Originally Posted by MER Performance

I have built a 496 8,1 using a Whipple 3.3 kit... It made 900 lbs ft torque and just shy of 900 hp. Replaced the heads with Dart cast iron, cleaned the chambers up, and very little bowl work. Replaced the crank with a 4340 Scat stock stroke forged in the USA , and machined on Scats priority equipment made for the custom cranks this crank was right at $2600. used 6.700 rods and ordered custom pistons from CP, this was a + .005 oversize piston. .990 pin. Used ARP main studs and head studs. MArine Kinetics did the cam. lifters have to be a shrouded type with a .700 wheel or you will dump oil at the wheel slot in lifter , due to the lifter oil galley location.... I used ARP rocker arm studs and locks with Scorpion Endurance rocker arms, this all cleared the valve covers, not using any Loctite on nuts. I used .120" wall pushrods.Timing chain set came from Crane, the most important thing to check is the cam sensor distance .040- .060... do not damage reluctor wheels on crankshaft.. If they are you can order from GM, heat them in the oven and slide them on...
The oil pump is a regular BBC, use a Melling 10770 or 10778. Put a new crank sensor in, no air gap just install set on wheel and tighten bolt.
I tried buying Aluminum heads from Larry@ Raylar, he gave me the runaround, thinking I was friends with his old partner Ray, because of the information I knew on who designed the heads, who cast them and who machined them... There's no doubt in my mind, I would have made more power with the aluminum heads.....Larry, later admitted; to his thoughts on my knowledge after it was too late for me to cancel the Dart heads. There was some secrecy on his part on certain questions I ask relating to pistons and even the oil pump. Being in business, myself I would have answered those questions if ask too me..... I was told some not the truth statements referring to reluctor wheels and locking mechanisms on the rocker arms. I wanted to buy; bare heads with a CNC program porting, no valves or components..Larry, tried to tell me it wouldn't work without his set-up WRONG !!!!!!
Dustin, did all the calibration for this package... we started with a stock crank and decided; the next season we would use the custom so to up boost to 8 psi and not worry about breaking the crank snout off. Scat typically, makes this crank for a 4.500 and 4.750 stroke. I had to machine about .300" off the counter weights to remove the excess weight or the counter-weights would have looked like Swiss Cheese !!!!

Originally Posted by PARASAIL941

Make sure you stick to the factory head bolt torque sequence . Our local marina contacted me searching for 496 cores a couple weeks ago. They had a pair of Volvo Penta 8.1's with bad risers ( not the same as Merc stainless Risers) and had to do the heads. On reassembly , old school tech used regular BBC specs and started pulling threads out of the blocks immediately. He thought they were rotted , so he tried other motor and killed that one . Lightweight blocks ?

Originally Posted by BUP

^^^^ correct and 9 out of 10 times wrong torque is applied because of the operator. Not to go into great lengths here but you can have your snap on guy come out and if all possible bring the torque wrench tester with him. You would be surprise how many techs use a torque wrench wrong. One is you never go past the first click (if click tyoe TW) and stop immediately as soon as the click

I just had a class on this and the testing machine. Not one operator torque was on the money. Everyone was past the torque setting testing it on the machine.

Originally Posted by MER Performance

Thats, correct little shy of 900....the 3.3 Whipple makes the difference..... camshaft, piston dish that was 8:1 cr also 5800 RPMs

Originally Posted by BUP

496 heads not really power makers and really the stock valve springs are not that good for durability especially for increased HP levels.

Dart has some good 8.1 Gen VII products to look at.