3/8" pushrods and SB Edelbrock head clearance

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dilley340

dilley340

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I'm looking for some input with the clearance needed for 3/8" pushrods and Edelbrock SB heads for my 340. I received my Smith Bros. pushrods and did a mock-up to check for the clearance and found that they rub although not shown in the pics below. What's a safe bore size to open these up?

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Get the die grinder out and open up the holes. You really don't want to just bore the holes larger. Take material from the areas interfering. You'll likely have the heads on and off multiple times to get it right.

Are you running a big roller or solid? 3/8 rods are kind of overkill in most SB applications.
 
I'm running a mild Crane hydraulic cam (.454"), 1.5 Crane roller rockers, dished 8:1 Ross blower pistons, Eagle H-beams on a 4.0" forged stroker crank and a BDS 6-71 blower. I needed custom length pushrods (7.05") with a cup tip for the adjuster screw, so I contacted Smith Bros. Pushrods and told them what I had. They sent the 3/8" diameter pushrods.

I wanted to drop the heads off at the machine shop and have them enlarge the clearance holes.
 
I like smith bros, but, IMHO, they sent you something that you don't need.

I run 5/16 .083 on my hyd rollers up to about .600 lift. The rods you have are overkill for a .454 lift camshaft. just my 2 cents.

Is the cam a Hyd Roller? If so, you'll have to clearance the head using just about any diameter pushrod. Bad compound angle on the SB mopars are fun in this case.

You might think about calling Smith and ask why the 3/8 rods when a 5/16 is more than adequate. Spring pressure can't be more than maybe 300# range open. You'll have a bunch of money in clearancing the pushrod holes. Took me better part of 5 hours to do the ede's I had with. Figure that time period and the shop rate and it will add up fast.
 
Thanks for the input crackedback. I'll give Smith Bros. a call. No roller cam.
 
As said.. I run 5/16s but good pushrods and I have the holes slotted to about twice the original length.
 
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