eastoncatcher3

So i put my motor completely back together wouldnt start. checked all the wiring vacuum lines etc. after i checked all that checked compression. no compression.
So a local mechanic said the guy who set my rings might not have set them right? sounds reasonable.

I go to La tech for automotive now. so i brought it in and pull pistons out. checked with a micrometer the inside diamater of the cylinder walls and they are off. so needs to be bore over. well two pistons arent circular (if thats the right word?)

now the questions:
1. bore it over .20 how much more hp/torque ya think it would give me?
2. do you have to run a higher octane fuel?
3. engnbldr have a good set of pistons and rings?
anything else i would need to know?

Sportsmanphil

If you had no (as in zero) compression, its not a ring off or a cyl out a few thousands. You later said only two were out, yet no compression in all 4 i assume.

If this happened after you put it back together, your timing chain was off and the valves were not closed on the compression stroke.

xxxtreme22r

You might notice a slight gain in torque with the 20 over mainly in upper RPMS I think, I have the EB 20 over in mine. No need for higher octane. Just keep an eye on the ring gaps when you put it all together.

eastoncatcher3

sportsman i brought it to a mechanic to set my timing. he said he set it right. and he couldnt get it to started. then we checked compression and he was getting no compression and no leaks from intake or exhaust side. so i brought it to school and checked the inside diameter of the cylinder walls two cylinders checked out even. two cylinders were off.
xxxtreme22r thanks thats what i needed to know.

Sportsmanphil

What were the cyl #'s wet and dry?

eastoncatcher3

come again on that one? wet or dry.
i dont remeber the exact numbers i have them written down on a paper at school
im pretty sure the 2nd and 4th cylinders were the good ones.
1st and 3rd are the messed up ones. my micrometer only measured down to so far. and those numbers were off. like it could be .0008 off or something and still be fine. im not sitting in front of the paper so i dont know. but my meter only went down to .000 and the last number was off. meaning over .0008

Sportsmanphil

You should do a dry compression test (cold- dry cyl walls) and a wet test by injecting oil through the plug hole.

corax

nada - the head, exhaust and induction make power - the short block is just the pump (unless you start reducing reciprocating mass, etc). You can use the same grade fuel no problem


let's do the math:
3.63" stock bore = 10.287 sq in x 3.5" stroke = 36.004 cubic inches
3.65" new bore = 10.458 sq in x 3.5" stroke = 36.604 cubic inches
so this will give you 1.6% more volume, but you'll still be flowing the same amount of air and fuel. I didn't figure the very very slight bump in compression because it won't make much either. What you will get though is a nice fresh seal on the rings, so less blow-by will mean more power to push the pistons - that would be noticable

BTW, just to be a stickler, it would be bored .020" over -> 20 thousandths, I took my last truck to .080 which is pretty much the hairy edge and it was the cam, intake and exhaust work which gave me more power

eastoncatcher3

i would test it all but its all the way torn down to the block as of yesterday morning.

Yeah i couldnt remeber the exact figures.
Thanks for the info that break down helped alot.

Now another question i want low end torque i seen engbldr had a crawler cam. any suggestions on what kind of cam?
i want to order one asap before i bolt the head down.
and if my ticket gets fixed then im ordering it by friday

jr671

Heading to the store when suddenly I press the gas to climb the hill thats when it just started bogging pls help cant fine the problem

Terrys87

iTrader: (1)

Fuel injected or carbureted? When was last tune up with plugs, filters, wires, cap, rotor, and any vacuum leaks?

jr671

Fuel injected. ....about lest then 3months. .

jr671

How do I check for vacuum leaks ?