So basically it's came down to this, the only place I can find flat tops for my 350 bored .060 over are these two sources. I've read alot of mixed reviews about Egge in here but I really want some flats to improve my compression. Pros and cons anyone on either of these two places??

 

I thinking finding a new block would be easier. I have given them away and bare blocks can be had dirt cheap. Why are you stuck with .060. You could always pay a little extra and have custom pistons made.

 

There are numerous ways to raise compression other than a flat top piston. Have you considered any of them?

 

Egge has been in business for a very long time, and is pretty much the company in the US for custom or unusual pistons.

I don't know about reviews, but I wouldn't think twice about buying from them.

- Eric

 

Well I have the #5 heads with an increase in valve size and was milled .010 and also which has some the highest compression out of all the olds heads and using a .41 head gasket. I'm no mechanic so I'm just doing what I know so far... Any suggestions??

 

Dirty mechanic. Paid 1600 for a brand new remanufactured engine then the piston started slapping around 500miles. I have so much money tied up into this engine I didn't want to just start over. Didn't find out is was .060 over until after I pulled it to check the slapping noises smh

 

Yeah I've did alot of reading on them and seen how long they've been around. That's why I was interested in them. But then I read in here on some threads and some guys didn't talk too highly of them so I was kind of stuck in which route to take

 

If you got a bad (and apparently non-warranteed) engine, then the first thing I would do is to start from scratch with a new block.
Who knows what else was done wrong in there.

- Eric

 

That's already been done. I've pulled it out and broke it down to just the bare block and took it to a machinist. Everything has been checked and is good to go. Now I'm trying to select pistons

 

I don't think there is anything wrong with Egge as a company or with buying from them. What you will find is their pistons are cast, and like all aftermarket cast pistons, they will be shorter than factory Pistons or aftermarket forged Pistons. This will severely impact your expected compression ratio unless you do block and/or head machining to compensate for the short Pistons.

 

If it's at the machinist, have them measure the depth of the pistons in the bores at TDC, and measure the piston height from the wrist pin, then mill another 0.020-0.030" from the heads, measure the CC volumes, then, based on all of this information, determine the best piston to use for your desired CR.

Egge used to be able to make up pistons to your specifications - I don't know whether they still do.

- Eric

 

Sonic check your block & bore it out to a larger size & run custom pistons.


Deck to block.


Mill the heads more.


All of the above.


Lots of options left.


I am not an engine builder but there are many on here.


Try PM to CutlassEFI (Mark) or others & get advice from them.

 

I have Egge in our automatic Jetfire and no problems. I also know of a guy with egge flat tops in his 350 engine with no problems. I am not claiming that are great pistons but for the two applications I know of them they are just fine. Our Jetfire is 10.0 compression with 6.5 lbs of boost and I run it hard enough to boost at least one time every time I drive it.

 

I have to disagree. I offer a MUCH better piston for just a couple hundred dollars more than an Egge. Any size, any configuration.

 

Mark has spoken.

I didn't know you did pistons, too, Mark.

I'll keep that in mind.

Thanks!

- Eric

 

Thanks. Appreciate your input. So they even advertised a set for a 10.5:1 for my car and you're thinking I won't even get that out of those pistons from them? False advertising maybe lol?

 

If you don't mind me asking what is the difference between your pistons and Egges? I just want quality products in my car so no insulting intended at all. I just want everything done right while everything is broken down at the moment

 

Egge's pistons are cast. I'm assuming Mark has forged.

 

Not false advertising, just typical description of replacement pistons that were used in a factory 10.5:1 application. You don't get a particular CR just by the pistons used; the head combustion chamber volume and distance from the top of the piston to the head mating surface on the block (piston to deck clearance) affect CR as well. The piston to deck clearance is a combination of the piston compression height and block deck height.

All this means you can build an engine with "10.5:1" pistons and actually have a lot less than 10.5:1 compression ratio.

 

Most factory-built production engines don't provide the CR that's advertised. This is just a function of mass production. There's a reason why racers "blueprint" their engines - to remove these production tolerances and ensure the engine is built exactly to the factory design. For example, advertised chamber volume for most SBO heads are 60-64 cc. These are the design specs, but due to machining and casting tolerances, the as-delivered chamber volumes are closer to 68 cc or more. This is done intentionally both to reduce scrappage rates and to allow room for the heads to be resurfaced in the future without excessively increasing CR. Contrast this to newer engines where there isn't enough material to overbore them and you need to replace the block if the cylinders are worn.

Also, the advertised CR on Oldsmobile pistons assumes the use of the factory steel shim head gasket. Changing to a thicker FelPro blue gasket (as an example) results in a loss of 1/4 to 1/2 a point on CR. Excessive deck height on the block similarly reduces CR. All of these items (and more) must be evaluated when an engine is built.

 

Inbox me some info you would please.

 

Thanks I appreciate it. As you can tell I'm a newbie just wanting to learn. I need to call my machinist and have some things changed. The pistons I currently have in there advertised a 7:2 made by Sealed Power. He said right now with everything I have my CR is 8:2.

 

I see. Makes alot of sense now. I planned on using the steel gasket. My next question is, which size do I buy as far as bore size. My current bore is 4.117 and I can't find any that size. The closest I found was 4.110 and 4.120. Using an unmatched size is OK?

 

Pistons typically come in standard sizes, usually the standard bore (4.057" for an Olds 350) and standard overbores of +0.030 and +0.060. Sometimes you can get other overbore sizes (like 0.020 over), and naturally custom pistons can be machined to whatever you want.

You MUST bore the block to match the pistons. Figure out how much the block must be bored, buy correct size pistons, THEN have the block machined to match (with appropriate piston-to-wall clearance). A machine shop should know this.

In your case, the regularly available pistons for a 350 Olds will be 4.057", 4.087", and 4.117". If you are using cast pistons, the piston-to-wall clearance should be 0.00075" to 0.00125", per the CSM. Forged pistons typically will want a little more.

 

Yeah I got all that already lol my question was about the head gaskets. What size head gaskets should I use? You can look up head gaskets by the size of the cylinder bore. My cylinders are 4.117. Can't find any head gaskets that size. 4.120 and 4.010 are the closest I can find

 

Adding to this, 425 pistons have the same pin to piston top height, so standard bore 4.125" pistons would be an option (if you can find them).

 

Dick Miller has them.

 

I just looked a their catalog.

http://www.dickmillerracing.com/imag...Rings_Kits.pdf

DMR-P5350
These are Diamond custom quality flat top forged pistons made exclusively for DMR in quantity so we can sell them to you at a price far less than custom pistons. Available for 350 Oldsmobile engines in +.030, +.068. 10.25 to 1. Flat top with 3.98 cc valve relief. Approximately 556 grams. Uses less drag 1/16x1/16x3/16 ring set combination with a .980 wrist pin. Includes spiral locks. Set of 8.

DMR-P5425
Same as DMR-P5350 except for 425 Oldsmobile engines in STD.+.030,+.060. 10.25 to 1. Flat top with 3.98 cc valve relief. Approximately 567 grams.