10:1 pistons

Anyone got a good source for 10:1 piston's 'cept ebay? I always think master kits there are a 50/50 deal and buying piece meal I can get double rollers, ta's oil pump kit & cam, etc. that I really want. I'm also a bit scared of cast aluminum 'cause if it detonates on the high ratio :shock: KA-BOOM!

Problem is everyones website / call center is giving me crude about finding 10:1's... I found some 340 10:1's would they work?

Are they out of manufacture or is there a part # someone has to make life easier?

Thank you in advance.

 

I don't know what your budget is,but with these pistons you can dial in any compression you want with minimal machining.(rings included)

http://www.buyracingparts.com/pisto...stons/autotec-forged-350-buick-pistons-1.html


Here is a quote from their website about the pistons;

"AutoTec is a High Quality, Precision Manufactured piston option. That comes at a very respectable price. Our Design Specific Forging allows us to manufacture our parts with less machining time, thus allowing us to keep production cost down. Then pass that savings on to you, the customer. Made out of 4032 High Silicone Aluminum Alloy, it has great wear resistance, a low expansion rate, is very durable, and is very low in friction. These pistons accommodate multiple uses including. Your local auto shop, muscle car restorations, performance street rods, as well as many spec racing classes. They can also withstand mild nitrous kits and small turbo or super chargers. Just about everyone can benefit from the excellent value the AutoTec line carries. Keeping in mind these pistons were originally designed for about 600 Horsepower. In Small Block applications, we have customers that frequently fine tune engines that yield 850+ Horsepower with a bit of Super Charger boost. Bore, Ring Pack, and Compression Distance changes can be made to any shelf part at no extra charge. Meaning that if you do not see your application listed in the guide, we can make what you need without charging a custom price. Every part is made with same high quality machines and tools as our RaceTec line including diamond turned ring grooves, and skirts. Not to mention our parts are 100% made in the USA."


Derek

 

Autotec has pistons and will come with ring set.if your not turbo or supercharging or using NOS then you shouldn't have that kind if damaging detonation. Tuning will be able to control that.

 

Forged is a bit of overkill for my needs...

anyone got the part for the aluminum ones or cast iron?/ know if the 340's would fit (stroke there is 3 Instead of 3.5 not sure if skirts clear)

 

summitracing. you can use 85 buick 3.0 v6 pistons just get 8

 

Had to do with that not legal in CA thing at the bottom
http://www.summitracing.com/parts/slp-340p30/applications/make/buick?prefilter=1

 

Look up summit racing uem-1734 flat tops from a 3.0 ltr 85 Buick v6 this piston has been used by a few people on the board for 350s. Just order 8 and whatever overbore.I actually have 6 of these myself in standard bore.Brian just put a set in his build after the shop put in stock dish during a rebuild.he ended up shaving heads .030 to get 10.5 to use the ta290 can.

 

Those forged pistons Derek spoke of are a good choice. You'll pay more, but you'll have less machining to do and you'll have a better piston. The 4032 alloy (from what I've read) has about 11% silicon in them compared to the typical 12-12.5% for cast pistons, and 16-18% for hypereutectic pistons.

This means those forged 4032 slugs could be set pretty close to stock clearances, maybe a smidge looser, and expansion would be pretty close to stock. This means very little noise when cold and it would be one hell of a tough piston and could take some heavy duty punishment.

The cast pistons from Summit seem to be fine for mild builds of course. There's a few options, though not as many as there would be for another engine.

If you want the '10:1' pistons offered by various manufacturers, there's less to choose from. The flat tops I hear have been successfully used for 350's.

Hypers would be good for maximum economy with the least amount of clearance and blowby, along with maximum scuff resistance and long life. Coupled with Buick's high nickel content in the blocks, a set of these would make for a very long lasting bottom end.

Problem is, they're all low compression so you'd need to do some machining.

I've read a lot about 8:1 DCR being the goal, but I've also read that 7.6-7.8 is a better goal, then there's the generic 'shoot for 7.5:1' with no polishing or other attempts to reduce detonation risk. This would be particularly helpful if one were using hypers.

Edit:

Dude...I'm cluttering up your post with my prattle, so I'll move it to the camshaft thread. Sorry.

Gary

 

The Autotech says they can change compression height so would .050 on top of those pistons make them too heavy? and would that include raising the ring lands .050 also? Or maybe deck .020 and have them add .030.

 

Just a suggestion on the pistons.
Not sure how much they are at Summit and if you can buy the 2 you need seperate but I bought the V-6 kit. 151.20 for 6 and 83.00 for the other 2 including shipping at United Machine. They are Silvolite Pistons Phone number is 1-800-648-7970 ask for Sarah or Cynthia

Part number for the set of 6 stock bore is 1734 and for the singles it's S1734

Nice people to deal with. I wasn't sure if it was going to work so I ordered two first to check everything. They are flat top pistons and they sit in the hole about about .080 if I remember right. Static compression worked out to around 9.6 with a 043 gasket and 58 cc chamber more or less. There was at one time a set of these on the board that were .030 over also if they are available.

David

 

Ron,.050" on top of their pistons would only be a few grams more weight,but would be minimal if the inside of the piston is also raised. Something you would have to call and ask to get a more accurate answer though,but one thing I am sure of is that they WILL be lighter than ANY off the shelf piston you can buy(probably up to 100 grams or more lighter) even with the added compression height.

As far as decking the block,find a shop that can machine the deck parellel from the mains and just have them do a clean up cut and make both sides the same. Then have them tell you what the deck height measurement is so you can order the pistons the height you want if you're going to go this route.

As for the ring lands,you can tell them to raise them also,or tell them to leave them where they are. If you plan on spraying with NoS,these won't handle a "big" shot,but would be ok with up to a 150 HP shot. Give them a call,its free(if you don't buy).GL

Derek

 

I think autotec piston are .030 taller already an wiesco makes the v6 piston .050 taller.must be common for the blocks not to be at proper height.

 

Atutotecs forged 350 Buick piston has 1.850 comp height with 13.5 cc dish.pins are .945. Versus silvOlite replacement pistons at 1.805 comp height. So .045 taller compression closer to the piston spec of 9.6

 

Did anyone see these??

http://www.v8buick.com/showthread.php?275761-New-350-TRW-forged-pistons

 

Wow! thanks for all the imput.

But NOS, Forged, etc. is for building a motor I don't plan to. Also, I don't really need pistons that'll outlive the rest of the rebuild.

my build plans are pretty mild:

bearings, ta 212 cam, clean stock crank, etc. 10:1 pistons with and decked around .03 for a DCR of 7.5-9 with the cam straight up.

Heads > fix any issues, gasket match, blend intake valve guides to tear drops & smooth down any cast.
Gasket match intake and manifolds, stock carb rebuilt, and up alternator for a high output.

There are other issues with the vehicle, I need to replace the entire cooling system, no clue on timing cover till it's appart, brake booster is bad, have a single rust repair to do (under the rear side window, and lots of maintenance to catch up and cosmetic stuff... I'd also rather get the suspension dialed in because I prefer curves to straights.

It's an x-body 75 coupe, and I think that plan gives me well over the old SAE 155hp @ 3 stock, about 25+ for the cam and 6%+ for the comp and maybe 1% for the head and maybe 3% for the carb tunning and 5% for changing the timing scheme. So I expect about SAE net 197hp @ 3 with a lot of torque and that's a pretty close powerband to the '70's SAE gross 260 @ 4. In fact, i hope that the sum of the parts here wins. HP TV got 300 out of thiers but I can't find a build list.

That's relatively cheap, it's no longer a dog, and it stays well within the car's max 5k value (about 2k for the job)

 

Forgive me if I am overthinking this but you do know that using something called a 10:1 piston doesn't mean the engine will be 10:1 Example, the pistons I recommended are flat top no dish pistons with a stock compression height but without decking my block the static compression ended up at 9.6 which was perfect for where I wanted to end up. When a manufacturer says their piston is 10:1 that generally assumes a zero deck clearance. I can almost guarrantee you that those pistons will be at least .060 in the hole. Every engine is slightly different. You won't know for sure until you actually install one and see how far it sets in the hole. I was able to get 9.6 compression without decking my block.
Good luck with your build.
David

 

HP tv used comp cams muther thumper cam.i think it was the biggest one.a TA intake and big valves from AM&P machine(know for buicks in engine master challange) and i think they used kieth black hyperutectic pistons but in a 77 block the actually netted about 8.7 to 1. notice they claimed 38 degrees of total advance on timing.
try the 3.0 liter piston #1734 from summit. i got a set of 6 myself but wont be using since i need customs

 

I checked out some inexpensive flat top cast pistons at Summit made by Keith Black. Didn't look too bad. Might be a good choice with a 'budget build.'

You'll have pretty much 10:1 with minimal material removed from deck or head, and may even need to open the head chamber up a CC or two, but seems like these would be the way to go for the least amount of machining required.

I did the math on a compression calculator, and compression ended up between 9.73:1 to a little over 10:1 (10.0x), depending on how far it sat in hole (from .080 to .070), how much overbore was used, and where the head volume sat. It would be super easy to achieve a true 10:1 this way, and with minimal expense.

This is with 1.808 CH and sitting somewhere between .070-.080 below deck, so notching wouldn't be needed.

Gary

 

Yea I emailed them at competition components and they said they can't do the flat tops with the 1/16 rings for the .060 but they could for the 5/64 rings and in any compression height with the ring lands moved to the amount added to the height. so depending on weight that is probably the way to go unless JE can do it for the same price.

 

What about for the dish pistons? You do know that if you get zero deck flat tops with valve reliefs that the compression will be closer to 12:1 plus or minus.

What is the ".060" suppose to be? Is it oversize on the diameter,or the extra compression distance?

If you want 10:1 you will need the dish pistons with a zero deck(.005 in the hole and a .040" head gasket to be safe from rod stretch),and probably will need a bigger than the advertised 13cc dish.

Shoot for .005 in the hole and use a .040" compressed thickness head gasket to optimize clearance and quench.GL


Derek