Late 1600 8mm heads/case

Hi tech wizards need some more assistance

I am chasing after info re what year the 1600 motors from the superbug had the 8mm studs. I am told to go for a late superbug motor for the crankcase and heads to build a 1916 motor and need to know engine numbers and identification to make sure I have the right motor.

Thanks guys

I have one ! seagull F case hard to find

As far as i know all the cases till the 1500 H case had 10mm head studs and 6mm studs for the oil pump and elsewhere

The engine case that superbugs used is called the AS41 or AS21 case AKA Dual relief case

The AS41/as21 case had the 8mm studs with case savers - has the larger 8mm ancillary studs and larger oil passages These cases have dual oil reliefs too. The way to tell them apart, other than looking at the studs is by engine number

here's a page with engine numbers
http://www.hvwc.net/postnuke/html/modules.php?op=modload&name=News&file=article&sid=50

The AS41 can be identified from looking at the bottom of it. There is a big fat screw towards the pulley end, as well as one near the flywheel. These are the two oil reliefs as mentioned earlier.

Also the late cases can only really be fitted with dual port heads so that is another way to tell them apart.

If you're gonna build a 1916 engine you might as well get a new case (an aluminium one perhaps?) anyway.

It's hard to put a date when they changed from 10mm to 8mm head studs, I have seen a 1300 "F" case with thin studs, they would have been fitted by an engine reconditioner.

From the factory I think it was around '73 - '74, I know all the cases with the engine number prefix "AS" were 8mm studs and "AD" prefix cases, some were 10mm and some were 8mm, all these were dual relief.

Again, if you are building a 1916, get a new case.