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  #1  
Old 01-28-2000, 03:52 AM
jay jay is offline
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Location: Harrsion,Ar. USA
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This is a question for 340king or anyone that likes. I'm thinking of building a SB to compete with 433cin chevys on a 3/8 hight bank dirt track. We've been running a BB for 5 year but as the speed increases the handeling decreases. The motor I'm thinking of builbing needes to be as large as possible within reason. I'm thinking of a 340
block bored .030,putting in a 3.79 stroke forged crank, from Mopar, Ross zero deck forged pistons, Eagle 6.123 bushed rods, Melling oil pump, Mopar 258@50 630lift int. 262@50 645lift ex. roller cam #P4529985, W-2 race heads 2.02int-1.60ex. true roller rockers @ hardened shafts, valve springs to match to cam, Mopar headers 2-31/3@ shorty race mufflers, requiered a track, TCI rattler balancer, roller timing chain & gears and 10,000 RPN tripple disc clutch. The intack is open for suggestion. I,ll be running 6.33 or 6.20 gears in a 9inch. RPMs will be in the very high 6000 to low to mid 7000. I'll also be using a 2bl race carb. Any ideas anyone has will be most helpful.
Thanks Jay Thomas
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  #2  
Old 01-29-2000, 12:25 AM
Jim C Jim C is offline
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I'm not an engine expert, nor do I race on dirt, but I do know you guys all seem to run big CIDs for torque. So why not start with a 360 motor if you're going to a small block?
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  #3  
Old 01-29-2000, 12:55 AM
340king 340king is offline
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Location: Fort Pierre, SD
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In your other post, you said that the track was usually dry slick if my memory is correct. This is what I am running against well prepped 377-406 cid engines.

I use a 340 as the base engine. My reasons for this are I have several of them, it has a lower rotating mass, has a smoother torque curve than a 360 and runs cooler typically than the 360.

I built the engine with stock flat top KB pistons. I had to trim the pistons to fit into the 273 commando heads. This yielded a 11:1 compression ratio. I wanted to stay low on compression to avoid head studs and run cooler. The lack of domes made the slugs lighter also. We had to trim 1/4" off of all the crank counterweights before fine tuning the balance. I run gas instead of alchohol because of my sparatic racing. Also too much torque is a handicap on dry slick, at least until you are in Tony Stewarts league of driving. The gas is burned off at a slower rate and helps for more consistant weight balance and better handling at the end of the feature.

I used a Reed Cams tight lash solid, we can't run rollers. It is designed for low compression or resrticted/restrictor plate engines. It worked very well.

I concentrated on reducing rotating mass all through the car. In my opinion it is easier to drive a light drivetrain car on dry slick. I use a 904 trans with a direct drive coupler. It is plumbed to bypass the pump pressure into the pan with a ball valve. It really works well. The car reacts like it is injected even in gear on the jack stands, very responsive.

I might run your combo on the computer dyno programs to see how it works. What W-2 heads are going to run. My recommendation is to go with the 64cc heads if you can. They have a quench chamber head design and aren't so small that shrouding is a problem like the 57cc heads.

I would be inclined to run the Victor 340 W-2 intake. I am not impressed with the W-2 M-1 I have.

As for strokers, I have thought about them, but the check book says no. Besides, 550 hp is easy to make with the 340.
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Old 01-29-2000, 03:12 AM
jay jay is offline
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why doe I what to run the 340 block over the 360 block is a good question. Here is my answer, right or wong, the 340 block is bored 4.040 and the 360 is 4.000. Remember I need as many cubic inches as possible without having to buy a R-3 racing block. I can get over 420 cu in by using the R-3 block but can't justify it until I see how the part combination works together and find a good sponcer. A 340 .030 overbore with 3.79 crank will give me approx. 392 cu in. The 360 .030 overbore is approx. 387 cu in. Hope this clears thing up a little.
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  #5  
Old 01-29-2000, 04:19 AM
340king 340king is offline
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What kind of tires do you run? What class and weight of car are planning to run?

I can spin the tread right off of these Hoosier Dirt Bozz tires. I can roast them all the way down the straight with my little 340. It bangs against the 7,400 rev limiter in hot laps and heat races, and I run it to 6,700 in the feature, trying not to spin the tires.
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  #6  
Old 01-30-2000, 08:43 PM
jay jay is offline
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We per track rules we must run a asphalt pulloff. We can groove them any way we want. They must tech out at 55 hardness. Our cars must weigh 3300lbs. Spinning the tires when its dry slick is a big problem. But straightaway speed on these car is something you have to see to believe. AS far as the frame goes, I'm not sure if I'm going to use a mopar like out of a 76 Newport, shortened of coarse, or a metric which I allready have. For a body I plan on using A 5-Star alum. Avenger, not stock I know but I think I can get by with it. No one at the track thinks a Mopar can win a race.
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  #7  
Old 01-31-2000, 04:25 AM
340king 340king is offline
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In my other post I told you about traveling with the Dollar Transportation crew and their IMCA mod(s). They ran 302 Fords against all comers. They built them with about 11:1 compression, mild heads and cast pistons.

The idea was to build an engine that could rpm out and make HP, but would hookup coming out of the corner. These guys were very successful. They ran the engines to 8,300 rpm religiously. The cars were very tough on dry slick. That is why I stayed away from strokers, along with the cost.

I tried to mimick their successful setup right down to the low compression engine that likes to wind up. It really seems to work well on dry slick.
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