gasket is covering up my idle jets enough to cause me to have the idle screw turned in almost all the way. My old carb gasket was "open" to all 4 venturis and did not cover up the idle jets as much.

I had it running fine with about 12* advance and idle screw far less in with the other type gasket.

Thanks for the replies.keep 'em coming while I try a different gasket.

Joekool · 07-02-2005, 09:58:00 PM

Quote:

Originally posted by jeff81:
That's why I'm thinking it's a fuel problem. I think the 4-holer base gasket is covering up my idle jets enough to cause me to have the idle screw turned in almost all the way. My old carb gasket was "open" to all 4 venturis and did not cover up the idle jets as much.

The idle fuel slots are up inside the throttle plate, no base gasket that I know of bends up and thus covers the idle fuel slots.

Gary S · 07-02-2005, 10:58:00 PM

Quote:

Originally posted by jeff81:
I gotcha onofakind67 & Gary. I did that. Problem is it won't idle (with vac disconnected) until the mark on damper is waaaayyy past the scale.

It probably won't idle with the vacuum line disconnected. If it doesn't, help it along just a little with your hand on the throttle. My Camaro was like this since new in 1970, and it has never changed. As long as you keep the idle below the point where the mechanical advance starts to come in, you still get an accurate timing setting even if you have to help it stay idling.

CanadianZ28 · 07-04-2005, 01:13:00 AM

Did you change the timing chain cover and the time tab by chance? The timing tab might be in the wrong spot. this happened to me with the an after market chrome one. I had to map out the balancer with new marks to match the new timing tab!

[This message has been edited by CanadianZ28 (edited July 04, 2005).]

jeff81 · 07-06-2005, 11:15:00 PM

The only thing I changed when replacing my 305 heads with the Eddys was the carb base gasket type. It idled fine enough before the head swap so that I was able to set the timing.

The difference in base gaskets may not be the problem, but it is the only thing I "changed". I'll let you know tomorrow hopefully, when I go back to the other kind of gasket.

BrianBerry · 07-07-2005, 08:15:00 AM

From what I understand...
1. you had an open bottom gasket, but you changed it to a 4 hole Q-jet style.

Now, is your carb a spread bore or a square bore? What intake are you using? Are you using a square to spread bore adapter plate?

I'm assuming that since you said Q-jet type, that you have a spread bore carb, possibly an actual Q-jet.

I never use gaskets with the "webbing" in the center of them, unless the gasket will be sealed by both of the surfaces that are being bolted together. For example, a stock Q-jet and a stock intake manifoled with have metal on both pieces to sufficiently seal the gasket. But a Q-jet and an edelbrock aftermarket manifold will not. There is a slight chance that the gasket could interfere, but that's unlikely.

I'm wondering if your valve lash is too tight to idle at a low rpm with timing set perfect. Have you reset your valve lash while the engine was running?

jeff81 · 07-07-2005, 10:01:00 AM

Thanks for the reply Brian. I am using a Q-Jet and an Eddy Performer intake. I do not set valve lash with motor running. Too messy for me. Never had a problem before by doing it static.

I'll let you know if changing carb base gaskets helps. I think my idle problem must relate to fuel flow and the difference in the 2 types of gaskets could have an effect. I have my idle screw almost all the way in to give the motor enough gas to run at idle.

Thanks again.........more to come.

jeff81 · 07-07-2005, 09:25:00 PM

Well I changed the carb base gasket and it helped improve the idle. I had to, as Gary said above, "help" it run with vacuum disconnected to set my timing. I ended up at about 16* mech. advance, and the idle with vacuum hooked up is at 900 rpm.

My problem now is that the motor will rev nicely if I give it throttle slow and even. If I bring it up to 1500 to 2000 and then "stab" the gas, she backfires through the carb.

When it did this first, it backfired out of the secondaries. I figured it had too much initial timing (16*), so I retarded the dist. a bit. When I tried to quick rev it again, it backfired out of the secondaries and primaries, ran rough for a couple seconds, and then smoothed out.

Does this mean I have too much advance too soon? Maybe go for heavier springs in dist?? Or is the engine not getting enough gas fast enough???

INPUT Please. I did some searches but I'm coming up short on resolutions. Thanks for any advise you guys can offer.

[This message has been edited by jeff81 (edited July 07, 2005).]

BrianBerry · 07-07-2005, 10:25:00 PM

Quote:

Originally posted by jeff81:
My problem now is that the motor will rev nicely if I give it throttle slow and even. If I bring it up to 1500 to 2000 and then "stab" the gas, she backfires through the carb.

When it did this first, it backfired out of the secondaries. I figured it had too much initial timing (16*), so I retarded the dist. a bit. When I tried to quick rev it again, it backfired out of the secondaries and primaries, ran rough for a couple seconds, and then smoothed out.

Does this mean I have too much advance too soon? Maybe go for heavier springs in dist?? Or is the engine not getting enough gas fast enough???

INPUT Please. I did some searches but I'm coming up short on resolutions. Thanks for any advise you guys can offer.

[This message has been edited by jeff81 (edited July 07, 2005).]

IMO.. could be too much advance, or you could have 2 plug wires crossed. I'd rather see 8 degrees idle (static) & 14 degrees at 2500.

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Pic of My Camaro Z28

jeff81 · 07-07-2005, 11:54:00 PM

Thanks Brian for the reply. No plug wires crossed. I'll try retarding the distributor some more in the a.m.

Keep the ideas coming guys, need INPUT.

[This message has been edited by jeff81 (edited July 07, 2005).]