[ChallengeThis340]

They closed the last drag track on Long Island (NY) and the next closest track is over 3 hours away and through city traffic. I don't have anything to trailor the car so it's going to be tough to get it out there. I will probably wait till I have more mods to bring it out there (I still want to do a higher stall and exhaust).

Anyway, im really wondering what my 1/4 times would be about. Im not talking about an exact time, but i'd like to know if you guys think this car has what it takes to break into the 12's.

I'll do my best to list everything that is in it. I helped build the engine at a speed shop I work part time at, but my boss picked out most of the parts and I forgot some of the details.

motor:
69 340
balanced rotating assembly
bored .030 over
speed pro pistons (I want to say the car has a 9.5:1 compression but im not sure)
Eagle forged rods
comp exhaust valves, hardened valve seats and valve springs
3 angle valve job
edelbrock performer duel plane manifold
holly 670cfm street avenger carb
hooker super comp long tube headers
MSD 6al
Freddy Brown built 727 tranny with manual valve body/shift kit
3.91 gears

Here are the comp cam specs off the card: intake: gross valve lift: .480 Exhaust: .480
.006 tappet lift : 280
Grind: CRS 280h-10

We recently did a whole suspension overhaul with pst front end rebuild, kyb+lakewood shocks (70/30), weld prostar wheels and Micky Thompson l60's in the rear. The car hooks as if it was all wheel drive. Barely any spin at all when those tires are warm. Of course we are still running the stock stall so that might have something to do with it. It still launches pretty hard for a 340 though. Traction is NOT an issue here.

Most people tell me the car has what it takes to go into the 12's, but they aren't mopar guys.

I've only ran the car at the track once, before they clsoed the track. It was about 85-90 degrees out with VERY high humidity. Something went wrong at the staging lanes and I had to wait. I shut the car off, but when they said they fixed the problem, i turned the car on and the temp was around 210 when I launched. Pretty hot, the car normally runs at 180. I was also only shifting at 5800 when I found now that im getting more power when I shift at around 6000. The launch was also pretty bad because we were still working out some vacuum issues with the brakes. I ran a 14.4 (first and only track run ever), im sorry but I don't recall the mph. That was about a year ago, since then my boss has jetted the carb /swapped springs , which made a HUGE seat of the pants difference.

What do you guys think? Do I have a shot at 12's? Maybe with a higher stall and exhaust system? The current exhaust from the headers back is stock and SHOT. It's rusted to bits and the mufflers have holes galore. I would imagine that is killing some power and the stall isn't allowing it to launch anywhere near 3000rpm-where the came starts making power.

BTW, I am at sea level.

Thanks!

[dave-r]

With a full but good flowing exhaust system you probably have just under 400hp @ 6000rpm and about 400lbs of torque at 4500rpm in the engine. Somewhere around 330hp at the rear wheels.

You would probably get a better time with a higher stall converter and with a 4.10 rear gear. You also need to shift at 6500rpm with this cam.

I don't think you quite have enough to go 12s as it is (assuming your car is near original weight) but I would expect you to run very low 13s. Say around a 13.2 @ 104mph.

But I couldn't rule out high twelves with this combo completely.

[ChallengeThis340]

Thanks.

My boss, the builder of the car has been pushing me to go with 4.56 gears in the rear. The car is a street car, but isn't driven on highways that much. I mostly drive it locally around town with the occasional blast off from a dead stop. Im willing to sacrifice some driveability for power, it's not my daily driver anyway. Do you think that this would be over gearing it (not in a driveability way, but hurting 1/4 times)?

Also, when I bought the cam it said that it made power from 3000 something up to 6000rpm. Does this still mean I should shift at 6500? I know these 340's like the high revving, and with the fully forged internals I wouldn't be pushing it correct?

[dave-r]

Keep reading my theory posts.

Remember peak power is only there for a second. The rest of the time you are at some other rpm.

If you shifted at 6000 your rpms would drop to about 4000rpm.

Your average HP over that rpm range would be lower than if you shifted at 6500 and let the rpms drop to 4500.

The best results with your combo you would have to find out through trial and error but I would guess shifting at around 6750rpm would yeald the best results.

However I would stick to 6500 for safety and not to push your engine too hard.

As for the rear gears. A mate of mine uses very low gears in his almost stock 318 powered car and runs mid 13s. I admit his car is a lot lighter and set up very well for the track but it is still impressive for such a low budget car.

I personally would not use anything lower than 4.10s to run around in but there is no reason you can't go lower than that especially as you don't intend to drive very far very often. The lower the rear gear the more torque you have at the wheels but of course you loose top speed as a result.

I actually use 4.30 gears but also have an overdrive so it is like using 3.30 gears when cruising and the track I go to is a 500 mile round trip.