looking for opinion

[David J.]

I am about to disassemble my 1966 BB 425 horse short block and check every thing out. My question is has any body re-used the solid lifter cam. I am of the belief that if the lobes look good that mybe a new set of lifters will be all it needs. Any body have any experience with this situation and what was the out come? The motor I am working on was replaced with about 45k on it. The motor dropped a valve and was shut off right away. The original owner replaced the short block but I do not know why yet.

[Joe L.]

Re: looking for opinion

I am about to disassemble my 1966 BB 425 horse short block and check every thing out. My question is has any body re-used the solid lifter cam. I am of the belief that if the lobes look good that mybe a new set of lifters will be all it needs. Any body have any experience with this situation and what was the out come? The motor I am working on was replaced with about 45k on it. The motor dropped a valve and was shut off right away. The original owner replaced the short block but I do not know why yet.

David-----


Personally, I'd be VERY reluctant to re-use the camshaft. If I did, I'd want to re-use it with the existing lifters on the same lobe of the cam that they previously "lived with". If the cam is ok for re-use, the lifters ought to be, too.

While the cam might look OK when you take it out, that doesn't necessarily tell you what it's going to look like 1 hour after running with a new set of lifters.

[Joseph M.]

Re: looking for opinion

Relatively cheap insurance to replace the cam. Why risk problems after all the work involved in disassembly and reassembly.

[Joe R.]

Re: looking for opinion

David,

If you do get a new cam, make sure it has the rear groove added. That and a three hole rear cam bearing is required for 65-66 big blocks. Otherwise the top end doesn't get enough oil. You can get the cam from NAPA. Let me know if you need the part number. Also, make sure you get the second design valve spring, the first design is prone to breakage. I can get the part number for that too. I got mine from my friendly neighborhood Chevy dealer. As you might have guessed, I'm rebuilding a L-72 right now.

Joe

[David J.]

Re: looking for opinion

David-----


Personally, I'd be VERY reluctant to re-use the camshaft. If I did, I'd want to re-use it with the existing lifters on the same lobe of the cam that they previously "lived with". If the cam is ok for re-use, the lifters ought to be, too.

While the cam might look OK when you take it out, that doesn't necessarily tell you what it's going to look like 1 hour after running with a new set of lifters.

Thanks you Joe for the imput.

[David J.]

Re: looking for opinion

Relatively cheap insurance to replace the cam. Why risk problems after all the work involved in disassembly and reassembly.

I was thinking of using the original if in good condition only to keep the car as original as possible. Thanks for your imput.

[David J.]

Re: looking for opinion

David,

If you do get a new cam, make sure it has the rear groove added. That and a three hole rear cam bearing is required for 65-66 big blocks. Otherwise the top end doesn't get enough oil. You can get the cam from NAPA. Let me know if you need the part number. Also, make sure you get the second design valve spring, the first design is prone to breakage. I can get the part number for that too. I got mine from my friendly neighborhood Chevy dealer. As you might have guessed, I'm rebuilding a L-72 right now.

Joe

Joe, are the specs for the cam the same as original ?

[Michael H.]

Re: looking for opinion

David,

If you do get a new cam, make sure it has the rear groove added. That and a three hole rear cam bearing is required for 65-66 big blocks. Otherwise the top end doesn't get enough oil. You can get the cam from NAPA. Let me know if you need the part number. Also, make sure you get the second design valve spring, the first design is prone to breakage. I can get the part number for that too. I got mine from my friendly neighborhood Chevy dealer. As you might have guessed, I'm rebuilding a L-72 right now.

Joe

I absolutely agree with Joe's recommendation on the valve springs. Don't even consider reusing the old design single fat wire springs. They are responsible for a LOT of completely destroyed early big blocks and likely the same thing that caused the broken valve in your engine. I think the part number for the new spring is 3970627, right from a Chev dealer.
I installed a set in my 66 26 years and probably 40,000 miles ago without problems.

I also agree on the possible use of the original cam. If the lifters show no signs of damage/wear and the cam lobes look good and check out dimensionally, you may be ok with it.
As previously recommended, keep the lifters in order if you plan to reuse them.

[Joe L.]

Re: looking for opinion

Joe, are the specs for the cam the same as original ?

David-----


Yes, the cam manufactured by Federal-Mogul (probably the one that NAPA sells) and others is identical in specs to the GM original.

You can purchase the improved valve springs as a set under GM #12371061. This kit contains 16 of the GM #3970627 springs. Don't even think about re-using your originals.

[Kenny C.]

Re: looking for opinion

I would spend the reasonably small amount of money to replace the cam. I have reused cams in my younger broker days but that's only due to no choice. As for keeping it original who cares on a internal part as long as its specks are close? A big reason not to re use it is lets just say it looks okay how do you know how good or how much of the hardened surface is left? Back in 78 or so I had a Buick regal with a 305 and after 40k miles the cam went flat, as it turned out the factory had installed a large amount of cams that were not heat treated. They had to do a massive recall and replace cams. So you tell me if the factory couldn't tell the new shafts were soft how can you? All that being said if you insist on re using the cam be absolutely certain you label each tappet and install back on the same lobe or it will eat itself up along with the cam. Remember shinny don't mean good!
Kenny

[Steven B.]

Re: looking for opinion

As Joe and Michael recommend. If your replace the cam also do the lifters, springs, etc. Cam lobes and their respective lifters each wear a unique pattern and mixing new with old causes a new wear problem.

I did two engines some time back and I bought new cam, lifters, springs, studs, pushrods, valves, fasteners. No need to worry or tear down again.

Steve

[Joe R.]

Re: looking for opinion

David,

Yes, the specs for the Federal-Mogul (Sealed Power) cam are the same as the original (GM 3863143). The cam and lifter kit is Sealed Power part number KC-165R. I got it from NAPA for $175.00. You can take originality too far. A judge will never know the cam is not original. A new one seems like cheap insurance to me. Also, make sure you use CI-4 (or CJ-4) oil. I plan to use a can of GM Engine Oil Supplement (EOS) GM part number 88862586 with my new cam during cam break in. After that I will just use CI-4 oil. Have you read the Duke Williams oil article? I can send you a link to that.

Don't let the machinist deck the right side of the block. That'll wipe out your numbers and broach marks. Measure the deck clearance before tear down. Do you know if the engine detonated? Manage the compression ratio to avoid detonation while not throwing away power.

My machinist installed a Sealed Power engine kit P/N 22248800MK. You may want to consider upgraded connecting rods for durability reasons. Do a search on Crower Sportsman for some thoughts on this.

I attached two documents. The first one shows some parts I ordered with part numbers and other info. The second one is a conglomeration of knowledge pulled from this board. It's disorganized, but has a lotta good stuff in there.

Joe

[David J.]

Re: looking for opinion

Thank you all for your information and ideas. I will follow your recommendations because I really do not want to have any problems once I have put the engine together. Thanks again!