1967 427 400HP cam

[Mike H.]

I have read the past posts done in 2008 on this subject but find different part no. etc. I am looking for OEM replacement for 1967 427 400HP. The following no. have been given Crane 969391, Crane 968711, Crane grind No. 3883986, and GM# 12364055. The orig. cam in the engine, replaced 30 yrs. ago, had no grove in the rear journal but present cam(3883986) has grove. Is there a definative answer on what cam is OEM and where to buy it. I know Crane is back, but I can't find a web site or phone No. Any help would be appreciated.
CORDially Mike

[Patrick H.]

Re: 1967 427 400HP cam

Hi Mike.

I saw your engines today.
Dropped off a big block to have some work done at the shop and saw your name on the tags. I know Bryan, and you have a VERY nice white 67 coupe.

Patrick

[Clem Z.]

Re: 1967 427 400HP cam

I have read the past posts done in 2008 on this subject but find different part no. etc. I am looking for OEM replacement for 1967 427 400HP. The following no. have been given Crane 969391, Crane 968711, Crane grind No. 3883986, and GM# 12364055. The orig. cam in the engine, replaced 30 yrs. ago, had no grove in the rear journal but present cam(3883986) has grove. Is there a definative answer on what cam is OEM and where to buy it. I know Crane is back, but I can't find a web site or phone No. Any help would be appreciated.
CORDially Mike

3883986 is the correct GM number as i ran that cam in one of my BBC pickups. .460/.480 lift. 12364055 is the same cam by crane. you don't need a groved cam in a 67 BBC. it is the same cam used in a 396/360 HP chevelle engine

[Michael G.]

Re: 1967 427 400HP cam

Mike,

Think you find the Speed Pro/Sealed Power cam CS 1093M has the specs your looking for.

[Clem Z.]

Re: 1967 427 400HP cam

Mike,

Think you find the Speed Pro/Sealed Power cam CS 1093M has the specs your looking for.

that is listed as a marine cam so if you have no luck with any of the other cams try a marine dealer

[Michael G.]

Re: 1967 427 400HP cam

Clem,

Not sure about the marine dealer comment as the cam was purchased along with many other engine parts from Northern Auto Parts....http://www.northernautoparts.com/

[Joe L.]

Re: 1967 427 400HP cam

I have read the past posts done in 2008 on this subject but find different part no. etc. I am looking for OEM replacement for 1967 427 400HP. The following no. have been given Crane 969391, Crane 968711, Crane grind No. 3883986, and GM# 12364055. The orig. cam in the engine, replaced 30 yrs. ago, had no grove in the rear journal but present cam(3883986) has grove. Is there a definative answer on what cam is OEM and where to buy it. I know Crane is back, but I can't find a web site or phone No. Any help would be appreciated.
CORDially Mike

Mike------


The cam originally used in your engine was GM #3904359. This is the cam used for all 1967-69 L-36 and L-68. It was also used for 1970-72 LS-5. It is the same as the GM #3883986 EXCEPT it does not have a grooved rear journal.

The GM #3883986 was the cam which GM sold in SERVICE for all 66-69 L-36 and 70-72 LS-5. In PRODUCTION, though, it was used only for the 1966 L-36; the 3904359 was used for all the rest.

GM NEVER cataloged the 3904359 for any of the above-referenced applications but it was once available in SERVICE nonetheless.

Strange thing about this: the 3883986 was available in SERVICE from late 1965 until it was discontinued without supercession in August 1999.

The GM #3904359 became available about the time the 3883986 was discontinued but was never shown as supercessive to it. So, it was nowhere cataloged and, therefore, there was virtually no way anyone could have found out about it or know it was available. I found out about it by accident. Even more strange: I ordered, successively, about 5 of these cams [none for sale] and most of them came in tubes with GM parts labels from the early 70's period! I posted photos of one recently in another thread.

[Duke W.]

Re: 1967 427 400HP cam

I have read the past posts done in 2008 on this subject but find different part no. etc. I am looking for OEM replacement for 1967 427 400HP. The following no. have been given Crane 969391, Crane 968711, Crane grind No. 3883986, and GM# 12364055. The orig. cam in the engine, replaced 30 yrs. ago, had no grove in the rear journal but present cam(3883986) has grove. Is there a definative answer on what cam is OEM and where to buy it. I know Crane is back, but I can't find a web site or phone No. Any help would be appreciated.
CORDially Mike

It goes like this. The original 390/400 HP cam/pin assembly used for '67-'72 Corvette hydraulic lifter big blocks is 3904359. The '66 390 HP cam/pin assy. is 3883986. The ...986 assy. has a groove in the rear journal, which, along with the "three hole" rear cam bearing is required for early big blocks through 1966. Other than not having the groove, the ...359 is identical - same lobes and lobe indexing.

Now follow closely. The ...359 was never listed in the parts books. The ...386 is listed as the replacement through '72. (The '73-'74 Corvette BB cam used different lobes/indexing, but that's a whole other story.) That's because it's okay to use either a grooved or non-grooved cam in a '67 up casting, but earlier castings require a grooved cam.

So GM decided to offer only the grooved cam as a service replacement since it is okay from an engineering standpoint to use it for all Mark IV blocks.

Now along comes Federal Mogul, which acquires the rights to make an exact OE replacement of the GM design. Since most big blocks don't need a grooved cam, their version has no groove, but they cross reference it to the ...386, which is the only number published in the GM service parts catalog. Technically they should have crossed it to the ...359, but nobody knew what that was because it was only used by Tonawanda and never made the service parts catalog, although you could order it for a time, IF you knew the number.

So the FM CS1093M is an exact replacement for the ...359. If one installs this cam in a pre-'67 block, it will need to have the groove machined in the rear journal, or the lifters/rocker boxes will be oil starved.

In past years Crane made an exact replacement for the ...359 that was sold by GM as a "kit" of cam and a set of lifters, and Crane also sold it under their own part number. Even though the "grind number" is the same as the early grooved cam, I don't think the Crane ground cam has a groove - same as the Federal Mogul deal.

Both GM and Crane have been through bankruptcy in the last year, so things are a bit disorganized. Crane is grinding automotive camshafts now under new ownership (I started a thread on the subject a couple of weeks ago- use the search function), and essentially all of their old design library is available, but I don't know if they have any inventory.

The simplest thing to do is to order from NAPA online or from your local NAPA store a Sealed Power CS1093M. The specs at the NAPA web site are identical to the original GM specs, and it likely has no groove, which is okay for your engine. If it has a groove, that's okay, too.

The same deal applies to the SHP mechanical lifter cam. The Sealed Power/Speedo Pro CS165R is an exact duplicate of the non grooved 3904362, which was never listed in the GM parts books. The only listing was the grooved 3863143. So the CS165R must have the rear journal grooved for use in '65-'66 SHP engines and can be used as is for '67-69 SHP 427s and the later LS-6 engline.

Duke

[Mike 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

[Joe L.]

Re: 1967 427 400HP cam

It goes like this. The original 390/400 HP cam/pin assembly used for '67-'72 Corvette hydraulic lifter big blocks is 3904359. The '66 390 HP cam/pin assy. is 3883986. The ...986 assy. has a groove in the rear journal, which, along with the "three hole" rear cam bearing is required for early big blocks through 1966. Other than not having the groove, the ...359 is identical - same lobes and lobe indexing.

Now follow closely. The ...359 was never listed in the parts books. The ...386 is listed as the replacement through '72. (The '73-'74 Corvette BB cam used different lobes/indexing, but that's a whole other story.) That's because it's okay to use either a grooved or non-grooved cam in a '67 up casting, but earlier castings require a grooved cam.

So GM decided to offer only the grooved cam as a service replacement since it is okay from an engineering standpoint to use it for all Mark IV blocks.

Now along comes Federal Mogul, which acquires the rights to make an exact OE replacement of the GM design. Since most big blocks don't need a grooved cam, their version has no groove, but they cross reference it to the ...386, which is the only number published in the GM service parts catalog. Technically they should have crossed it to the ...359, but nobody knew what that was because it was only used by Tonawanda and never made the service parts catalog, although you could order it for a time, IF you knew the number.

So the FM CS1093M is an exact replacement for the ...359. If one installs this cam in a pre-'67 block, it will need to have the groove machined in the rear journal, or the lifters/rocker boxes will be oil starved.

In past years Crane made an exact replacement for the ...359 that was sold by GM as a "kit" of cam and a set of lifters, and Crane also sold it under their own part number. Even though the "grind number" is the same as the early grooved cam, I don't think the Crane ground cam has a groove - same as the Federal Mogul deal.

Both GM and Crane have been through bankruptcy in the last year, so things are a bit disorganized. Crane is grinding automotive camshafts now under new ownership (I started a thread on the subject a couple of weeks ago- use the search function), and essentially all of their old design library is available, but I don't know if they have any inventory.

The simplest thing to do is to order from NAPA online or from your local NAPA store a Sealed Power CS1093M. The specs at the NAPA web site are identical to the original GM specs, and it likely has no groove, which is okay for your engine. If it has a groove, that's okay, too.

The same deal applies to the SHP mechanical lifter cam. The Sealed Power/Speedo Pro CS165R is an exact duplicate of the non grooved 3904362, which was never listed in the GM parts books. The only listing was the grooved 3863143. So the CS165R must have the rear journal grooved for use in '65-'66 SHP engines and can be used as is for '67-69 SHP 427s and the later LS-6 engline.

Duke

Duke------


The non-grooved version of the GM #3863143 was GM #3904362. It was once cataloged and available in SERVICE. In fact, it replaced the 3863143 in February, 1988 and was discontinued without supercession in February, 2000.

Of course, while it became available in SERVICE in 1988, it was used in PRODUCTION for 67-71 SHP big block applications, Corvette and otherwise.

I'm not so sure about the grooved rear journal cams being directly usable for 1967+ applications. The GM-sourced recommendation I've seen says that when a grooved rear journal cam is used for a 1967+ application, the oil hole in the rear cam bearing should be soldered closed and re-drilled at 0.060". Personally, I would greatly prefer not to have to make this modification to a camshaft rear bearing.

[Clem Z.]

Re: 1967 427 400HP cam

Duke------


The non-grooved version of the GM #3863143 was GM #3904362. It was once cataloged and available in SERVICE. In fact, it replaced the 3863143 in February, 1988 and was discontinued without supercession in February, 2000.

Of course, while it became available in SERVICE in 1988, it was used in PRODUCTION for 67-71 SHP big block applications, Corvette and otherwise.

I'm not so sure about the grooved rear journal cams being directly usable for 1967+ applications. The GM-sourced recommendation I've seen says that when a grooved rear journal cam is used for a 1967+ application, the oil hole in the rear cam bearing should be soldered closed and re-drilled at 0.060". Personally, I would greatly prefer not to have to make this modification to a camshaft rear bearing.

if you don't do the rear cam bearing mod you will have a big internal oil leak because of the clearance between the cam bearing journal and the bearing. use a countersink on the cam bearing hole to give a larger surface for the solder to bind to and you will have no problems. just don't drill the solder drill the .060 hole in the solid part of the bearing

[Duke W.]

Re: 1967 427 400HP cam

Yes, I remember you telling the story of the non-grooved ...359 and ...362 cams, but forgot that you stated they actually did show up in the parts books - nearly 15 years after the last big block was installed in a Corvette!!!

The Chev. Power Manual cautions about using a grooved cam in a '67-up block including reducing the bearing oil hole size, but in thread a couple of years ago someone posted a letter or other document from GM that rescinded this caution/modification, making it perfectly okay to use a grooved cam in the '67-up block, but subsequent versions of the Power Manual were never updated.

It's a somewhat moot point now since I am fairly certain that both the F-M and Crane manufactured OE replacements of these two big block cams don't have grooved rear journals.

The guys that have gotten screwed are the '65-'66 BB owners who had non-grooved cams and/or the single hole rear cam bearings installed in their blocks by machine shops that don't understand the unique requirements of the early big block configuration.

Duke

[Duke W.]

Re: 1967 427 400HP cam

if you don't do the rear cam bearing mod you will have a big internal oil leak because of the clearance between the cam bearing journal and the bearing. use a countersink on the cam bearing hole to give a larger surface for the solder to bind to and you will have no problems. just don't drill the solder drill the .060 hole in the solid part of the bearing

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?

Duke

[Mike H.]

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

[Mike H.]

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