318 Circle Track Engine

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Dirtfish

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I'm building an engine for my dirt track car, an 81' Mirada and need some help selecting the best cylinder head to run. The rules say 9.5:1 max, .420 lift, 1.86 intake 1.50 exhaust. Must run dished pistons. I have a very good std bore shortblock from my parts car, which was rolled years ago and don't have many miles on it. I need some help selecting a cam and heads for my setup.
 
I'm building an engine for my dirt track car, an 81' Mirada and need some help selecting the best cylinder head to run. The rules say 9.5:1 max, .420 lift, 1.86 intake 1.50 exhaust. Must run dished pistons. I have a very good std bore shortblock from my parts car, which was rolled years ago and don't have many miles on it. I need some help selecting a cam and heads for my setup.


Call Jim at Racer Brown and be done with it. That is the BEST way to select the CORRECT cam.
 
What are the carb restrictions? The 360 2bbl manifold is better for adapting the bigger carbs....
 
The trick for this would be to run magnum heads so you get flow and compression. Drill them for the LA bolt pattern and run a good 360 TQ intake with adapter.
 
Jim Dowell
Racer Brown cams
410-866-7660

Jim is a one man shop. It is best to call him after 5 eastern time. He wants customers to call that late. I have talked to him as late as 8 PM ET.

Keep us posted on what he spec's for your combo.
 
1. ENGINES WHICH ARE STANDARD BORE MUST USE STOCK POSITIONS. ENGINES MAY BE BORED TO A MAXIMUM OF .040 OVER THE STANDARD BORE SIZE. STOCK TYPE CAST ALUMINUM DISHED PISTONS, WITH A MINIMUM RECESS OF .040 MUST BE USED IN ANY ENGINE WITH AN OVERBORE. ALL ENGINES, INCLUDING THOSE THAT ARE OVERBORED FROM STANDARD SIZE MUST STILL ADHERE TO THE MAXIMUM COMPRESSION RULE. 9.5 TO 1 COMPRESSION RATIO,150 COMPRESSION MAXIMUM. NO INTERMARRIGE OF RODS OR CRANKSHIFTS TO BLOCKS ALLOWED 2. THE ENGINE MUST BE THE SAME MAKE AS THE CHASSIS. GM TO GM, FORD TO FORD-MERCURY-LINCOLN OR MOPAR TO DODGE-CHRYSLER-PLYMOTH. MUST BE MOUNTED IN THE STOCK LOCATION. STOCK CAMS ONLY!! 3. MOTORS: 307 OLDS,305 CHEVY,302 FORD, AND 318 MOPARS ONLY NO FUEL INJECTION STOCK APPEARING OIL PANS,NO KICK OUTS 410 LIFT RULE + OR - 10 NO ANGLE MILLING OR PERFORMANCE ENHANCING WORK ON HEADS OR BLOCKS. BLOCKS MAY NOT BE DECKED STOCK HEADS ONLY. NO VORTEX HEADS NO GRINDING OF ANY CASTINGS. CASTING MARKS AND NUMBERS MAY NOT BE REMOVED. VALVE SIZE MUST MATCH HEAD USED. 1.86 VALVE MAXIMUM, 1.5 EXHAUST MAXIMUM. NO MORE THAN .40 VALVE SHIMS ALLOWED TO OBTAIN STOCK VALVE HEIGHT. NO INTERCHANGING OF ROCKER ARMS, RATIOS. NO SCREW IN STUDS. NO ROLLER CAMS. STOCK BALANCER ONLY, AFTERMARKET BALANCER ALLOWED BUT MUST BE MINIMUM OF 6 3/4" IN DIAMETER AND 1 3/8" IN WIDTH/THICKNESS. NO LIGHTENING OF BALANCER. NO ALUMINUM BALANCERS ALLOWED STOCK IGNITION ONLY(STOCK WORKING ORDER) NO AFTERMARKET IGNITION ALLOWED. O.E.M. DISTRIBUTOR ONLY. NO CENTER DUMP MANIFOLDS. MUST BE CAST IRON ONLY. NO FACTORY O.E.M. OR AFTERMARKET TYPE OF HEADER ALLOWED. NO 1987 OR NEWER TRUCK MANIFOLD ALLOWED. EXHAUST MUST EXTEND BEYOND THE DRIVER'S SEAT. OVAL OFFSET MUFFLER ONLY. NO CLAMPS,MUFFLER MUST BE WELDED.
 
One issue I see right off the bat is valve sizes.....magnum heads would be great, but valve size would be to large. Might think about the mid 80s "302" heads, with a GOOD valve job, and 100% WITHOUT question, it needs a custom grind cam, as mentioned.
 
Also, small stem valves (like chevy size) are a big plus, more airflow through the tiny port, and lighter valvetrain weight.
 
Be aware that there several 318 stock piston types, flat-topped, but different compression heights. Silvolite 1278 is one.

Time for some oversize wrist pins offset bored in the rods, and offset ground rod journals on the crank with undersize bearings and all that trickery....LOL

How long is the track and what shape?
 
put the pistons in backwards it off sets the wrist pin and is worth 15hp on a restricted engine ,use the 318 flat piston without valve reliefs and 273 head. also the 360 2 barrel intake it has a 1 5/8 throttle bore or the 273/ 318 single plane intake from68 and take it to a shop and have the bores open to 1 11/16 so it will look right (I have a 273 with the holes opened up if you would like to pay shiping cost its yours)and for cam have it ground .
 
Teringer, I sent you a message. Do you mean make the arrow that points to the front of the block point back instead?
 
We found that on large tracks, "im talking 1/2 mile banked oval) that the factory early 340/360 themoquad intake worked great with the 2 barrel, it seemed the engine liked the extra plenum volume, think of it as "extra" carburetion in reserve, so-to-speak.
 
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