When i race my car it will tach out at 7k in first and second gear but as soon as i hit third it will go to 5k and stay there threw the trapps.
It is a th400 with manual valve body and a hughes 4k stall in it. 4.10 rear gears being pushed by an L-72 BBC.
Any ideas as to why it will tach out in first and second but not in third?

Thanks in advance. graemlins/thumbsup.gif

What kind of fuel system are you running?
A big block turning 7 grand needs a lot of gas.

It may also be too much ignition timing.

Bob.

I up with the gas thing. Either a restriction in the tank/line/carb or just not enough delivery.

running number 8 braided from tank to a 850 double pumper, using a holley blue pump. all brand new.

why would it go to 7k in first and second if it was a fuel problem? wouldn't that limit it to 5k in first and second also?

My 69 would pull hard in the first three gears and level off bad in fourth before I fixed the fuel problem. The bowls are usually full when you come off the line and then gradually run dry if the fuel system can't keep up. It seldom happens instantly. Even after it levels off you're still putting fuel in the bowls, just not enough. Check your total advance on the ignition too. Either way you risk detonation which can be costly.

If he was running out of fuel would he notice any popping coming out the exhaust from running to lean. Just wondering because it sounds like the same problem I'm having with my camaro.

Dean

Are you running out of gear on top end, can you bury speedo? Have you run over that rpm before?

not running out of gear and there is NO popping, it just wont go above 5k in third.
Hits 5K and stays there threw the traps. does show sings of running on the lean side, with plugs and exhaust.

BBC1 have you had it to the track to see what you are running for a time and speed and what size tires do you have?

Deano

yes, 12.24 consistently with 1.78 60 foots and going threw the traps at around 109 if i remember correctly.
Tires are 14 year old goodyear wrinkle walls 9 inch wide by 30 or 31 i think, I'm at work right now so I'll have to check tonight and make sure it is all correct. seems like i should be running in the 11's at least with my combo.I'll dig up some of my time slips and let you know all the specs tomorrow. graemlins/thumbsup.gif