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Feb 05, 2022 .2 New Pushrods Category: Engine
My Revmaster contains stock length 281mm chromoly steel push rods of the type commonly installed in "racing" VWs. They are designed for high valve spring pressures and high RPMs. While undoubtedly stronger, these weigh almost double what the stock ones do and make additional valve train noise (described as a "clatter") since the steel does not expand at the same rate as the stock aluminum.

I ordered a set of stock pushrods on eBay and the seller kindly included some extras after I mentioned wanting to make my own adjustable pushrod tool. Inspection revealed one unusable pushrod that had scrapped against the case, just like in Bill Fisher's book; nice to see it in person and actually know what I was looking at. I weighed the remaining 11 and discarded the outliers, which you can see in the graph. I'm more interested in maintaining a tight grouping than lowest possible weight and the lightest pushrod was almost a half gram lighter than any of the others.

So my "new" pushrods weigh 38.4+/-0.2g across the entire set - 306.9g total (10.83 oz). The stock steel set from Revmaster weighs 554.1g (19.55 oz) for an engine/airframe weight reduction of 247.2g (8.72 oz); so just over half a pound. This reduction is doubly valuable since it comes out of the valve train geometry in a part that moves 1,600 times a minute in cruise flight.

Next step is to roll them across my granite-tile-turned-surface-plate and check for straightness. Those that pass will get a run through the parts washer and cleanup with some bore brushes, ready for installation.

REFERENCES:
I use Steve Bennett's old weights webpage to corroborate everything I weigh on my engine (now archived) and he lists 20.8 ounces for a "Pushrod Set Steel 8 each":
https://web.archive.org/web/20190711153015/www.greatplainsas.com/weights.html. This is also a great place to go check before putting any components on a "diet".

ACN gives even more information in their parts description (note that 11.600" length should be 11.060"):
http://vwparts.aircooled.net/ACN-Heavy-Duty-Aluminum-Pushrods-Set-of-8-p/acnhdalpr.htm

"WEIGHT: For reference, in a 11.600" length, the weight of a stock pushrod is 39.1g, ACN HD Aluminum are 47.8g, ACN Dual Tapered HD Aluminum is 55.8g, Manton Chromoly Straight are 90.2g, and Manton DT Chromoly are 100.5g."


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