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Old 11-07-2000, 01:45 AM
guy guy is offline
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Join Date: Nov 2000
Location: california
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Question

I am swithing from a chevy to a dodge Intrepid in Late model. We have been very successful and fast but feel the switch can make us better. I currently race at a half mile track where I can run a 361 cubic inch motor with 11.5 to 1 compression with a two barrel 500 cfm holley (gas). The approved manifold is a victor Jr. with a 1" restrictor plate. The restrictor plate took away about 40 horsepower when we dynoed our chevy. We turn about 7400 rpm. Cars weight 2950 lbs. with driver.

The heads must be OEM straight plug cast iron production heads with no limited production heads allowed. No titanium valves, no port matching, no flow work, or any porting. A three angle valve job is permitted. Maximum valve size is 2.020 intake and 1.625 exhaust. Roller rockers permitted.

Crankshaft is limited to 49 pounds and must have a oem part number. A steel dampner with 6" diameter minimum. Any three ring piston may be used and steel connecting rods.

Camshaft must be hydraulic or flat tappet. No roller camshafts.

Our Chevy combonation gave us 415 horsepower. Any information on this type of engine or the name of a top quality engine builder would be greatly appreciated.

Thank you.
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Old 11-07-2000, 04:38 AM
355 racer 355 racer is offline
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Join Date: May 2000
Location: lansdale,pa.usa
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Guy,
Look at 6/9/00 post by Rons dirt,subject R1a & W-2 heads, also, 7/26/00 post by speedway,topic R-3 Parts. I can give you the names and phone numbers of several top notch builders, but they are here in the east. I note you are in the Cal.area. I run an R-3 355 motor just new this year and am very pleased with it. Harry
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  #3  
Old 11-07-2000, 06:30 AM
sanborn sanborn is offline
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Join Date: May 1999
Location: shelbyville,tn,USA
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RAM Automotive of Lynchburg, VA has a lot of very competitive limited engines such as you describe out all over the country. Bill Richardson is the owners name.

You may have bore size limitations but it might be interesting to consider a 3.305" stroke from a 318-340 and a 4.180" bore from a "R" block with a short 9" deck. That would also help to get your crank weight down to 49 lbs. The rules may not allow W2 heads but some of the other Chat Room guys have lots of experience with the high swirl heads that I'm sure would be legal.
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Old 11-08-2000, 07:25 AM
340king 340king is offline
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Join Date: Oct 1999
Location: Fort Pierre, SD
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There are a few things that I can tell you about this type of switch. First, I would look into the new Mopar Performance cranks that offer both a Chevy and Mopar crank flange. This will allow you to run your Chevy clutch and transmission that you currently own. There is a shop in Minnesota that converts Chevy bell housings to accept a Mopar engine too. This makes things a little easier and cheaper.

The other thing is that there are two choices for heads. One is the high swirl 360 head the other is the Magnum head. The problem with the Magnum heads is the availability and the work that may be required to use them. In your class however, the problems with intake and valvetrain are much simpler with the use of an aluminum intake and roller rockers. I am not in favor of the valvetrain reliablity that seems available in the stock Magnum head. The studs are too small and the stud bosses as cast are not big enough to support a big stud in my opinion.

The differences in the heads are that the 360 HS heads outflow the Magnum heads by about 10 cfm out of the box. The valvetrain on the 360HS head is tried and true. The main advantage in the Magnum head is the closed chamber. This allows more compression without using pop-up pistons.

Final answer, 360 HS heads with .020" out of the deck flat top pistons with a full circle radius above the head land. I used 1.94" nailhead 5/16" stem Ferrea valves for the intake and 1.60" tulip 3/8" stem Manley valves for the exhaust. They flowed about 215 cfm out of the box on the intake side.

[This message has been edited by 340king (edited November 08, 2000).]
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Old 11-08-2000, 07:36 AM
sanborn sanborn is offline
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340 King, I don't know anything about 360HS heads (wouldn't know one if it fell on me). But, can you mill these heads like we did the old "X" heads to a closed chamber? Also, would you still recommend the 1.94 intake valves even on a big bore engine?
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