UPDATE on page 3--Here's a couple of pics I took.....

Topic: UPDATE on page 3--Here's a couple of pics I took..... (Read 2165 times) previous topic - next topic

UPDATE on page 3--Here's a couple of pics I took.....

Reply #15 – September 03, 2008, 08:53:55 PM

Quote from: kitzdnm;234777

Hey Vinnie,you keep at it all of the pistons will have valve reliefs!! Lol

Quote from: massCougarxr7;234838

lol im just trying to figure out what half of you guys are talking about most of the time,,,,,, no idea what an e6 or whatever all the numbers mean!!!! i just know if i can take it apart and and tork it down correctly .. i should be fine....my bb swap is definately my first big project..... hoping to learn a bit....

E6 and E7 are just part of the casting numbers in the heads.

UPDATE on page 3--Here's a couple of pics I took.....

Reply #16 – September 03, 2008, 11:52:51 PM

Quote from: Bob;234840

E6 and E7 are just part of the casting numbers in the heads.

They are different heads.

As far as being quick,It wasn't that bad of a problem to work on.I've had the thing apart so often it seems like just another day almost.It appears that if tomorrow is a decent day,part of it may be applied to swapping the steering rack.It's been leaking from where the inner tie rods connect.I have a new one in the box,but just haven't had a lot of time for swapping it out.I have to fill the pump every morning.That has to stop quick.

UPDATE on page 3--Here's a couple of pics I took.....

Reply #17 – September 03, 2008, 11:59:51 PM

Quote from: ZondaC12;234779

Alright then its the terminology that keeps messing me up. Maybe its just me, but when I hear FLAT TOPS, I think.....FLAT....TOPS....as in flat. Solid NO indentations or surface irregularities of ANY kind. I would think those would just be referred to as having reliefs. At least I know now. This has been confusing me for at least 2 years. Frigin part designers. Oh well.

I would personally rather have your pistons than the vinnies.

Yours are dished,,
In a line up,, I would take flat tops with valve reliefs over flat tops or dished.

Your pistons are pretty much the same design as the 3.8 pistons. You dont need all that open area in the center of the piston,, thats why there are flat tops with only valve reliefs. The more piston metal you fit in there, the less cubic centimeters of air there remains inside with the piston at top dead center.

With vinnies pistons, you can float a valve in a situation where you rev R's so high that the valve can not get out of the way of the piston in time. The valves are limited in speed proportional to the tension on not only the springs but the quality of the spring inside the lifter as well.

The more you play with the fine tolerances of a motor, the more important things like slack in the timing chain, ect become important. YOu ahve a cam that lags a lil too long and you end up with a crash. Ill bet it took a lot of r's for vinnie to do that. not sure whay he didnt think about marking and grinding valve reliefs in while the head was off. the least little bit would help. I would always be afraid to hot dog it with those pistons personally. A thinker gasket would be my only sound solution to give the valves more room to float.

with less room and the fuel mixed with spark makes for a bigger presure difference when pushin the piston back down.

think of it like letting a firecracker go off on your open hand vs a closed hand.

Same fuel source,, but one can take your fingers off while the other will burn your skin.

Domed would be sort of convex and are the ideal piston because the leave the least amount of cubic centimeters in the combustion area with teh piston at tdc. messing with domed calls for more smarts than i have because you gotta know your cams , the grind, the time inwhich the lobe will lead the lifter / pushrod/spring and valve into action and avoid a crash for max compression and best bang for the same buck.

UPDATE on page 3--Here's a couple of pics I took.....

Reply #18 – September 04, 2008, 09:16:53 AM

In my next engine,I'll have aftermarket pistons with valve reliefs,and different heads,probably GT40's or a set of aluminum heads if I can find a set at that time that I can afford.These work fine because they are what I have.The engine has been fine until I over revved.It's actually been trouble free for months.I'm on the lookout for a new block,then I'll get busy acquiring parts for it.

UPDATE on page 3--Here's a couple of pics I took.....

Reply #19 – September 04, 2008, 11:04:51 AM

Quote

In a line up,, I would take flat tops with valve reliefs over flat tops or dished......Domed would be sort of convex and are the ideal piston because the leave the least amount of cubic centimeters in the combustion area with teh piston at tdc

http://sbftech.com/index.php/topic,3472.0.html

**EDIT** You have to log in to read the thread -- Here's what's important concerning the above quote. Keep in mind it is for all things being equal including compression ratio.

Quote from: Its1FastCat

Dished pistons offer more surface area compared to flat top pistons. But it's not the 'volume' of the dish, it's the fact that the dish is FARTHER down than the piston top in the cylinder at BDC. As the piston travels down in the intake stroke, the air is drawn inward and the increased distance created by the dish causes more air to be drawn into the cylinder. Since the only difference being considered is the type of piston, the dish creates a higher demand for air to fill the cylinder. Since the intake runner, intake valve, lift and duration are being kept equal between the two piston options the velocity of the air being drawn into the cylinder is increased. In other words the increase in the distance created by the dish demands more air and fuel to be drawn into the cylinder in the same amount of time as the flat top pistion. Higher velocity allows more air to be scavenged into the cylinder by tailoring the valve timing events of both the exhaust and intake valves which will create more power.

BTW; Its1FastCat is a member here as well. He doesn't post too often, but when he does one should pay attention because he knows his stuff.

FWIW, if I wanted a smaller combustion chamber, Id take from the head instead of adding to the piston...

UPDATE on page 3--Here's a couple of pics I took.....

Reply #20 – September 04, 2008, 11:16:53 AM

Right on.

jcassity - thanks for all that but I *am* pretty familiar to that extent. It was really just the names that everyone uses to refer to each particular component that threw me for a curve, and the different combos that occurred...as TurboCoupe50 pointed out. Now lets hope I dont forget or I can at least find the thread again :hick:

UPDATE on page 3--Here's a couple of pics I took.....

Reply #21 – September 04, 2008, 01:06:01 PM

Nice work Vinnie, let us know how the long drive goes. You could drive to Choctaw where I used to live for about 10 years :D

UPDATE on page 3--Here's a couple of pics I took.....

Reply #22 – September 04, 2008, 05:35:45 PM

I'll have to wit for tomorrow to go driving after I swap steering pumps at Autozone after work.I can't wait.I spent the mid morning hours swapping the power steering rack for a new one,new tie rods,very nice.I then picked my boy up from school and we stopped and had the front end checked to make sure the tie rods were right.I was close,but not where it needed to be.No charge for that since the boss was gone from the tire place and I know the people who work there.Sweeeeeet !!!!