1.6:1 rockers 101

[Moparmal]

Couple of basic questions -

1/ Assuming a deck height of around 9.570 and .010th off the heads - Running factory cast 360 heads and a 318 block - Will I need to enlarge the pushrod holes in the heads using a solid lifter and 1.6:1 Crane golds?

2/ Assuming a deck height of around 9.570 etc - will I need longer push rods than factory?

 

[moper]

1/ More than likely yes. If this is roller lifters, yes. Truthfully it cant hurt to clearance them anyway.

2/ Depending on the valve job and stem heights you will need shorter ones. How short, not sure. But your deck is .020" shorter, your head is at least .010 shorter, and the valve seats may be deeper in the head depending on the parts and machinist. So I would plan to buy pushrods... and plan to buy good 5/16 ones.

 

[D-mailman]

Moparmal, Be careful when enlarging the pushrod hole. Most people use a drill and drill out to a larger size, and that is ok as long as you don't have or plan to do any porting on those heads. The drill bit will remove material on the wrong side where you don't have enough anyway, the port wall itself. Going to a different rocker ratio will tilt the pushrod closer to the rocker itself so clearancing only needed on that side. Best to use a mill cutter to relieve this area only and not give up wall thickness you will need if/when you want to widen the pushrod pinch. Making the wall thinner will only reduce what you can do in there if you choose to port these heads. AND the PRP is a BIG restriction area. The wider the port here the better in most cases. JMHO. Good luck.

Terry

 

[Moparmal]

Thanks Dave and Terry

No roller lifters - XS282S solid cam -

I have a set of 1.5:1 Comp steel rockers as well as the 1.6 Cranes - I'll examine the geometry when the time comes and make a decision then..and check P-V clearance also!

 

[70Hardtop]

Mal, whats the lift at the lobe on that cam? I too have just bought some 1.6 RR (Comp Cams copies) but plan to use a Schneider hydraulic (mild, only 0.31 lobe lift). I bought these as they were a great price, also so i could get a valve lift of 0.497". I have not had heads faced, only deck minimally cleaned up. I was planning on using the stock pushrods -mild 340, nothing special. Thanks

 

[Moparmal]

Lobe lift is .347 / .353

http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=671&sb=0