Aluminum Heads and Dowel Pins?

[SSing]

Back in the days some racers practiced not to incorporate dowel pins when using aluminum heads. To keep heads from cracking when they expand. 426 Hemi heads in this case.
Is this still a common practice?
Thank you.

 

[lewtot184]

I have opened the dowel pin holes a little in alum heads but never removed the dowels. if the heads fit snug on the dowels i'd definitely loosen them up.

 

[beanhead]

Lew's statement matches my engine builder's instructions. New dowel pins got lost in shipping during my rebuild so I didn't have them until after I had the block home. He said if they are tight to bring him the pins and heads and he would open the holes a fractional amount at a time to give them some breathing room. Wasn't needed in my case, as there is a slight enough amount of clearance there already. I see how you could just leave them off, might make installing gaskets and heads a little more work to get aligned that's all.

 

[zyzzyx]

I've always been told to use roll pins on aluminum heads as they would let the heads
expand and contract without imparting too much force on the block or heads. Just
what I was taught!

 

[BSB67]

Be cautious on loosening up dowels as it will not take much to impact the intake to head alignment and sealing. I just file the front and rear facing sides of the dowels. I don't open the holes or reduce the dowel diameter. If you end up with any head movement from dowel slop, consider installing the intake and snugging it up before tightening any of the head bolts. After you snug a couple of head bolts, remove the intake and then tighten the head down.

 

[lewtot184]

Be cautious on loosening up dowels as it will not take much to impact the intake to head alignment and sealing. I just file the front and rear facing sides of the dowels. I don't open the holes or reduce the dowel diameter. If you end up with any head movement from dowel slop, consider installing the intake and snugging it up before tightening any of the head bolts. After you snug a couple of head bolts, remove the intake and then tighten the head down.

mocking up with intake after dowel hole "adjustments" is exactly what I do. what got me into this was blown head gaskets on a bracket engine I used to build, and what really stuck with me on this was a pair of crappy EZ junk.