# #16 heads



## 1coolduck (Apr 3, 2012)

Is anyone running a 400 with #16 heads, on PUMP gas ?? If so what combo do you need to run?? (lotta talk that they create too much comp.)
Thanks, Duck..


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## BearGFR (Aug 25, 2008)

It can be done on a 400, much harder on a 455. 16's have a nominal chamber size of 72 cc's, so to get the needed clearance volume the "best" solution is usually to run dished pistons.

Bear


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## PontiacJim (Dec 29, 2012)

If you are rebuilding your engine, Bear is correct. Usually you get the correct pistons with more cc's, aka dished pistons, or you can talk with a cam manufacturer who can "bleed off" some of the compression -type in "static compression verses dynamic compression" into your search engine and get ready for a lesson in compression ratio's. Another trick I have not seen in a long time used to be to add a water/alcohol injection system that was supposed to cool the intake charge on higher compression engines as well as give a little more power. Ever notice how your car runs stronger on a good cool damp night? I have seen a how-to article where the windshield washer pump/container was used and misted into the top of the carb via the air cleaner lid. I have seen kits for sale as well. It kicks in during wide open throttle. Might look into that as an option. I am considering one myself just as a precaution should I ever need it -even though I will have a reasonable compression ratio to run pump gas.


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## pontiacmatt (May 19, 2013)

I run pump gas ( premium/ 10 percent ethanol) in mine but don't know if engine was ever rebuilt before I got it 20 some years ago. I drive like an old lady anyway.


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## GTO JUDGE (May 14, 2005)

pontiacmatt said:


> I run pump gas ( premium/ 10 percent ethanol) in mine but don't know if engine was ever rebuilt before I got it 20 some years ago. I drive like an old lady anyway.


Try using Ethanol Treatment. I use Sunoco 93 oct it has 10% corn/water. . I use Lucas's Ethanol Treatment 1 oz per 5 gallons. I noticed a difference in detonation. Their treatment can be used on E-85 it states, but there is no way in hell that garbage is going in any of my vehicles.


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## BearGFR (Aug 25, 2008)

Also, consider this: In my 461, the difference between 9.2:1 compression and 10.0: compression, with no other changes made, is only worth a whopping 8 hp. (in an engine that's already over 500 hp). That makes pushing the envelope on compression to the razor's edge just not worth it.

Bear


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