Roller Cam Thrust Button

[Captainfab]

We're still working on assembling my son's 406 and we're having a little issue with the cam thrust button. We're running a Comp hydraulic roller, Cloyes timing set, and a Comp 200 roller thrust button. The problem is with the cam, timing set and thrust button in place, when we go to put the timing cover on, the cover makes contact with the button, but it is almost 1/8" from the front of the block. We tried both a stock timing cover and a Milodon reinforced cover, and both are the same. This is my first time installing a retro roller, but I was under the assumption that it would need shimmed to get ~.008 endplay. Is it common to have to 'grind' on the button? that just doesn't seem to me like a good idea with a roller button. The books we have don't explain much and I've tried searching online for some answers with no luck. Can someone here help us out? TIA

[2tons of fun]

dent or grind the cover, it will be hidden and coverd by the water pump any how.


measure the button and call summit to see if they have a shorter one.

[AirMale]

Had the same problem in my BBC, went through 2 dist. gears before I realized the problem. I used a Edelbrock cast alum. cover and clearanced inside. Next build I'm gonna clearance the button.

[Wild83C10]

A two/three piece timing cover should provide the proper distance, but obviously more expensive.

I would massage the cover before I grind anything.

[Marv D]

A cloyes Quick button timing cover will solve all your problems. The hex-adjust timing set and a Quick-button cover is all I'll use on a roller SBC. It ought to be law IMO.

Myself I'd be cautious of altering the cover in any way. The Milidon covers are reinforced to help support the thrust of the cam, and a stock (or the POS chromed junk) stamped steel cover on a roller motor is just a bad idea IMO. You need all the support you can get there to keep the cover from flexing.

Most of the good cam buttons are steel with a shim pack / torrington bearing so you can adjust the 'fit'. Or there soft aluminum, cost a few bucks and I'd for sure stick it in a drill / lathe and make it fit the clearance before I'd alter anything else. But again..... that's just if you refuse to spend the bucks for the quick-button / Hex-adjust.

[Rodms]

I am still using stock cover and welded my washer to the cover but it would'nt pull up to the block so I laid it on a probably 2" socket and gave it a good smack with the hammer till it fit .And they do make different buttons.

[Captainfab]

Thanks for all the replies guys.

We're a little baffled as to why this turned into a problem. As common as a SBC with a retro roller is, you would think that you could buy a thrust button that fits without having to 'massage' a timing cover.

After some discussion it looks like the Cloyes Quick Button cover is the most appealing option. My son is going to order one tomorrow.

[KQQL IT]

What retro roller are you running. I got hr 288 comp cams and love it.

[Captainfab]

We're running the NX288HR. I'm thinking it should run pretty good.

[Rodms]

OK 2 buttons listed in book,under those years,1 is .642 in and I think thats the diameter,length measures about 9/16 of a inch,the other is .925 round and length is the same I think.The .642 is the one I used with the cloyes timing chain,and the washers are about 1/8.Ok comps book says your button is.795 in length,is that with or without the washer?Mine is max maybe 11/16 all together.

[KQQL IT]

Originally Posted by Captainfab

We're running the NX288HR. I'm thinking it should run pretty good.

My cam is xr288hr 12-433-8 in a 9.5:1 406 dart 200cc edelbrock air gap RPM hp950 holley so far its been 12.20s@4020lbs

[Captainfab]

Originally Posted by Rodms

OK 2 buttons listed in book,under those years,1 is .642 in and I think thats the diameter,length measures about 9/16 of a inch,the other is .925 round and length is the same I think.The .642 is the one I used with the cloyes timing chain,and the washers are about 1/8.Ok comps book says your button is.795 in length,is that with or without the washer?Mine is max maybe 11/16 all together.

Thanks for having your wife look that up Rod. My son decided to go ahead and order the .642 one today and give that a try. As I understand it that is the length. I would think the diameter would be the same for all SBC's? Could you elaborate on the 'washer'. Does it go between the button and the cam, or against the timing cover?

Originally Posted by KQQL IT

My cam is xr288hr 12-433-8 in a 9.5:1 406 dart 200cc edelbrock air gap RPM hp950 holley so far its been 12.20s@4020lbs

That sounds like a good combo. Is that on just fuel, or with a little juice? either way that's a respectable time for a truck.

I really want to build a 406 some day......been wanting to for about 25 years

For now I can get my fix helping my son with his

[KQQL IT]

Nope all motor drove it to the track 45 miles one way that combo is two years old with 100plus runs and a ton street time

[Rodms]

The washer goes on the cover,the button runs against washer OK.

[Captainfab]

That's what I thought, but I just wanted to make sure. Thanks.

[Rodms]

don't burn a hole in it,where the x cross on the stock cover thats where it goes,if it starts walking thats what a hammer is for.You should'nt have a problem.You do want the washer tight against the button if you tap it with whatever should not sound hollow!

[Captainfab]

My son received the new roller cam button yesterday. We'll be using the Milodon reinforced timing cover that we currently have. Sunday is the scheduled day to work on the engine again. I'll let you know how everything works out. Thanks for the help.

[Rodms]

Originally Posted by Captainfab

My son received the new roller cam button yesterday. We'll be using the Milodon reinforced timing cover that we currently have. Sunday is the scheduled day to work on the engine again. I'll let you know how everything works out. Thanks for the help.

We don;t have any of the high tech parts but we make stuff work,as long as the cam don't walk out you should be OK.You should be able to tell when you put the cover on.

[KQQL IT]

Capt. fab Ive got this water by pass on my 406 and it runs 165/180 degrees all day with a electric fan in 100plus days got it from jegs

[Captainfab]

Do you have that plumbed into the rear water ports in the intake at the heads? We haven't had any cooling problems with the SB 400 yet, but we've been running an engine oil cooler too. I'm thinking that must help to some extent. The first one my son had was in a '79 GMC K15, and it came with an engine oil cooler from the factory. That one didn't have any cooling problem, so we've just kept an engine oil cooler on it

Originally Posted by KQQL IT

Capt. fab Ive got this water by pass on my 406 and it runs 165/180 degrees all day with a electric fan in 100plus days got it from jegs

[KQQL IT]

Yes plumbed into the rear water ports on the intake. I dont have a oil cooler tho, but the oil pan holds 9 qts also,10 with the tall filter

[Captainfab]

Well we finally got the cam end play set today with the shorter Cloyes thrust button. My son got to the shop early and had been working with it for 3 hours when I got there. He ended up welding the supplied washer onto the back of the thrust button for two reasons. 1) the button didn't seem to want to stay straight when sitting in the cam gear and 2) there was very little clearance between the cam gear bolts and the washer if it were to be tacked to the timing cover. I finally suggested fabbing a plate to bolt onto the back of the water pump (long pump) so that we could put tension on the timing cover. That did the trick and we got it set at .0065. We should be able to get this engine in the car and fired up by next weekend.