Sewing machine noise
08-18-2015, 04:00 PM
#1
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Thread Starter
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Sewing machine noise Engine: Stock LH8 5.3L
Cam: GM ASA
I did a 5.3L swap into a 1967 Cougar. Before I dropped the engine in the car, I did a GM ASA cam swap and installed Lingenfelter .660" lift springs and I used stock pushrods (7.385"). From day one I was getting the sewing machine noise.
I did some digging around, seems that the ASA cam might have a reduced base circle, despite being only .525" lift. So I picked up a set of 7.400" pushrods.
I went through the procedure outlined in a thread I found to check preload. I made sure the lifter was on the base circle using the EO/IC method. With the stock pushrods it only took about 1 turn to achieve the 22 lb/ft torque on the rocker studs, which indicated that I need a longer pushrod. I confirmed this on a couple of cylinders with the same results.
Then I checked with the 7.400" pushrods and it took between 1.25-1.5 turns to achieve 22lb/ft on the rocker studs. By what I gather this is about optimal and will net about .060" of preload.
The issue is that I am still getting the sewing machine noise. Perhaps it is more noticeable because I have a hole in the hood with a Holley Hi-Ram sticking through, but it is pretty annoying driving around town. I can hear the valve clatter clearly when I get off the gas but with the engine around 2000-3000RPM, coasting.
Any ideas or suggestions are welcome.
Andrew
Cam: GM ASA
I did a 5.3L swap into a 1967 Cougar. Before I dropped the engine in the car, I did a GM ASA cam swap and installed Lingenfelter .660" lift springs and I used stock pushrods (7.385"). From day one I was getting the sewing machine noise.
I did some digging around, seems that the ASA cam might have a reduced base circle, despite being only .525" lift. So I picked up a set of 7.400" pushrods.
I went through the procedure outlined in a thread I found to check preload. I made sure the lifter was on the base circle using the EO/IC method. With the stock pushrods it only took about 1 turn to achieve the 22 lb/ft torque on the rocker studs, which indicated that I need a longer pushrod. I confirmed this on a couple of cylinders with the same results.
Then I checked with the 7.400" pushrods and it took between 1.25-1.5 turns to achieve 22lb/ft on the rocker studs. By what I gather this is about optimal and will net about .060" of preload.
The issue is that I am still getting the sewing machine noise. Perhaps it is more noticeable because I have a hole in the hood with a Holley Hi-Ram sticking through, but it is pretty annoying driving around town. I can hear the valve clatter clearly when I get off the gas but with the engine around 2000-3000RPM, coasting.
Any ideas or suggestions are welcome.
Andrew
Last edited by Project GatTagO; 08-19-2015 at 04:02 PM.
08-19-2015, 04:00 PM
#2
TECH Senior Member
Thread Starter
iTrader: (7)
Nobody has any thoughts on this? I would hate to order a set of 7.425" pushrods for no reason. It seems that where I am at right now it should not be making any noise.
They use the ASA cam in the LS3/525 with stock pushrods. Do they sound like a sewing machine?
Andrew
They use the ASA cam in the LS3/525 with stock pushrods. Do they sound like a sewing machine?
Andrew
08-19-2015, 08:04 PM
#3
I have the same issue with my ls2. I never heard it run with the stock cam, before I put it in my car I put a tsp Magic stick 3, prc .650" springs and 7.4" pushrods. I need to get a pushrod length checker or something to see if my current ones are too short. I was going to try the 7.425" to see if it quieted down.
08-19-2015, 11:12 PM
#4
more aggressive lobes and stout springs just make more noise. The reason you never hear it on stock cars is the noisy exhaust. Your car has a pretty street friendly exhaust.
IIWY I'd call Kip at C.M. and get a gentle lobe 224 sized cam with better lifters or maybe he'll talk you into a low lash solid roller which most claim to be really quiet, plus you'll gain 20 or so ponies
IIWY I'd call Kip at C.M. and get a gentle lobe 224 sized cam with better lifters or maybe he'll talk you into a low lash solid roller which most claim to be really quiet, plus you'll gain 20 or so ponies
08-20-2015, 10:37 AM
#5
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Thread Starter
iTrader: (7)
more aggressive lobes and stout springs just make more noise. The reason you never hear it on stock cars is the noisy exhaust. Your car has a pretty street friendly exhaust.
IIWY I'd call Kip at C.M. and get a gentle lobe 224 sized cam with better lifters or maybe he'll talk you into a low lash solid roller which most claim to be really quiet, plus you'll gain 20 or so ponies
IIWY I'd call Kip at C.M. and get a gentle lobe 224 sized cam with better lifters or maybe he'll talk you into a low lash solid roller which most claim to be really quiet, plus you'll gain 20 or so ponies
I am not swapping cams, yet alone pulling heads to change the lifters...LOL
Andrew
08-20-2015, 02:51 PM
#6
TECH Apprentice
To answer this question a weak spring does not load the valve train like a heavy spring. So the more spring presser the more valve train deflexion. When you have this deflexion you will open the valve later and close is sooner. When closing it sooner you are higher up on the lobe so the valve will seat at a higher velocity causing valve noise. The more aggressive the lobe to louder the valve noise. Another way to see how heavy spring presser has an effect is when you check VTP on a Race engine. Is you check VTP with a checking spring and you clearance is .02 then put the racing spring with the higher presser that clearance can jump up to as much as .055 so that would be the deflection in the valve train system.
08-20-2015, 07:05 PM
#7
I was obsessed briefly with the intense "ticking" with my first LS1, now? Meh, they all tick with a cam and springs. IMO its mostly the valves slapping back on the seats your hearing and very seldom an issue with the lifters. Ironically too much preload and they will run quiet but its not safe to run them with the same high factory pre load after a cam swap so consider it healthy ticking if everything is set up right. Headers seem to amplify the ticking sound too fwiw.
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08-20-2015, 08:51 PM
#8
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How do "stout" springs make more noise?
To answer this question a weak spring does not load the valve train like a heavy spring. So the more spring presser the more valve train deflexion. When you have this deflexion you will open the valve later and close is sooner. When closing it sooner you are higher up on the lobe so the valve will seat at a higher velocity causing valve noise. The more aggressive the lobe to louder the valve noise. Another way to see how heavy spring presser has an effect is when you check VTP on a Race engine. Is you check VTP with a checking spring and you clearance is .02 then put the racing spring with the higher presser that clearance can jump up to as much as .055 so that would be the deflection in the valve train system.
To answer this question a weak spring does not load the valve train like a heavy spring. So the more spring presser the more valve train deflexion. When you have this deflexion you will open the valve later and close is sooner. When closing it sooner you are higher up on the lobe so the valve will seat at a higher velocity causing valve noise. The more aggressive the lobe to louder the valve noise. Another way to see how heavy spring presser has an effect is when you check VTP on a Race engine. Is you check VTP with a checking spring and you clearance is .02 then put the racing spring with the higher presser that clearance can jump up to as much as .055 so that would be the deflection in the valve train system.
I appreciate the input. To be honest, I picked this cam because it was supposed to be "gentle" on the valve train. Originally, I was going to run the GM blue springs, but Lingenfelter was out of stock on the "matched" set of the blue springs. They gave me a deal on the .660" lift springs instead, so I went for it.
I get what you are saying, so my option is basically to deal with the noise? Right?
Andrew
08-20-2015, 08:55 PM
#9
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iTrader: (7)
I was obsessed briefly with the intense "ticking" with my first LS1, now? Meh, they all tick with a cam and springs. IMO its mostly the valves slapping back on the seats your hearing and very seldom an issue with the lifters. Ironically too much preload and they will run quiet but its not safe to run them with the same high factory pre load after a cam swap so consider it healthy ticking if everything is set up right. Headers seem to amplify the ticking sound too fwiw.
I am using the Hooker manifolds, so headers are not an issue. I have also heard that injectors can make a lot of noise and the fact that I have a Holley Hi-ram pocking through the hood can also magnify the noise.
At the end of the day, I am OK with the noise (mostly) I just want to know that this thing won't fall apart on me...
Andrew
08-20-2015, 09:02 PM
#10
Some injectors are very noisy. Regardless if the ticking is consistent, oil pressure is good, and its running well with no smoke out the tail pipe? Good to go imo. Worthy of note; I have noticed valve tip wear with cam/springs over time. Adding some ZDDP every oil change helps
08-20-2015, 09:30 PM
#11
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Some injectors are very noisy. Regardless if the ticking is consistent, oil pressure is good, and its running well with no smoke out the tail pipe? Good to go imo. Worthy of note; I have noticed valve tip wear with cam/springs over time. Adding some ZDDP every oil change helps
I am not running any sort of "special" (5-30 that was on sale...LOL) oil at this time, but if you have suggestions, I am all ears....
Andrew