1966 427 425HP Valve Clearances

[Duke W.]

Re: 1966 427 425HP Valve Clearances

I don't think a mechanical roller cam is a good idea. Most are considered "racing cams" and the mechanical rollers often have limited life before they disintegrate. A hydraulic roller would be a better idea, but it's tough to "match" any roller cam with a flat tappet cam due the differences in dynamics and lift.

With proper installation (lobes/lifters liberally coated with "assembly lube") CK-4 oil, a pint of EOS and a proper break-in (start the engine as quickly as possible an run it at 2000-2500 for 20-30 minutes) a flat tappet cam should have long life.

One issue is valve springs... the '69 second design dual spring with integral retainer and umbrella seal are no longer available from GM, and there are no know aftermarket exact duplicates, but Joe had identified a spring of nearly equal specs, but it will require a separate retainer and seal system.

Duke

[Jack C.]

Re: 1966 427 425HP Valve Clearances

As I mentioned, a solid roller cam was a consideration, and I appreciate your input. The cam in it may actually be good, showing 66K miles. The "story" is the engine was not running properly, the prior owner took it apart then determined the only issue was the quality of the gas, so he reassembled it and believed it was in good shape.....over 40 years ago. So, of course it is coming apart to check everything.

I'm glad you mentioned the valve springs. I'll look up Joe's input on this and I have a local friend who is as much an "expert" on 427 engines that I have known. I'll run the valve spring issue by him and revisit this post with anything i can add. I'm sure he's done enough engines to be aware of this issue and I'm curious now what his fix is. I'm still disassembling. From the unbelievable gunk build up under the thermostat I can assure you if you had any doubt it is not in running shape. Thanks again.

[Chris H.]

Re: 1966 427 425HP Valve Clearances

I had the same valve spring dilemma with my ‘69 L71: what do when replacing the original valve springs. I wound up using Crane Cams stock/street valve spring/retainer package. I have since acquired 16 of the special dual spring retainers needed for the service replacement dual spring and will be installed over the winter when I have the heads rebuilt.

[Duke W.]

Re: 1966 427 425HP Valve Clearances

The cam in it may actually be good, showing 66K miles.

When I rebuilt my SWC's 327/340 back in the seventies at 115K miles, the only wear I could measure was the bores. Two had five thou taper and the rest were three thou, and I attributed that to the lousy foam air filter. #7 rod had a crack across a bolt seat, so I replaced all with the second design, and "race prepped" them - Magnaflux, grinding down the die flash, lightening, shotpeen, and high strength bolts. The oil pump was "like new" so I just did a little surfacing on one gear and the housing to minimize gear end clearance. The OE bearings were also literally like new, but since I had to remove them, they had to be replaced in order to have proper crush on installation, and I used the same OE Morraine 400 aluminum bearings.

The Duntov cam was still within OE spec and could have been reused, but I wanted a LT-1 cam. There's no reason why a cam/lifters with no wear can't be reused, especially on a collector car that will see low mileage accumulation over time, but you need to carefully ID the lifters to make sure each goes back on the same lobe. Similarly, all pushrods/rockers/balls should be maintained as a matched set, but they don't have to go back to the same position. I installed new second design, '67-up 3911068 valve springs.

If you want "more power" massage the cylinder heads.

I don't remember the total cost, but I know it was less that what guys were spending to rebuild disk brake systems back then. It was certainly labor intensive with all the rod and head massaging, but that was a labor of love.

Duke

[Jack C.]

Re: 1966 427 425HP Valve Clearances

Chris, I spoke to my knowledgeable friend last night and he is of course aware of the spring issue and has identified a replacement style he likes and had had success with. Again, I'll post what that is when I have more specifics. Just to ensure I understand what you are doing, are the service replacement springs readily available but it is the special dual spring retainers you found that are unobtanium? Apparently you believe the service replacement dual spring is superior to your current Crane Cams stock/street valve spring/retainer package? Thanks for your input.

[Jack C.]

Re: 1966 427 425HP Valve Clearances

I've actually had my SWC with 327/340 since the 70s as well. I have driven it a lot, actually used to drive it to work before restoring it and I have done the heads but believe it or not I have never had the cam out or the bottom end apart. It runs great and typically only goes to cruise night or local show functions now so I don't believe I'll be redoing it anytime soon. I'll have to check my receipts for my 70 LT-1 but I believe I used the Federal-Mogul comparable solid lifter LT-1 replacement cam and lifters, but might have been Crane Cams. That car had been worked on and apart in a barn for 26 years before I got it and it even had the wrong cam in it so nothing was salvageable.

The concerns with my L72 are the unknowns. As I mentioned, I know it has been apart and put back together, and I know the seller was completely wrong in his assertion that it should be ready to run (albeit it's been sitting for decades). What I don't know is....did he get the lifters back in the same holes??

Just a month or so ago a friend of a friend found a set of NOS lifters for his L78. Apparently rare as chicken lips and he paid all the $$ for them and was glad to find them. Was this really a big deal over what Federal Mogul supplies to match their CS-165R? I don't know.

As for "more power" I want it to perform as designed with the best longevity I can put into it so the heads will be done but no massaging is in the plan. Just trying to preserve this piece of automotive history and have it perform as it did back in its heyday. Still disassembling, bagging and tagging and I'll be measuring tolerances soon.

Jack

[Chris H.]

Re: 1966 427 425HP Valve Clearances

Hello Jack, I don't know if I'd say the Crane Came spring / retainer is superior, it was just what I found that would fit my needs. Here's an exhaustive thread on this subject.

https://www.forums.ncrs.org/showthre...ghlight=hewitt

[Joe L.]

Re: 1966 427 425HP Valve Clearances

Just a month or so ago a friend of a friend found a set of NOS lifters for his L78. Apparently rare as chicken lips and he paid all the $$ for them and was glad to find them. Was this really a big deal over what Federal Mogul supplies to match their CS-165R? I don't know.


Jack

Jack-----

Regarding the 1965 L-78 valve lifters, if your friend is talking about the original 1965-66 GM #5232439, yes they are very hard to find---probably about impossible for a set of 16. These were discontinued and replaced in April, 1967 by the 1967-69 GM #5232550. A set of these would be hard to find, too.

However, the 5232550 was discontinued in November, 1969 and replaced by the GM #5232695. The latter was available for 30 years until finally being discontinued without supercession in July, 1999. These are the easiest to find and, albeit expensive, can usually be obtained. By the way, all of the aforementioned lifters were piddle valve type.

GM lifters were once manufactured internally by GM's AC Division. I've always considered the GM lifters, be they mechanical or hydraulic, to be the best. However, if I were using mechanical flat tappet GM lifters in an engine (which I would not because hydraulic roller lifters have made them obsolete), I would only use the 5232695 even if I had the others. Why? You don't think that GM discontinued both the 5232439 and 5232550 in favor of the 5232695 because the others were just as good, do you? Plus, once installed in the engine, who could discern the difference?

[Jack C.]

Re: 1966 427 425HP Valve Clearances

Duke - We're now 10 months out and I'm having to revisit this issue. A LOT of repair has gone into this car that is unrelated to this issue which is why I'm just getting back to this but here's the bottom line. I went with the Comp Cams Factory Muscle 242/242 Solid Flat Cam Sku 11-106-3. For specs it is the same as the CS-165R. I went with Comp Cams because I have a 66 and buying direct from Comp they were able to deliver with the necessary oiling groove, and I stayed with one supplier for cam, lifters, valve springs and rockers. The bad news is the cam went bad on initial break-in. I have not assessed full damage to other engine parts yet but even if Comp would replace this cam I do not want another. I would like to know if anyone knows a direct source for the Sealed Power CS-165R where I could get one with the rear journal oiling grove?

[Joe L.]

Re: 1966 427 425HP Valve Clearances

Duke - We're now 10 months out and I'm having to revisit this issue. A LOT of repair has gone into this car that is unrelated to this issue which is why I'm just getting back to this but here's the bottom line. I went with the Comp Cams Factory Muscle 242/242 Solid Flat Cam Sku 11-106-3. For specs it is the same as the CS-165R. I went with Comp Cams because I have a 66 and buying direct from Comp they were able to deliver with the necessary oiling groove, and I stayed with one supplier for cam, lifters, valve springs and rockers. The bad news is the cam went bad on initial break-in. I have not assessed full damage to other engine parts yet but even if Comp would replace this cam I do not want another. I would like to know if anyone knows a direct source for the Sealed Power CS-165R where I could get one with the rear journal oiling grove?

Jack------


I do not know of any source that could provide a CS-165R with rear oiling groove "out of the box". However, any machine shop should be able to cut this groove with no problem, at all.

By the way, your experience with the cam you obtained is one of the reasons that I would no longer build an engine with ANY flat tappet camshaft. I didn't like flat tappet cams 50 years ago when they were pretty much "the only game in town" for street applications. I like them a lot less now.

[Duke W.]

Re: 1966 427 425HP Valve Clearances

Sorry to here of your situation, Jack. I've been advising AGAINST buying anything from Comp Cams for years because there are just too many reports of early failures of their products. My first choice for camshafts is Federal Mogul, but it appears that many vintage parts are being discontinued from F-M. Crane is my second choice. Both F-M and Crane cams are Parkerized as were OE cams, and this process aids break-in and long life.

A Parkerized cam has a mottled gray surface finish except for the journal because it is polished off, so they are easy to identify. I don't think Comp Parkerizes cams, though it may be "optional".

The other issue with big blocks is valve springs. The second design dual spring with integral retainer and oil seal that went into production in 1969 are no longer available from any source that I'm aware of, but Joe identified a replacement that has similar specs although it doesn't have the integral seal. I don't remember the manufacturer part number off hand, so maybe Joe can restate it.

Duke

[Jack C.]

Re: 1966 427 425HP Valve Clearances

Duke - Unfortunately, I had not read any of your prior posts advising against Comp Cams. I read a lot of sources before buying that were complementary to Comp but as we know many could be puff pieces for the magazines. I'll be in your camp from here forward. Now that I think about it, my 69 hydraulic cam and my 70 LT-1 solid lifter cams are both F-M.

[Jack C.]

Re: 1966 427 425HP Valve Clearances

The Comp Cam version was Parkerized by your description. By pics on their respective sites they all look comparable but you can't see metal quality. I have another known "old school" engine builder in my area that I am going to consult before new cam purchase.

Has anyone had any experience with the lifters with the oiling hole in the bottom?

Comp Cams version-
https://www.compcams.com/factory-mus...k-396-454.html

Crane Cams version-

https://cranecams.com/powermax-solid-flat-242-242-camshaft-for-chevrolet-396-454-big-block/

Sealed Power is now Speed Pro- Federal Mogul is now New Tenneco with no cams listed-

https://www.summitracing.com/parts/slp-cs-165r

[Joe L.]

Re: 1966 427 425HP Valve Clearances

Sorry to here of your situation, Jack. I've been advising AGAINST buying anything from Comp Cams for years because there are just too many reports of early failures of their products. My first choice for camshafts is Federal Mogul, but it appears that many vintage parts are being discontinued from F-M. Crane is my second choice. Both F-M and Crane cams are Parkerized as were OE cams, and this process aids break-in and long life.

A Parkerized cam has a mottled gray surface finish except for the journal because it is polished off, so they are easy to identify. I don't think Comp Parkerizes cams, though it may be "optional".

The other issue with big blocks is valve springs. The second design dual spring with integral retainer and oil seal that went into production in 1969 are no longer available from any source that I'm aware of, but Joe identified a replacement that has similar specs although it doesn't have the integral seal. I don't remember the manufacturer part number off hand, so maybe Joe can restate it.

Duke

Duke-----


The L69+ GM valve springs of which you speak were GM #3970627. However, this was actually a SERVICE only kit which included a dual valve spring of unknown part number (because it was never available separately in SERVICE) + a valve spring cap of GM #3964264 with attached umbrella seal. A conventional BB umbrella seal will not work with this valve spring because it will not fit within the inner spring. Most positive seals won't fit, either. The 3964264 valve spring cap is also designed so that it centers the inner spring.

The Federal-Mogul spring #VS-708 is, in my opinion, identical to the above-referenced GM spring. As you know, I do not believe that in the vast majority of cases aftermarket parts are the same as their corresponding OEM parts. However, in this case, I have carefully compared the Federal-Mogul spring to the OEM spring. As far as visual appearance goes, they are identical except that the FM spring does not have paint stripes (add them if one wants such nuances). It's my belief that these springs were never actually manufactured by GM OR FM. There was likely some company that no one ever heard of that manufactured them for both.

However, the valve spring cap with attached seal, GM #3964264, was NEVER available in the aftermarket including FM. In fact, in an instruction slip that accompanies a set of the FM valve springs, it states that the springs must be used with the GM valve spring caps. Those caps are long-since GM discontinued.

It might be possible to use the VS-708 springs with some of the more recently available positive valve stem seals with a viton seal within a metal frame. These MIGHT fit OK within the inner spring. However, there's still the problem of a valve spring cap that will properly center the inner spring. I do not know of one.

By the way, there is essentially no more Federal-Mogul. It was acquired by Tenneco Automotive about 2 years ago. I think that Federal-Mogul and all its associated brands (e.g. Speed Pro, Sealed Power, TRW, etc.) are being phased out and replaced by a new brand-----driv. Of course, this situation might portend other changes in the old FM product line in the future.

[Jack C.]

Re: 1966 427 425HP Valve Clearances

Thanks to you both. A friend of mine knows the well known engine builder in my area (Mike Kodenko in Santa Paula, CA) and called him about this issue and before my friend could say anything other than 427 Mike said flat cam, yeah, we're having problems with all of them right now. Are Sealed Power, Comp, Crane, etc., all getting stock from China and it's all junk steel now? I can give up on Comp Cams and go with Sealed Power but it's sounding like it's a wing and a prayer crap-shoot either way. I'll re-post after I have a chance to talk to Mike and see if he has a solution at best or his recommendations at the least.