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Author Topic: 302 replacement piston options  (Read 6306 times)
olympic69
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« on: February 17, 2007, 01:28:44 AM »

As I move forward on my project, I have narrowed down the options for 302 pistons to those made by Wiseco ( Pro Tru forged), the TRW L2210 forged option, and the hypereutectic pistons offered by Rick's First Gen. I am a little intrigued by these, as I understand the hyperutectic design can offer some advantages, and the salesperson said that Jerry M. recommends them. I would love to have opinions/ personal experience, particularly from Jerry MacNeish. BTW, the car will run stock manifold, headers, and stock carb rebuilt and Dist recurved for 302/ pump gas by JM.

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Rob
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Jerry@CHP
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« Reply #1 on: February 17, 2007, 09:00:19 AM »

Forget the TRW and Pro True Forged.  They are not like the originals and have the wrong ring configuration.  You have three choices, the Rick's pistions, J&E and CE.  We have used all three and stock all three.  The J&E and CP are identical to original GM 302 pistons as they are made for the class that I run, NHRA Stock Eliminator.  Good to 8000 plus rpm.  More expensive because they are forged aluminum.  The Hyperutectic pistons are not as strong because they are not forged.  They fit somewhere between cast pistons and the forged aluminum.  Forged are more money.  About $750-800 w/ pins.  The Hyperutectic are good to 7000 rpm without problems.  Ask some of our customers.  We build more 302 engines than anyone in the country.......and none has ever failed in the field.  Gary Sommers who has a day two 69 Z28 can run in the mid 13's in street trim, on pump gas granny shifting the car.  Need I say more? 

Jerry 
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olympic69
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« Reply #2 on: February 17, 2007, 03:13:43 PM »

Thanks Jerry for the reply- I am glad you are hanging out here!

I had overlooked the SRP 202890 product cause it seems to have a smaller dome volume than stock at 6.5 cc vs 10.8 cc NHRA Spec- but the spec sheet shows it to have a CR of 11.4 at "168" ( typo?) CC. What is up with that, or does it matter.

They show to be $499.00 at SUMMIT, so seem to be a good value relative to the Rick's HE piston.

So I guess you used the Rick's HE in Mr Sommers car? This level of performance is right what I am after.

I appreciate your comments!

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Rob
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Jerry@CHP
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« Reply #3 on: February 17, 2007, 04:01:37 PM »

Don't buy the pistons from Summit.  Buy the ones from Rick's.  The dome on Rick's, J&E and CP are all the same and correct for the 302.  Don't have time right now to look up the dome spec. 

11:1 is no problem on the street as long as you know how to tune the engine.  Use the GM .030" head gasket.  DO NOT let your machine shop talk you into installing hardended valve seats.  You don't need to and you run the risk of breaking into the water jackets when doing so.  This has happened to SEVERAL customers of ours and we wound up with the engine rebuild to make it right and replace the costly heads.  There was an article just published about this but I can't remember where I saw it.

Jerry
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olympic69
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« Reply #4 on: February 17, 2007, 07:24:45 PM »

The old L2209 reportedly had a dome of 0.220", 10.84cc + volume, which was why I was wondering about the SRP dome size.

Anyway, if the Ricks product is good- and it appears to be ( I certainly trust your word!) , then so be it. Heck, its got a great warranty.

As for tune, you did my Carb and Dist, I do intend to run 11:1 on pump premium, and I follow you and JohnZ's posts very carefully- I dont need to re-invent this stuff when others such as yourself are already getting excellent results.

Again, thanks for the quick responses, and for hanging out here in general.   
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Rob
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Flowjoe
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« Reply #5 on: February 17, 2007, 09:14:04 PM »

...DO NOT let your machine shop talk you into installing hardended valve seats.  You don't need to and you run the risk of breaking into the water jackets when doing so....Jerry

I am intrigued by your comment.  Is the risk of hitting the water jacket your only concern here?  Or do you have other concerns too?  How do you deal with seat degredation without leaded fuel?  Or do you not see this as a problem?  I have a good friend locally who used to crew for NHRA top fuel cars and now runs a cylinder head porting and flow service and maintains several nostalgia dragsters - he also doesn't think that the hardened seats are "ALL THAT" but he is in the minority for sure.  I'd love to hear your thoughts.

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Jerry@CHP
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« Reply #6 on: February 17, 2007, 10:51:54 PM »

Flowjoe,

The only time hardened seats is an issue is if you drive your car 15-20K miles a year or more in hot weather w/ a hot thermostat.  As little as we drive our Camaros, it's not a concern.  Lead is a lubricant, which in our old cars helps to maintain the valves and valve seats over a long period of time.  With today's fuel, you can control many of the issues by following certain guidelines.  Run a cooler thermostat or no thermostat to keep the water temp down.  This helps a lot.  Run a colder spark plug.  That keeps the combustion chambers cooler so the engine will not detonate.  If the engine is running cooler, there is less chance for seat degredation.  Couple this with running the carb a step or two richer, shortening the distributor curve, etc.  All of these things help a lot.  There is too much to go into trying to explain how to deal with today's fuels as I'd be writing all night.  This has been an on-going learning curve that I've had to deal with over the past 20 years or so. 

Over the years, we have had many Z28 owners come to us over the same issues with their cars, pinging, no power, engine run on, etc.  In all cases, we were able to solve these problems by following most of the parameters that I've mentioned here, and some others.  For example, running AC 45 plugs with today's gas in a stock 302, w/180 degree thermostat and factory jetting during the summer months will have your Z28 engine sounding like a marble machine.  Just by taking the thermostat down to a 160, adding AC44 plugs, and stepping up the jetting makes a world of difference.  Just ask any of our Z28  customers.

One last thing to mention, I do highly recommend adding some leaded Av Gas, Cam II, VP, etc. to your fuel tank if your car is going to sit for a long period of time.  The unleaded fuels are harder on carb parts than anything else if the car sits for a long period of time...........six weeks or longer.

Hope this info is useful to all on this site.  Call me during shop hours if you have any questions about these issues.  Be glad to help.

Jerry   

     


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olympic69
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« Reply #7 on: February 18, 2007, 01:23:31 AM »

Thankfully I have found a machine shop I am comfortable with in Dallas- this guy actually raced a '68 Z/28 in the 70's so a least speaks the language- and did not try to sell me the seats.

Jerry- you write we ( at least 302 owners) will read!

Thanks-
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Rob
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Flowjoe
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« Reply #8 on: February 19, 2007, 04:08:58 PM »

Jerry,

the low mileage and short duration of opertating run time (as in not commuting) was essentially my friend's position.  You are only the second person I've run into who holds the same opinion.  My machine shop (as seperate from my friend who does the hihg end head work) refuses to install hardened seats in a 2.02 head for exactly the same reason you state above. 

Your response raises another question for me.  You suggest runing a colder thermostat to keep combustion temperatures down...at 160 wouldn't excesive piston slap be a consideration?  I always thought that forged aluminum pistons required at least 180 to expand to the appropriate size.  Is that another non-issue for you?

I know next to nothing about the engines that you prep for the street but the numbers you throw up with Old Reliable speak for themselves so I am all ears.  (and yes, I realize that street and race applications create two distinctly different engine environments) 

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Jerry@CHP
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« Reply #9 on: February 19, 2007, 07:09:08 PM »

Piston to cylinder wall clearance is the same for a stock 302 versus the Stocker type engine set up for Stock Eliminator.  And I'm saying this because we do not warm up the engine in my 302 before I go to the starting line.  Ben Wenzel too.  When we are called to the staging lanes in the morning, we go there, shut the engine off and drift into the burnout box.  No problem at all.  In the 14 years that I've been running this car, I have never lost an engine.  Wiped two camshafts before I started using the Shubeck lifters but that's it.  Bottom line is a 160 is fine.

Jerry
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69z28rsbilly
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« Reply #10 on: February 12, 2008, 05:16:20 PM »

what is the part #(order #) for the above mentioned 302 J&E pistons.i went to the J&E website and could not find the 302 pistons for sale
thanks in advance.
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69z28302
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« Reply #11 on: February 12, 2008, 09:25:21 PM »

I found this under the NHRA pistons in the JE catalog. I think this is what number Jerry is talking about.

#123567 Chevrolet '67 -'69 290 302

Mike
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crobjones2
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« Reply #12 on: February 12, 2008, 10:12:16 PM »

Jerry
Do you recommend not using hardened valve seats on all motors? I have a 350/300 and it was given hardened seats years ago when CA switched to unleaded gas. Is it difficult to switch the seats back?
Thanks for your time
Chris
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Chris
69 SS 350
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