1967 427 400HP cam

[Clem Z.]

Re: 1967 427 400HP cam

[quote=Duke Williams (22045);478815]I never quite understood this. I assume that the rear cam bearing clearance is in the same range regardless of what cam bearing/cam is used.

A grooved cam will likely result in a bit more oil passing through the rear cam bearing, but I don't see how this can be significant, since the typical .001" clearance on either side of the groove is still going to be a significant restriction to oil flow.

The Power Manual instructions say to solder up the oil hole and drill it to .060", but what is the size of the original hole. I assume it is larger.

Do you recall the thread where is came out that Chevrolet rescinded the this advice?
the original cam bearing hole was about 1/4" and with a non grooved cam journal the hole which is on the bottom of the bearing a direct feed from the rear main bearing was closed off because the valve train is pushing down on the camshaft and only some oil got by the cam bearing journal. with a grooved cam bearing journal which lined up with the cam bearing hole allowed full flow of oil in around the groove. this could cut down on the amount of oil passing thru the groove in the block behind the cam bearing and not allow enough oil to get to the hyd. lifters

[Clem Z.]

Re: 1967 427 400HP cam

I have been running the 3986 groved cam in my 67 for the last 30 years with no alteration to the cam bearing.
CORDially Mike

you and thousands of others and on a street engine the internal oil leak may not cause a problem but in a race engine you can not afford the internal oil leak as it could starve the bearings

[Patrick H.]

Re: 1967 427 400HP cam

Hi Patrick, Thanks for the complement on the car. I bet you didn't know that Bryan used to work for the shop we are speaking of.
CORDially Mike

No, they didn't tell me that, nor did he. I'll have to ask him about it next time I see him.
I was at his office also yesterday morning, though not to see him.

[Ridge K.]

Re: 1967 427 400HP cam

Mike, I purchased a "kit" over the counter of a Chevrolet dealership parts counter a little over three years ago for my own 1967 L68 400hp Corvette.
The "kit" includes the camshaft and a set of lifters.

Here's a post I left about this in another thread a little over a year ago:

can tell you Chevrolet still stocks a 427/400 (L68) camshaft and hydraulic lifter kit over the dealership parts counter. It's a duplication of the original 390 and 400hp camshaft, now manufactured by Crane Cams.
For the 390/400 hp, it is currently, GM parts number 12364055, and lists for around $185, complete with lifters. Pretty good price.
I would suggest you talk to your local Chevy dealership parts sales persons. Give them your application, and see what they come up with. A search of the archives will display many, many favorable comments about Crane camshafts. Hope this helps.

[Duke W.]

Re: 1967 427 400HP cam

Thanks for the education on BB cam groves and the clarification on 427 400HP cams. I have CS 1093M and CS 274 ordered from NAPA. CS1093M was $154. and CS274 was $56. I don't get a price break.
CORDially Mike

It's probably a matter of volume for both the cam blank and the finished cam. The CS274 ('67-up base engine cam) was used in millions of SBs from 1967 into the eighties, and I expect a lot of them are still sold. There's only one SB cam blank that everyone uses to grind the hundreds of different flat tappet SB cam designs - both OE replacement and aftermarket, so Textron CWC, the manufacturer of the blank, still manufactures them in large quantities compared to any other engine architecture's cam blank.

Big block replacement parts are much lower volume and always seem to be more expensive, but the low price of the CS274 is pretty amazing!

Look at valve springs. A set of Sealed Power VS677s ('67-up SB spring) is about 20 bucks if you shop around. The second design BB valve spring kit, which I've never found from an aftermarket source - only available from GM - is something on the order of $150. Granted, it's an assembly with dual springs, retainer, and seal, but it follows the pattern of BB parts being much more expensive than SB parts.

Imagine what a set of cams cost for a vintage SOHC Porsche or Ferrari engine - probably equals or exceeds the entire parts cost for a high quality SB restoration!

BTW, if you haven't already done so, replace the first design single valve spring/damper with the second design dual spring/retainer/seal assembly available from GM - 12371061 for the kit of 16 3970627 assemblies. The second design, which went into production circa 69/70 has proven durability. The first design single spring/damper has a high failure rate.

Duke

[Wayne M.]

Re: 1967 427 400HP cam

....The Power Manual instructions say to solder up the oil hole and drill it to .060", but what is the size of the original hole. I assume it is larger. .....Duke

Here's a pic of the grooved rear bearing (you can see the corresponding hole in the block because the bearing hole is misaligned a bit. This is a 396 2-bolt 3855961 block, cast mid May 1965.

[Clem Z.]

Re: 1967 427 400HP cam

i think GM went to the non grooved cam deal was because even the original setup like you picture caused a internal oil leak that could cause a warranty problem.

[Mike H.]

Re: 1967 427 400HP cam

I just checked with GM on 12364055 cam kit. It was discontinued on June 5, 2009.
CORDially Mike

[Ridge K.]

Re: 1967 427 400HP cam

That roughly coincides with the February, 2009 annoucement that Crane Cams was closing it's doors.
Many sources were reporting that Crane was manufacturing this camshaft for GM.
When Crane closed, I knew of several Corvette enthusiasts purchasing the cams to "put them back".

I think the re-opened Crane is the source to check. Good luck, Ridge.

[Patrick H.]

Re: 1967 427 400HP cam

I just checked with GM on 12364055 cam kit. It was discontinued on June 5, 2009.
CORDially Mike

A little Google search using 12364055 camshaft shows that there are a few sources that appear to still have it in stock.

[Ridge K.]

Re: 1967 427 400HP cam

A little Google search using 12364055 camshaft shows that there are a few sources that appear to still have it in stock.

Great news, Patrick!

[Mike H.]

Re: 1967 427 400HP cam

I checked about ten of the sources that came up on a google search and none of them actually have the cam in stock and when they call me back they all tell me it is discontinued. Got both cams today from NAPA. Thanks for the help every one.
CORDially Mike

[Duke W.]

Re: 1967 427 400HP cam

Are you talking about one Federal Mogul/Sealed Power CS-274 on one CS-1093M?

Does the CS-1093M have a groove in the rear journal?



Duke

[Mike H.]

Re: 1967 427 400HP cam

Duke, I was also looking for a 300 HP cam and that is what I meant by both cams. SB CS 274 and BB CS 1093M. They are both FM cams and the BB is not groved
CORDially Mike.

[Mike H.]

Re: 1967 427 400HP cam

I thought you might like to know the cam specs. I got with the CS1093M NAPA cam for 400HP 427. They are at .050. Valve lift intake .475 exhaust .495. SAE J604d duration intake 290 degree, exhaust 303 degree. Rocker ratio 1.76. Gross lift intake .270 exhaust .281. duration at .050 intake 214 degrees exhaust .218 degrees. Maximum lift intake 110 A.T.C. How true are these specs. to the orig. cam?
CORDially Mike