I am tuning my first lm7 timing and am used to SBC timing. my total timing on the SBC was 36ish. My current timing on the 5.3 is set at 28. Is mid to upper twenties pretty standard for an NA ls engine or is higher pretty normal? What do you tend to see for maximum timing for maximum power output?
I don't own a dyno but I stop around 24-26 on just about everything. I'm sure in some pretty wild applications they will still make great power all the way out to 28-30 degrees of timing.
I see no reason in a LM7 even with a camshaft to run 28-30 degrees, but that is my opinion.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
that is about what i was thinking. during my tuning process I went to 26 and logged then went to 28 and logged. I didn't get any knock but did drop 25 calculated horsepower which could also be attributed to the 30F increase in ambient and intake temp. I was going to run it at a cooler temp and see hoe it did before adjusting anything else.
I have a cammed 5.3 with exhaust and intake. What kind of rpm is a stock bottom end good for?
If you have good valve springs you could run it to 6,400+. I've seen guys with 4.8's run them close to 7,000rpm.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
I have my shift points set to 6250rpm currently but I am still gaining power up to that point. Was thinking about trying 6500 then maybe 7k to see if or when the power drops off.
The camshaft has to make power there, otherwise you are just wasting your time revving it that high.
Whoever you bought the camshaft from will have the cam specs and where it's designed to make power. If it stops at 6,200-6,300 it's no use to spin it to 6,500 or 7,000.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
the rpm range says idle to 5000 rpm however I am still making power significantly higher than that. it is a low lift cam with a 523/524 lift and 218/227 duration. was trying to avoid springs then had a little anxiety about them and got some anyway. I do have a higher rpm short runner sheet metal intake though.
Without a dyno we are both just guessing here. I wouldn't say you need to spin it a hell of a lot higher, maybe a few hundred rpm give or take.
If you have a good stall converter for that size camshaft you do want it falling right back into the meat of the hp/torque curve.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
lol, still the stock converter. Just trying to get everything out of the tuning that I can. it is in a 1940 chevy pickup
No stall is surely not helping at all. Can't get around that with tuning.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Those cam specs line up with the summit stage two truck cam (8701) that has a power band of 2200-6500 with at least new ls6 style valve springs. You definitely need at least a 2200-2600 rpm stall converter, otherwise the bottom end will be much weaker than a stock lm7 cam. I run the stage one truck cam in mine, and it does great with a mild converter, but it ran ok on the stock one for a good while.
As far as timing. My personal truck runs best at 22-23 degress of timing. Any more will and it will show knock on the log. My dad's 6.0 2500 is at 24-25 since the lq4's have a lower compression ratio. Hope that helps.
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
I have been logging as I increase the timing and I am getting some false knock on the first wot pull but none of the rest. even at 100F ambient I am seeing no knock on any of the pulls outside of the first pull for some reason. I built this setup just for a fun street truck to race every once in a while so I didn't put a bigger converter in it. I am still running the stock 4l60e. And to top it off, it is kind of a PITA to pull the transmission out. The cam I bought is the jegs cam and that is what they say for the powerband on the website, that is where I got the information. I mostly was interested in if the stock bottom end would be ok to run at 6500 or 7k for shift points and what everyone is running for timing to see if these are similar to SBC timing or if they were seeing less timing. Thank you for the responses!
The stock bottom end will handle the rpms, but the rest of the valvetrain has to be in line or you can hurt lifters, pushrods, etc. I'm pretty sure the Jegs cam and Summit are made at the same place. The summit specs are identical to the ones you listed. 522/524 lift 218/227 112+2 lsa. The timing on ls engines tends to be far less than generation 1 sbc engines, but they will make more power with just a cam change and will turn some rpm. Your cam should make peak power around 6200-6500rpm if the rest of the valvetrain is stable. Good luck with your tuning. Word of advice though, most knock retard is not false knock. Sounds like you have cool hot rod truck. I hope to find a 65 chevy truck soon.
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
there are several trucks around here from the mid 60"s that are for sale. This is my most recent log with several pulls. If you could give me your opinion on the knock you see that would be great! I have put new ls6 springs in already.
As a side note. As engine efficiency the timing needed will decrease. If you compare inefficient cylinder head designs of the 60 they needed LOTS of timing. Modern cylinder head and piston design has changed all that.
I was going to post a couple pics of it but the forum isn't letting me add them.
Richard holdener has done a bunch of different dyno videos and with either a stock cam or a pretty wild cam, he said they made peak power at 29 degrees in the higher rpm range. And lower at peak torque and lower even below peak torque. And I have ran just over 7000 on multiple different engines with bigger cams and the only issue I have ever had was a broken weak gen 3 timing chain broke, which took out the whole engine. I would put at minumum a better timing chain and good valve springs if you plan on revving it much.
Last edited by ryan_axberg; 07-16-2021 at 10:43 PM.
I have watched a crap ton of his videos but never really payed attention to his timing stuff, I will see what I find. I do have some.550 lift springs in it.
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