Even and odd bank pushrod length difference
Thread Starter
Staging Lane
Joined: Dec 2019
Posts: 60
Likes: 4
Even and odd bank pushrod length difference I finished up installing my heads on my 408 lq4 today and measured the pushrod length, on the passenger side, #2 and 8 I get a bit of lash with a 7.400 pushrod, around 12.25 turns on the length checker, on the driver side #1 and 7 I have zero lash with a 7.400 pushrod and around 12 turns on length checker. The car has trick flow heads, morell 7177 Ls7 lifters and ls9 head gaskets. The cam is the same cam that was in the motor before I rebuilt it, the heads and block both got milled during the rebuild. Before I was running the gm performance Ls7 lifters and didn't have any noise. Now it's looking like I need longer pushrods even with resurfaced block and heads, and one side tighter than the other? My torque wrench was acting odd on the driver side but I verified torque with another wrench and I'd think it would have to be a crazy over torque to continue crushing the head gasket that much. With needing .040-.050 preload it seems on these lifters, just put in a set of 7.450 and call it a day?
On The Tree
Joined: Apr 2024
Posts: 129
Likes: 22
I’m. It expert but the 1/4 turn with the tool is finicky. Getting zero lash is not an exact science either. Did you recheck other cylinders ? I’d check them all, maybe even twice.
that said longer pushrods will make less noise. Shorter pushrods will allow for more RPM.
with he lifters you are using there is Antonio for error. Since pushrods can be changed after starting it, I would try whatever length and adjust accordingly , BUT I would check sll
thr colander’s and record it first.
that said longer pushrods will make less noise. Shorter pushrods will allow for more RPM.
with he lifters you are using there is Antonio for error. Since pushrods can be changed after starting it, I would try whatever length and adjust accordingly , BUT I would check sll
thr colander’s and record it first.
Thread Starter
Staging Lane
Joined: Dec 2019
Posts: 60
Likes: 4
I wasn't doing the turn method I had the actual measuring tool. The only thing I can think of was the side that's tighter did have lifters soaking in oil for a long time (had to order more parts and forgot about them) so maybe that's causing that side to be tighter until some oil bleeds out? I just wouldn't think that would affect measuring lash
Thread Starter
Staging Lane
Joined: Dec 2019
Posts: 60
Likes: 4
Yeah both were milled, they seem to be off by .0125, a quarter turn or so of the pushrod measuring tool. With a 7.400 pushrod you have lash on the passenger side and on the driver side it's just at zero lash
Thread Starter
Staging Lane
Joined: Dec 2019
Posts: 60
Likes: 4
Stem height wasn't checked, the heads were on the engine before, just milled and cleaned up with a quick lap on the valves, need to throw a straight edge across the head and check, but so far it seems like every cylinder is requiring the same amount on the even/odd side of the block
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Staging Lane
Joined: Dec 2019
Posts: 60
Likes: 4
They were being adamant that they would never take that much off a head. I'll be lucky to have them cover the thicker head gaskets and the cost to match the heads since I have no proof, just the receipt of when I purchased the heads 3 years ago
TECH Fanatic
Joined: Jan 2009
Posts: 1,063
Likes: 475
From: Bostwick, GA.
They were 64 when new and this is the first time they have been machined.
I have no proof, just the receipt of when I purchased the heads 3 years ago.
And you know this, because you measured for the pr's when it was assembled the first time?
Sounds more like your supplier sent you a pr of mismatched heads.
I have no proof, just the receipt of when I purchased the heads 3 years ago.
And you know this, because you measured for the pr's when it was assembled the first time?
Sounds more like your supplier sent you a pr of mismatched heads.
