By errol (205.188.200.155) on Monday, March 26, 2001 - 06:57 am:

What are the differences between the eb2 and eb3 pistons? I can get a set of eb2 (.75) new for $50.00. If i were to use them in a eb3 block/head would it drop compression?

By Todd (63.52.17.4) on Monday, March 26, 2001 - 08:46 am:

EB3 has a slight dome. EB2 does not. As you suspect, it will drop compression considerably.

By errol (205.188.200.154) on Monday, March 26, 2001 - 10:28 pm:

HHHHHMMMMMM.... These are 'domed' but have a flat around the outer edge, about 1/8". I looked them up in a very old parts manual from federal mogule(?). and the part number figures out to be a EB2 because a EB3 shows a 'dome' all the way to the edge

the manual also showed that the 80 1300cvcc as a domed one also, but for only that year (?) But then those two EJ 1300's that i have both have flat-tops..... "Make it go away MOMMA"

By Charles R. (64.170.157.173) on Tuesday, March 27, 2001 - 11:55 pm:

A long time ago, I went to a machine shop that had a book with all the different piston profiles available. According to that book, there were SIX(!) different piston tops for the EJ1300 between '80 and '83. They ranged from a .050" sorta dome, to a .050" dish.
Sick, huh?

By errol (64.12.103.32) on Saturday, March 31, 2001 - 10:18 am:

Charles R. So if i were to use those eb2 .075 over pistons on a ej 1300 rotating assembly and a eb3 head would it raise or lower compression?

It's just that they are a good price and in stock!

By Charles R. (64.170.157.231) on Sunday, April 01, 2001 - 12:56 am:

.075? That's not the oversize dia. is it? That's about 2mm,and that's VERY big for an EB2 engine.
If you're talking, boring the block .075" bigger and using a 1300 crank/rod set, you'll have nearly the same bottom end I have (mine's .080"dia.). The EB2 head will give you about 12:1, while the EB3 should be around 9:1. Displacement is a little over 1400cc's.

By Don (209.181.52.16) on Sunday, April 01, 2001 - 07:36 am:

I think he has .75 mm over size pistons, not .075 inch. Wont this lower the forcasted Comp # by about a point?

By david (208.130.246.237) on Sunday, April 01, 2001 - 02:02 pm:

has anyone had any experience with those crown convex pistons? the ones that came on the japanese RS's and GL's.

By Bill (65.27.98.82) on Sunday, April 01, 2001 - 10:09 pm:

I have a RS/GL motor.
Cam And crank are shot..Bores are Ok.
One piston skirt is nicked,due to thrown rod.
Looking for a piston although I have been told I could dress the skirt and be Ok.
Don't know about that.
Anyone have anything let me know.

What is the difference between the RS/GL and the EB3 heads 70mm vs 72mm as far as combustion chamber volume ?

I currently run an EB2 .010 oversize pistons, Web #102 cam and Holly\Weber carb,balanced with lightened flywheel and custom tri-y header.
Runs like a "Raped Ape"

Anyway..What about oversize EB3 pistons with the EB2 block Rs/Gl head{Thinking there will be some compression gain}
Twin Dellorto DHLB 35 mm and Web #68 cam ?
Thoughts...Ideas ?

Thanks
Bill

By Adrian (Civicguru) (203.42.97.227) on Sunday, April 01, 2001 - 10:31 pm:

70mm bore for EB1, 72mm for EB2/3, not combustion chamber volume. I can't find where I have combustion chamber volumes recorded just at the moment, but from memory EB3 is somewhere around 36cc. EB1 RS and EB3 heads are very very similar. At a quick glance you can't really tell the ports and chambers apart.

"Anyway..What about oversize EB3 pistons with the EB2 block Rs/Gl head{Thinking there will be some compression gain}" - Block makes no difference (basically all the same). Using EB3 pistons with an RS head basically gives you an EB3. You will have no significant compression gain over a standard bore EB3 unless you skim the head a lot.

By BritCivic (128.243.220.45) on Friday, November 09, 2001 - 03:14 am:

Errol,
my EB3 pistons are exactly as you describe 'These are 'domed' but have a flat around the outer edge, about 1/8".'
with 72 mm nominal bore. sounds like the pistons you are looking at are EB3 not EB2.
Hope this helps

John