Imca stock car 500 cfm motor

[CHRISTINE]

What is better 5.7 or 6.0 rods? what about weight of rods and pistons?

[dereksehi]

Depends on how many rpm you are going to run 6 inch rods will yield a lighter piston which is easier on the connecting rod.

[fastford]

ive always liked a long rod in a high rpm engine because of longer piston dwell and less rod angle, I like the 5.7 rod in a lower rpm engine, which is what you have with a legal 500 cfm.

[CHRISTINE]

Thanks kinda what i was looking for. Thanks

[dereksehi]

I agree with stock car driver unless you are going to run lower than 6000 rpm I would use a 6 inch rod that is what I use in about 90% of our chevy race engine builds unless they want to keep the rpm down.

[Brian Gray]

The shorter rod will also help the motor build better torque numbers as long as the pistons are of good quality the 5.7 rod will work well in a limited application. The rod bolts are usually the weak link so don't scrimp on them.

[JustAddDirt]

split the difference and go to a 5.8XXX rod. (XXX means I cannot remember the exact decimal numbers)
I believe that is the length that was produced in a Ford 351 W.
But there are a lot of aftermarket companies making that length rod for the chevy journal.

(sometimes you have to think outside the box, and not be blinded by the bowtie) LoL....

[dereksehi]

The 351w length was 5.956 which is a rod to stroke ratio of 1.7:1 the 351w never had any problem building torque. The stock 350 chevy has a rod to stroke ratio of 1.63 which really isn't that good if you are going to be running in the higher rpm range whereas if you were to run a 6 inch rod the rod to stroke ratio would be 1.72:1 which will still build low end torque but will be better in the higher rpm range.

[sj valley dave]

@ JustAddDirt, you might thinking of a 5.85 rod length. That is a real popular rod in the 406" Sprint Car engines..

[stockcar5]

6.0 rods are the way to go. Lighter piston is a big advantage.

[fastford]

I agree with stock car driver unless you are going to run lower than 6000 rpm I would use a 6 inch rod that is what I use in about 90% of our chevy race engine builds unless they want to keep the rpm down.

you cant hold that kind of rpm through the turn in a street stock, a 5,7 rod will out pull a 6in rod off the comer any day at 3000 rpm and still be fine at the end of strait away, ive got a 355in ford with 5.4 rods , pulls like he!! off the corner and to 7500 with no problems. I do agree with poster above, you need GOOD pistons and get coated ones, I do my own with ceramalube . JMO

[dereksehi]

I dont believe these cars are dropping down to 3000 rpm in the corner at least not the people that are running hard. I have ran a 347 ford with 5.4 rods that came out of the corner hard but it would not lug like a 351w windsor with a 5.956 rod would coming out of the corner.

[fastford]

yea but that Windsor is way to heavy, with the short rod you can pull less gear, but there are way more variables than just rods when it comes to torque curves, if you want that little 347 to pull all the way down, put you a parker funnel web on it, it want hurt bottom end and will pull to 7500 plus, but I better hush now before I tell to much lol.

[dereksehi]

Well that presents another issue I run IMCA Northern Sportmod and cant legally run the 347 anymore and cant run a parker funnelweb either but the 351w doesnt really seem that heavy just have to cut the weight elsewhere.

[fastford]

I had a friend that had very good luck with the 351 w in a modified, but his min weight was 26 or 28 hundred lbs, he had enough ballast to get good rear weight plus I think his set back was 10 inches, makes a lot of difference ,we run a all steel limited late model and on a 2300 min we had to weigh 2450 to 2500 to get any rear weight,

[dereksehi]

We have to weigh 2500 so we don't have to much of an issue getting rear weight