# Question about 400 Poncho heads



## Poncho Dan (Jun 30, 2009)

I've got a 400 in my '64 GP that was _supposedly_ out of a '67 or '68 Firebird. I had the motor built up a few years back with the standard goodies like 1.6:1 roller rockers and a 232/480 cam. However, I'm curious to know what year the block is from, and where/what numbers I should look for to find this out. I was told it was a 400HO... and I've also read that the 67s had different heads than the 68s. Whats the difference between the HO and Ram Air II/III? Is there numbers I can cross reference on the head castings? Also, how many degrees total advance should I be seeing with the hotter cam? My factory repair manual says 6 degrees for initial timing on a '67 and 9 degrees (which is what I have it set at currently) for a '68... and I'm not too sure my advance is working properly because it coughs and backfires under load.

Thanks!


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## 68greengoat (Sep 15, 2005)

As far as IDing your engine, check out this site. It shows you exactly where to look for the codes.....


Pontiac Engine Codes


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## 646904GTO (Feb 10, 2008)

As far as timing goes you can run as much initial as you can get her started hot...but a good base line for the Pontiac V8 is 9-13 BTDC(I find 10-11 best). As far as total, including vacuum and mechanical 34 degrees is what you want. Dyno tests have proven that anything over 34 degrees total advance on pump gas makes no more power. To achieve this you will probably have to limit the travel of the vacuum advance rod in the distrubuter. It is acheive simply by removing the pod and limiting the travel of the rod by welding the slot small, thus limiting the travel. You just have to get close because you can adjust the base timing a degree or two to get the total you desire. If you take to much out simply file the slot a little for more travel.


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## Poncho Dan (Jun 30, 2009)

Wow thanks guys! This has been troubling me for a while now. I'll give it a try.


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