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Discussion Starter #1
Hello,
I have a stock running 1969 396 out of a Impala. The deck stamping says a it is a 265 hp version. The engine has 148 heads on it, I want to put 215 heads on it. Assuming these are stock pistons is this a direct bolt on? With a better cam and intake with these heads I should see much better performance shouldnt I?
thanks

3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber
3917215....67-68...oval..CLOSED..396, 427, 101cc chamber
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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normally closed chamber heads won't fit on an open chamber piston at all. obvious exception would be flattops.
 

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hi jeff,
i to have a 69 396, 265hp out of a 69 caprice... i was surprised to pull the heads off and find open chambers...one of my books<how to rebuild your big block chevy> by tom wilson,says the head cc is 109.14.... i want to build it up,i want to get 10-1 to 10.5 to 1 compression... there is not to many pistons out there for the 396 with open chambers... if anyone out there could help me out i would greatly appreaciate it...
jeff w.
lebanon,pa.
 

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The 148 heads were the first oval port open chamber heads.....2v FLEET applications in 1969 IIRC, low compression for "regular" grade fuel consumption.

I'm pretty sure the pistons in the engine are standard 396 cast slugs with the small dome and they should be compatible with the standard closed chamber heads. The 265 horse engine should be the 325 horse shortblock with small cam and the larger chamber #148 heads on there to get the compression down to 9:1. Simple swap by Chevy and keeps their economies of scale going for regular 396 shortblock building.

With the KB 160 402" piston, 101cc, the calculator on the Keith Black-Silvolite site says 9.99:1.

I'm about 99% certain you'll have no issue swapping the heads but perhaps someone has a definitive answer. With nearly 10:1 CR, you'll have to run a fairly big cam to avoid too much low rpm cyl pressure....
 

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Discussion Starter #5
Thanks for the info, I was thinking that the same pistons might be used, due to the large diff in compression ratio on the 325 and 265hp engines. I didnt think that the big dome piston differences for open chamber heads had came into play yet in 69. I have some 781's heads but I didnt want to change pistons as of this moment. This is a good running low milage 396 i plan on using to get my big block platform established until I can throw some serious money at my 454. Thanks again and dont worry I will check everything out before bolting them on.
 

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I lined "The Kid" Brettd85 up with some pro-worked 148 heads.
Interesting chamber shape......
He'll see this post and send the pics.....

Jeff, send or post a pic of the pistons when you get the 148s off.....
 

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Chris,
Thanks for confirming.
 

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Discussion Starter #10
It should warm up this weekend for me to pull the heads off, thanks guys
 

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Discussion Starter #11
Yes, i know its been a long time, well I finally took the pistons out. Will this piston work with 215 closed chamber heads? Can anyone identify it? It is marked 1433 and 85 on the inside. As stated before it was running fine with 148 heads. thanks
 

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See my post #4 from January.
You have what looks like the cast piston for a 396 normally found with closed chamber heads, small dome, 10.25:1 list CR (what you will have with your 215 heads). For the 265 horse version, they put the open chamber 148 head on.

No issues at all putting 215 heads on this...
Put the 215 heads on, have 10:1--10.25:1 cr, install a decent cam, drive it like you stole it.
 

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Discussion Starter #13
thanks, i was just making sure. This was supposed to be my low milage virgin block, I discovered the pistons were 40 over, and I couldnt find the dome shape in my Colvin parts ID book. Thanks again George!
 

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Discussion Starter #16
thanks guys,
I already had the 215 heads gone through and bolted them on with no clearance issues. I was wondering which spark plug one would recommend with this set-up. I am running a Voodoo 60203 cam with Performer RPM intake, and the heads and pistons mentioned above. I have done some searches on here is a AC r45ts a good choice?
 

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Check your heads to ensure they are tapered seat instead of gasket seat.
 
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