Starting Help

[Adarcy]

She's idling good now. Found a vacuum leak. I had to get a 1/8" thick spacer plate in-between the pcv spacer and the manifold. Time to tackle timing.

 

[craigaria]

Sweet! Almost time for a test drive

 

[Adarcy]

What should the timing be set to? 1969 302, manual trans

 

[craigaria]

10 degrees Btdc

 

[Adarcy]

Got it set to 10. Took it for a spin around the block. Idles smooth, but stumbles bad on acceleration. Thoughts? Gonna go check the plugs and points again.

 

[craigaria]

Check for vacuum leaks, check fuel pressure. Did it run well with this carb before? New plugs?

I'm not real good with carbs, hopefully someone else might have some input if it is a carb issue

 

[Adarcy]

Just took it out for a spin again after replacing the plugs again. Still doing it. Falls flat on its face in any gear upon medium acceleration. Basically anything over parking lot type speeds causes it to stumble.

For what it's worth it did this before I did the new intake and carb. I attributed it to a known vacuum leak in the original manifold that has since been replaced and no longer leaks.

So now it's received a better sealed/new manifold, rebuilt carb, new points, new plugs, new wires, and a new fuel filter.


Left scratching my head on this one.


I suppose the mechanical fuel pump could be going out?

 

[Adarcy]

Ok. New theory. Perhaps my distributer is not creating any vacuum and not advancing w the timing. Maybe that's why it idles well, but stumbles on acceleration?

What's a good way to test that?

 

[wesleydax]

Do you have a vacuum pump? Like one for bleeding brakes. If so hook it to the vacuum advance and see if its moving the olate in the distributor

 

[craigaria]

If it has the same symptoms as before, I am leaning towards a fuel delivery issue, or an ignition problem.

If you have a fuel pressure gauge, you can rule that out easily.

As far as the vacuum advance. You can hook up the timing light and watch the timing as you remove the vacuum hose from the distributer and see if there is a change.

How did you adjust your points?

 

[Adarcy]

Just checked the vacuum advance. No change in the timing when I removed the hose from the distributer. I don't have a fuel pressure gauge, but i'll pick one up today.

 

[Adarcy]

If I increase the rpm's with the timing light on the balancing the timing increasing away past my 10 degree mark. Should it do this or should it stay constant on my 10 degree mark as rpm's increase?

 

[patterdale]

Got it set to 10. Took it for a spin around the block. Idles smooth, but stumbles bad on acceleration. Thoughts? Gonna go check the plugs and points again.

Stumbles on acceleration is either bad/misadjusted accelerator pump in carb or a timing advance issue. No need to check plugs and points.

 

[Adarcy]

Well this one is embarrassing. After going through all of the possibilities of what could be causing this stumbling I decided to redo the intake manifold job. Pulled everything off and found the problem. I used the Fel Pro 1250S3 intake manifold gaskets. I don't know how I missed it when putting it together, but those gaskets do not have the port for the exhaust crossover. I bought the Edelbrock gaskets that have the port, put it back together. Runs perfect.......I must have been tired or rushing that day when putting it together %)

 

[craigaria]

Happy you figured it out, good job!

 

[Rugby73]

Ok - I've got tunnel vision at this point. Just put the top end back together. New intake manifold, spacer, new carb (Autolite 4100). Won't start.

New plugs (Autlote 45's set to .034), new wires, new coil, new cap, new rotor, new points (set to .020).

It's got air, its got fuel (can see it spraying in carb), it cranks, but does not start. Every once in awhile it makes a puff noise (I know, bad description) from under the hood, but I can't be in two places at once so I don't know where its coming from.

Any thoughts?

You have a vacuum leak.

 

[Adarcy]

Update: For the most part its running pretty well. The only issue i'm having is that occasionally it can be hard to start. For instance tomorrow morning when I go start it for the first time it will take some cranking and pumping of the throttle. It'll cough and sputter (with a touch of black smoke - not a lot - probably from me trying too much throttle ), but with a few rev's it comes to life nicely. Once idling I can turn it off and turn it back on and first crank she fires right up like a new car. It rev's and runs through the rpm's nicely while driving. It seems that any time I let it sit turned off for more than a few minutes it is tough to turn on and takes a lot of cranking.

Thoughts? Timing is good, plugs and wires are good, points are good, new fuel filter, runs great while driving, stays right at 165 degrees.

My first thought was some sort of vapor lock, but I do not have any gas lines near headers or the rest of the exhaust and I have a 1" spacer under the carb.

 

[DirtDonk]

Have you re-checked your points gap? You should actually have a dwell-meter in your stable of tools as well. If you're going to keep points you're going to find it very handy.

No change in the timing when you pull the hose off is normal. If you've got the hose connected to the correct port on the carb, then there will be no vacuum signal at idle. It only comes in as you open the throttle.
With your timing light, you should be able to see the timing jump up just after you've started opening the throttle. Verify that this is happening.
Verify with the light too, that your timing event is relatively stable. If the marks are jumping around, you have something wrong/loose inside the distributor.

Incorrect dwell and/or a faulty condenser can easily create a hard cold-start issue.

The timing itself is very forgiving between the stock 6 degrees, and up to 12 or 13 degrees advanced.
And remember, the idle goes down as you retard the timing, and goes up as you advance. And every time you mess with the gap/dwell, you change the timing.
With some distributors too, any change in idle speed will make the mechanical advance move a bit. Most EB distributors won't have that issue, as their weights are a bit heavier and don't come in until a few hundred rpm later, but it's still common to see after all these years.

Just a few things to think about.
And now that you have it idling so you can mess with it, start looking all over again for any vacuum leaks. Use water or carb spray around every port, seam, gasket and seal that you can think of.
Just watch out for new paint if you use carb spray!

Paul