Box Stock

308 Cam and Rod questions

K

Kman1771

Member
I plan on doing a hemi . My piston was .028 in the hole so I plan on the +.020 rod Will I use a .022 gasket ? I’d like to use the 308 cam. Other than valve springs and push rods .Can I use the stock valves and rockers ? What will need done to the carb? Thanks for any advice.
 
I would go with a bigger carb! the cam will allow higher RPMs and your engine will be breathing through a straw . The stock carb is good for the 3500 rpms that it was designed for. But not for the 8 to 9,000 that the cam will turn. Probably something in the 26 to 32 mm range will get you the most. Depending on the rest of the build.
For valves and rockers , there are some really good aftermarket ratio rocker for that engine. and bigger valves are a definite hp gainer. Plus a billet flywheel is a definite must!!!!!!
Depending on how much you want to spend. !? You can build a real beast! if you pocketbook will support it.
 
One Fast Kat said:
I would go with a bigger carb! the cam will allow higher RPMs and your engine will be breathing through a straw . The stock carb is good for the 3500 rpms that it was designed for. But not for the 8 to 9,000 that the cam will turn. Probably something in the 26 to 32 mm range will get you the most. Depending on the rest of the build.
For valves and rockers , there are some really good aftermarket ratio rocker for that engine. and bigger valves are a definite hp gainer. Plus a billet flywheel is a definite must!!!!!!
Depending on how much you want to spend. !? You can build a real beast! if you pocketbook will support it.
Click to expand...
What is a good stock appearing 26-32 mm carb?
 
Be careful getting too carried away when you put springs on it. The stock hemi rockers will fold up pushing against heavy springs. The 26 pound springs are about the max, and even then plan on keeping spare rockers around.
 
mike97760 said:
Be careful getting too carried away when you put springs on it. The stock hemi rockers will fold up pushing against heavy springs. The 26 pound springs are about the max, and even then plan on keeping spare rockers around.
Click to expand...
What if I went with the 275 cam
 
Sink the valves (bad idea) thicker head gasket (bad idea )
Notch the piston ; could cause failure of piston crown .
Go too a standard head .
 
The valve angle on the hemi cause the main issue .
The simple answer is yes . Along with : that's something you need to verify for your self .
I put the standard head on the hemi block with a 356 dyno cam .
Did the modeling clay check and had a clearance that was acceptable to me .
I didn't document it so can't say what it was . Just that I was fine with it .
Spring bind is another must check .
The 308 should be no problem , again trust but verify .
 
flattop1 said:
The valve angle on the hemi cause the main issue .
The simple answer is yes . Along with : that's something you need to verify for your self .
I put the standard head on the hemi block with a 356 dyno cam .
Did the modeling clay check and had a clearance that was acceptable to me .
I didn't document it so can't say what it was . Just that I was fine with it .
Spring bind is another must check .
The 308 should be no problem , again trust but verify .
Click to expand...
So I talked to Jody from ARC he said P2V clearance shouldn’t be an issue. He did say coil bind on the exhaust could be a problem. What do you do to fix the coil bind issues if I run into it ? I’m new to this and want to try to build my own motor. But I don’t want it to go boom on the 1st lap maybe lap 5 lol.
 
Cut the *spring* pocket about .060" to eliminate coil bind. It brings the hemi installed height to about same as non hemi.
 
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Longer valves , different retainers or cutting the spring pockets .
Indy Harry stated the best option .
Maybe he can do it for you ?
 
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