Washers on head bolts ?
Staging Lane
Joined: Sep 2012
Posts: 85
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From: Virginia Beach, VA
The washers essentially service two functions: first, they distribute the bolt heads clamping force evenly across the cylinder head; and second, the smooth, upper surface of the washer allows an accurate torque reading (as opposed to just torquing the bare bolt head directly to the bare rough metal).
If you have cast iron heads, you should be okay. However, if you have aluminum aftermarket heads, you need the washers installed to prevent galling to the aluminum as it expands/contracts while heat cycling during normal use.
Hope this helps.
If you have cast iron heads, you should be okay. However, if you have aluminum aftermarket heads, you need the washers installed to prevent galling to the aluminum as it expands/contracts while heat cycling during normal use.
Hope this helps.
Thread Starter
Teching In
Joined: Mar 2016
Posts: 22
Likes: 0
The washers essentially service two functions: first, they distribute the bolt heads clamping force evenly across the cylinder head; and second, the smooth, upper surface of the washer allows an accurate torque reading (as opposed to just torquing the bare bolt head directly to the bare rough metal).
If you have cast iron heads, you should be okay. However, if you have aluminum aftermarket heads, you need the washers installed to prevent galling to the aluminum as it expands/contracts while heat cycling during normal use.
Hope this helps.
If you have cast iron heads, you should be okay. However, if you have aluminum aftermarket heads, you need the washers installed to prevent galling to the aluminum as it expands/contracts while heat cycling during normal use.
Hope this helps.
Staging Lane
Joined: Sep 2012
Posts: 85
Likes: 0
From: Virginia Beach, VA
Since you posted on the SBC/BBC forum instead of the LT1-LT4 forum, I phrased my answer to address the stock 1970-1972 LT-1 which came with cast iron heads. Your response leads me to believe you have a stock 2nd gen LT1 that came with aluminum heads. In that case, you need the washers to prevent galling to the cylinder heads.
What bolts did you use? If you used GM stock bolts I do not believe they use washers for the gen 2 LT1. It is a good idea, however to make sure the mating surface does have a coat of oil to produce a more accurate torque reading. Hopefully you also used a thread sealant on the bolt holes that are tapped into water jackets?
I know this to be true for the iron head Gen2 LT1, but I always assumed GM would have used "best practice" of steel fasteners upon aluminum and used washers on the F and Y cars. If that's not the case, then I'd assume they did enough development work/trials to compensate for the torque that's consumed when you torque a steel fastener into an aluminum face and/or used some special antigallant/lubricant at the interface.
I've never disassembled a bone stock Y or F body LT1. The one I did take apart (heads had been R&R'd by someone else) DID have washers, and bolts appeared to be stock.
In any case, I would not try that practice on a rebuild. Use washers, OP. If you'd rather risk it, then at least torque the fasteners +5 lb-ft OVER the max specified torque to put sufficient preload tension in the bolts.
The few head swaps I have done I do not recall washers being on the stock bolts. The ones I've done the owners swapped out to ARP fasteners and I thought it interesting they had washers. I believe the ARP's bolt head is a smaller diameter than the stock GM bolts used on the aluminum head LT1's/4's.
