cam tunnel size
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turbodave231
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Machining the cam bore bigger was common for Busch and ASA engines. I have a 153 block that was machined to accept needle bearings. It requires the cam journals to be smaller than the stock Buick size. I'm not sure of the dimensions of the bore. I can get you the dimensions if you need them.
Dave
Dave
oiling issues
You had better study up on how the mains recieve their oil before you try this.
You had better study up on how the mains recieve their oil before you try this.
Why would the cam bearing size effect the main bearing oil supply ? the oil holes are still in the same spot right ? my stage 2 block has the tunnel opened up to the small block chevy size due to the size of the cam the previous owner was running something like 780 lift N/A and the lobes were to big to fit the standard size . I had to have a custom cam made for my motor and everything is fine .
Because
Most of the blocks you mentioned feed the mains from the passenger side oil galley. The oil gets to the mains through a hole drilled from the mains up to the oil galley @ an angle. The drilled passage breaks through into the cam bearing journal. Once you drill the cam journals out to a larger dia.--what happens to you main feed hole?
Most of the blocks you mentioned feed the mains from the passenger side oil galley. The oil gets to the mains through a hole drilled from the mains up to the oil galley @ an angle. The drilled passage breaks through into the cam bearing journal. Once you drill the cam journals out to a larger dia.--what happens to you main feed hole?
hence my first post " you need to study oil flow to mains"
If you have access to a bare 109 block (no cam bearings in it)-- take the correct sized drill bit and stick it in the main feed hole going up to the passenger side oil galley. You will see the drill bit protouding through into the cam bearing bore. This will also show you how much the oil flow to the mains is restricted just by the stock cam bearings. So to answer your ?--depends on how much larger O.D. your new bearings are.
If you have access to a bare 109 block (no cam bearings in it)-- take the correct sized drill bit and stick it in the main feed hole going up to the passenger side oil galley. You will see the drill bit protouding through into the cam bearing bore. This will also show you how much the oil flow to the mains is restricted just by the stock cam bearings. So to answer your ?--depends on how much larger O.D. your new bearings are.
TurboCrazy
Turbo on the brain!
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incharge, You have nothing to worry about, as long as you have a Stage II block cast after July 1985. From that point on, all Stage II blocks had priority main oiling. So, the main oil feed hole does NOT intersect the cam bore.
LOT, You are correct for all stock, and Stage I blocks. And, Stage II blocks cast before July 1985.
LOT, You are correct for all stock, and Stage I blocks. And, Stage II blocks cast before July 1985.
Thanks Turbo crazy and LOT for clearing it up I really never paid that much attention to it as my block was already done by a machine shop when I got it and it has been running for a year now so I know the mains are getting oil . I was just tring to see if anyone else was running a small block chevy sized cam ... very good info
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