If I recall, this spring I had 13.5 in the middle of a 1/4 mile track....

I' llcheck again this week end

Let us know, I think it will run quicker and faster with AFR in the 12.4 to 13.3 at WOT, especially in the last 1/8 mile in the 1/4 mile Have you treid jetting it up yet? If not, test, test and test some more

If you are starving it for fuel (either by jetting or fuel supply) you can lose 1-200 HP! You basically kill the engine.

I'm not saying this is your problem, but typical 750 carbs with no PV's are jetted around 78-80's...and you have 2 carbs so think about it...it's an easy test. If nothing gets worse or better, it might be fuel supply.

Make sure you check everything else out too...I still say dyno testing is the best way to start with a new combo to get you close on tune up, and also easy way to make sure engine is healthy and happy...i.e. valve train issues is one that comes to mind.
Brian

I was thinking the converter might be in fault.........

What's it flair to?

This is where MPH data would help tremendously but also lack of fuel or fuel supply will show low MPH too....

I dont think its a conv issue.. its got a strong
60'... what are your rpms at the line.. if its
slipping hard up top the rpm will tell you... I
think its all a fuel issue.. either jetting or
supply
EDIT
You might want to change the needle and seats
to .120s... but normally with 2 carbs the .110s
work fine.. but something to think of

I recall last year going richer without success........the reason why I got myself a wideband

That's why I'm not sure going this direction will help, but I will keep an open eye on that this week-end....

Dan

You need the MPH... if you jet up 4 sizes and
if nothing changes or if it doesnt slow down
(MPH) then you have a supply issue... could be
a needle and seat being to small also... do you
have a fuel gauge you can see during the run...
and dont use a oil filled gauge... if its under
the hood and filled it will show a lower pressure..
thats the oil heating up and pressing back on the
gauge

Needle and seat could be an issue....I don't have a fuel gauge I can read during a pass: I can keep an eye on the fuel bowl and look the level trough the side glass ! lolll

Like I sais before, I have had that problem for the past 2 years. I went pig rich with plugs pitch black with no results...This on a single carb that went on a dyno...tested rich or lean....

What can happen on tunnel ram setups is they can pull a ton of fuel at high rpm causing performance loss in excess of 100HP and even pull enough fuel to sometimes cause the engine to rpm limit!

Hard to see when your trying to drive the car, shift, and all. Might be why the plugs are black?