Hey, is anyone familiar with the head casting number 3788380? It's the head that came off my rebuilt 67 292 that I bought. I'm in th middle of starting the lump porting and kinda started looking at things a little more closely. I have no history whatsoever on this thing, only what I've found pulling it apart. I looked in tech tips, and there's only question marks where this number appears. It does seem to fall closely in line with 194 head numbers. It came with 1.50 and 1.74 valves, I believe. The combustion chamber looks small, but that means nothing, obviously, without cc'ing it. Does anyone have photos of a stock 292 and 194 head(w/the 60 cc combustion chamber) from the bottom from that era? A long shot, I know. Thought I'd ask. Thanks, Ted.
I did a post that showed pic's of the 292 and the 194 combustion chambers. Should be real easy to find with a search.
Found it.
https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=54009#Post54009I would not run a 194 head with a intake valve bigger than a 1.84. It will restrict intake flow. Also prefer the 230-250-292 heads. They will be easier to make into a good running head.
Based on the photos, certainly the proximity of the OD to the chamber wall is too tight with the 194 head, and no flow around that area will occur until lift is fairly high.
However, how many differences between the castings are known as to where is the water, wall thickness, etc.?
The plug location and angle appear to differ significantly between the 292 and 194 heads; how much iron can be cut back toward the plug thread on the 194 before you get wet? In short, can be wall be moved back as far as is the 292?
The advantage is that this area will have lower volume after cutting, and can be made the "heart" shape with less work.
The wall behind (toward the plug) is about .400" away from the 1.94" valve on the 194 head, but about .600" (+.200" higher) for the same valve in a 292 head.
If the relief is contoured to the 292 distance toward the plug, and opened to the bore size at 90°, how bad is it?
For comparo, I made a .psd of the 2 heads, with a 3rd layer showing only the relief if anyone wants to take a look.
In order to make the 194 head flow,you do not just cut the chamber wall on the side. (where the valve is closest to the chamber)
You need to relieve/unshroud the chamber in other areas,it's not just one spot.
There is more involed & it's not hard to do.
There is nothing wrong w/the 194 head,you just need a person that knows how to work them properly. Mike Kirby,Larry AKA Twisted6 & others.
It is a viable option for more compression when you do not want to tear apart the bottom end & install higher compression pistons.
It's a simple cyl head swap & will get you about one full point of compression increase & can get more if you shave/mill the head.
MBHD
Panic,
I am interested in seeing your .psd. Please send it to me tom@12bolt.com