Difference in 1275 heads?

[bugedd]

I was thinking this winter of building a new head for my worn out 1275. The head that is on the car is from a smog car. When choosing a different head, is there any difference or are they all about the same?

 

[jlaird]

Check Vizard, some are better than others. He covers all of them.

 

[Hap Waldrop]

THey are basicly 3 1275 heads, 12G1316 smog port head, and the no smog 12G940 heads, the 12G940 that came on the early 1275 Midgets, then the later Cooper S 12G940 heads, which had a larger intake valve, but where prone to crack in between the valve seat, these heads can be easily indentified, they a raised area for the thermstat housing, where all the 1275 Midget heads are flat in this area, avoid the Cooper S 12G940, they are not worth the risk.

 

[Guest]

Basic rule of thumb is, a new head on a worn out engine is prone to start smoking. I did it once and it was epic.

 

[Spridget64SC]

Along the lines of what Hap related, I would call the latest 12G940 heads the "Metro" head. This head was quite sculpted in appearance. A lot of the "extra" cast iron was eliminated. This one can't be milled as much for compression, but is a fairly nice piece for street application using street size valving. The 1.4" intake application will increase the potential for cracking between the valve seats. Probably relates to the reduced casting thicknesses.

The commom USA heads are the emissions heads from 1968 to 1974. The early heads from the 68-70ish timeframe have the better exhaust porting due to not having the the big valve guide boss. However, what one usually finds is that the exhaust valve seats in the heads are just plain gone. Excessively pitted and recessed. Necessitates a valve seat, but not an issue since it is really needed for reliability when using unleaded fuels.

Some general guidance on USA 1275 type heads:

1967: 12G940 "non-smog" head, good ports, 1.310" intake, 1.15" exhaust
1968 - 1970ish: "early-smog" head 12G1316, good ports, same valve sizes
1970ish - 1974: "late-smog" head, "X" on casting above center exhaust. Okay for the street, but takes more to port the exhaust pocket.

12G940 "Metro" head: Sculpted, less casting materials. Good ports. Might find some of these with the heavy exhaust port casting surrounding the valveguide too, expecially latest ones. Often found with the 1.4" intake valves. Check between the seats for cracks.

May be some export heads for CN/AU/SA that were variants of the above. Vizard covers the 12G940 stuff pretty well, but does not go into the nuances of the 12G1316 smog heads. He also doesn't cover the casting shifts that affect full race ported heads. Many of the Mini magazines have covered the head scene as well.

HTH,
Mike Miller

 

[bugedd]

So I started reading the Vizard book, and talking about over my head! I think I will find someone to build my motor rather than trying it myself. Between scatter cam profiles, porting to match the cam, milling the head to get the desired compression, rim flow valves, and......well all the other stuff. My goodness.
So if there is anyone in northern California that can do this for me, let me know.

 

[jlaird]

Hap is the man, he ships all over.

 

[bugedd]

I will have to chat with him. I know my limits, and building a motor to the degree that I want it to perform is beyond what I can do.

 

[Billm]

Hap is VERY good but you also have the option of "Seven" and "Mini Mania" in your own backyard.
Might want to talk to them.
BillM

 

[Westfield_XI]

If I lived in Chico, I would drive over to Riverside and visit with David Anton of APT. That is what I did and I live a lot farther away than you do. He is one of the best in the country as far as the A-Series goes.

 

[Deleted member 8987]

Chico. Chino. 8 hours and 20 minutes one way, 506 miles one way.
Don't feel bad, I was born and raised down there, not only still get the two confused but Redding and Redlands, too.

 

[Gerard]

Yeah, It's a shame there's no one in Northern California with any decent skills.

 

[jlaird]

At the risk of letting my dumbness hang out, who does it for a living??

 

[bugedd]

Didn't know you did that kind of work Gerard. I wasn't trying to insult or anything. The only person I knew of around here is Huffaker, which I don't I can afford.

 

[Gerard]

Not insulted and not directed to you or anyone in particular. I'm just "raising my hand" to remind people I've got a little experience doing this (40+ years). I do this primarily for local people, but like everything else I do, I build engines to the highest standard. It's still expensive to do it right. I can give you local references if you want to contact me off list.

 

[jlaird]

Well darn, the things you learn in Basils forum. Sorry Gerald.

 

[smaceng]

I can second the work of Gerard. I was up to my elbows on a 5-speed conversion, and met Gerard at his shop. I was impressed with his help (thanks Gerard) , and knowledge of our little british cars!
Scott in CA

 

[nomad]

Gerard, I see a nice looking A14 Datsun engine there! I'll be bugging you about parts source's.

Kurt.

 

[Gerard]

Thanks Scott and Jack...

Kurt, I built that engine in 2000 or 2001. I don't remember where I bought parts for it now, but I can look it up when you are ready.

 

[elrey]

Looks top notch, Gerard. Neat as a pin electrics included.