Hi. I'm building an A65 single carb engine. I have a cylinder head number 68-705 and a set of barrels number 68-44 HSC. I believe that even though there's a 5/16 vs 3/8 inch bolt mismatch on the rear bolts, the head and barrels ought to work together. The barrels have 4 studs sticking up from the upper face - 1 stud in each 'corner'. The studs are 3/8 diameter. When I try to put the cylinder head onto the barrels, it won't go over the studs. The studs are straight and all seem perpendicular to the face of the barrels and parallel to one another. The head 'nearly' goes over the studs but I think the holes are about 0.25mm away from where the studs need them to be. I tried a bit of gentle persuasion but the head just doesn't want to go on. Does anyone know why the two components don't fit? Has anyone else had a similar problem? Is there any way of getting around this apart from looking for a different head.
Thanks
Regards
Tony
It's not the head that's the problem, if you start to remove the studs from the barrel, you'll likely find one of them is bent and you'll see it oscillate as you remove it. But all the heads and barrels will swap over with the only issue possibly being the rear bolts as you mention. But there's always a way around that. Best thing to do there is re-tap the rear 5/16 studs to bring 3/8 BSF
Hi Allan. Thanks for your reply. That was an excellent call - one of the shorter studs is bent. It's an incredibly small bend that is barely visible when the stud is rolled on a cast iron faceplate but it's there. With that stud removed, the head fits onto the barrels fine. It's a very exact fit with the head needing a bit of wiggling to work it down but it works.
Thanks again
Regards
Tony
Quote from: Tjwood on 09 May, 2024, 12:21
Hi Allan. Thanks for your reply. That was an excellent call - one of the shorter studs is bent. It's an incredibly small bend that is barely visible when the stud is rolled on a cast iron faceplate but it's there. With that stud removed, the head fits onto the barrels fine. It's a very exact fit with the head needing a bit of wiggling to work it down but it works.
Thanks again
Regards
Tony
No worries Tony, I've had a couple which are like that.