Camshaft oil groove

[gary mancuso]

Good morning all,

I intend to replace the camshaft in my 67 427/435 with an Elgin cam (can't beat the prices listed in the Competition Product catalog, www.competitionproducts.com)however the technical service rep. informed me that on this particular camshaft the back bearing surface does not have the necessary oil groove. He sugested I either groove it myself (doesn't have to be that accurate as long as no burrs remain) or use a bearing set thatcomes with the rear bearing face grooved. The bearing choice appears to be less problematic. Anybody experience this situation before? I'd appreciate hearing about the outcome.

Thanks,
Gary

[G B.]

Odd advice

If the technical service rep is talking about the '65-only oil groove in the rear cam journal, then I think he is full of beans.

The '67 427 block had a groove machined behind the rear cam bearing to distribute oil to the lifters. If you use a cam or bearing with a groove in a post-'65 big block, it will reduce the flow of oil to the valve train to the point of burning rocker balls and scoring valve guides.

Frankly, I wouldn't put any budget cam in any engine. I think they sometimes have poor quality steel and machining. The small amount you save on the cam purchase just doesn't seem worth the risk to me.

[gary mancuso]

Re: Odd advice

Jerry,

Are you saying the engine in question doesa not require this groove? The cam I'm replacing is an Isky that has the groove. Perhaps that why I've noticed valve train wear. I understand that Elgin cams have been around forever and have a good reputation.

[G B.]

Re: Odd advice

That is exactly what I'm saying.

Many service replacement cams have the '65-only groove in the rear journal. During the seventies, some GM over the counter cams even had it. Please trust me on this: it is a disaster waiting to happen to use such a cam in a '67 427 block.

I'll probably get a bunch of flak from the GM-Engineering-Was-Perfect Club on this next rant. I am also convinced that big blocks had inadequate valve train oiling from the factory for decades. Even with the right cam, the stock '67 427 oil pump doesn't get enough oil to the rockers. They finally addressed the problem around 1990 when they went to the oil pump with 1.3" tall gears. Yes, yes, I know many of you ran your 427's at 9,000 rpm for hours without any wear at all during the sixties. I must have just repaired a string of lemons.

And some day, perhaps during this century, GM will stop selling those commie plastic coated timing gears. Ever try to find all the ground up plastic pieces distributed by the oil in an old big block?

[John L.]

Re: Odd advice

Jerry

Doesnt the 66 427 also require the grooved cam ????

john lolli

[Clem Z.]

Re: Camshaft oil groove

only the 65 and 66 BBC need the groved rear cam journal. if you use a grooved cam in a later block you have a big oil loss internally and this could could cause you valvetrain wear because not enought oil is getting to the parts. i have never use a elgin cam but they have been around for years. i have used parts from competion products without any problems.

[G B.]

I think so.

I've read that some '66 big blocks require grooved cams, but I've never personally encountered one.

[Clem Z.]

Re: I think so.

jerry both 65 and 66 need grooved cams and if you use a grooved cam in a 67 and up BBC you need to solder shut the oil hole in the cam bearing from the mains to the cam journal and redrill it to .062(1/16") to limit the oil that gets to the groove. blocks # 3855962,3855961 need the grooved cam.

[gary mancuso]

Re: Camshaft oil groove

As the famous college motivational speaker and TV basketball analyst Dick Vitale would say, you guys are "awesome baby!"

[Joe L.]

Re: Odd advice

Jerry------

The high volume Chevrolet big block oil pump (1.30" long "gears") was around a long time before 1990. It was first used in PRODUCTION for 1969 ZL-1's and it's been available in SERVICE ever since under GM #3969870. However, the first use of a high volume oil pump in PRODUCTION since the ZL-1 was for the Mark V big block engines which were released in 1991.

[Terry M.]

Re: Camshaft oil groove *TL*

I just had a local shop ask me this same question - so I'll turn to all you for answers. The only Corvette related item is that the first case is a 1967 Corvette.

Case 1: 454 crate motor. I'm not sure what generation it is, but the casting number is a short number that begins with 140..... Date is C 8 9. Engine had a cam with rear grove, but was too aggressive for the owner (gasket evidence indicates it was not the original cam), so shop replaced the cam with one with no rear grove. They went to a lot of trouble to get a cam and lifters from Chevrolet for the crate application. Less than 100 miles later three lobes on the rear of the cam (all with lifters on the right side) are trashed and so is the center two cam bearings.

Case 2: 1972 Chevelle 454 original cylinder case. Car was stored for 17 years, but engine had been apart in previous ownership. Crane cam was in here with grove in the back, and had some lobe damage. Replaced with cam with no grove. Poor oiling to valve train now.

Could both cars have had rear bearing with oil hole closed up? Sounds like too much coincidence to me. Your opinions?
Terry

[Clem Z.]

Re: Camshaft oil groove

my guess that the rear cam bearing has the small hole drilled in it and not allowing enought oil thru to the valve train. GM sent out crate engines with grooved cams in later blocks and i bet they had the reduces oil hole size.

[roy braatz]

Re:what about a 265 cam`

I can't tell you how many 55 and early 56 265 engine corvettes and car owners pulled thier hair out after a machine shop rebuilt thier engine ,not knowing that the cam had a grove cut out at the back area. The shop eather placed the cam bearing ( having one hole) in wrong ( not UP)or used a newer today cam with out the cut that only the early 265 had.1. Cam bearing hole off ( no oil), 2. cam not cut (no oil on the left side (lifters).Any one knowing some one is rebuilding a 265 engine please advise them.

[Mike McKown]

Re:what about a 265 cam`

Hey Roy!

You gotta' be older than dirt (or me) to know about that! Good post for some of the youngsters!

Mike

[Clem Z.]

Re:what about a 265 cam`

you would think that GM would learn from that 1955 deal but they did the exact same thing on the BBC in 1965