C4 needs more first gear?

[BRADVAN 10]

I have 69 coupe that I bought as a basket case. After a few posts on here and some trials and tribulations, it's drivable. The car has a mid 80's 302 mated to a late 70's C4. PO says he rebuilt the transmission. The problem I have is that once I put the car into Drive take my foot off the brake and start to move forward, the car shifts from first to second almost immediately. As an example, from a dead stop I can't make it half way through a turn before I'm in second. I honestly think the shift occurs before 5 mph. The shift is very soft, almost can't feel it shift. Is there some type of adjustment possible? After driving, if I come to a stop, everything down shifts OK, but now the car wants to surge. Almost seems like it's wanting to surge between first and second? Then again the surge could be completely unrelated?!?! Thanks in advance for the help.

[LindenBruce 27]

Some vacuum modulators are adjustable. Remove the hose at the modulator and look into the port and see if there is a slotted screw head inside. If so, give the screw a few turns clockwise and take her for a test drive.

 

Make sure your modulator vacuum line is not leaking either.

 

And a sticking governor could cause this problem too.

 

 

Bruce

Edited June 1, 2012 by LindenBruce

[BRADVAN 10]

Thanks for the response. If I had just done a little more searching i would have found all the info available on the vacuum modulator, duh. I'll try adjusting it and then see what happens with the surging. Thanks.

[Lemon Owner 11]

To be honest all fords are like that. Both my early mustangs and late falcons are like that. But if you plant your foot a little harder it will tend to hold out a little more.

[BRADVAN 10]

Ok. so I've made two clockwise turns on the vacuum modulator. Now things shift much nicer, just under 10mph 1st to 2nd, and just over 20 mph 2nd to 3rd. Still have the surge. Drove around town, several stop signs, mostly 30 mph speed limit, some 45 mph speed limit. Then out onto the highway. surge gets better and goes away at higher speeds. I can manually shift 1st to 2nd and cruising in second at 30 mph it still kindof wants to surge. Warm idle is about 700rpm in park, 500 in gear. When coming to a stop sign it will occasionally die. The motor has an old Edelbrock 600 and the enrichment screws on the front don't seem to make much change when screwed in or out. Any ideas?

[PaleRider 12]

May want to increase idle a little - I'm right under 1000 on park. On vaccum modulator - you need to be a little careful. I think 2 turns is the max out. Make sure you have it connected to vacuum on car. Finally as Lemon Owner said they all shift quick. I ended up going with a ratchet shifter nd shift kit so I can control shift points.

[LindenBruce 27]

At idle you should be getting a noticeable change in rpms when you adjust the mixture screws too far in either direction. If not, then you may have some carb issues at work here as well. The transmission won't cause a surge. You will have an rpm flare if there is a problem there. The modulator can be adjusted four turns either way from the factory setting. Bruce

[Lemon Owner 11]

If your idle screws don't make much difference it usually means you have a blockage in the idle circuit. You can remove the screws and gently blow a little compressed air into the holes. Alternatively squirt some carb cleaner into the mixture screw holes and it may dislodge something. Wouldn't hurt to spray some around the venturi, particularly the air bleeds. If that doesn't work you may have to pull the carb and give it a good clean. As Linden said you probably have a few carb issues.

[BRADVAN 10]

I have an Edelbrock Performer 600 on my 65 fastback that is less than two years old with less than 1000 miles on it. It runs perfectly. Maybe I should just swap the two carbs to see it things get better or change?

[LindenBruce 27]

That would be a good way to narrow things down. Give it a try and let us know. Bruce

[BRADVAN 10]

Here's an update on the 69 coupe and its surge. I have a 65 FB with a essentially new 1406 Edelbrock. I swapped the metering rods and springs from the two carbs. The older 1406 had 7047 rods and ?black? springs, the newer 1406 had stock rods springs (7547 and ?yellow?). The ?black? springs had 22 coils and were about 1/4 inch longer than the stock spring. Anyway, I did the swap and the car ran even worse, more surging than ever. Seemed to be leaner than ever. I put the newer carb back to original specs, and then swapped whole carbs. After putting the newer carb on the 69 and adjusting the idle and choke the 69 ran like a dream. Perfect idle, no surging while driving, good throttle response. I'm leaving the 69 set up as is, and buying a new carb for the 65 FB.

[Lemon Owner 11]

It sounds like you air bleeds are blocked. I have a similar problem with my AFB that has been sitting for a few years and when I removed the venturi thingies they were blocked. Cleaned em out and now it runs much better. If you can be bothered try to give that old carb a good clean and see how it goes before you cough up for a new one.

 

Great to hear you got her going again!

Edited June 16, 2012 by Lemon Owner