ANOTHER Cam Selection Thread
10-20-2018, 04:38 AM
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ANOTHER Cam Selection Thread Long time reader, first post. I’m new to LS engines, but not to engines in general.
I bought an LQ4 a little while back, fairly complete, but knowing from the previous owner that there was a knocking sound and no oil pressure upon initial fire-up in his truck. (Long story short: he bought this engine as a replacement for his original [blown up] engine, and this one had its own set of problems. He wound up getting yet another engine, and this one sat in his garage for a year, which is where I come in.)
I finally got around to tearing it down, and found the source of the knocking sound, and a probable source of the lack of oil pressure: the number 1 and 2 rod bearings were spun and wasted, and that rod journal is scored up pretty badly; one of the cam bearings spun as well, and there are metal shavings throughout the engine block, so it looks like it was run with no oil, or very little. The oil pump is clean inside, and shows little to no wear. I’m pretty sure the crank can be saved, but the cam is wasted. That’s the worst of it. This was a 90,000 mile engine.
The upside of it all is that the cylinder walls still look good, and likely could be cleaned up with a hone. Also, the heads, pistons, rockers, valves, lifters, and pushrods all appear to be in good shape. The crank spins freely. So crank grinding, rod resizing, new bearings, rings, hone, ARP stuff and gaskets, and I’m good.
Except for cam selection. I’m planning to either supercharge or turbocharge this engine eventually, so I’m wondering how the LS9 cam will run N/A with 317 heads, the truck intake and cheap shorty headers until I decide (can afford) to boost it. I plan to keep the 317 heads, BTW, and I’d like to keep them stock except for springs. I understand about LS2/cam sensor stuff. Or should I get another cam to run in the meantime, that is more suitable for basic DD service until later.
The car is a 1970 Chevelle. Transmission will be a 4L80E, and it already has a 9 inch rear with 31 spline axles and 3.89 gears. Horsepower goals are modest: 450-500 RWHP. If this was a little long, I apologize. I’m trying to make sure that all pertinent information is included. Thanks in advance for any and all advice.
I bought an LQ4 a little while back, fairly complete, but knowing from the previous owner that there was a knocking sound and no oil pressure upon initial fire-up in his truck. (Long story short: he bought this engine as a replacement for his original [blown up] engine, and this one had its own set of problems. He wound up getting yet another engine, and this one sat in his garage for a year, which is where I come in.)
I finally got around to tearing it down, and found the source of the knocking sound, and a probable source of the lack of oil pressure: the number 1 and 2 rod bearings were spun and wasted, and that rod journal is scored up pretty badly; one of the cam bearings spun as well, and there are metal shavings throughout the engine block, so it looks like it was run with no oil, or very little. The oil pump is clean inside, and shows little to no wear. I’m pretty sure the crank can be saved, but the cam is wasted. That’s the worst of it. This was a 90,000 mile engine.
The upside of it all is that the cylinder walls still look good, and likely could be cleaned up with a hone. Also, the heads, pistons, rockers, valves, lifters, and pushrods all appear to be in good shape. The crank spins freely. So crank grinding, rod resizing, new bearings, rings, hone, ARP stuff and gaskets, and I’m good.
Except for cam selection. I’m planning to either supercharge or turbocharge this engine eventually, so I’m wondering how the LS9 cam will run N/A with 317 heads, the truck intake and cheap shorty headers until I decide (can afford) to boost it. I plan to keep the 317 heads, BTW, and I’d like to keep them stock except for springs. I understand about LS2/cam sensor stuff. Or should I get another cam to run in the meantime, that is more suitable for basic DD service until later.
The car is a 1970 Chevelle. Transmission will be a 4L80E, and it already has a 9 inch rear with 31 spline axles and 3.89 gears. Horsepower goals are modest: 450-500 RWHP. If this was a little long, I apologize. I’m trying to make sure that all pertinent information is included. Thanks in advance for any and all advice.
10-20-2018, 10:39 AM
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The LS9 cam will be fine since you do plan on huffing it sometime. I would still put a new high pressure oil pump (Melling 10295) as added insurance. The way the rest of the engine was trashed, I would not trust the old pump.
10-20-2018, 11:50 AM
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Thanks for your reply!! High pressure or high volume? Or both? The reason I ask is because back when dinosaurs still roamed the earth, we used to shy away from high pressure oil pumps in our SBCs because of the fear of the pressure wreaking havoc on our gaskets and seals
10-20-2018, 01:44 PM
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Gaskets and seals on LS engines are way different than back in our day. You do NOT want high volume as it is just not needed. High pressure is added insurance and won't hurt a thing gasket and seal-wise.
10-22-2018, 12:35 PM
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10-22-2018, 01:12 PM
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I’m sorry, I should have pointed out that I’ll probably be using an aftermarket computer for the engine and trans (this engine didn’t come with an ECU/PCM), and since I’ll be using the LS9 cam, I have to change to the front cam sensor anyway, correct?
10-22-2018, 01:32 PM
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Does the aftermarket computer necessitate the 58x reluctor? Which one are you going to use?
True, the LS9 cam does use the front cam sensor, but that can still be used with the 24x reluctor.
True, the LS9 cam does use the front cam sensor, but that can still be used with the 24x reluctor.
10-22-2018, 02:25 PM
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No, I can choose between 24x and 58x. I remember reading somewhere that the 58x reluctor/sensor was capable of higher resolution. There is no price difference in the computer between the two, mostly I was wondering if there was any sort of advantage to using one over the other.
10-22-2018, 03:13 PM
#11
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I doubt it's enough of an advantage to offset the cost of tearing apart the engine just to change the reluctor. In other words, you won't feel the difference.
10-22-2018, 07:15 PM
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58x vs 24x
I'm guessing the engine will be coming apart to fix the other issues. So I'd strongly consider 58x.
I recall seeing Pantera EFI mention NA the more accurate timing with 58x could allow for up to half a point more compression. He was key player involved with development of the 58x system. If I recall correctly 24x in a running engine can have the timing vary by 1-2 degrees. The 58x variance is about half of a degree.
The more accurate 58x timing would in theory allow for more hp due to more precise tuning. Given that LSA superchargers are used factory with the 58x set up also helps sway me toward favoring the 58x set up.
If think 58x has the edge if it's not too much hassle to use the matching electronic gas pedal & drive by wire throttle body.
FWIW - that's my .02
I'm guessing the engine will be coming apart to fix the other issues. So I'd strongly consider 58x.
I recall seeing Pantera EFI mention NA the more accurate timing with 58x could allow for up to half a point more compression. He was key player involved with development of the 58x system. If I recall correctly 24x in a running engine can have the timing vary by 1-2 degrees. The 58x variance is about half of a degree.
The more accurate 58x timing would in theory allow for more hp due to more precise tuning. Given that LSA superchargers are used factory with the 58x set up also helps sway me toward favoring the 58x set up.
If think 58x has the edge if it's not too much hassle to use the matching electronic gas pedal & drive by wire throttle body.
FWIW - that's my .02
10-22-2018, 07:24 PM
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Thanks for your input. Yep, the engine is already apart, and the crank is going in tomorrow for grinding and polishing. No time like the present for another opinion on the reluctor.
That’s an interesting point regarding the LSA engines being equipped with the 58x reluctor, and one I hadn’t considered. Thanks for that.
Interestingly, my LQ4 came with the DBW throttle body, which was just another selling point for that particular engine as far as I was concerned. My Harley has TBW, and I love it.
That’s an interesting point regarding the LSA engines being equipped with the 58x reluctor, and one I hadn’t considered. Thanks for that.
Interestingly, my LQ4 came with the DBW throttle body, which was just another selling point for that particular engine as far as I was concerned. My Harley has TBW, and I love it.
10-22-2018, 07:39 PM
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Yeah, in light of the fact you must go thru the engine anyway, THEN go to the 58X, as 99Blackbird TA says. I didn't catch that pertinent little fact..
10-25-2018, 04:12 PM
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The crankshaft is coming home tonight, along with new Clevite bearings for the rods and mains. I’ll have have the heads rebuilt next week, after the new valve springs arrive from Scoggin-Dickey.
Its definitely going tk be supercharged, not turbocharged. I got a used LSA supercharger off eBay today, along with a ZL1 lid. I’d post photos, but y’all know what that stuff looks like.
Its definitely going tk be supercharged, not turbocharged. I got a used LSA supercharger off eBay today, along with a ZL1 lid. I’d post photos, but y’all know what that stuff looks like.
Last edited by AtomiCapricorn; 10-25-2018 at 07:16 PM.