Lightweight parts????

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68stcracing

Lightweight parts????

Post by 68stcracing »

Im building a stock car motor. 9.8:1 compression just below the max, and a limit of 360 w/1% error. 4412 gauge legal carb, 1" 4412 TO 4150 adapter, on a 2701 Edelbrock intake, 6600 rpm pill. 50 lbs crank rule. Must use Stamped style rocker arms(no rollers). any cast iron head with 23 degrees. Pump gas.
Where is there a better advantage increasing power, if budget dictates,bottom end lightening the rods/pistons,pins OR spending money on lightweight valve train parts, including light weight lifters?
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Re: Lightweight parts????

Post by Krooser »

The best answer is BOTH….I'd buy the lightest piston that are in th budget then work on th valve train. The SBM engine I just bought has over $500 worth of Ti retainers and locks… wow! But it still has heavy 3/8" valves which I will deal with before it runs again.
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Re: Lightweight parts????

Post by PackardV8 »

Where is there a better advantage increasing power, if budget dictates,bottom end lightening the rods/pistons,pin
In a technical discussion, correct terminology is everything. Lighter weight rods/pistons/pins don't increase horsepower. Lighter reciprocating components can help the car gain or lose speed more quickly. Is there a flywheel rule?

Sometimes "flutter" or seat bounce is present even at 6600, so lighter weight valvetrain can help the springs control the valve train and more accurately follow the cam profile. Smaller valve stems reduce weight and can slightly increase flow. Better valvetrain control can sometimes allow a slightly taller gear, thus maintain the pull just enough longer to put a wheel on the guy you're trying to pass before hitting the rev limiter.
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Re: Lightweight parts????

Post by psychomotors »

Both are excellent answers in my book.
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Re: Lightweight parts????

Post by pamotorman »

the stamped steel rocker are your limiting factor. heavy valve springs or lobe design will cause a problem as the after market ones sold now do not seem to stand up. I had better luck using older OEM rockers from scraped engines if you can find them.
68stcracing

Re: Lightweight parts????

Post by 68stcracing »

Have to add no titanium parts. rule is 1.250 valvespring
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Re: Lightweight parts????

Post by psychomotors »

Does that include or exclude "beehive" springs?
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Re: Lightweight parts????

Post by groberts101 »

psychomotors wrote:Does that include or exclude "beehive" springs?
lol.. beat me to it before I could even log in.

I would agree with the above.. both is always better. The quicker the engine cam come up onto the cam via the lighter rotating compnents.. the more it will tax the springs due to quicker transient throttle control. Lightening the valvetrain not only helps improve lift control.. it also sets you up for less overall spring pressure needed to get the job done. Some reduced losses to be gained back there too. And many times those reduced rate springs will still allow a buffer to run more aggressive ramp rates on the chosen cam. Reduced pushrod flex.. less overall wear and tear.. and even relating to valve control and geometry improvements despite being forced to use those stamped steel rocker arms too.

Cam limitations?.. and can you also run aftermarket stamped rocker arms that are known to have more ratio consistency as well?
Last edited by groberts101 on Mon Jun 27, 2016 3:56 pm, edited 3 times in total.
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Re: Lightweight parts????

Post by psychomotors »

groberts101 wrote:
psychomotors wrote:Does that include or exclude "beehive" springs?
lol.. beat me to it before I could even log in.
LOL. At least I finally asked a legit question.
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Re: Lightweight parts????

Post by pamotorman »

make sure the oil does not overshoot the rocker arm ball by using some type of deflector.
68stcracing

Re: Lightweight parts????

Post by 68stcracing »

Valve springs, 1.250-inch maximum diameter, 0.195-inch wire, steel retainers. Five (5) full coils is the rule. we can use aftermarket stamped rocker arms.
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Re: Lightweight parts????

Post by wyrmrider »

so the hd elgin 1.6 rockers on the intake if you have an open cam rule
can you run "stock" SB Olds or Buick 6" rods you can really lighten up the pistons
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Re: Lightweight parts????

Post by ap72 »

Don't blow your budget on one item. Trick valves won't help ring seal and fancy lifters won't fix the wrong cam. A balanced approach will yield the best results.
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Re: Lightweight parts????

Post by BigBro74 »

ap72 wrote:Don't blow your budget on one item. Trick valves won't help ring seal and fancy lifters won't fix the wrong cam. A balanced approach will yield the best results.
^^^^^this, and i'll add don't skimp on the "any 23 degree cast iron head" rule! get good ones, for this engine...
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