[[email protected]]

I think I may have continuing problem with the cam in my 68 bird with a 350. Last summer I installed a new cam in my car that I bought from summit. It was the summit brand 2801 model. Car ran great with this cam, and I had no troubles at all up until about the middle of this summer when the car developed a lifter tick. I pulled the intake and valley pan off and realized that the cam was shifted in the block and the rear-most lifter and cam lobe had worn each other out. Basically, the corner of the lobe was stripped off. So, I bought a new cam (this time a 2802 from summit) and installed it. This time I shimmed the thrust plate out from the block with washers to get the cam to align correctly with the lifters.

Now the car runs well, but I have reduced oil pressure and the top end doesn't seem as tight as it once was. What I'm worried about is that because i shimmed the thrust plate, maybe I'm losing oil pressure across the first cam bearing.

Does anyone have any ideas what could be going on?

Thanks in advance for the help.

Bob

[hal101]

This time I shimmed the thrust plate out from the block with washers to get the cam to align correctly with the lifters

when you say align correctly what do you mean ??

[74t/a]

First of all, If you have a worn cam, Where do you think the metal goes?

I always recommend removing the engine, or at least the oil pan and removing the metal out of the pan. I personally remove the engine for inspection if that happens to inspect the bearings and piston skirts for metal imbedment.

Second, if you shimmed the thrust plate to get the lifter centered on the lobe, that is the wrong way for 2 reasons. The first is, the lifter is positioned offcenter for a reason, to make the lifter turn. The lobes are usually ground with taper as well to promote lifter turning. The other thing with shimming the thrust is the timing chain will be out of alignment and will bind because of it.

Get those shims out of there!!!

[chiphead]

OMG, you shimmed the thrust plate??? If you remove this cam and inspect the cam bearings in the block, it'll indicate the health of the engine. Worn, pitted or grooved brngs will indicate the need for a rebuild. The cam bearings have a large impact on oil pressure.

If you're lucky, you can replace the thrust plate with a new one and be OK. I would check cam, fuel pump eccentric, timing chain/gears, distributor gears, lifters, and top end for damage or lack of oiling. Carefully cut open oil filter and look for metal in filter.

You running an adjustable valvetrain? What springs are you using?

hope this helps

robertg

[[email protected]]

haha. I take it you guys don't approve of my shimming technique.

When I installed the new cam, it appeared to be shifted in the block such that the lifters were not centered on the camshaft lobes. I would have thought that the lifters should ride on the center of the camshaft lobes.

I don't really think this is an adjustable valve train. I don't adjust the valves or anything like a small block chevy. The lifters are hydraulic, but I still torque the rocker nuts on the studs to a give torque spec (20 ft lbs I think).

So you guys agree with me by saying that because the thrust plate is shimmed out, I'm losing some oil pressure out of the front cam bearing? And you also think that the lobes of the camshaft are to be offset from the lifters?

Thanks again for the help.

[Z Code 400]

Interesting....Lifters hardly ever rest in the center of a lobe on anything, not even roller applications and I have seen more core shift in Pontiac blocks than on any other.

I would not shim anything, least of all the thrust plate. I think it is quite possible you simply have a soft lobe...Robert

P.S. What kind of quality control does these inexpensive camshafts have??? Who is grinding them nowadays??? The same place that is making the other Chinese products???...Robert

[Geoff]

Ofcourse, the washers you used as 'shims' were hardened weren't they..............

[[email protected]]

Ok. I will take the "shims" out. This has certainly been a learning experience for me. I would have never ever thought that the lobes on a camshaft are supposed to be offset from the lifters.

Thanks again for all of our help fellas. I appreciate it.

[pro-tour79]

the engine mever had shimed retaining plates from the factory so WHY would you do that, and as stated above the lifter is not centered over the lobe and you have uncoverd the oil slot reducing oil presure, as far as who grings the cams, it does not matter as they as cast cores only the journal and the lobe surfaces are ground, do you have an adjustable valve train?

[BVR421]

Summit cams are Crane in a Summit box

with a 2802 cam you are going to break something tightening to 20lbs, no wonder lobes wore out, its worth checking the rockers to see if there is any galling.

get a set of locknuts and adjust like a chivvy

[Malky]

Bob, you are getting a lot of good advice here but the big picture is that there is a lot of s**t that has to be checked when installing cams, especially non-stock, higher performance ones, and especially after you have just had a failure. So, no offence meant, but you may be out of your depth. The options are you can get someone else to fix it up, which will cost, or you can do it yourself and use it as a learning experience. But to do it yourself, you will need to get a good rebuild manual, and you will need some specialized tools and measuring equipment, which will also cost. It depends on your circumstances. I do it myself now but I had to screw up many times before I got the hang of it.