• Hello there guest and Welcome to The #1 Classic Mustang forum!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Freshly Rebuilt Roller 302, pics!

There should be two ports on the dist. for the vac. One is functioning all the time, the other functions only upon throttle opening. Sounds like you have the wrong one. If the car is idling, there should be no vac. pulled at the dist.

Now, with that, if you have the idle screwed up to high, you could be opening up the vac. port that is normally closed.
 
Oops ya that was the problem. I had the vacuum hose on wrong carb port. All is well now. Except for the total advance. The machinist recommended 32 degrees total at 2800 rpm. But its advancing well beyond that at lower than 2800. There are weights or something inside of the distributor to adjust the timing curve ya?
 
Yes, the weights can be adjusted. I am not 100% up on that so you might do a search on line. I do remember some good articles out there about how to.
 
If it's an aftermarket distributor you should have received different weights with it, if it's not, you can buy a spring kit to stiffen/reduce the advance.
 
"jonward786" said:
Oops ya that was the problem. I had the vacuum hose on wrong carb port. All is well now. Except for the total advance. The machinist recommended 32 degrees total at 2800 rpm. But its advancing well beyond that at lower than 2800. There are weights or something inside of the distributor to adjust the timing curve ya?
Click to expand...

You can't measure total timing with the vacuum attached; the total timing referred to is the mechanical advance only.

Timing with the vacuum attached can only be reliably tested under load conditions, not by blipping the throttle while the car is parked.
 
I called pertronix tech line and he told me to plug off the vacuum advance. and sure enough, it only advanced to around 33 degrees. so i guess im not using the vacuum advance for now, cause i dont know any safe way to check the timing with vacuum under load conditions...guess i can sit on the bumper while someone drives down the highway... :po
 
Jon, you only plug the vacuum advance while testing the mechanical advance. During part throttle cruising conditions where you have high vacuum and little load on the motor, you want more advance for better fuel efficiency. As soon as you step on the gas, that vacuum goes away and you go right back to mechanical advance.

So yeah, plug the VA back in now that you've verified proper maximum mechanical advance.
 
Oh i see. Freaked me out when i saw it advance well past 40 degrees while giving it a little gas in the garage. i was probably paranoid cause the engine builder was adamant that it not have more than 32 degrees at 2800, said "too much advance is a good way to say bye bye to your engine"

its not cruising that well anymore either, last time it acted like this a couple sizes up in the jets solved the problem. i suppose the engine could want more jetting now since its got a bit of surging going on while cruising.
 
Yeah, I imagine you'd have to upjet to allow for all the extra air going into the motor.

You going to be back by next month for MITM? I'm bringing my car back down in a couple weeks, and me and my gf are planning on going on the Saturday cruise.
 
So, i went up on the primaries from 58s to 62s and the surging at cruise is gone. My idle speed in park is right where i want it, however the idle speed in drive is a bit too low. my question is, the idle mixture screws on the sides of the primary bowl, is it possible to richen them up so much that they pop out? im trying to bring up the idle speed with these screws by backing them out a bit, but im worried i could back them out too much and they will come out.

And Tad- ya ill be back to slo in a couple of weeks. I might be able to get the gf to come down for the cruise
 
Once you set the proper mixture with the idle screws you mention, set the idle speed using the screw on the throttle (the throttle stop).
 
The screws on the side are only to set the proper mixture, not the idle speed. There is only one screw on the linkage for engine idle and it is normally set with an automatic warm and in drive.
 
Ok, so i get the engine idling at a good speed in drive and put it in park and its way too high. why is that

a 500+ rpm drop from park to drive just doesn't seem right to me
 
Christ, this idling issue is such an annoyance. I cant win. Initial timing is set at 8 degrees. There is a huge drop in the engine rpms from park to drive, like its about 600 rpm. i have not the slightest clue why. the car drives perfectly, so we can rule out vacuum leaks.

I set the idle speed in drive (as you're supposed to with automatics) and then put it in park and it races. the choke is not engaged, butterfly is wide open and engine is warm. There has got to be more going on here than just idle and mixture screws. The car should not lunge forward and almost kill itself from such a drastic rpm drop.

Anyone have any ideas?
 
Pull the hose from the vac advance. If the drop changes, you have the vac advance hooked to the wrong port on the carb. If that doesn't change anything, you have a mixture problem. Generally, too lean a mixture will cause this. Here's a good way to set it:
http://www.chevyhiperformance.com/howto/45638/index.html
If you don't have the vac guage (they are cheap) - start with the screws 1 1/2 turns out, turn in until it starts to miss (turn 1/8 turn, wait 10 seconds, turn again). Note that setting. Turn out the same way until it misses. Note that, then set the screws 1/2 way between the two. That will be close. Then set the speed in drive. If it still revs up (more than 300 rpm or so), recheck for vac leaks. It can drive OK and still have a leak.
 
When warm and shut off, are the throttle plates completely closed. Look down the carb with a light. Just searching for possible things now.....
 
"AzPete" said:
When warm and shut off, are the throttle plates completely closed. Look down the carb with a light. Just searching for possible things now.....
Click to expand...

The throttle plates are below the carb; don't be confused with the choke horn plate which is visible right on the top of the carb.
 
Well i went and grabbed a vacuum gauge to test and the needle on the gauge was twitching so wildly it was impossible to get a reading. It was twtching from like 15 to 8. Yes throttle blades are closed. What does that mean?
 
As long as they are closed, you are actually running on the idle circuit of the carb. If they are open to much, you get into the transition from idle to main jets.

You might try a different setting for the timing....maybe 12 and reset things. Somewhere is the happy medium for that engine to run good all the way around. It is just trying the different combinations.
 
You must log in or register to reply here.
Back
Top