308 2V hesitates on acceleration after 5000 RPM

My car is 1978 308GTB. The problem: when I accelerate hard to 5,000 RPM, the car bogs down and does not want to accelerate past the 5,000 RPM mark. If you accelerate slowly it will pull to 6K but still has a hesitation. Otherwise it runs fine, idles great, the problem is only under hard acceleration...The plugs, wires, cap and rotor are new. Timing is set properly. I was thinking that the cats might be bad? What else could cause this hesitation problem? Thanks for any suggestions...

You need to confirm proper distributor advance IMO.....If one of them is not advancing fully the motor will behave as you have described...

Clogged, bad cats are pretty rare without glowing, overheating symtoms, OTOH if yours are original, replacement with new hi flow designs might be your answer!

Do you have a timing light to check both ditributors behavior????

HTH

Actually one whole bank can drop out and it will still run like that..

Check your ignition first, then investigate the cats for blockage......

Sounds like the ignition has been worked on. Assuming it was done correctly.

It's a carb car- any chance it sat around for awhile without being driven? Perhaps the carb jets need cleaning & adjustment.

Rare to find a '78 that has cats on it.

Thanks for the response...I really do not think it is the cats after more investigation. The car has had the distibutors modified to work with one set of points, instead of the two point system...the distributors have not been set-up on a distributor machine? How important is that? It has been recommended to me to put both sets of points in the distributors and dial them in on a machine. There is also a throttle switch that controls their action (as I understand it), I am not certain what effect this switch has with only one point set per distributor? I think it is best to set it up in the original manner? The Ferrari mechanic that is recommending this procedure has offered to set-up and sync both distributors and assures me that this will remedy the problem? If anyone has ideas or can confirm this thinking it would be helpful...Thanks

Well, let's work thru it...he is actually correct the USA cars have two sets of points per distributor BUT as you noted one set is "idle only" for emissions compliance...it is controlled as you noted by a microswitch on the throttle linkage, BUT the car once you move the throttle at all is on the "RUN" set of points that have the proper dwell.....

JRV took my idle set of points out and left the remaining "RUN" set only......it's a pretty common mod.....

Moving on to advance calibration, this is CRITICAL, IMO and can only be done with the unit in a Tester...The advance is mechanical and IMO again pretty bulletproof ONCE set up..

You watch the behavior of the unit in the Tester then installation back in the car is 'plug and play"....he's on the right track, bushings can be worn out, someone messed with the springs and missed it, or lots of things happen over time.....

Distributors should be cleaned and lubricated every 15K or so, to keep them happy!

Go with it...I had mine totally rebuilt and calibrated at TRutlands and the engine really came to life!

Just like it was in 1977....;)

From memory the idle set is about 5 degress dwell angle and the run set is the more normal 30 degrees........

Running all the time at 30 degrees makes for a richer idle micture, that's all.....

Experts can correct me if I have misspoken here.....

..and you have some spare points for later!

The two sets are identical, IIRC......

You need to get your schematic from the Manual it'll show how the microswitch grounds out the ones not needed in "run" mode..

Pretty clever stone age engineering actually, IMO.....

Thanks Alan for your input.

We got the distributors set today using only one set of points per distributor, reset the timing and it runs great. I noticed a much smoother engine note than ever before and after test driving, there is no sign of hesitation. The acceleration is amazing when it is right. Looking forward to an extended drive, this was a good experience and I learned more about the car. I think it is importaant not to be afraid of these cars. Ferraris are precision devices, but in reality all the same principles that apply to most automobiles apply here...logic, step-by-step elimination and a little help. Ferrari-Talk is a great resource!

Thanks again for the support.

Sounds like your guy nailed it!

Drive on..........;)

As you noted the V8 design really works like two four cylinders tied onto one crank...many things have to be coordinated, but when they pull together, you go fast!!!!