Crate motors

[hipower17]

i wondered that to and whats the max bore for this.

[MLR19]

Here's what I have found with the 604 pistons, keep RPM 6800 or lower (or more importantly no valve float) and stay away from detonation and overheating ,they will last a long time.
Over 6800 leads to valve float and also loads the wrist pin bore excessively and the piston life is shortened considerably. Unfortunately the racing is getting close enough that someone willing to over rev his engine has an advantage on corner exit & restarts (but shortened engine life). I would love to see all tracks institute a RPM rule .
This is similar to the tire problem, at the tracks where we race if you aren't bolting a new RR on for every feature, and LR every other ,you are giving up speed, because there are multiple guys doing it. Same with engines, abuse & replace as necessary. These cars are so hooked up on soft tires that they are working these engines beyond their designed purpose. It's not uncommon to run a 10 lap heat race without lifting. I'm amazed they last as long as they do.

[brad hibbard]

Have to agree with the statement from MLR19
the guys that insist on running 7000 to 7200 or actually anything above 6800 are significantly shortening the life of the entire engine

let me add this to be more direct about the question
top ring land wear is overlooked by many rebuilders
top ring lands will wear more quickly with high timing, low grade fuels and poor air cleaner systems
a piston can look perfect---the skirt can measure perfect---but once the top ring land is worn it will have what is called ring flutter
when the ring flutters it wears the ring, block and piston at a very quick rate
I am sure many folks can remember having an old worn out engine rebuilt and the thing runs great for 5 races or so and then it is back to lacking on RPM, using oil and over all down on power.
this was because the ring flutter wore the parts quickly.
the GM piston used to be $100 each which made it a hard choice as to whether or not to replace them
They now are in kit form and price out substantially less
In our shop we find that almost always on the second rebuild the engine will need new pistons due to top ring land wear

hope some of that helps
Brad

https://www.race-1.com

[CCHIEF]

Ring flutter = poor sealing at max RPM too.

[hipower17]

on the rockers can u run anything other than 1.5's ratio?

[MLR19]

None of the tracks or series we run allows you to change rocker ratio, I think that is pretty much the standard.

[hipower17]

can u run any brand of rocker as long as its 1.5?

[brad hibbard]

there are a few outlaw sanctions that permit aftermarket and higher ratio rockers but for the most part and I truly mean the MOST part---the rocker arm ---push rod and valve spring are the tech areas concentrated on the most and there are no substitutions or upgrades permitted---must be the CORRECT GM part

Brad

https://www.race-1.com

[hipower17]

why do they call them powder rods and do they have the same dimensions as stock 5.7 gm rods and fit a sbc crank from say the 70's?

[Krooser]

The rods are made by putting a "powdered" steel into a form pressing/forging it to produce a high quality rod. It's then put into a sintering oven which heats the rod and bonds the powder together.

A regular rod is made from a steel "billet" then hammered in a drop forge.

I've found GM PM rods to work very well in limited HP applications. My sons B mod uses them and I have two more sets in stock in my shop.

[dirty white boy]

were sposed to been the next great thing in budget racing but there limitations came in lil lower than at first expected!! do great in limited hp builds and believe cat uses powdered metal rods in some of there motors!

[hipower17]

would these rods fit a two piece seal crank?

[hipower17]

what yr did gm make the upgrade to the rods?

[brad hibbard]

2010 ish
cranks made the change in 2010 for sure and rods followed
by 2012 I am sure we were on the new rod

brad

https://www.race-1.com