CH 270 Engine rebuild project

[irobertson]

Quick update. I spent quite a bit of time doing all the disassembly. Both engines were seized, and It took a couple of weeks to get the pistons out. The blocks went off to be cleaned and evaluated. Each had one cylinder that was worrying due to the amount of corrosion in the bore. Long story short, they are both junk. The guy who checked them for me cleaned and magnafluxed them, then started boring out the questionable cylinders to see if either would be usable. We decided on a .040 overbore as a limit, and there was still pitting after he cut that far, so we called it. He had a couple of 2 bolt main blocks in his shop that he sold me for a reasonable price, so these blocks are going to form the basis of my rebuild. They will each be bored .030 over and honed to fit a new set of pistons. Next is evaluating the crank shafts and removing the old pistons from the rods.

[bud37]

Sorry to hear that,How do the cams look? If you are thinking of using them again, before you order new lifters, check all the lobes for lift, your guy should be able to do that for you ( GM had some soft cams back in the day ) and make sure they are marked as to which engine they belong to.......

[irobertson]

Cams and cranks look good. However I'm not planning on reusing the cams. My guy is saying I should abandon the geared cam drive on the reverse rotation engine, and do timing chains on both. I'm inclined to agree with him. He can provide me with a set of matched cams, one LH one RH, and the reverse cam has the distributor gear cut the other way, so the dizzy & oil pump maintain correct rotation. The next step is ordering two sets of .030 over pistons and having them fit to the bores, and having the cranks properly inspected and polished. This is going to be a year long project, taking my time and just going through each step as $$ become available. I also have a list of things that need to be done to the car

[waybomb]

I wonder what the concern is with gear driven cans. I view that as a big plus.
Id stay with gear drive.

[Viper]

Qr Bbpost ....abandon the geared cam drive on the reverse rotation engine, and do timing chains on both.....

WHY?

[bud37]

Qr Bbpost Cams and cranks look good. However I'm not planning on reusing the cams. My guy is saying I should abandon the geared cam drive on the reverse rotation engine, and do timing chains on both. I'm inclined to agree with him. He can provide me with a set of matched cams, one LH one RH, and the reverse cam has the distributor gear cut the other way, so the dizzy & oil pump maintain correct rotation. The next step is ordering two sets of .030 over pistons and having them fit to the bores, and having the cranks properly inspected and polished. This is going to be a year long project, taking my time and just going through each step as $$ become available. I also have a list of things that need to be done to the car

Only thing I might ask him, would there be an issue with thrust load direction on the distributor ?.....actually the gear drive is cool, you will never have chain stretch or timing wander and you get that whine lol......

[irobertson]

Thanks for the feedback. I will discuss with him. I did ask about the thrust on the dizzy, but the new pump/dizzy drive gear would be cut at the opposite angle, and the dizzy gear would change, so thrust would still be the same. His position on this may just be his experience, he is a well respected race boat engine builder.

[bud37]

Qr Bbpost Thanks for the feedback. I will discuss with him. I did ask about the thrust on the dizzy, but the new pump/dizzy drive gear would be cut at the opposite angle, and the dizzy gear would change, so thrust would still be the same. His position on this may just be his experience, he is a well respected race boat engine builder.

Cool....sounds like you are in good hands there.......keep us posted ... there are no good days if you don't learn something....