On Center Build questions

TURBOELKY

Well-Known Member
Your Keyway broke because your cam is too big for a 1.75” rockers and the valves hit the pistons, and sheered off the key. Yes 2.02” valves have been ran on TA heads.
 

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750H.P.V6

Brutal 6 Racing
Your Keyway broke because your cam is too big for a 1.75” rockers and the valves hit the pistons, and sheered off the key.

This could be the root cause. I remember when you had Earl spec out the pistons I asked why you didn't have valve notches.

Neal
 

dank GN

BlackArts Automotive (661)993-8277
I really don’t think that is the cause. I had Dynoed it and raced it and put maybe 4-500 miles on it before this happened. Anyway I will double check my exhaust valve clearance when I install the new ones just to be sure
 

NY Twin Turbo

All the good stuff.....Times 2.
I really don’t think that is the cause. I had Dynoed it and raced it and put maybe 4-500 miles on it before this happened. Anyway I will double check my exhaust valve clearance when I install the new ones just to be sure
You have taken it to the track?

No updates on your progress along the way?
 

dank GN

BlackArts Automotive (661)993-8277
You have taken it to the track?

No updates on your progress along the way?
No track runs . I just ran the #1 guy out here on the street and unfortunately he got me but by less then a car . So when I come back I should be the fastest on our lil list we have in out in our valley.
 

ttypewhite

Well-Known Member
Your Keyway broke because your cam is too big for a 1.75” rockers and the valves hit the pistons, and sheered off the key. Yes 2.02” valves have been ran on TA heads.

I don't think that's the case. I have had the same luck years past doing the exact same damage as well. Cam lift isn't the issue. I have done that with a hydr roller and a solid roller using 1.75 T&D rockers. We have zero tolerance engines, doesn't matter if the key way snaps and the chain is intact, it will always smash the valves. If you look closely, there isn't much holding it. All that key way and just the tip is holding the gear set in place. You can notch your key slot deeper near the gear and make a custom key way that is rectangular instead of rounded, or notch the cam and the gear for another key way so it is really strong using 2 key ways instead of one.
 

TURBOELKY

Well-Known Member
I don't think that's the case. I have had the same luck years past doing the exact same damage as well. Cam lift isn't the issue. I have done that with a hydr roller and a solid roller using 1.75 T&D rockers. We have zero tolerance engines, doesn't matter if the key way snaps and the chain is intact, it will always smash the valves. If you look closely, there isn't much holding it. All that key way and just the tip is holding the gear set in place. You can notch your key slot deeper near the gear and make a custom key way that is rectangular instead of rounded, or notch the cam and the gear for another key way so it is really strong using 2 key ways instead of one.
I used the 3/16” cookie cutter and chucked my billet cam in the mill, and did exactly that. I was not fond of the small amount of key way, but if I’m not mistaken it’s only there to sync the stack up in order, the bolt is what keeps them in place. Other possibility is the bolt holding the stack up in place was left loose, or not torqued properly with loctite. This engine Chris has was built by a shop if I remember correctly. Has had quite the array of issues since it was put into commission.
 

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dank GN

BlackArts Automotive (661)993-8277
I used the 3/16” cookie cutter and chucked my billet cam in the mill, and did exactly that. I was not fond of the small amount of key way, but if I’m not mistaken it’s only there to sync the stack up in order, the bolt is what keeps them in place. Other possibility is the bolt holding the stack up in place was left loose, or not torqued properly with loctite. This engine Chris has was built by a shop if I remember correctly. Has had quite the array of issues since it was put into commission.

Since I have had it running this is the first issue that has come up with it . I believe you are thinking of when ether I had the wrong size pistons that left me in the hole way to far or the time my dumb ass decided to drive it the last 1/2 mile home with low oil because of a massive leak I had in my AN hoses . Instead of stopping and getting a trailer. That second one was my fault not the motors . Anyway the keyway issue is new to me so I guess u can say I’m learning these motors the hard way . Thanks for
The tip on punching it out bigger . On a better note I have reassembled the heads with new exhaust valves . I gave them a 44.5* face for a tad bit of interference with the 45* valve seat face .
 

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dank GN

BlackArts Automotive (661)993-8277
and also the key does a lot more then just to sync up the stack it has to transfer the rotating forces from the chain/gears to the cam itself and deal with the spring pressures . The bolt is actually controlling my cam for and aft thrust and keep everything sandwiched like the oil pump/cam sensor drive
And my short block was assembled by jms racing the very first time I with those pistons a 1/8” in the hole so I didn’t even fire it before I had to take it all apart to get the correct pistons in
 

750H.P.V6

Brutal 6 Racing
and also the key does a lot more then just to sync up the stack it has to transfer the rotating forces from the chain/gears to the cam itself and deal with the spring pressures . The bolt is actually controlling my cam for and aft thrust and keep everything sandwiched like the oil pump/cam sensor drive
And my short block was assembled by jms racing the very first time I with those pistons a 1/8” in the hole so I didn’t even fire it before I had to take it all apart to get the correct pistons in

The design intent of the key in the camshaft is to align the components on the nose of the cam not prevent them from rotating. Anyone trying to tell you otherwise doesn't understand basic engineering. The root problem with the upper cam gear coming loose on the nose of the cam is the lack of clamping force (ie: bolt torque) and surface area between the aft contact face of the cam gear and the camshaft itself. More aggressive cam profiles with additional spring pressure will only make this problem worse.

Neal
 
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