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283 chevy rod length

21K views 8 replies 7 participants last post by  deathtoricers 
#1 ·
I heard the rod angle in 283 chevys are close to perfect. Anybody know the stock length on one? Do you think it would help my 302 ford if i put similar length rods in it?
 
#3 ·
the way to fit longer rods in a 302 is to fool the engine to think that the rods are longer... confused? you install 289 rods (that are marginally longer) but install the pistons facing the "wrong" way (notch facing rearwards). that way the pin offset is to the opposite side and dwell at TDC after ignition will be longer.

the effect is simmilar to putting in .400 longer rods, but it makes for a little noisier engine when cold

also be sure to check piston height with the 289 rods, it should put you right at zero installed height, making for higher compression and more importantly better quench, which will also help your engine run better

[ December 03, 2002: Message edited by: deuce_454 ]</p>
 
#4 ·
You can run longer rods in a 302 it does require custom pistons though.

The 283 Chevy uses a 5.7" rod and a 3" stroke. A 302 ford uses a 5.09 rod and 3" stroke. The Ford has a lower deck height which does not allow as long of a rod as the Chevy does.

I seem to remember people using 5.4" rods and custom pistons. This should be able to fit, as many use make the 347 stroker with the 3.4" stroke and a stock 302 block.

Adding longer rods to your 302 will improve the revving properties and increase the dwell time of the piston at TDC as well.
 
#5 ·
I agree with Double, a long rod is very beneficial to high performance engines. The target rod length is a ratio as close to 2:1 (rod length to crank stroke) as you can get. The 302 Chevrolet racing engine, with 6 inch rods and 3 inch stroke is close to ultimate. The long rod gives you more piston dwell at (and near) TDC and with less rod anglerity, there is less side thrust on the cylinder walls. HOWEVER - there is more to it than that!! Long rods are only beneficial in an engine with custom pistons (little or no pin offset) AND must be used with a camshaft profile that takes advantage of the additional piston dwell at (near) TDC. You will not see any additional horsepower gain by just putting long rods in the engine, IMO. Intake and exhaust manifolds designs should also be taken into consideration when engineering a long rod racing engine. We can expect a goodly amount of debate over my statements in this post, get ready.
 
#6 ·
Originally posted by engineguy:
<strong>I agree with Double, a long rod is very beneficial to high performance engines. The target rod length is a ratio as close to 2:1 (rod length to crank stroke) as you can get. The 302 Chevrolet racing engine, with 6 inch rods and 3 inch stroke is close to ultimate. The long rod gives you more piston dwell at (and near) TDC and with less rod anglerity, there is less side thrust on the cylinder walls. HOWEVER - there is more to it than that!! Long rods are only beneficial in an engine with custom pistons (little or no pin offset) AND must be used with a camshaft profile that takes advantage of the additional piston dwell at (near) TDC. You will not see any additional horsepower gain by just putting long rods in the engine, IMO. Intake and exhaust manifolds designs should also be taken into consideration when engineering a long rod racing engine. We can expect a goodly amount of debate over my statements in this post, get ready.</strong><hr></blockquote>


Specifically what cam profile do you like for long rod engines?
 
#7 ·
Generally I will consult with the cam grinder for the best profile, as it is influenced by so many things. Bore diameter, stroke, combustion chamber design, intake design, etc., all come into play when designing a long rod engine. A long rod engine will be able to benefit from more overlap/less LSA. One of the first things I do, before calling the cam manufacturer, is to make a graph of the complete engine cycle - comparing crankshaft degrees to piston movement, plotted at every 5 degrees of crank movement. This information is very useful to the cam designer, especially in determining where the exhaust valve opening will begin.
 
#8 ·
im thinking about putting a 347 together with 5.4 inch rods. Do I need to get a custom cam with it? I have a performer RPM intake, 2.02/1.60 RPM Heads , 1 5/8 shortie headers, and FMS E303 roller cam with 220° @.050 and .498 valve lift.
 
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