Why Different Thickness Tappet Block Gaskets ?
Thread Starter
|
Supporter
Joined: Oct 2015
Posts: 1,170
Likes: 32
From: Ft.Worth, Texas
Why Different Thickness Tappet Block Gaskets ?
While researching my impending lifter change, I found that the lifter block gaskets come in different thicknesses (.020, .031). Why is that?
Extreme HDF Member
Joined: Aug 2013
Posts: 16,271
Likes: 15,108
From: Somewhere SW
Fixed pushrods? It doesn't make sense to me unless your changing the base/head gaskets and using OE pushrods.
You have an evo? Gasket thickness would depend on the above factors that I noted, on twincams the lifters are in the lower end, not lifter blocks.
So if you change the head gasket .010 thinner you need to bring the blocks down the same amount if you are using the original pushrods to keep proper lash adjustment. With a set of decent set of adjustable pushrods it wouldn't make a difference.
Edit: Never mind
You have an evo? Gasket thickness would depend on the above factors that I noted, on twincams the lifters are in the lower end, not lifter blocks.
So if you change the head gasket .010 thinner you need to bring the blocks down the same amount if you are using the original pushrods to keep proper lash adjustment. With a set of decent set of adjustable pushrods it wouldn't make a difference.
Edit: Never mind
Last edited by JustDave13; Apr 25, 2016 at 05:37 PM.
Can't see how it would matter, other than general preference/philosophy on getting a good seal. Any variation in the gasket thickness will be automatically compensated for by the spring in the pushrod covers.
Extreme HDF Member
Joined: Aug 2013
Posts: 16,271
Likes: 15,108
From: Somewhere SW
Don't the lifters sit in the lifter blocks on an evo? If so would the height of the block/lifter assembly factor into the lash adjustment?
Road Warrior
Joined: Oct 2011
Posts: 1,376
Likes: 36
From: Round Rock, TX
Lifter rides on the cam. Block is a guide to keep it centered, just like in your twin cam. Your guides are just built into the cam chest and get nice chrome covers.
Extreme HDF Member
Joined: Aug 2013
Posts: 16,271
Likes: 15,108
From: Somewhere SW
Which brings back the question...Why different thicknesses?
Trending Topics
Advanced
Joined: Nov 2015
Posts: 81
Likes: 7
From: Arizona
It doesn't change any of that. The only reason I can see to use thicker than stock gaskets is with a high lift cam with a larger than stock base-circle, or to get a better seal.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Extreme HDF Member
Joined: Aug 2013
Posts: 16,271
Likes: 15,108
From: Somewhere SW
I get it, this way the cam doesn't push the lifter up to far making it hit the block. Now that makes sense.
Relying on a thicker gasket to address that is (to put it mildly) not a good practice. When installing such a cam, you either need to clearance the lifter block, or buy new ones set up for that application.