Coughing Under Acceleration

[Webb Sledge]

Finally got around to driving the 6 again, with this beautiful weather and all, and I noticed something. When I'm cruising at about 2000 rpm, and suddenly floor it, the car will "cough" (like its lost power for a split second) and then accelerate hard. I've got twin DGV Webers, and suspect that the linkages just aren't set up right. Any suggestions?

On an unrelated note, I got my starter put back in after having a new drive put on, only to find that I need a new ring gear after all... oh well. Also, my freakin' brakes are almost totally gone do to a master cylinder whose seals blew out again. I pledge to never buy from Vicky Brit again. This is the second one that's done this. I think they might have bored the clinders to big for the seal kits that go in them. If anyone is in the market for a 6 master cyl, don't buy from VB.

 

[sammyb]

If it does it when fully warm:

There are actually a bunch of things that can cause this. One of the big issues can be distributor-related. Make sure your points gap is correct, that you're getting full advance and that your overall timing is correct.

If you were using SUs or Strombergs, I'd say "check to make sure your dashpots aren't dry," as this also can easily cause the 2000RPM flutter.

But yes, you also want to ensure the carbs are properly balanced.

 

[SkinnedKnuckles]

I'm no expert with Webers, but the "cough" you describe on acceleration is too lean a mixture. Maybe the accelerator pumps aren't working.

 

[Webb Sledge]

nah, the pumps are working, its probably either the distributor gap or lean, more than likely the former. The carbs have been off for about a month, but it did this before they were off too. I'll look into it.

As far as timing goes, I'm pretty sure it's right, but it's hard to know. I had to order a new harmonic balancer, and it did not have timing marks on it, so I found TDC and guessed from there. Having looked at another harmonic balancer with marks though, it's really darn close if it's out any at all. My advance works, but I haven't measured it to see exactly how much. Even points gap was set recently, but who knows... it could have easily gone out of kilter.

 

[Alan_Myers]

Hi Webb,

I know DCOEs better than DGVs...

But if they are the same general jetting arrangement, maybe you need larger idle jets. This is not, as the name seems to indicate, a jet that controls the idle. Actually it's an enrichment that kicks in during initial, partial throttle. However, it's usually most noticible on DCOEs from a standing start, such as when the car has been idling at a stop light with the throttle fully closed.

The accelerator pump is another area I'd look closely at.

And, air leaks can cause this sort of symptom by leaning out the mixture.

All in all, I think you are on track that the mixture is too lean for some reason.

Again, I have no real hands-on experience with DGVs, so my "insights" may be of little value!

Alan