Installing new camshaft 427 425hp tips

[Jerry N.]

The previous owner of my 1966 427 425 had the engine rebuilt and a hydraulic cam put in so he would not have to adjust the valves. I want to put the original style mechanical cam back in and want any tips as to the best part numbers, do I replace the rocker arms, the springs, pushrods, etc. Also what is best to remove for access, such as the grille and do I have to lift the motor. I also need help on getting the correct grooved or drilled rear cam bearing for correct oiling. Some posts suggest taking it to a machine shop. I have read the archived posts, but would really appreciate the best part numbers and pitfalls such as the correct oiling groove or bearing and the best breakin oil and proceedure. The archives were helpful, but some members advise conflicted with others.
Thanks for your help, Jerry Nutt

[Lynn H.]

Re: Installing new camshaft 427 425hp tips

Jerry-
If you have or have access to Volume 22, No-4 (spring '96) of "The Corvette Restorer" magazine, there is an excellent article entitled "More Power Tuning Tips on the "427" ", in there concerning the different BB cams, by Ken Anderson. Includes factory part numbers, as well as specifications. In this same issue is an article by Rolf Krueger entitled "Big Block Engine Camshaft Utilization" that may be of interest and helpful to you also. It goes into the utilization and interchangeability of the grooved and ungrooved camshafts.
Lynn

[John H.]

Re: Installing new camshaft 427 425hp tips

I also need help on getting the correct grooved or drilled rear cam bearing for correct oiling.

Jerry -

You must have the groove in the rear cam journal, and you must also have the correct 3-hole grooved rear cam bearing in order to get oil to the lifters; no options.

[Timothy B.]

Re: Installing new camshaft 427 425hp tips

John,

Are the oil holes in the engine block larger so the bearing is easier to line up when installing?

[Joe R.]

Re: Installing new camshaft 427 425hp tips

Jerry,

I'm going off pure memory here, which is always suspect, but I believe the GM part number for the cam is 3863143. Its equivalent is made by Speed Pro (part number KC-165R) and can be obtained at NAPA, CarQuest or even Summit Racing. There is also a cam and lifters kit, but I don't remember the part number offhand. I would recommend the kit.

As far as the valve springs go, the first design is prone to breakage and should be avoided at all costs. The one to use is the GM # 3970627, available in kit form, too. It's available only from GM as far as I know and can be purchased as a set.

Search the archives using the GM part numbers for more info.

There is a video that you may find helpful. It's called "How to build big block Chevys like a pro."

Let me know if you need more info, I'm a bit pressed for time today.

Joe

[Joe R.]

Re: Installing new camshaft 427 425hp tips

The previous owner of my 1966 427 425 had the engine rebuilt and a hydraulic cam put in so he would not have to adjust the valves. I want to put the original style mechanical cam back in and want any tips as to the best part numbers, do I replace the rocker arms, the springs, pushrods, etc. Also what is best to remove for access, such as the grille and do I have to lift the motor. I also need help on getting the correct grooved or drilled rear cam bearing for correct oiling. Some posts suggest taking it to a machine shop. I have read the archived posts, but would really appreciate the best part numbers and pitfalls such as the correct oiling groove or bearing and the best breakin oil and proceedure. The archives were helpful, but some members advise conflicted with others.
Thanks for your help, Jerry Nutt

Jerry,

How many miles are on the engine since the rebuild?

Check out this thread, it answers a lot of your questions!

https://www.forums.ncrs.org/showthread.php?t=74135&referrerid=2667&uid=9559

This one has some answers, too:

https://www.forums.ncrs.org/showthread.php?t=66913&uid=4620

I'm planning to replace the entire valvetrain. Maybe the rocker arms could be recycled, but I'm not willing to take a chance. One of my pushrods shattered, so obviously I cain't reuse them.

If you leave the engine in the car, I'm pretty sure you have to pull the radiator. My engine is out of the car already, making the job easier. Do you have a Corvette Shop Manual (CSM)? I would recommend looking it over. I don't know of a reason why the engine would need to be tilted.

As far as the groove in the rear of the cam goes, I plan to have a machinist do it to my Federal-Mogul cam. If you're up to the task, more power to you!

Joe

[Mike Z.]

Re: Installing new camshaft 427 425hp tips

Great pics of an original type cam and one version of the alternative rear cam bearing. TRW and probably others also have a version of the bearing that has the groove on the back side of the bearing (what I used in mine), both versions allow the use of a non-grooved cam, which is about all that is available from Crane, etc. and the serv repl version is likewise not grooved.
Jerry, what you may decide to do before having a cam grooved: pull your present cam out and see if it is grooved or not. If not, one would have to assume they also changed out the rear cam bearing (or you would have a melted motor by now) and a new mechanical non-grooved cam is good to go. If that is the case, once you remove the hood and everything in front of the engine, the cam can be R&R'd with the motor in place. You may want to buy one correct valve spring and push rods to compare to what is installed in the motor, as recommended parts for a hydro stick would be different, but who knows if they changed out or not. If the present cam is grooved, but you would like to not run a grooved cam, the rear cam bearing can not be (at least not easily) changed out while the engine is in the car. Good Luck!
Mike Zamora
#12455

[Joe R.]

Re: Installing new camshaft 427 425hp tips

Mike,

Are you sure about using a non-grooved cam in a 65 or 66 BB? I'm no expert and I don't mean to insult you, but I have seen it repeatedly said on here that you must have the groove for a 65 or 66 - no exceptions.

Joe

[Clem Z.]

Re: Installing new camshaft 427 425hp tips

Mike,

Are you sure about using a non-grooved cam in a 65 or 66 BB? I'm no expert and I don't mean to insult you, but I have seen it repeatedly said on here that you must have the groove for a 65 or 66 - no exceptions.

Joe

i never saw a rear cam bearing that was grooved on the outside diameter that allowed you to use a non grooved cam in a 65/66 BBC but i have been out of the engine building business for 15 years

[Mike Z.]

Re: Installing new camshaft 427 425hp tips

Joe-
I have built a couple of 65-66 BB and just checked my receipts for my last 425HP I built about four years ago, then called the machine ship I bought the cam bearings from and they installed: Durabond brand (probably other have an equivilent) P/N CH 9 H (still available for about $38.00 dealer price for the set); the rear bearing has the groove on the backside, so oil is allowed a path to travel vs. a groove on the cam (and no groove front or back on the original bearing) to the oil galleys. Works great and no oiling problems-I melted down one motor before I learned about this alternative. Hope this helps, good luck on your cam change out.
Mike Zamora
#12455

[Duke W.]

Re: Installing new camshaft 427 425hp tips

Grooving the backside of the bearing likely yields a much smaller flow area than the combination of the grooved cam and bearing or the machined groove in the block on '67-up blocks.

This will likely reduce overhead oiling, which is critical for both valvetrain lubrication and valve cooling if the engine is run at sustained high revs.

As long as the correct '65-'66 "three hole" rear cam bearing is available I recommend using it along with a grooved rear journal on the cam.

A note on the finished drawing of the grooved cam says the blank for the non-grooved cam can be used to make a grooved cam with the extra machining to form the groove

The early grooved cam blank had the groove in the casting and only required finish machining, which may have only included a chamfer at the top.

Any competent machine shop should be able to measure and duplicate the groove from the removed cam and machine the groove on a lathe including any radius at the bottom corners of the groove chamfers at the top.


Duke

[Clem Z.]

Re: Installing new camshaft 427 425hp tips

Grooving the backside of the bearing likely yields a much smaller flow area than the combination of the grooved cam and bearing or the machined groove in the block on '67-up blocks.

This will likely reduce overhead oiling, which is critical for both valvetrain lubrication and valve cooling if the engine is run at sustained high revs.

As long as the correct '65-'66 "three hole" rear cam bearing is available I recommend using it along with a grooved rear journal on the cam.

A note on the finished drawing of the grooved cam says the blank for the non-grooved cam can be used to make a grooved cam with the extra machining to form the groove

The early grooved cam blank had the groove in the casting and only required finish machining, which may have only included a chamfer at the top.

Any competent machine shop should be able to measure and duplicate the groove from the removed cam and machine the groove on a lathe including any radius at the bottom corners of the groove chamfers at the top.


Duke

the groove is 3/16" wide and 3/16" deep