If you are thinking about buying some Egge Machine pistons for your Nailhead build, don't. I learned the hard way hopefully I can save others some grief. Originally I bought a set of Rebuilders Choice pistons for my build. When I received them I was unhappy with the general appearance, (Chinese Made). So I sent them back and bought a set of Egge 425 pistons for my engine. My thoughts were higher quality USA made pistons but when I received them they looked no better then the rebuilders choice. After spending a few hours de-burring the domes, and balancing then, they were 12 grams of spread on the weight. I had a decent looking set of pistons. I just got around yesterday to putting the engine together and I discovered the pistons were down a little in the bores. I removed .015 from the deck to clean things up and I expected to have very little to no deck height. After getting out my depth mike I discovered each cylinder had .100 deck clearance. After removing one piston and pressing it off the connecting rod I measured the compression height on the Egge piston vs. a OEM Buick. Specs I got on the OEM were 1.995, for the Egge piston it was 1.900. Egges catalog lists compression height at 2.25. How they determine this I do not know possibly considering the dome? This small change drops compression nearly 2 full points. Using KB Silvoites calculator with a stock 124cc chamber and a .045 thick head gasket compression works out to be about 8.43:1. So scratch one balanced rotating assembly, and a set of useless pistons that they aren't going to take back since I have modified them. :af: Anybody have a recommendation for a good quality cast 425 piston?
yes ractec or autotec same company use them on the 340, they are forged not cast, but are only about 450-500 bucks. they have nailheads ones they just did for someone. stock height is 1.930
I have some still available original never used TRW forged .020 pistons and Ramco TRW rings in the original box , they are for a 425 nailhead regular compression , I couldn't use them since I bought them before taking my heads apart to find out they were .030 overbore. I really wanted to use these.
Looks like there are still some of the Ross pistons available. http://www.fastengineparts.com/ross-forged-racing-pistons-for-425-buick-nailhead-030.html
These are probably what is wrong with my 425. At the Time of rebuilding engines, no one had the things so I am suffering now. btw, why why why would they trouble themselves to make them wrong? We can reduce compression enough through gasket change, why why why change pin height?
I am going to guess that they had problems with piston failure, people putting together otherwise stock engines with 10.00:1 compression, 87 octane and too much advance. So they decided to drop compression for the people that don't check anything. Why they decided to drop it down to 8.50:1 I have no idea. While it will last forever on regular gas it is going to run like a pig. My biggest complaint is that it doesn't mention reduced compression anywhere in their catalog. I will be calling them Tuesday when they open. I don't have high hopes for them doing anything for me. 5 or 6 years ago I had problems with their flathead Mercury pistons. The dome shape is entirely different then OEM, and they will hit the heads. When I called them their response was that my block or heads had been milled excessively. I knew that this was BS as the engine was all standard and it even had Ford bearings dated 1951. I ended up chucking the pistons in the lathe and reshaping the dome to match an OEM piston. Aside from Rebuilders Choice, Egge is really the only source for many obsolete parts. TRW and Siv-O-Lite still make 401 pistons but neither have a part number for a 425 engine.
Thanks for the warning on the Egges. I've heard other reports of issues with them. Willie at RaceTec gave me a rough estimate of $618 to $687 for a set of Nailhead forgings. These would be custom made to your spec. Could get a 5% discount on orders of 5 or more sets. Group buy anyone? Silvolite/KB/UEM pistons still make cast pistons for the 401. Compression height is also low on those at 1.912" according to their catalog I've used a set of NOS Zollners which were very nicely made.
sometimes going to one of there dealers is cheaper, I used marollo racing engines. Walt, we had a good thread going about pistons, and you listed the brands and pin heights. cant find the thread. I think Greg gsconv started the threado No:
Joe, that thread is called 401 short block. I have to tell you I went with the Egge piston. After the heads were shaved down the block mill down the steel head gaskets. Mike at AMP told me that my cr is going to right at 9:85, 9:87, I didn't think that was to bad for a motor that most people tell me they didn't think it was 10:25 cr from the factory. And the other news is my motor is done. Mike at amp broke in the cam friday or saturday and he is waiting for me to come down to do the the dyno. I will be posting this info soon.That thread 401 short block has all the goods that my build has on it. My goal was not build a race car just a very strong street car. And I think I'll have that combined with the 3:36 rear and a ST400 trans. and the 12" converter
Sealed Power has cast pistons listed for a 401, but not a 425o No: It might be worth a phone call to them to see if they are avail. http://www.fme-cat.com/Application....T&cat=Engine&subcat=Cylinder Block Components Greg, good to hear that engine is running!:TU:
When we rebuilt the 425 about 10 years ago, 0.030" over cast pistons from TA were used. Inside the box was a tag from Egge. Anyway, the pistons at that time were all about .055" down the hole with just a clean up cut on the deck surface. I will see if I can find the tag and see what it lists for a part number. Cheryl
I found the install directions from Egge for the .030" over cast pistons from TA. The Egge part number was L2195 and they were made 6/20/01. They recommended a .0025 bore clearance. I also checked our assembly notes for that engine and the Egge pistons were .060" down the hole - not .055". I wonder when they changed the design? Cheryl
Even though you altered the pistons,you should try to get a refund anyway,because they are not as advertised.Although 2.25" seems like a mis-print,that would be over a 1/4" taller compression height than stock,unless you meant to write 2.025" deck height. If so,it shouldn't matter that you altered the pistons(unless you altered the deck height) you should be able to either get a refund or pistons that are as listed in the catalog as replacements. The deck height should be determined by the flat surface of the piston,not the dome(the dome height should be seperate).Perhaps thats why they list them as 2.25"? ,because they are factoring the top of the dome?) And if they are factoring in the dome height in for the total compression height,this would be mis-leading to list them that way. (the top of the dome doesn't = the compression height.) Is the dome volume listed? If the dome volume makes up for the lower compression height,your compression may be more than you have calculated? If the dome volume isn't listed they can be measured to do an accuate compression calculation.You just can't assume the dome is the same volume as the factory pistons,unless the manufacturer claims to be?(even then?????????) You can measure the dome volume by wrapping some masking tape around the top of the piston,and using a piston ring compressor(the "hose clamp" style ring compressor that is tighened with a allen wrench) and set the top of the ring compressor to the top of the highest point of the dome.Then measure from the top of the ring compressor to the flat of the piston for your depth measurement. And simply fill it with water with a cc seringe from a phamacy,what ever one they will sell you,and you won't need the needle for it. Then subtract that measurement from what the volume would be in that space without a dome.(Radius squared times pi times the depth=cid) 4.342/2= radius of 2.171 x 2.171=4.71324 x 3.1415(pi)=14.80664 x .25?(depth?)=3.70166 cubic inchs of volume. 3.70166/.061024=60.66306 CCs.(divided by .061024 is the conversion from cid to cc) So however many CCs of water it took to fill the ring compressor,subtract that from the answer above if the depth mearsurement is correct,if not recalculate.(math is fun!:Brow Then you can do the compression calculation and know for sure what you will actually end up with those pistons with the actual compression height that you measured.GL Derek
