Quote:
junior wrote:
Yes, I'm in the US. I was comparing hp on the engines from the A series and this is what I found:
73 A12 69HP @ 6000 70 Torque @ 4000
74 A13 75HP @ 6000 77 Torque @ 3600
75 A14 78HP @ 6000 75 Torque @ 4000
76-78 A14 80HP @ 6000 83 Torque @ 3600
79-82 A14 65HP @ 5600 75 Torque @ 3600
79-82 A15 67HP @ 5200 80 Torque @ 3200
This is from a US Repair Manual. So you say it's not worth rebuilding it ? I already have it with A15 pistons in it
I didn't say that it wasn't worth rebuilding, I said that if it needed a major overhaul, or reconditioning, then an A14 or A15 will be a worthwhile substitute, but if it was running fine, then leave it.
That's quite a bit different from what you suggest I said.
You say that you have it rebuilt already with A15 pistons? That's most interesting for the following reasons.
The 1974 A13 used 1200/A12 pistons of 73mm diameter & with the 17.5mm wrist pin.
The A15 piston is 76mm diameter, has a 2.5mm lower crown, or deck height, & uses a 19mm pin diameter.
The block should bore to 76mm OK & by using A14 or A15 rods, which are the same length as 1974 A13 rods, you could fit the A15 pistons without problems.
You could also bore out the small end of the 1974 A13 rod to fit, but this of course reduces the strength at this critical location.
What did you do when you found that the pistons fell short of the top of the block by 2.5mm?
This would reduce the compression by a fair bit & since the bowl volume in the A15 pistons is also greater than the A14 piston [which would have been the much better choice], this would reduce the compression even more.
If an A15 crank & oil pan was also installed at the rebuild, then the A15 pistons would be the right choice & you end up with an A15 engine that carries an A13 engine number prefix.
The 1974 A13 also has the larger valve sizes of 37 & 30mm but I do not know if the ports are the small oval size of the A12A head, or the larger oval size of the A14/15 head.
Hell, I can't even be sure that it doesn't use the round port head like the 'Thrift' version of the later A14's that are to be found in some US model 210's [B310]