1967 main bearing cap's 327ci

[tom #33509]

i need some help trying to locate where i can buy them it's all i have left for my complete rebuild!! and maybe a distributor if mine is worn

thank's in advance tom

[Gene M.]

Re: 1967 main bearing cap's 327ci

Tom,
Main bearing caps have to be matched to your block. You don't replace them without machining them as assembled to the block. This is known as line boring. The machine shop can supply the raw caps where you get it machined.
Are you sure this is what you intended?

[tom #33509]

Re: 1967 main bearing cap's 327ci

yes the block came without main bearing cap's thank you

[William C.]

Re: 1967 main bearing cap's 327ci

You can either "borrow" another set of main caps from another 870 block, or have your shop purchase a set of aftermarket caps and install them. The installation process is similar in either event as Gene described it, either way the replacement caps must be fit to the block and then sized, although in my area most shops line hone rather than line boring these days.

[Joe L.]

Re: 1967 main bearing cap's 327ci

Tom-----

As other have mentioned, you must have the block line-honed or line-bored if you install new or used replacement main caps. If at all posible, you want to select a shop that will line-hone them rather than line-bore. They may or may not be able to depending upon the situation, but you don't want a shop that just automatically goes right for line-boring. Line boring is an "if all else fails" type of thing, as far as I'm concerned.

Replacement caps for 55-67 small blocks are discontinued from GM. The #1-4 caps were discontinued several years ago; the #5 (rear) cap was discontinued a LONG time ago. Most machine shops can come up with these caps if you need them, either aftermarket or used (donated by "lunched" blocks). If you want to get real fancy, you can even obtain aftermarket billet steel caps.

As far as the distributor goes, you shouldn't need a new or replacement. The most you should need is to have yours re-bushed and other worn parts replaced. That will make it like new. Distributor housings or complete distributors rarely need to be replaced.

[John C.]

Re: 1967 main bearing cap's 327ci

I understand about replacing caps on a small journal 327. My '64 came with the original block but lacked main caps. New replacement caps could not be had so I called one of the engine salvagers advertising in Hemmings that specialize in old engines. He agreed to send me two sets of caps (machinist's recommendation) with the understanding that I would send the unused set back. My machinist used the set that fit the best but said he still had to peen one of the caps to get a tight fit.
I do not recall the name of the business that sold me the caps but they advertise in Hemmings every month in the Corvette Parts section, they sell correct numbered blocks in heads, I believe they were out of Michigan.

[Mike M.]

Re: 1967 main bearing cap's 327ci

Peening caps for fit is inferior to welding then refitting caps to block. good luck with peening but keep fingers crossed as SBC hits 6000+ RPM. Another option would be to purchase aftermarket 4-bolt main caps which won't need welding, just fitted to your block. mike

[Clem Z.]

main bearing caps

the inset in the block of the caps only locates them and the when the power is put to a engine the cap are forced downward which pulls the ends of the caps inward and they get loose in the block register. you can tell if the caps have been moving around by the surface of the block and caps where they seat. even 4 bolt BBC the caps get loose in the block register if they are overreved and i used a special caulking chisle in a air gun to tighten them back up. whether you add metal to the cap or move in the cap register in the block is does not make any difference. the only way to stop the cap movement is to use dowel pins which are a tight fit in the block and cap. i made hollow dowel pins that fit around the cap bolts and machined the cap and block for a press fit to keep the caps from moving around at 8000+ RPM in BBC drag race engines. i also did the same with all 2 bolt blocks including pontiac and chrysler. if there is enought room around the bolt head you can just drill into the cap and block to press in solid dowel pins. the fact that the parting line of the block and cap pulls inward is the reason that bearing inserts have more clearence at the parting line than they do at the center

[Mike M.]

Re: main bearing caps

clem: thanks for enlightening this old dog. The dowel pin trick sounds far superior to what my local machine shop did for one of my 870 blocks with loose main bearing caps. And almost certainly far less painful on the pocketbook too.. thanks, mike