3.0 Build Project: "Green Machine"

[Reaper1]

Sorry to hear about all the bad luck. I think for the money you spent with RPW, you could have had a machine shop or maybe even another TM'r who is good at machining build you adjustable cam gears! The concept really isn't THAT hard. Heck, I've seen it done to the 8V gears using VERY primative techniques and they worked fine!

As for the pistons, all I can say is that Race Tech has never really been on my radar for custom pistons. JE, Weisco, Ross, *maybe* Diamond are pretty much the only companies I'd deal with for those. I know for FACT that JE and Weisco are not only more than capable of doing the job, but they do it in a fairly timely manner.

I hope your project starts to go better for ya!

[MC#4]

Sorry to hear about all the bad luck. I think for the money you spent with RPW, you could have had a machine shop or maybe even another TM'r who is good at machining build you adjustable cam gears! The concept really isn't THAT hard. Heck, I've seen it done to the 8V gears using VERY primative techniques and they worked fine!

As for the pistons, all I can say is that Race Tech has never really been on my radar for custom pistons. JE, Weisco, Ross, *maybe* Diamond are pretty much the only companies I'd deal with for those. I know for FACT that JE and Weisco are not only more than capable of doing the job, but they do it in a fairly timely manner.

I hope your project starts to go better for ya!

Thanks. I agree with everything you said. I had intentions of taking the cam gears to a local machine shop but at the time I had the money and wanted something "proven" or so I thought.

For pistons, I initially had plans to go with venolia after talking to shayne, Then when I took my block to the machine shop the owner told me that he uses race-tech all the time and had nothing bad to say about them + they were a good bit cheaper.

If I could rewind the clock I would have done things very differently, but here I am so I'll just try to make the best of it.

[Reaper1]

I can't believe I forgot Venolia!

[shayne]

dont give me too much credit, i went with who ordonti used because i could be sure they have already made a very similar piston to what i wanted. plus my understanding is that they are one of the few companies that actually make their own forging blanks for machining a new piston. very good people to deal with.

[MC#4]

Well I got some good news. Race Tech called and said the pistons are done and I should have them by friday. Not sure if he meant this friday or the next but regardless I'm pretty excited. Cam gears were shipped yesterday. Then to top it off, I sold my old motorcycle tonite which will make it a lot eaiser to buy all the odds and ends to get this car running again. Now I just hope the machine shop pulls through and I can start assembly soon.

[Reaper1]

dont give me too much credit, i went with who ordonti used because i could be sure they have already made a very similar piston to what i wanted. plus my understanding is that they are one of the few companies that actually make their own forging blanks for machining a new piston. very good people to deal with.

Venolia does that because they use a different alloy with less silicone content in it than most of the others. This is why they call for a little more piston/wall clearance, because their pistons dimensionally change more with temperature.

[shayne]

my understanding from them is they use the same 26xx alloy that everyone else uses. otherwise some companies offer a 4xxx alloy in addition too, that expands less and isnt quite as forgiving under abuse. my pistons required no special wall clearance compared to other forged piston manufacturers. what i did notice is that the sheet they send with pistons regarding wall to skirt clearance is a generic sheet for all of their pistons. my 92.1mm bore pistons expand much less than than a set of 4+" bore pistons, and when i contacted them in regards to clearance they said to "use my discretion" and they clarified that my theory of using a tighter clearance than spec'd (their minimum is .005, i went with .0045) is probably fine as long as i can manage engine heat and tuning properly.

[Reaper1]

To my knowledge, unless something has changed, Venolia is the only one of the "major" piston companies to use the 26xx alloy. Everyone else uses the 4XXX. I remember when I got my first set of Venolias they called for .007" wall clearance! :O They were noisy when cold, and still sounded like a diesel at lower rpms, but once above a certain point, they quieted right up.

I'm not bashing them at all, BTW.

[Ondonti]

dont give me too much credit, i went with who ondonti used because i could be sure they have already made a very similar piston to what i wanted. plus my understanding is that they are one of the few companies that actually make their own forging blanks for machining a new piston. very good people to deal with.

I didn't even know this was a problem until now. I ordered a wacky huge size when I got mine. Didn't think about the fact that the inside is forged and not machined so they can't have everything waiting on the shelf to be machined or the thickness of the walls etc would be different from piston diameter to piston (some diameters being heavy and others light).

My shop went too big on the clearances IMO, they did full race everything.

I still did seize a piston or 2 in the cylinder on its first drive where I lost an oil line and oil pressure gauge was not hooked up. That was not a happy day.

Shayne, what ring pack did you go with? That was my other problem. Total seal gapless style was a mistake (considering I just run huge gaps on my current stock motors and don't care).

[Force Fed Mopar]

Just read through a thread on Speedtalk about issues with piston manufacturers, and the long and short of it seems to be that any custom pistons ordered between December and March are prone to have delays, as that is the off-season and everyone is building engines, therefore the piston companies get swamped.

[shayne]

^ i did mine after march so that would explain part of why i got mine a bunch faster.
ordonti: the rings i got with my pistons were spec'd at 1.5mm, 1.5mm, 4mm, 92.1mm bore. total seal made them (i assume based upon the total seal leaflet that came in the same baggie the rings were in, total seal was not mentioned on the invoice), they looked like a chrome top ring and fairly normal looking 2nd ring and oil rings. basically i just talked to them about what im doing and said i will need rings too, and they took care of all of it. the rings even came with gaps you "could" use without filing but i chose to file based upon others' experience (like yours) for gaps based upon abuse.

[Ondonti]

That is nice to hear they worked out the ring package for you. That was something I didn't enjoy. That and I can't remember exactly but either Venolia had to make new pistons for me because they accidentally ground 1.5mm top rings and I had 1.2mm or Total Seal sent me the wrong set at first.

I do think that getting anything done during race prep season is potential to get lower quality results. The guy who fixed up my valves/seats after I inspected them for damage found chatter marks all over the seats from someone going too fast on the original setup.

[MC#4]

Got everything back from the machine shop today. I could type an endless rant but I'll try and stick to the important things here.




Just a few things I noticed after a quick glance.

Pistons were not made to my specs and no reason was ever given why. I wanted the valve reliefs to be 50% depth of a stock piston and they cut them same depth as stock.
Supplied rings appear to be for a stock size piston (91.1mm) and look to be plain cast rings. I asked for rings designed for heavy nitrous use and I wanted file fit. BTW the new pistons are .020" oversized.
Some of the connecting rods show signs of what looks like excessive heat. Looks like they turned it cherry red on the small end to get the wrist pins in. ( the one in the pic doesn't show this )
I have to double check but my bill appears to be about $100 too high for services/parts listed.
The wrist pin seems to fit too tight and it takes to much force to rock the piston back and forth imo.

Yeah I'm kinda bummed

I do have a question though, does anyone know what is up with the groove between the ring lands? I've never seen that done before.

[Force Fed Mopar]

What compression are the pistons? Is the crown thickness the same as stock?

[MC#4]

Well the idea was to recreate the stock 10:1 mitsubishi piston but I ended up with this. I'm guessing based on appearances these will be around 9.5:1. I'm not sure what you mean by crown thickness.

[Force Fed Mopar]

The top ringland to the top of the piston.

[MC#4]

The top ringland to the top of the piston.

The new pistons are .040" taller. btw I plan on cc'ing this motor and I'll know the true compression ratio then. Between the pistons, heads were resurfaced and the block being decked, I may end up pretty close to 10:1.

I did double check my bill and I just read the sloppy handwriting wrong.

[Ondonti]

Sucks about the pistons. Definitely lighter then what I bought. I had full skirt. Not sure what that space between the 1st and 2nd ring is called but I have seen it quite a few times. That area is what scuffed the cylinder walls when my pistons were overheated. Maybe its an attempt to greater a larger gas chamber between the 1st and 2nd rings. Pressure between the 1st and 2nd rings is why modern engine builders gap 2nd rings bigger then 1st. Big power turbo motors will shatter top rings when the pressure gets too high because the 1st ring won't seat and will just flop around.

Sucks about the rings too.

[MC#4]

I know its not much but I call it progress! Really hoping to get reduced hours at work soon so I can really get into it.

[MC#4]

Got a little bit more done today. Main bearing and crank installed, plasti-gaged, end play checked. Also got one piston installed with rings gapped. Went with .021 2nd ring and .018 top ring. To my surprise the rings supplied with my pistons were correct. The box said 91.1mm which is stock bore size but the part number had 020 in it so they are correct for a .020" oversize. Also after searching the part number I found they are advertised as "chromoly". I've seen several sources say there is no such thing as a chromoy ring so I have to assume they are simply "moly" rings because they don't appear to be "chrome".