Rhythmic and pulsing. No--- it is my car!

[billschroeder5842]

Now that I have my 4bbl opening I now have another problem....

Under acceleration I get a rhythmic, pulsing on the power of the engine. My guess is that it is not electrical but fuel driven (or lack of) so a heavy sputteringbut feels like a fuel starving issue??

Is there any adjustments I can make on a Carter Thermoquad that might smooth out the acceleration? The car run great and is super smooth when steady. I only get this under acceleration. Is this a float thing?

Oh, if it helps I have a ever so slight fuel lead on the drivers side from the underside of the by the accelerator pump. This lead only happens after the car has run and when turned off----my guess is that the fuel pressure forces this out. There is no leak when running.

Thanks!

[myk]

First things first: see why the 'acc pump is leaking as it's a safety issue among other things. Then you can look into other things like fuel delivery and pressure.  There is a procedure for testing fuel pump output when you get to that point...

[Ghoste]

If the cruise vacuum happens to be at that just right point that the metering pistons in a Carter can't quite pull the rod in but the springs can't quite release it, the rod sort of flutters in and out.  That can make it do strange things.
But I'm no carb guy.

[billschroeder5842]

Thanks. I'm not sure where to go...

I believe I have good pressure (the slight leak is evidence)

Timing is 10 btc

Idle vacuum is SUPER steady at about 17

Hmmmmmm......?

[Dino]

It's the floats.  I set mine in the thermoquad at recommended specs.  Cruised beautifully until I put the pedal down, it started doing the same pulsating thing.  After checking several things I figured it had to be the floats so I ignored the  numbers and set them by feel and now she's happy camper!  No bog, no sputtering or pulsating, just a smooth run all the way up the rpm range.

Oh and I got rid of the crappy foam floats and got a set of brass floats from Napa.  The foam floats just don't last and once they soak up fuel you'll never get them adjusted right.

[Ghoste]

Oh yes, forgot about that, the Carter carbs are very fussy about float setting too.

[billschroeder5842]

Ok...

Please tell me there is a way to adjust the floats without taking the to of the carb off? I did a bit of research and it looks like you need to dismantle the carb to set the floats?

I miss my Holley.

[Dino]

The top has to come off, no way around it.  You could leave the carb itself on the manifold but I never did, it's easy enough to just remove it and work on a bench.  Still it is an option and you'll have the floats reset and the carb back together within minutes.  Once you have it dialed in properly you will never have to tune it again and I doubt you will miss the Holley.

[Ghoste]

Yes, because it isn't just float level with a Carter but it's also float drop.  That spec is just as important in one of those.