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Author Topic:   i thought i knew ????????
Dirt Newbie

Total posts: 1
posted April 26, 2001 01:26 AM
I am building my first car and i have a few(lot of) questions. I am going to be running on a 1/4 mi. dirt track,the car will weigh 3100 lbs., 2bl 500cf only, 355 c.i.,cast iron factory heads only.I have the block back from the shop.i have a scat crank. we can do what we want to the engine but no alum.(except for the intake)
1.what cam should I use?
3.big valve heads or small?(I have both)
4.350TH,400TH or glide?
6.springs rates?(76 monte chassis)
I can change rear ends if I want. will a 10 bolt hold up? 12 bolt? 9inch? I just don't know where to go.
I know most guys I talk to run about a 630 final gear.

[This message has been edited by badboydale (edited April 26, 2001).]

Dirt Newbie

Total posts: 3
posted April 26, 2001 01:00 PM
1 Use a nine inch with 6:50 gears
2 Bigger the valves the better, but get the combustion chambers as small as possible- mill the heads it is cheap power, lots of compression really helps even on 2 barrel cars.
3 Try 1200-1400 rt front and 150 less on left front, rears should be 350 -400 on this heavy car, maybe less - if you do not get some body roll you will get no side bite. Lots of rear stagger helps in this type of class (2-4")
Remove all the weight you can ahead of the front wheels and keep the most mass between the axles. Try to get 52% rear weight without adding lead behind the axle. 49% cross weight. Use stagger and body roll to promote good corner exit / bite.

[This message has been edited by fast19 (edited April 26, 2001).]

Dirt Newbie

Total posts: 3
posted April 26, 2001 01:43 PM
I currently race on a 1/4 mile track and I believe on a short track you should keep the cam simple. Many guys over cam their cars on short tracks. Stay away from the big wazu cams.

The cam you choose (along with other factors) will determine your gearing. Bigger cams with longer duration = lower gears.

I think a simple and effective & inexpensive transmission set-up you can use is a standard 3 speed with a stock type clutch - if the rules allow it. I know some rules that require automatics - if so, use a glide.

If you use the 10 bolt rearend get aftermarket axels. A 12 bolt is better and the 9" better yet because of strength, ease of gear changes and parts availability.

No offense, but I think fast19's spring setup is a little stiff. I would go along the lines of 1000 - 1100 rf, 925 - 1000 lf, 200 - 250 rr and 275 - 250 lr. Other than that he's got some good points.

E-mail me if you would like exact casting #s and part #s.

[This message has been edited by hirschi49 (edited April 26, 2001).]

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