Clickety clack keeps cumin back!!!
Thread Starter
Instructor
Joined: Feb 2013
Posts: 193
Likes: 2
From: Illinois
Clickety clack keeps cumin back!!!
Here's the deal, dropped my newly rebuilt L48 to 383 Stroker in last fall.
Went with a Comp cam #12-210-2[49] grind #268H. Comp flat hyd tappets, Comp high strength push rods, 1.5 Comp roller rockers in Flow-Tek Alum heads w 64cc Combustion chambers. I set the valve lash on the engine stand per the Comp instructions. (lifter on base circle rocker adjustment to zero clearance add 1/2 turn and lock). I ran Comp break in oil for the first 500 miles and changed to Mobil 1 high zinc 15-50 (per CF recommendation).
When I cold start the engine I hear some predominate ''Clacking" which I believe is coming from the valve train (checked with stethescope). As the engine temp rises up to operating temp (165deg), the ''Clacking gradually diminishes to zero.
IS THIS NORMAL for my set up or should I pull valve covers and re adjust (have not had them off since engine fire up)??
Thanks much guys.
Went with a Comp cam #12-210-2[49] grind #268H. Comp flat hyd tappets, Comp high strength push rods, 1.5 Comp roller rockers in Flow-Tek Alum heads w 64cc Combustion chambers. I set the valve lash on the engine stand per the Comp instructions. (lifter on base circle rocker adjustment to zero clearance add 1/2 turn and lock). I ran Comp break in oil for the first 500 miles and changed to Mobil 1 high zinc 15-50 (per CF recommendation).
When I cold start the engine I hear some predominate ''Clacking" which I believe is coming from the valve train (checked with stethescope). As the engine temp rises up to operating temp (165deg), the ''Clacking gradually diminishes to zero.
IS THIS NORMAL for my set up or should I pull valve covers and re adjust (have not had them off since engine fire up)??
Thanks much guys.
Melting Slicks
Joined: Oct 2011
Posts: 2,748
Likes: 90
From: Sacramento California
C2 of Year Finalist (performance mods) 2019
2018 C2 of Year Finalist
I beleive with aluminum heads you want one full turn of preload.
However, if it goes away when warm, it should be ok.
However, if it goes away when warm, it should be ok.
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
Which Comp lifters did you use? High Energy or Pro Magnum? The Pro Magnum have a higher bleed down rate so they perform better at higher rpm but are a bit noisy at idle, sometimes more than a bit... The High Energy are closer to stock and are fairly quiet.
Drifting
Joined: Jan 2012
Posts: 1,908
Likes: 129
From: Fredericksburg Virginia
I'm running aluminum heads with solid rollers, so I figure mine would be much more susceptible to valvetrain noise because of dimensional changes when cold than any hydraulic setup. Alas...mine runs like a sewing machine cold or hot.
Given that the motor has been stroked, and without knowing what all was done to the block, rods, rod ends, or checks on the piston-to-cylinder clearance, what is the chance that you are actually hearing piston slap?
There are some clips you can buy to reduce oil splash so you can actually adjust the rockers while the engine is running...perhaps running the car with the valve covers off would/could allow you to isolate one particular part that is giving you trouble.
If the valvetrain checks out, then you can look for some issue with the stroke kit...some close tolerance that is JUST fixing itself when hot...
Given that the motor has been stroked, and without knowing what all was done to the block, rods, rod ends, or checks on the piston-to-cylinder clearance, what is the chance that you are actually hearing piston slap?
There are some clips you can buy to reduce oil splash so you can actually adjust the rockers while the engine is running...perhaps running the car with the valve covers off would/could allow you to isolate one particular part that is giving you trouble.
If the valvetrain checks out, then you can look for some issue with the stroke kit...some close tolerance that is JUST fixing itself when hot...
Thread Starter
Instructor
Joined: Feb 2013
Posts: 193
Likes: 2
From: Illinois
Actually I looked them up and the lifters I used where Sealed Power stock replacements #HT-817.
Thread Starter
Instructor
Joined: Feb 2013
Posts: 193
Likes: 2
From: Illinois
I'm running aluminum heads with solid rollers, so I figure mine would be much more susceptible to valvetrain noise because of dimensional changes when cold than any hydraulic setup. Alas...mine runs like a sewing machine cold or hot.
Given that the motor has been stroked, and without knowing what all was done to the block, rods, rod ends, or checks on the piston-to-cylinder clearance, what is the chance that you are actually hearing piston slap?
There are some clips you can buy to reduce oil splash so you can actually adjust the rockers while the engine is running...perhaps running the car with the valve covers off would/could allow you to isolate one particular part that is giving you trouble.
If the valvetrain checks out, then you can look for some issue with the stroke kit...some close tolerance that is JUST fixing itself when hot...
Given that the motor has been stroked, and without knowing what all was done to the block, rods, rod ends, or checks on the piston-to-cylinder clearance, what is the chance that you are actually hearing piston slap?
There are some clips you can buy to reduce oil splash so you can actually adjust the rockers while the engine is running...perhaps running the car with the valve covers off would/could allow you to isolate one particular part that is giving you trouble.
If the valvetrain checks out, then you can look for some issue with the stroke kit...some close tolerance that is JUST fixing itself when hot...
Scat stroker crank (3.75'' total throw).
Block clearenced for rotating ***'y.
Stock rods reconditioned and re-used (5.7'').
Stock wrist pins (press in rod, float in pstn).
Sealed Power flat top hyperutectic pistons w/skirt coating.
Entire rotating ***'y externally balanced
Block bored to new piston specs.
.040 quench.
10.24 Static CR.
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Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
I run 1/2 turn after zero lash on my cast iron heads and get a bit of clack on start-up (since it sits alot) but it clears and, thankfully, is in now way approaching 'knocking' noises. I run high energy rollers and figure they need some time to get pumped up as the car sits a lot.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
I wouldn't worry about it if it gets quiet when hot.. Worry about it when it never gets quiet.
A bit more preload may help but...it's not really a problem as long as they get quiet. XE series cams are notoriously noisy anyway.
Just keep an open ear on it and make sure it doesn't get worse. If it does continue to get worse over time, it could be wiping a lobe and there is no good way to verify this without pulling the intake and visually looking at the lobes. Lifters bleed down when it's not running so measuring lift at the valve isn't accurate.
A bit more preload may help but...it's not really a problem as long as they get quiet. XE series cams are notoriously noisy anyway.
Just keep an open ear on it and make sure it doesn't get worse. If it does continue to get worse over time, it could be wiping a lobe and there is no good way to verify this without pulling the intake and visually looking at the lobes. Lifters bleed down when it's not running so measuring lift at the valve isn't accurate.
Le Mans Master
Joined: Oct 2007
Posts: 7,451
Likes: 974
From: RI, Now Franklin/Nashville TN
I was told 1 full turn on the rockers for pre load with my AFR heads by the builder who did my short block and that is exactly what I did. FWIW-I also followed the engine builder's recommendation on breakin after I installed the top end and cam to run Driven Breakin oil for 30 minutes with the new roller cam (yes, you should breakin roller cams just like flat tappet cams) keeping the RPM's up between 1,800-2,500 RPM and then I drained the Breakin oil and filter and replaced with Driven conventional oil 15W-50 for the first 500 miles. I will be changing that oil this spring and replacing with Mobil 1 0W-40 European Formula (1,000 PPM ZDDP) moving forward which is the oil that I run in all my cars and power equipment.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
I agree, I wouldn't worry about it, if it goes away.
Do you have forged Pistons? Forged Pistons will rattle in a cold engine until it warms up. GM had a bunch of people worried when the LS motors were doing it, so they had to put a memo out stating its normal.
Do you have forged Pistons? Forged Pistons will rattle in a cold engine until it warms up. GM had a bunch of people worried when the LS motors were doing it, so they had to put a memo out stating its normal.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
This is what I was thinking it sounds like also.