427/425 cam vendor

[John L.]

Looks like I am going to tear the engine apart as there is a problem with oil in the exhaust ports. Engine only has 3500 miles since full rebuild. No doubt the guides or seals or both. The previous owner put a hydraulic comp cam with an almost exact profile of the 427/425. Who would be the best vendor source for the stock 427/425 cam and solid lifters etc.

thanks in advance

[Clem Z.]

Re: 427/425 cam vendor

GM performance parts #12364057 cam and lifter kit. do not forget you will have to groove the rear cam journal if your block is a 1966

[Joe L.]

Re: 427/425 cam vendor

John-----

Your oil problem might not be a case of worn guides and valve seals, especially if the engine was just rebuilt 3,500 miles ago, or so.

When you remove the intake manifold bolts, be very carful to check for signs of the bolts binding against the holes in the intake manifold. Among other things, this will be evidenced if you can't hand-rotate the bolts after you loosen them with a socket. If so, after the bolts are removed, carefully inspect the manifold bolt holes for signs of bolt-to-manifold interference, especially on the upper surface of the hole. This MAY be evidenced by the appearance of thread marks or galling on the upper surface of the hole. If you find anything like this, post again and we'll go from there.

[Clem Z.]

Re: 427/425 cam vendor

joe is hinting at oil being sucked into the intake thru the ports and if the engine was rebuilt with non stock type gaskets this could be your problem. you should always use the GM type of intake gasket as these "glue" themselves to the heads and intake for a better seal. you can check for oil in the intake by removing the carb and running your fingers in the plenum and runners and see if they "feel" oily.

[John L.]

Re: 427/425 cam vendor

Clem -- Thanks. Joe really had me on this one. I have been trying to figure it out all day. Joe -- thanks also for the advice.

[Joe L.]

Re: 427/425 cam vendor

John and Clem-----

Actually, it's not the gasket situation that I was referring to. This is a situation which I have "studied" and anguished over for a long time. I can't say that I, personally, ever figured it out. However, another fellow who posted some information to this board some time ago did, I believe.

Without going into great detail now (it's in several of my posts in the archives), I once "pulled my hair out" over this oil burning problem with wet ports. This was with an engine that I, ultimately, assembled from a NEW GM short block, NEW GM cylinder heads and several NEW intake manifolds. I tried ALL of the fixes imagineable and NEVER solved the problem. Every gasket type you could imagine and every sealer you could imagine. Nothing even put a "dent" in the problem.

I always thought that this was due to an angularity problem between the heads and intake manifold, but I could never prove that or solve it. The thing is that when cylinder heads or block deck surfaces are machined (although mine were not; I think that my problem was a factory-created maching problem of some sort), the angularity of the intake manifold to the heads changes a slight amount. In this case, of course, the cylinder head intake manifold surface can and should also be machined to "compensate", but by how much (especially since, in my case, there was never anything taken off the head or block deck surfaces)? Even if this is done, you can still end up with an angularity problem between the heads and intake manifold or a "wide set". This is a VERY subtle thing; you absolutely CAN'T see any angularity problem and I've never been able to measure it. However, I believe that this problem creates the oil burning problems in both small and big block Chevrolets. I'll know more when I get that 350 out of my 69 (to be replaced with the "ZL-1" while my other, original 350, already fully rebuilt, "rests" for awhile) and "autopsy" it.

Anyway, do as I mentioned with the bolts and intake manifold holes and we'll go from there.

[Clem Z.]

Re: 427/425 cam vendor

the way to check this is to set the intake on the block with the heads installed and no gaskets a use a feeler gauge to check the fit between the manifold and the heads.the SBC head angle is 10 degrees and the BBC is 0 degrees from the block surface to the intake surface so this can be checked with a percision protractor. several companies now make a large 90 degree device to check the block head surfaces. intake warpage is is one of the big reasons for the leak. this can be checked using a machinest straightedge and feeler gauge just like checking the aling bore of a block. you can check for a leak by closing all the intake valves and use a hand vacuum pump to pull a vacuum on the intake manifold by making a seal off plate for the carb flange. some people use air pressure but do not go over 10/15 # because you can unseat the valves and get a bad reading. i have seen porous oil leaks from the valve spring area of the heads into the ports but these were aluminum heads. another problem is not using sealer in the rocker studs that go into the intake ports. like they say "there ain't no easy way"