I went to the track last sunday for so little test and tune...

my car went 13.2-13.1 @ +/- 105 mph all day long (over 12 pass with those time) and my best 60ft was 1.801

almost got into 12 with a 13.063 @ 105.61mph with a 1.811 60ft

but even with a 1.8 60ft I could easily feel a bog out of the hole...

I have a mild 350, with an unknowed cam (it idle really smooth with 16-17" of vaccum) , 624 heads, flat top piston, performer intake, headmans headers, 3" cutout, Q-jet carb (74 primary jet with 36 or 38 primary metering rod, and I can't remember secondary rod) the float is set at .250" from the top of the bowl, I have my timing set a 37 total degree (this is where I had my best time and MPH)...

I have a 3.27 9 bolt with a tight posi, MT et drag (26X15X8.5), a T5, and I can really feel a bog out of the hole even with a 5500RPM launch (I've got many 1.8 60ft by lauching that way...) just like it is lacking torque to get momentum.

now I really want that 12 second pass and i'm pretty sure tat if I could solve this **** bog, I would be where I want.

btw if it can help I've weight my car at 3450lbs with me and half a tank of gas...

 

Tighten up the AV tension a little bit.

More gear.

Known cam (say, XE274).

Properly matched intake manifold (like RPM or Stealth).

This is one application where I'd recommend a Holley (like a 650 DP) over the q-jet.

Looks like you've got the power (i.e., MPH), now you need to get the ET to match it.

(Remember, $'s/ET is not linear.)

 

this is exactly what I bought, but I did not plan to install it before next winter...

Also, why do you recommend a 650 dp over a Q-jet?

 

Easier to tune. Not everyone knows how to tune a Q-jet with the rods and hangers. More aftermarket parts are also available.

I'd suggest at least a 750 carb.

I'd say you need a bit more gear also but then I also ran high 11's with a 3.27 geared 9 bolt years ago. I also had a lot more HP. A deeper gear will get you off the line quicker and lower the 60' time providing you can still get traction.

A 5500 rpm launch is way to high for your engine and diff gearing. You should be launching somewhere in the 2500 - 3000 range.

 

Because it's not nice to "speed-shift" a T-5. If you don't do that, you close the secondaries between gears - this requires some amount of time, albeit only a split second, for the q-jet AV to re-open when you hit it again.

With mechanical secondaries, the re-open occurs when you hit it again.

Although you might do okay with a 750, a 650 is probably big enough to handle your engine's "real" need (CID x RPM / 3456 : a 355 shifted at 6500 would want 667 CFM assuming 100% VE). If you're concerned about bogging, don't go any bigger than necessary with a DP. The max DP CFM is dictated by the minimum RPMs you go WOT - 5500 RPM launches are not T-5 friendly. Again, you'd probably be okay with a 750 at 2500 RPM launches (see Holley.com under carb, tech info, mech secondaries), but a 650 would be sure-fire.

 

Don`t dual plane intakes usually need to be overcarbed a bit compared to a open throat?

 

The theory is the larger plenum area of a single plane will reduce the pulsing seen by the carb, so you can feed a larger engine with the same size carb. But, VE is typically better with a single plane, too, so there can be an offsetting effect (if VE is less than 1, you need less carb).

People tend to overcarb. I didn't see any difference between a 650 DP and 750 DP on my 396 shifted at 5600 (dual plane intake). But, the 750 didn't hurt me, either, because it's above the line on the Holley chart.

 

I have a very similar combo, mild 350, Qjet, T5 etc... but the major
difference I see is the 3:73 gears which I run. I ran 12.88 with even less MPH. That would be my recommendation. See sig for details.