After cam/lifter/head/pushrod/oil pump swap the cars runs great at idle...welll great enough considering still on stock tune...but when I park over 5 hours my lifters seem to bleed down...lots of lifter noise at start up. Then idle noise is fine...drive for a few miles 2-3000 rph at 45 mph engines egst warm and I get lifter noise. I installed OE Comp Cam lifters, kept stock rockers, manley springs, FM13, AFR heads unmilled, 7.4 harderened push rods.. any ideas? We are ready to go inspect lifters but hate to pull heads if unnecessary. Anyone had this issue?

 

How much preload do you have cold? If there isn't enough preload, the lifter can bleed down just a hair and make it loud when you crank it.

 

Vinci recommends longer push rods with their Crane rocker setup with the AFR heads due to the higher deck height. I wonder if your push rods are too short. Did you check them with a swipe test? I think 7.4 might be good for stock heads, but with unmilled AFR's you might have the wrong length. Give Tony Mamo a PM.

 

Thank you!! I've done push rod length calculations with all the data I have an 7.4 come up short. I did PM Tony and he concurs that we have to check pre-load no matter what...I amazes me how many times i've heard "7.4 should be right" and it probably "should". Anyway we will get whatever we need overnight and be sure to know as much emperical data as possible before unnecessary tear downs...thanks again!!

 

Measure twice and cut once. I ran all kinds of spread sheet calculations and all my calculated figures were off. After I measured all the componets on my valve train I found what I missed in the calculations. Push rod length checkers and dial indicators are cheap and wise investments

 

AFR's are .015 taller in the deck.
what gasket are you running?
also .59x lifts are at least .020 (guess) smaller in the base circle.
That would put you at least .035 short.
I estimate 7.425's to 7.45's

 

Cometics -- 0.051
I ordered an pushrod length check kit today with springs etc today...we will be checking over all measurements...i'm depending on measurements not calculators for this...that's good advice given earlier. All feedback is appreciated...thanks again.

 

Well, well well. Measured pre load tonight. Looks like 7.35" rods will give us 0.065 preload. I caught Shane in technical and Chris in sales at Thunder who worked us up a set of appropriate pushrods. I was suprised that we need shorter than 7.4. Anyway, whatever the outcome, we will have the correct rods. Hopefully they will allow the lifters to act right. I still have my stock lifters if they still are noisey...if that doesn't work...to the bottom we will go. We are doing another oil change just to look for metal in case there is a spun rod bearing. Any thoughts are still welcome!

 

Installed 7.35 push rods...man the valve train really settled down...sounds better; however, the tick tick I get after warm up still comes back. I may have hurt a lifter with the 7.4 push rods...we will drain oil and look for metal which might mean bad rod bearing so i'm told. If the oil is clean out come heads and the stock lifters go in again...I guess we would rather do heads. I wonder what chances of having 7.4 push rods in when 7.35 was the correct length did to lifters?
BTW - a big thanks to Thunder Racing. These guys are the best. Patient. They answer their phone too. They are even eager to help me on a personal level when my cam manufacturer and supplier are not available on the phone during their normal business hours. When we get this sorted out I will write an open letter concerning the last true differentiator in sales: customer service.

 

How long did you run it with 7.4's?

 

Could you please discribe how you went about measuring preload and length needed.
Also, was it cold or hot.

 

I'm confused. Why would the longer pushrods make the valvetrain noisier at idle than the shorter ones when the engine is cold? If anything, the longer ones would be quieter but could possibly be holding the valve open to due to much preload. Sounds like Predators numbers work out better and you would need a longer pushrod and not a shorter one. But you're right, calculate and measure.

 

Mind you the numbers I through in there were by no means accurate.
To do it right I would need:
Deck height (Heads)
Compressed gasket thickness
Valve length
Cam Base circle

But I am wondering the same thing than you.
And of course a live on measurement is the way to do it, but calculations are pretty accurate if all parameter measurements given (some poeple just do not like calcs)

 

I'm as puzzled as anyone right now...

We ran 7.4 pushrods about 100 miles...easy miles not even a single WOT run for what its worth.

The temp of the car was I guess cold. The car had been sitting for 6 hours, moved from side of building to bay (so lifters pumped up). Left to cool for 45 min and thenworked on.

How we measuered Pre Load. I didn't do this and I fix amplifiers for a living so my best explanation would be incomprehensible. We did use an adjuatable PR and test spring and Dial Indicator. Specifics I can't tell you. We also measured exhaust temp of individual cylindars. Pretty even cyl to cyl...side to side.

Anyway the setup with the 7.4s was very very chattery. I expect that. The car was also about 2 x louder exhaust wise using 7.4s tahn it ever was during acceleration which may mean nothing. With the 7.35s the car valve train noise is much more like the proverbial sewing machine. The idle has a great rumpty rump. The problem is that after 1-2 miles of easy driving after the car is warm...we get a pretty loud tick, tick, tick that sounds alot like a lifter tap. When the car returns to idle, it slowly goes away in 2-5 min toi the point where it is almost unnoticeable again. Let it sit for 10 min and it may stay quiet form the next 3 miles...then the tap will creep back in. Bizarre eh?

We are scratching out head. Something doesn't add up though. As far as I know: We went from:
Stock LS1 2000 Cam to FM13 114 which the spec sheet says: Lobe size bc/ht IN:1.450 EX 1.450. The heads were AFR #1510 never milled new out of box...I guess I may contact AFR with the SN to be sure of specs if they keep records. The head gaskets were Cometoc 0.051 which I figure to be stock replacement MLS. The lifters were the OE CompCams replacement lifters and that part number was checked again.

Given the info from here and there, I would have figured longer push rods, but after hearing the difference...the 7.35s "sound" more like i'd expect...which is a subjective statement.

We will be checking oil today...if no metal form bottom of motor then we will pull heads...

 

Macon you have a PM

 

Got it and replyed thanks!! Thansk to all you guys, again. Well looks like there is metal dust in the oil. Pulled heads, 2/3s of the new CompCam OE replacement lifters are real spongy compared to the stock ones whcih we kept...maybe from too long a push rod? I'll ask CompCam tech tomorrow. We plan on pulling the motro and inspecting the bottom end next saturday. Better to be sure I suppose. It's a bunch of work. It is what it is...

 

that's not supposed to happen unless you've bottomed out the plunger in the lifter.

 

okay...after talking with Comp Cams this morning, they said if the stock lifters were still filled with oilthey would not be springy. I need to soak the new one in mineral spirits 12 hours and resoak in new oil 12 hours to know. My guess is that the lifters are fine.

 

1- About 1/3 of the CompCam Lifters were toast and metal in oil and metal on cam position sensor
2- First two cam bearings in front were shot
a- After real close look at replaced (stock) cam...the bearings were already going bad.
3- The rod bearings are fine after inspection
4- I have been noticing a little smoke over the last 6 mos...piulled the pistons and they showed a fair amount of blow by at the rings and underneath.
5- New Iron 408 built for nitrous is being built.

Review...we did a good, clean, prepped cam swap and got lifter noise after 2-3 miles of driving. We learned how important preload is on an LS1. Using a PR length checker is very inportant when using stock rockers. Best to inspect cam bearings with light and mirror. Use best prep methods always. Check oil carefully for unusual color and metal after first cam swap oil change. I hope my set backs help someone!!

 

Thanks for the feedback. I am getting ready to swap lifters, any prep work advice? I think they are shipped with a special sticky substance to prevent corrosion, sounds like you need to clean them out good and then oil prior to use.