[alleyCat]

Guys I just swapped a cam out in my 350. When I got the car it had aN Edelbrock 7157 hydraulic flat tappet cam which has similar specs to a RA IV cam. Its a 4200 lb wagon and it was not a good combination. 9” of vacuum and absolutely no torque. I replaced that with a 2157 Eddy which is closer to stock somewhat. Replaced cam and lifters. There are only 5k miles or so on the engine so left the timing set and roller tip rockers and pushrods.
My problem is I have zero end play with everything installed properly. The eccentric is on correctly . So is my issue likely the cam retainer or the cam gear ? Trying to wrap my head around this before I buy parts I dont need. Help !

[Schurkey]

"Zero" end-play as measured with a dial-indicator; or "zero" end-play as felt by hand?

How deep is the camshaft hole core-plug set into the rear of the block? Is the distributor installed yet? Are the pushrods and rockers installed yet?

[chuckies76ta]

Endplay is set by the Cam Thrust plate. Check the thickness of the Cam plate. There are different thickness plates out there now. From what I understand .007-.010 is what endplay is set too. My engine is at .004. No issues. As mentioned, Camshaft core plug at back of block. Hopefully not installed where it's hitting the back of the cam. Like Schurkey say. Remove dist, rockers, lifters then check end-play.
With Cam gear installed, it should go over the cam snout. In other words the cam snout should protrude past the cam gear. Are you using the Cam fuel pump Eccentric?

Charles

[alleyCat]

Thanks for the replies. The lifters and push rods are installed but have not been set yet. They are just basically sitting on the lobes. Distributor is not installed yet. Zero lash by hand...no forward or rearward movement at all even when “prying” on it behind gear or pushing hard at gear. When gear is removed I get plenty of easy movement. Feels like its pulled tight to the thrust plate when gear is installed and torqued. I did not notice or check end play on cam I pulled out but its the same thrust plate. I am thinking I need a thinner thrust plate pr the gear step is not working well here.

[Schurkey]

Originally Posted by chuckies76ta

Are you using the Cam fuel pump Eccentric?

Good catch. I'm thinking that the Pontiac engine must have the fuel pump eccentric installed to get proper thrust clearance. Been awhile since I was into one.

The BBC/SBC roller-cam/thrust plate design results in about 002--003 clearance. Almost too small to "feel".

[chuckies76ta]

I guess at this point remove all valve train hardware and dist. Remove cam bolt, see if cam moves back and forth.. which you did. Then go from there. The Cam plate sets the endplay is all I know. What's the thickness of the camplate you have?

[chuckies76ta]

I have about 10 camplates here, including stock ones. Let me know if you need a measurement on them.. I think the stock ones were .024. some after market ones are around .016

[alleyCat]

Yes with the bolt out I get plenty of end play. Once I install eccentric and torque things get tight. I will pull it apart tomorrow and measure that cam plate. There was no real wear on it from the last cam that was installed but maybe it doesnt match for the new cam. I have seen two places that actually give a measurement of their cam plates. Butler has one that is .110 and the other is .070. Will measure tomorrow and see what on there now.

[chuckies76ta]

Ok. sounds good.

[Paul E]

I had to have my end plate surface ground ground to get the correct clearance. Likely your local machine shop can do it quickly.

[steve25]

How does it spin without the thrust plate bolted up completely tight and with no chain on the Cam gear?

If it spins but is tight then one of the 2 valley pan bolts could be in deep enough to pinch down on the Cam bearings since those 2 holes go into the Cam tunnel.

[alleyCat]

It spins freely with now gear or eccentric bolted up. Going out later to pull it apart and measure thrust plate and cam gear snout

[Entropy11]

It seemed confusing when I ordered mine. Most places didn’t appear to give a measurement of the plate thickness, and those that did appeared to be very thin. I believe the original GM 488883 was referenced @ 0.123.

I grabbed the Nightmare Perf. cam plate that’s advertised as precision ground to 0.121. Price was reasonable and maybe there’s some benefit to their additional oil grove, who knows. My end play is right at 0.006 assembled and torqued (using Cloyes 9 way billet timing set and existing eccentric and related parts).

I thought the only way the cam plug could come into play in this scenario was if you set it way too deep therefore bottoming it out against the cam itself and eliminating all play. Specifically speaking of the “smaller” cam plug that seats in the inner step and not the larger plug that couldn’t go in that far.

[NeighborsComplaint]

If it spins freely without the timing gear installed, then the problem is not the thrust plate. You have some type of timing gear interference.

[steve25]

Make sure the front oil gally plugs on the left and right of the Cam tunnel are not sticking out off the face of the block too far and also if those plugs have been replaced with screw in pipe ones then they can only stick out by no more then 1/8" depending on the Cam gear used.

Note that if pipe plugs are used that the left side plug can only go in so far without blocking off a much needed oil passage.

[alleyCat]

Originally Posted by NeighborsComplaint

If it spins freely without the timing gear installed, then the problem is not the thrust plate. You have some type of timing gear interference.

I just measured my cam plate and it is .123 and its not bent. Another good member suggested the timing gear snout may be too short causing the cam to pull too far forward and that also could make sense. I may sacrifice the old cam plate and see if I can get a few thousanths off it before I but a new timing set. It is an edelbrock timing set and both cams are Edelbrock so who knows at this point. Glad I checked it for sure.

[Schurkey]

I have a couple of Luminas with overhead cams. GM released a bulletin for an oil system modification that used thinner camshaft thrust plates (4 per engine) along with re-routed camshaft oil passages. I tried to sand my thrust plates down to the new spec using plate glass (for flatness) and sandpaper.

I wore my arm out scrubbing the first thrust plate back and forth over the sandpaper, and when re-measuring, I'd removed half of a thousandth when I needed to take off three thousandths.

The thrust plates went to a local machine shop where they easily knocked off the required amount, for twenty dollars each plate. That was about the cost of the new, updated parts--but they'd been discontinued by GM by the time I was doing this work.

[alleyCat]

I hear ya on the arm. I am using dead flat granite and stick down papers in my kitchen ! I have it down to .119 after an hour. I want to at least get to .001 end play so I at least know what I need going forward. I should probably just go,get a new timing set . There was asmall amount of wear on both sides so I supect the guy before me may not have checked it.

[alleyCat]

Well I got .005 off and cam plate is now .118 so tomorrow I will test fit and see how far off that cam gear is.

[chuckies76ta]

I made a mistake in post #7..Stock plates were .124 and some after market ones are .116

Charles