<VV> 'Helt Design' combustion chamber

[Bryan Blackwell]

Hi Bill,

I built the old 140 in the red Corsa with the step milled out of the  
heads and .032 copper gaskets.  It would ping a little on 91, but 93  
worked very well, much better than stock.  Those basic heads will get  
rebuilt and go back into that car on the next version of the engine.
--
Bryan Blackwell bryan at skiblack.com
http://autoxer.skiblack.com/
   Corvairs: '61 Lakewood, '64 Greenbrier, '65 Corsa, '66 Corsa
   '69 Road Runner, '97 Ford F-150, '99 Neon R/T
"Why do something if you're not going to obsess about it?"


On Aug 3, 2007, at 2:47 PM, Chris & Bill Strickland wrote:

> I would appreciate reports from those of you who have actually used  
> this design in street performance style engines, especially if  
> anyone has done this with 95 hp heads and carbs, ala Bob Helt's  
> Tech Guide article 'Running on Regular' and http:// 
> www.corvaircorsa.com/mann03.html
>
> What was your piston-head gap, final compresion ratio, and what  
> fuel are you running -- PON, % alcohol, etc.  Were you satisfied  
> with the results?
>
> Bob has written, " ... if you will take a look at the article, you  
> will see a chart (Figure 2) on page 5. This chart clearly shows  
> that for a quench gap of 0.035 in., a CR of about 9:1 will support  
> REGULAR gas. (PS, Corvair engines actually had lower CRs than  
> advertised.) Higher CRs need higher fuel octane. So if you were to  
> make the modifications mentioned and wound up with a CR of, say,  
> 10:1, you are most likely going to need premium fuel."