Main cap dowel pins
02-06-2019, 07:18 PM
#1
Staging Lane
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Main cap dowel pins I’m building a NA 434 using a Darton sleeved gen 4 aluminum 5.3 block, 14.1 CR, plan on spinning it 7500-8000, at what point would it be worth using aftermarket main caps with dowels or even just doweling the stock caps
02-06-2019, 11:15 PM
#2
I talked to several builders in my area and searched the web when trying to decide if and when they are needed and I got different opinions. I'm running a roots blower with a Callies crank and was told that anything I could do within reason would help, So I'm running billet pinned mains and adding a crank support ( only needed for running a blower off the crank snout)and may even add a main girdle at some point.
There are even differing opinions on how pinning the mains help, The reasons were similar but not identical. One says they keep the cap from moving around when the crankshaft is forced down into the caps, Another said it strengthened the bottom end only and another says by pinning the caps the whole block becomes more rigid, Another suggested just a girdle because it accomplishes the same thing but much cheaper.
When I got my engine it had already been hurt on the dyno and it had a broken main cap, I was all set to just use used stock caps and get it line bored but I found a deal on set of new Katech billet mains so I grabbed them. As much as I have in the engine I figured spending a little extra even if it may not be needed is better than finding out it was needed after the damage was done. For what it's worth, There aren't a lot of threads where people reported having problem with cap walk and the ones I did see were around the 1,000hp range running boost with most using stock cranks.
My opinion is this, If you can add it to your budget without taking away from something else then add main girdle or pinned billet mains of both. It might only be for peace of mind but it can't hurt.
There are even differing opinions on how pinning the mains help, The reasons were similar but not identical. One says they keep the cap from moving around when the crankshaft is forced down into the caps, Another said it strengthened the bottom end only and another says by pinning the caps the whole block becomes more rigid, Another suggested just a girdle because it accomplishes the same thing but much cheaper.
When I got my engine it had already been hurt on the dyno and it had a broken main cap, I was all set to just use used stock caps and get it line bored but I found a deal on set of new Katech billet mains so I grabbed them. As much as I have in the engine I figured spending a little extra even if it may not be needed is better than finding out it was needed after the damage was done. For what it's worth, There aren't a lot of threads where people reported having problem with cap walk and the ones I did see were around the 1,000hp range running boost with most using stock cranks.
My opinion is this, If you can add it to your budget without taking away from something else then add main girdle or pinned billet mains of both. It might only be for peace of mind but it can't hurt.
02-07-2019, 03:06 PM
#3
ModSquad
iTrader: (6)
I feel like it’s rpm related. My 434” has Katech pinned caps. When I bought the block, there was substantial evidence of center three caps moving around. The block, an LS2, came from RYR (Robert Yates Racing) and was a 7000+ rpm deal it’s entire short life with Yates, in the K&N NASCAR series. I had it sleeved by Steve at RED, and I installed the billet pinned caps as well.
