Pop up Pistons
Thread Starter
Racer
Joined: May 2005
Posts: 470
Likes: 1
From: Amelia Ohio
Pop up Pistons
As some of you know my non vette 350 started rattling a rod. The wife put me on a winter budget so my dream 383 is out of the question. So what my plan is to play with the boat anchor I have. The block is in good enough shape that I'm just going to hone the cylinders and have the crank and rods reworked. I'm going to put in new pistons and was thinking about 11-1 pop ups . The heads are the standard smogs that I'm going to port and polish. The question is, Is this going to be too much compression for premium pump gas and street driving? I had a friend years ago that had a 302 DZ motor with 12-1's and camel hump heads that he drove on pump gas and seemed fine. Actually reeeally fine. Let me know what you all think.
Chris
Chris
Pro
Joined: Feb 2001
Posts: 558
Likes: 0
From: Dallas TX
What kind of smog heads? Are you talking about the 882's? If so, they have 76cc chambers. You can probably run 11:1 pistons on pump gas (91 octane) with no problems, except for the fact that you'll have to retard your advance quite a bit more than a lower compression motor to avoid detonation. I'm sure others will chime in with lots more stuff I didn't mention. 
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Originally Posted by evalu8r
Yea, there 882's. 
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Originally Posted by evalu8r
As some of you know my non vette 350 started rattling a rod. The wife put me on a winter budget so my dream 383 is out of the question. So what my plan is to play with the boat anchor I have. The block is in good enough shape that I'm just going to hone the cylinders and have the crank and rods reworked. I'm going to put in new pistons and was thinking about 11-1 pop ups . The heads are the standard smogs that I'm going to port and polish. The question is, Is this going to be too much compression for premium pump gas and street driving? I had a friend years ago that had a 302 DZ motor with 12-1's and camel hump heads that he drove on pump gas and seemed fine. Actually reeeally fine. Let me know what you allthink.Chris
Or ... a set of 58cc heads from an OE 305 will bump dish-pistoned 350 from almost 8:1 to nearly 9.5:1 ... cheap in junkyard or "left behind" at machine shop ... the OE 305 heads don't work real well above 4500-5000 ... & they won't do well w/ a 383 ... but they will get your 350 a big jump in CR and low-mid torque. Note: Do NOT use 305 head gaskets between 305 heads & 350 block ... DO use 350 head gaskets.
Last edited by jackson; Dec 7, 2005 at 11:05 AM.
Le Mans Master
Joined: Mar 2004
Posts: 7,477
Likes: 1,495
From: Little Rock AR
I run that cam in my 302 and it is not that great as far as I am concerned. Those heads are pretty bad as well. The valve job cost alone will make you think twice about reworking those heads not to mention the port work you have planned.
Flat tops and modern small chamber aftermarket heads would be SO much better without breaking the bank.
I plan on pulling my 302 cam and dropping in a Crane F-278-2. You might consider that one. It would probably work well with the 10.4 C/R 350 you could build from the above parts. 
-Mark.
Flat tops and modern small chamber aftermarket heads would be SO much better without breaking the bank.
I plan on pulling my 302 cam and dropping in a Crane F-278-2. You might consider that one. It would probably work well with the 10.4 C/R 350 you could build from the above parts. -Mark.
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
I'm running 993 heads (76cc) with .125 domed pistons, Lars carb and tuned dist. and the ill-famed XE268H cam and I've gotten detonation on 91 gas on very warm days...CR of the engine is around 9.5:1, but I'm not sure what the quench is. There's lots of factors when it comes to detonation.
trw
trw
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Brett Foote
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
Skip the pop-ups. Run flat pistons and put the money into a good set of 64cc heads. This will give you great flow and reasonable compression for a great street engine. If you run 11:1 comp with your smogger heads, you'll have lots of compression, detonation, no flow, and poor power. Great combination...
