Finishing new pistons
G3GM :: G3 Tech :: Engine & Driveline
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Finishing new pistons
by Sinister Sat Apr 21, 2012 9:20 pm
Just received a set of pistons for my Chevy 396 build..obviously they have been sitting on a shelf for 25 years.
Box says 86 but who knows...anyway looks like a rough casting,not polished like the pics you usually see.
I need to finish the pistons somehow?
Also 3 pistons seem to have a loose fit of the piston pins,as i can push them through the piston with finger pressure.
.990 is the correct pin size...the loose pins measure .989...1/1000 gonna make that much of a difference?
I called Rock auto for 3 new piston pins. :
Thanks.
Box says 86 but who knows...anyway looks like a rough casting,not polished like the pics you usually see.
I need to finish the pistons somehow?
Also 3 pistons seem to have a loose fit of the piston pins,as i can push them through the piston with finger pressure.
.990 is the correct pin size...the loose pins measure .989...1/1000 gonna make that much of a difference?
I called Rock auto for 3 new piston pins. :
Thanks.
Sinister- G3GM Member
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Re: Finishing new pistons
by Sinister Sun Apr 22, 2012 6:51 am
There are no markings towards the front of piston.
By the instructions,the rounded portion of the dome should be closest to the valley area of the engine.
I'll be marking the pistons on the top,so once installed I can easily remember where they go.
Thanks for the help.
By the instructions,the rounded portion of the dome should be closest to the valley area of the engine.
I'll be marking the pistons on the top,so once installed I can easily remember where they go.
Thanks for the help.
Sinister- G3GM Member
- Street Cred : 0
Re: Finishing new pistons
by Sinister Sun Apr 22, 2012 6:52 am
You'll notice one piston has a very small rough area on the crown and will need to be smoothed out...you can hardly see it,but it's there.
Sinister- G3GM Member
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Re: Finishing new pistons
by Sinister Sun Apr 22, 2012 6:52 am
I was able to press the pins out after a little PB Blaster...must have been a slight bit of corrosion.
I have one piston where the pin will only go through one way...will not completely fit through the pin bore.
The instructions state to keep the pins with the piston...would you swap the pin with another piston that has more clearance?
Some pistons have more of the area removed under the piston...I'm guessing these pistons have a more dense area in the piston head?
The cylinders with the shortest intake runners should run richer than the cylinders with long runners?
Use the denser pistons on these leaner cylinders?
Thanks.
I have one piston where the pin will only go through one way...will not completely fit through the pin bore.
The instructions state to keep the pins with the piston...would you swap the pin with another piston that has more clearance?
Some pistons have more of the area removed under the piston...I'm guessing these pistons have a more dense area in the piston head?
The cylinders with the shortest intake runners should run richer than the cylinders with long runners?
Use the denser pistons on these leaner cylinders?
Thanks.
Sinister- G3GM Member
- Street Cred : 0
Re: Finishing new pistons
by Sinister Sun Apr 22, 2012 6:54 am
Underside showing different pad markings
Sinister- G3GM Member
- Street Cred : 0
Sinister- G3GM Member
- Street Cred : 0
G3GM :: G3 Tech :: Engine & Driveline
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