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Author Topic: 302 engine build piston recomendations  (Read 6545 times)
zman1969
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« on: September 11, 2012, 01:02:21 PM »

Hello guys I am looking for recomendations for pistons for my 302 +.030 build - I have searched, I spoke to Jerry M (he recomended J/E pistons but I cant see $1200$ for a set of race pistons for a driver) I know they say TRW or Speed pro have wrong ring grooves 1/16" vs 3/32" but is there anything wrong with them? plans for my car is for cruise nights and some trips in my car no drag racing (not official anyway  Wink  )  what have Y'all used on yours and pros/cons? and whats the stock dome height .250? I want to be at 11:1 no decking done to DZ block
Thanks
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Rich

69 RS/Z DZ302 Daytona bumble bee
69 T/A clone LS6/6sp
69 Nova SS 396
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« Reply #1 on: September 11, 2012, 02:35:17 PM »

Well the skinny rings were designed for light weight and less drag for racing.....not long life on the street, like the stock ones.

If you don't mind using a hypereutectic piston instead of a forged piston here are a couple of vendors....

     http://www.rickscamaros.com/camaro-piston-set-302ci-11-1-0-030-over-high-performance-1967-1969.html

     http://secure.classichq.com/302-PISTON-SET-8-30-OVER-P44C8.aspx

I have been advised that you should keep your RPM down to around 6000 with these pistons....just to be on the safe side.  Just the difference in strength between the forged and hypereutectic construction.

And another thing...I'm not positive about the weight of the pistons, do they match the stock piston weights.  If you plan on re-balancing the rotating assembly, then the weight wouldn't matter.  If you are concerned about weight, might give the vendors a call or maybe someone on the forum might know for sure.
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Jerry G.

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zman1969
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« Reply #2 on: September 11, 2012, 02:51:12 PM »

I have looked at the Hypereutectics and they are also avail, thru summit for about 40$ cheaper. I am wanting to stay forged as OE and I dont think the ring thickness will matter it wont get alot of miles on it
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Rich

69 RS/Z DZ302 Daytona bumble bee
69 T/A clone LS6/6sp
69 Nova SS 396
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« Reply #3 on: September 11, 2012, 09:17:19 PM »

First design 302 pistons used the narrow ring, '67 up to very early '68, when it was changed to the wider ring groove/second design piston. I'm pretty sure as I have the .030 over early '68 design in my '68 Z engine on the stand (hand filed the rings myself) - like yours, it won't see that many miles, so I decided to use them. They look different (see Jerry's book if you haven't already) but I like 'em. Second design 302 pistons used the wider ring, obviously, plus floating pins instead of press fits. I was fortunate enough to buy a NOS '68-9 set from GM right after they were discoed - wish I could have bought a bunch of them.
Biggest difference between the hypereutectics and the forged piston is piston growth - the cast pistons don't expand near as much as the forged ones under use, and are more stable/seal better in the bore, and don't require as near as large of a bore (read as skirt clearance), therefore less blowby. On the other hand, as was mentioned, I don't trust them at the higher rpm ranges (piston manufacturers would probably not want to hear that from anyone !)
The third set of 302 pistons I have is a set of forged Manley 12.5:1's - I actually ran them on the street in the 302 for nearly 30K miles - of course, I was putting 100+ octane leaded Union 76 gas in the tank at the time - '73-'75. The look exactly like the std. GM 302 pistons, except taller dome, and were floaters themselves. Made a liar out of my machinist - he said I'd pound the mains out of it within 10K miles - bearings still look brand new - plus you could have probably run kerosene in it and it wouldn't have complained.
Just some opinions -
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zman1969
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« Reply #4 on: September 12, 2012, 07:52:44 AM »

anyone have thoughts on the speed pro pistons available now with the coated skirts? they show 11.8:1 w 64cc heads I assume i would need to mill them down to get 11:1
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Rich

69 RS/Z DZ302 Daytona bumble bee
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tmodel66
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« Reply #5 on: September 12, 2012, 11:08:52 AM »

Speed Pro has been around a long time and I've used them in dirt track cars. These cars as you know hit 6 to 7 grand on the straights.  I've never had a problem with them.
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Daniel  
'69 SS 350/4 speed  Fathom Green--POP
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« Reply #6 on: September 12, 2012, 04:55:34 PM »


Copy this into your browser...This is a set of used of .030 JE piston for sell...

http://www.ebay.com/itm/DZ-302-PISTONS-/290772270972?pt=Motors_Car_Truck_Parts_Accessories&hash=item43b360bf7c&vxp=mtr

Eddie
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Eddie
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« Reply #7 on: September 12, 2012, 07:07:19 PM »

I agree with tmodel - Speed Pro makes good stuff, research point-of-origin for where they come out of, and I believe they purchased/merged the TRW Automotive Group parts division when TRW got out from under it. Still, if you can find a set of used +.030 L2210's, I would buy them if it was me - still hard to beat good 'ole TRW pistons.
Good luck - hope you find a worthy set.

Regards,
Steve
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1968 Z28 BRG/W
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1969 X66 L78 Cortez/BVT
1969 Z11 L48
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« Reply #8 on: September 12, 2012, 08:06:44 PM »

My 302 was rebuilt years back with TRW's - actual ID is L2210AF (in the .030" oversize) and they use the narrow ring set. They can be milled down a considerable amount (if I recall up to .250") to vary the compression to suit various needs and situations and TRW reccomended .005" - .007" of bore clearance depending upon application.
When I last had the 302 in my car it was running between .007" & .008" and cold it still had no piston slap although it did smoke a bit at 6000 rpm and up - but not at all badly considering those tollerances with that type of set up..

Randy
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zman1969
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« Reply #9 on: September 12, 2012, 09:19:41 PM »


Copy this into your browser...This is a set of used of .030 JE piston for sell...

http://www.ebay.com/itm/DZ-302-PISTONS-/290772270972?pt=Motors_Car_Truck_Parts_Accessories&hash=item43b360bf7c&vxp=mtr

Eddie
OK what can we tell about these pistons JE appears to be a good brand and idea what compression these may be or the specs on them?? price seems reasonable
Speed pro is all i have found and they are discontinued I would figure that these would be fine but need a little milling down to 11:1 they are listed at 11.8:1 any machinist know how much needs to be milled down? I believe they are at about .400 - so down to .250?
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Rich

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« Reply #10 on: September 13, 2012, 04:14:52 PM »

These are listed on e-bay : Just search DZ 302 and select newly listed items..   New TRW 67 thru 69 302 pistons. L2210AF .030.  I'm not sure who make Seal Pro. Pistons. though...

TMR,,
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Eddie
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« Reply #11 on: September 13, 2012, 11:58:40 PM »

Sealed Pro used to be made by TRW..  but that was long ago..?
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
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zman1969
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« Reply #12 on: September 14, 2012, 06:07:19 PM »

Sealed Pro used to be made by TRW..  but that was long ago..?
sealed power or speed pro?
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Rich

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acelr8
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« Reply #13 on: September 14, 2012, 10:36:28 PM »

Sealed power, Speed pro and TRW are all morphed into the same CO, Federal Mogul.Speed Pro is the performance line of Sealed Power.Me personally use Diamonds. 1/16 ring package with no issues and are significantly lighter than the originals.About $800 a set.Jeff
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69Z28-RS
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« Reply #14 on: September 15, 2012, 12:13:22 AM »

I think two of us screwed up 'speed pro' and sealed power... Smiley
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
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zman1969
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« Reply #15 on: September 17, 2012, 07:39:13 AM »

after thinking more about the use this 302 will get I am thinking more about the Ricks pistons - correct dome , tighter fit, less oil consumption - who has used these? what ring thgicknesses? 3/32 or 1/16" ? I really cant find any more specs on them but I did find that Summit Racing carries them
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Rich

69 RS/Z DZ302 Daytona bumble bee
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69 Nova SS 396
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« Reply #16 on: September 17, 2012, 12:47:54 PM »

tighter fit = more friction, lower horsepower, lower RPM... 
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
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zman1969
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« Reply #17 on: September 17, 2012, 05:09:37 PM »

tighter fit = more friction, lower horsepower, lower RPM... 
this is going to be a driver,   I'd really like to see that comparison on a dyno LOL less clearance than forged yes but there is still clearance - more friction from the rings than the piston
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Rich

69 RS/Z DZ302 Daytona bumble bee
69 T/A clone LS6/6sp
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Stingr69
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« Reply #18 on: September 18, 2012, 10:37:40 AM »

Hypereutectic pistons do not tolerate detonation or high RPM very well. Lots of pictures on the net of top ring grooves blowing out when used hard. You will find plenty of people blaming the installer not opening up the ring gap like they were advised when they bought the Hypereutectics but even with that, there are too many broken high performance hypereutectic pistons out there.  The castings do not behave the same as a forging when subject to hard use.  High heat causes the top ring gap to close up and butt and then the piston blows out at the top ring with a big chunk of aluminum flying aound causing all kinds of damge. That is why you pay more for forgings.  In a "driver" L48 type stock application they make a lot of sense and yes I would use them there but I can't see puting them in a 302 that will be driven like it was intended. Too much RPM's, and potential for detonation.    JMO.

-Mark.
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69Z28-RS
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« Reply #19 on: September 18, 2012, 11:43:41 AM »

and WHY have a Z28/302... unless you're going to build it and drive it as it was designed??...
If you want a 'daily driver' with 'Z28 emblems'...then pull the original 302 (store it away for *resale day*), and stick a stock 350 or 307 in it...

...the 302 (as designed) was classified by Chevy as a SHP (special high performance) engine....  not very many got that classification.
without the full gamut of factory parts, it ain't special...  (it's not the DZ stamp on the block that made it special)... Smiley

  Smiley     Just One Man's Opinion..  Smiley
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
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zman1969
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« Reply #20 on: September 19, 2012, 12:57:57 PM »

and WHY have a Z28/302... unless you're going to build it and drive it as it was designed??...
If you want a 'daily driver' with 'Z28 emblems'...then pull the original 302 (store it away for *resale day*), and stick a stock 350 or 307 in it...

...the 302 (as designed) was classified by Chevy as a SHP (special high performance) engine....  not very many got that classification.
without the full gamut of factory parts, it ain't special...  (it's not the DZ stamp on the block that made it special)... Smiley

  Smiley     Just One Man's Opinion..  Smiley
well your right i should sell it and buy a 307 car
in the past my Z has had a 327 in it, a 396 a 427 and a 350 now I want the real 302 in it. with exhaust manifolds whats so wrong with having this as a driver? no more str$$t racing, no track time so I dont need a $1200 set of JE pistons... yes i will spin it up  and have some fun. after looking at all the options- Speed Pro, SRP, KB, Ricks, Wiseco its amazing that for whatever reason they are all different in compression and dome heights, rings, compositions
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Rich

69 RS/Z DZ302 Daytona bumble bee
69 T/A clone LS6/6sp
69 Nova SS 396
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« Reply #21 on: September 20, 2012, 01:40:52 PM »

The J&E's are about $650-700.00.  Not $1200.00, this is what I use in all the engines that we build.......

Jerry

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zman1969
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« Reply #22 on: September 21, 2012, 12:00:01 AM »

The J&E's are about $650-700.00.  Not $1200.00, this is what I use in all the engines that we build.......

Jerry


Jerry, after we spoke that's what they quoted me maybe I should try another vendor?
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Rich

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« Reply #23 on: September 21, 2012, 09:11:32 PM »

You should.  The J&E's will make more power too.  I've been getting 365-4000hp with a stock rebuild now using the 30-30 cam.  Stock Eliminator ring combination and some other tricks that pick up the power band.  The heads is where the vary so much.  Core shift, etc.  No two head flow the same. 

Jerry
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zman1969
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« Reply #24 on: September 23, 2012, 11:36:10 AM »

JE piston # 123567 and I cannot find any one that prices them online - any suggestions where to try?
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Rich

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« Reply #25 on: September 24, 2012, 09:44:29 AM »

Yes, call Burtonsville Machine and ask for Bub.

301-490-3131,

Good luck,

Jerry
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zman1969
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« Reply #26 on: September 24, 2012, 11:47:38 AM »

I spoke to Bub he suggested the JE/SRP piston 202890(for .030) he said this is what you use in your rebuilds and the 123567 was a custom built piston we didnt talk $ he suggested Jegs $832 for a set of those SRP are around $563 any issues with the SRPs?
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Rich

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« Reply #27 on: September 24, 2012, 08:08:31 PM »

You can use them.  We have in the past when cost is an issue with a customer.  Dome configuration is slightly different but very close to the NHRA Stocker pistons. 
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lynnbilodeau
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« Reply #28 on: September 25, 2012, 12:53:58 PM »

Only slightly off topic.

Jerry, are you using the comp cams 12-107-3 camshaft in stock z28 builds?  Do you consider it a dead on match for the original 30 30?

I know JohnZ recommends the Federal Mogul.  Quote:  "Don't know offhand if the Comp cam is a dead-on duplicate or not, but the Federal-Mogul/Speed-Pro/Sealed Power cam is - their #CS-118R (cam only) or #KC-118R (cam and lifters)."


One more questions, as I am getting ready to put together a couple 302's:  what valve springs are you using?  Thanks.

Lynn
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JohnZ
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« Reply #29 on: September 26, 2012, 10:51:55 AM »


One more questions, as I am getting ready to put together a couple 302's:  what valve springs are you using?  Thanks.

Lynn

The original springs were GM #3911068, same as used in all other small-blocks. They're still available from GM, but the same spring is available from Federal-Mogul for about 1/3 of the GM price as their #VS-677 (F-M makes them for GM - it's the same spring). "Improved" non-FM aftermarket versions of the "30-30" cam may require different springs - the originals were 90# closed, 190# open.
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« Reply #30 on: September 26, 2012, 07:29:10 PM »

deviating a little bit more... is there a current good reproduction of the "pink" rods? or a good source for reasonably priced originals?
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Chris
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« Reply #31 on: September 26, 2012, 08:43:10 PM »

Thanks John.  I would like to know what spring Jerry uses with the comp cams 30 30 12-107-3 grind.

I plan to use the springs you suggested with the one 30 30 cam I still have.  I also have two of the 12-107-3 cams and am wondering if I can use the same springs.

Lynn

As for Pink rods, there are still some originals out there. 
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« Reply #32 on: September 26, 2012, 08:56:34 PM »


I plan to use the springs you suggested with the one 30 30 cam I still have.  I also have two of the 12-107-3 cams and am wondering if I can use the same springs.

Lynn

The springs that Comp Cams recommends for the 12-107-3 are rated at 105lbs @ 1.700" and 273lbs @ 1.250", part # 981-16.  Don't know what Jerry M. is using.

Summit Racing quotes the ratings for the Sealed Power #VS677 at 76lbs and 194lbs.  Don't know if there are other springs with the same number that are rated different.
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Jerry G.

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« Reply #33 on: September 28, 2012, 06:51:03 PM »

Using the Comp Cam springs.  About 115 on the seat, these are very forgiving and will last a life time.  I think $75.00.

Any late '60's 3/8 bolt connecting rod will work fine for the 302 application.  Just have them shot peened and magged with good ARP rod bolts and you're good to go.

Jerry
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« Reply #34 on: September 29, 2012, 06:56:19 AM »

Hi Jerry...is this you..... http://www.youtube.com/watch?v=tAt8N-vH0gg     looks like a blast...
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« Reply #35 on: September 30, 2012, 09:21:59 PM »

Yes, last year at the Cecil County points race, August 2011.  It's about 8600 rpm each gear and 8300 through the traps.

Jerry
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