• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

12A185

Share this page

racingenglishcars

racingenglishcars

Darth Vader
Country flag
Offline
Hey guys and gals. I'm looking for a little identification of a cyl head. It is on my original sprite engine that came with the car when I got it back in '73. The engine is a 9CUH and the head is casting 12A185. That all sounds textbook except that when I took the head off the first time, now we're talking back in 1974, I remember very well that the block has been pocketed. I thought it was weird at the time, but I was 16 and didn't know what I know now.

According to the head page:
https://drcwww.uvt.nl/~bogaard/heads.htm it could also be a Cooper S head 1 13/32" In and 1 7/32" Out

Anyway the engine is completely assembled right now with manifolds and all, as it has been for the last 32 years, and is sitting in my shed. I didn't want to pull it apart to check the head so I was wondering if there are any other ways to determine the type head from casting numbers or something.

Whaddya know? Can anyone give me any more information?

Thanks, Donn.
 
The Sprite Service Parts manual shows the correct part number for a Bugeye Sprite as 2A613. I didn't find a part numbered 12A185.
 
Vizard's book has a pretty good tree to find head (and blocks too I think). I'll look it up and post tonight when I get home.
Bill
 
Bill:

Thats exactly what I was thinking, my book is at home as well.

Where is Jack when ya need 'em.

Patrick
 
My Vizard book is at home too...
Wait...
I'm at home...
 
inlet dia 1.4 in
ex dia 1-5/32 in
chamber volume 21.4 cc

Used on all S engines other than MG1300, 1300GT and last S's

Let me see if there is more.
 
Here I am in Ark. even have my Vizard book but it is upstairs in the room. hehe.

You guys doing fine so far.
 
According to David, the 185 heads were the early version, and were prone to cracking between the valves. Apparently a reduction in exhaust valve size to 1.156" alleviated the problem.
Jeff
 
Roger all above.
 
Jack:

I hope all is going well and you are finding us some nice places.

Patrick
 
The 12GA185 is what you find on most 948, I believe the 12G206 is the 1098 if I'm not mistaken, it may have been used on the 948s as well. The 1098 and 948 heads can be swapped around on the two motors, the 1098 is only .060" larger in bore, the 1098 get it's extra deplacement from it's 3.300" stroke compared to the 948's 3.000" stroke.
Just to complete this strok thing on the A-series engine, the 1098 had the longest stroke, the 1275's stroke is 3.200".

Engine size/Std. bore size/stroke
948/2.48"/3.000"
1098/2.54"/3.300"
1275/2.78"/3.200"
 
you wouldnt happen to be in NW Arkansas would u, jack? /bcforum/images/%%GRAEMLIN_URL%%/wink.gif
.........zimmmmy
 
Yeah, that's what I read about the 12A185, but it is the same casting number as the Cooper S. I guess I'll just pull it apart next week and see what I can do with it.

The long stroke on the 1098 is what gives it so much torque. Of course bigger pistons would do the same thing, but then the tax man steps in.

Donn
 
Hap Waldrop said:
Just to complete this strok thing on the A-series engine, the 1098 had the longest stroke, the 1275's stroke is 3.200".
Click to expand...

So, this may be a silly question, but what would happen if you put a 1098 crank in a 1275 (and would it fit?)
 
Back
Top