Hi There are two cam size available for the Tomahawk block. What are the pro / cons between the standard small Buick and the bigger Ford cam's ? cheers Robert
I have no real test data but I would think people like me that run high spring pressures and high RPMs that the shaft would not flex as much to affect valve timing on the back part of the cam.
Larger diameter cam and cam tunnel in the block allows for higher lift cam lobes. You can have a high valve lift without going to a high ratio rocker arm which is easier on the valve train or you can go high lobe lift and a high rocker ratio for very high valve lifts for racing.
You want to get as much lift as you can on the lobe. Rocker ratio also multiples the acceleration rate of the ramps and beat up valvetrain parts in a high rpm engine unless they're specifically designed for a high ratio rocker which comp does have. If your building a street strip type car the stock cam size will be ok. Any race motor without the bigger cam is a mistake especially if your trying to be competitive N/A and turn real rpm. It's just going to cost more money but if your worried about 1200 bucks for a cam you probably shouldn't spend 7k on a block lol
BTW The option for cam size is free, location is not. The cam was in the $800.00 range for the 54mm size. That was the shipping also (let me find my receipts). Unless you do some Mechine work, you will have to buy new lifters from TA ($369.00 I think).
From what Dave Johnson told me, besides the obvious higher lift with the 54mm, there is less flex which means more HP. Also, if you have the standard size bore you can have it machined for the 54mm bore. That is what Dave did for me. Wasn't much money to have done....think it was $250 bucks.
Thanks for your replies. The cam would be a hydraulic with intake 250*and exhaust 260* duration at 0.05 LSA 113. Target valve lift should be around 0.64 with 1.55 roller rockers. So does it matter in this case? Thanks Robert
Folks, Please don't figure that it only cost $50.00 to open up a cam tunnel. Dave was owed some favors at that machine shop. Dave was kind enough to pass that to Guy. Normally you would be looking at around $450.00 for the cam tunnel using babbit bearings. If you want the lifter bores opened to .904" around $275.00 for that alone and to bush the lifter bores around $750.00
Huh...didn't know that. This was by memory, it might have been $150.00, but either way sorry for the confusion. And it looks as though I owe Dave one. ***edit*** Looked back at the checks I sent out. First was $250.00. must have been for boring to 54mm. Then later sent out another for $175.00 and that must have been for installing the cam bearings. Sorry, will edit my first post.
