Reply With QuoteThanks Fiat!
I'll turn down the button tonight at work.
No more than .010.
Thanks Fiat!
I'll turn down the button tonight at work.
When I got done with mine I had .004 clearance...keeps things nice and straight as well as your timing rock solid
Well, I shortened the button, first by turning it down close to finished size and then finished it with a surface grinder. I'm getting about .0025 without any real pressure on the cam. If I give it a light tweak, I can squeeze .004 out of it.
Too tight, or just right?
Thanks to all you guys. Without you and this board, I'd be freakin' lost on this rebuild!!! It's nothing like throwing together a small block for some shitbox that I'm forced to drive around in.
This one really matters!!!
The cam thrust is only important that it doesn't wear out the sides of the chain and sprockets or that the chain doesn't hit the front cover,if it is too excessive it can cause small changes in the ignition timing because the distributor and cam gears are ground at an angle and as the cam walks back and forth it advances and retards the timing at idle and LOW engine speeds ONLY. Once the engine rpm gets above about 1500 rpm, the oil pump creates enough drag that it keeps the cam pulled to the rear of the block. If your button clearance is too tight, the cam gear is forced into the block and will cause excessive wear there. Notice that when the engine is idling, the cam and button will walk back and forth slightly and when it moves toward and touches the timing cover it makes a whirring noise,with open exhaust you probably won't hear it. It is normal and harmless and once again, when the rpm climbs,the noise disappears. We build and run LOTSA roller motors! Hope that explains it!
I know its too late John but when I did mine I machined a small groove from the cam bearing housing to the front of the block...it fed pressurized oil to the back of the timing gear...no wear baby.. BBC are notorious for the lifter bores being out of whack. Sometimes they will create a tremendous force forward ..other times it will push the cam into the block wearing it away....My cloyes set had a needle bearing on the back as well as my needle thrust bearing.The groove on mine just kept the needle well lubed but on others without the needle bearing it really seems to help keep the wear down.I'll do the same on my new summer bros set as well...
WFO, my timing set is a Manley. It has the bearing behind the cam sprocket also. Where did you put the oil groove exactly It seems like the valley drains right above the cam would provide plenty of oil washing over that bearing. But I'd like to see exactly wht you did. It's never too late...At least not until the engine goes in!
well I figure acceleration would push that oil back.I also have my valley screened which would slow the return somewhat.Under the cam bearing I machined a small groove from the oil hole to the front of the block.when the cam bearing is in you cant even tell its there.I figure I want my stuff built for overkill.cover my bases before they're loaded so to speak.
Oohh, under the cam bearing. You're right, it's too late.
What about a pin sized hole in one of the front galley plugs? wouldn't that ensure a steady flow of oil to that bearing too?
And what do you mean about acceleration throwing the oil back, away from the valley drains? Aren't you running a V-drive?
On hydraulic lifter motors that used to be a GM applied fix. The lifters would lock air in the galley and not pump up. Yes a teenie tiny hole would put a nice spray in there to keep things well lubed and cooled.I used to do it on all my rebuilds in our shop on small blocks too...Hey has Ric given you a ride yet????
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