Technical 1100 and 1300 heads

[rawill]

I have been checking where I can trying to find the differences between an 1100 and a 1300 head. I am going to put a Tipo 1600 in one of my Unos with either an 1100 or 1300 head. From what I can tell from Haynes they are the same. Valves are the same at 35.850 - 36.150 dia inlet and 30.850 - 31.450 dia.

According to Haynes the only difference is the bore size.

I know JJhepburn put the 1300 head on his 1600 with a few other mods.
But my 1100 motor has quite a bit of blowby, still goes very well though. So if the heads are the same I thought I would use the bits off the 1100 to make my 1600 go into the Uno.

 

[alexGS]

I think there might be a difference in combustion chamber size - which the usual specs won't show. I have a recollection from 12 years ago that the pistons on the 1301 don't go all the way to the top of the bore. If that's the case, the two heads might be identical after all.

Either way it should fit and will give heaps of compression - good torque and efficiency. Power at the top end could be restricted by the smaller valves - in theory - in practice it won't matter with the standard camshaft. Take care to get the head surface really clean and use new stretch bolts. I learned that the hard way when a gasket blew between two cylinders

That was actually quite long to type on my phone - hope it makes sense

-Alex

 

[rawill]

Yes, it makes real sense. I wonder if the increase in compression will be too much. I guess a few measurements and then time will tell.

Top end won't be an issue until (if/when) I decide to make it into a real racer.

 

[SteveNZ]

Uno's dont have stretch bolts, but new one wont hurt.

I would be wary using a head with smaller valves just to get an increase in compression. Sure you'll get more torque but maybe no more power. 1600 valves are small enough as it is. Fiat twin cam 1600 engines have 43mm valves.

 

[alexGS]

Uno's dont have stretch bolts, but new one wont hurt.

Well, they're angle-tightened. I know that it's a lot harder to get the angle tightening with re-used bolts. The second 90 degrees is a real killer (over 200Nm) but easy with new bolts (about 120Nm). Therefore, I assumed they are stretch bolts.

-Alex

 

[rawill]

Uno's dont have stretch bolts, but new one wont hurt.

I would be wary using a head with smaller valves just to get an increase in compression. Sure you'll get more torque but maybe no more power. 1600 valves are small enough as it is. Fiat twin cam 1600 engines have 43mm valves.

Steve: What is your issue with smaller valves, for a road car, I thought more torque would be just what is wanted. Top speed and power at the high end is not so much of an issue. I am just doing this project because I can. Don't want to spend a fortune at this stage. I will wait to see how the first part goes.

It seems like I need new synchros for the gearbox as well. Seems to crunch a bit when you try to change gears quckly. Might change the oil in it first and see how it goes.