Bucking like crazy in 3rd

[BeachBum]

I have a '78 1800 California edition with smog pump removed. I recently dropped a valve and had to replace pistons and head. The head I put on was the original for this motor (I had replaced with a '76 years ago). I got everything buttoned up and fiddled around with the timing and got her running pretty smooth.

My problem is that it was running pretty rough and bucking in first and second. Just trying her out in the neighborhood I couldn't get much faster or into 3rd. It's been pretty cold and I noticed that it wasn't heating up to 190 and the fan wasn't coming on. I put in a new thermostat and now it's getting up to temp and the fan is working fine. Now I've gotten it out in the neighborhood and it runs well in 1st and 2nd. I have now ventured out to the road and attempted to open her up a bit. I can run through 1st and 2nd with no problem but as soon as I switch to 3rd I feel an immediate loss of power and it starts bucking like a wild pony. I have to down shift to second. Over time, I can get it to switch to 3rd only if on flat or down hill road and with a slow acceleration. If I try going to 3rd while going up hill or really punching it, it goes to bucking.

I feel like it has something to do with the 3/4 gear switch on the transmission but I thought that has more to do with emissions. I read another post that said it may switch to second set of points. The fast idle valve is still connected though and I know that is activated by the 3/4 switch. The carb is a Weber 32 ADFA.

All of the emissions is set up just like it was before I changed the head. Never had this problem before.

Any thoughts? Be gentle, I'm a newbie and not much of a mechanic.

[nelsonj]

Have you checked the ignition timing? I think spec is 0 degrees, but once it's smogged most people set it at 10 degrees at idle.

Also, I recommends changing to an electronic ignition and ditching the points completely. Check you Vicks they have new distributors set up for electronic ignition at really good prices. (Other vendors may have them too and it worth looking around.)

[wetminkey]

I agree,...and there's more info on ignition upgrades in the Performance section here,...
Best of luck with your Spider!
Todd.

[Odoyle]

Not sure where you hang your hat at, but these little cars need about 10 minutes to warm up if its cold outside.

[BeachBum]

Thanks to all for speedy feedback. I've been very close to pulling the trigger on an electronic ignition upgrade. I think now's the time.

I'm just south of Raleigh, NC but the weather has been unseasonably cool recently. Bummer too since this time of year i really like to drop the top and get out.

[Odoyle]

Electronic ignition won't solve the issue, and likely won't produce vastly different results from dual points, unless you go top end. Best to see if you can narrow the issue before replacing things. This forum has a wealth of knowledge that can help steer you in the right direction.

[BwBrown]

One more thing to check if you haven't already - the rubber driveline "donut".
They have a limited life expectancy, and is the connection between transmission and driveline.
When getting into a "new" Spider (I'm on number seven since my first one in 1968) I change it just as suredly as I change the timing belt.

[davidbruce]

I would go back and start with the basics. Double check what you changed. You changed the head. Was it rebuilt? Are valve clearances correct? Did you double check cam timing after rotating the engine a couple of times? Is your firing order correct? Is the choke stuck off or on? Do you have any vacuum leaks. I am not familiar with the 3/4 switch or it's function. The 32ADFA has a fuel cut off solenoid to cut fuel on decelleration. Is it possible the wires are swapped between it and the high idle solenoid? Try turning the key on and checking voltage to the cut off solenoid in neutral. Then place the trans. in 3rd and see if the voltage changes. Or just try disconnecting the wire and then take it for a drive. When you say it runs well in first and second, does that mean it seems to have normal power? Or does it idle O.K. but still lacks power in 1 and 2? We've all had a turn at crossing wires and missing a vacuum line. Hope something here helps.

[Texafornian]

How is your fuel supply? I had similar symptoms that improved when I replaced the fuel filter, but didn't really go away until I replaced the fuel pump.

[BeachBum]

thanks all for the great advice. I haven't had a chance to get back on it but did crank her this past weekend. Fired up and idled at 8500 to 9000 but just a little rough. I'm going to go thru all the timing...again...and see if I can dial it in better.

[blazingspider]

Doubt it is the 3/4 switch. When activated, it engages the fast idle capsule to keep the rpms up between shifts. It was a crude emissions related set up.

The dual point system was another crude emissions related system. In order to meet the emission requirements of the day, the engine was spec'd to run at 0 degrees TDC and that made starting a cold motor a lot harder so Fiat designed a distributor with a second set of points for cold starting that is fixed with 10 degrees more advance. That allowed faster starts with a cold motor. The running set engages once the engine temp rises and is sensed via a relay that controls the swap. Most folk ditch the dual point set up and run on one set of points set at around 10 degrees BTDC.

As others have said re-check your valve timing, ignition timing, dwell angle, points, condensor, rotor and cap , carb settings and your fuel pump output.

[GeorgeT]

thanks all for the great advice. I haven't had a chance to get back on it but did crank her this past weekend. Fired up and idled at 8500 to 9000 but just a little rough. I'm going to go thru all the timing...again...and see if I can dial it in better.

8500-9000 idle is way past the redline - you did mean 850-900 I hope?

[BeachBum]

It's been quite a while since I had this problem but wanted to share what I found was the fix.

I did a rebuild of the engine when I dropped a valve and destroyed a piston a couple years ago. During the process of rebuilding, I made the brilliant decision to put in an electric fuel pump and removed the mechanical pump. Of course, I bought one of the cheap box style pumps. Fuel was definitely getting to the carb and I can't stress enough how smooth she was running. But when I made the switch from 2nd to 3rd and pushed her, she would start acting up. I kept telling myself there was no way it was the fuel pump (it's brand new, it's electric, it's great!). Finally, I decided to re-install the mechanical (in line with the electric). Since then, she's running great.

OK, I feel kinda stupid but I'm glad to have her back on the road. Been driving all summer.