rcwilbur

I just finished installing TSP 5.3 heads and 224R cam on my 99 C5 Corvette with manual transmission. I finished tuning the VE and MAF and ran it at wide open throttle. AFR at WOT is 12.8. The ECM is pulling as much as 10 degrees timing--to about 18 degrees in some places. That seems like a lot.

I also get a little knock in sixth gear at 2400-2800 RPM, but only taking out one degree so that part is easily correctable.

I changed the timing to 18 at WOT, but will not be able to run the car until this coming weekend--we got a big snow storm here in Illinois yesterday.

Just wondering what others have for timing with similar heads/cam. I also have LG Street Headers and Blackwing Intake. Thanks.

redtan

iTrader: (5)

28 degrees at WOT with that setup seems steep...but it should be able to take more than 18 degrees, so try something 20-23.

Was this timing being pulled because of knock, or because of other factors (IAT, ECT)

rcwilbur

The timing is being pulled because of knock. At wide open throttle KR pulled as much as ten degrees.

Perhaps I should start with 20 and see how it works?

redtan

iTrader: (5)

I would honestly start looking elsewhere first, like seeing if there's something banging around the engine causing false knock or if your wideband is calibrated correctly and you are indeed running 12.8 AFRs.

10 degrees of knock seems excessive, even with 28 degrees of timing. Start around 20 and see how much it likes.

HCI2000SS

iTrader: (2)

Well I have those heads and Texas Speed said they usually set it at 28 or so. I'm going on the dyno in a few weeks though, so i'll soon find out

rcwilbur

Thanks for you help. It sounded excessive to me too. I calibrated the wideband before starting and it seems to be accurate because it is showing 14.63 when the narrowbands are switching. Is there some other way to calibrate it to make sure it is accurate?

Interestingly, I looked at a stock 2001 LS6 timing map and it is pretty significantly lower than a stock 1999 ls1 map. In the wide open throttle area timing is between 22 and 23 depending on the cell. Texas speed told me that these heads would produce more compression (somewhere around 10.95 to 1) so maybe 20 is not too far off.

I will have to wait to try because it is still winter here in Central Illinois. Getting tired of all this #### snow.

rcwilbur

Probably not comparing apples to apples, but stock timing for a 2000 5.3 liter chevy Silverado is 15-19 in the same area of WOT.

badazz81z28

iTrader: (6)

I would be conservative on the timing until you can get it on the dyno. That will tell you how much timing to can run, but keep in mind balance between power and fuel economy.

rcwilbur

Redtan,

Thanks for your response. I am starting to pull my hair out here. The wideband shows 12.76 (the commanded AFR). I reduced the WOT timing to 18 and it is still pulling a couple degrees of timing. I am new to all this.

How would I determine if it is false knock. I don't hear any knock at WOT, but may miss it because of the engine noise generally. I also see there is a way to desensitize the knock sensors, but that seems risky if this is in fact true knock. Any suggestions you might have would be greatly appreciated.

flattusmaximus78

iTrader: (1)

Any chance of carbon build up? $10 dollars and 2 minutes and some waiting to see. My kr was incredibly audible and my car is loud as hell.

rcwilbur

There was some carbon build up on the piston tops. Attached is a picture of the pistons.

I could hear some slight pinging at low load in 6th gear, but took care of that by taking out a few degrees of timing. However, the engine is pretty loud at WOT and 4000-4500 RPM--I'm not hearing anything audible.

When you say $10 is that for a can of sea foam or some other product?

Thanks very much for you help!!

flattusmaximus78

iTrader: (1)

My car had a fresh engine, but sucked a ton of oil in through the pcv. I found out way later then I had wished. I hardly every beat on my car, but I put a ton of miles on it, so that didn't help. I'd rip on it or race it maybe 1 time every other month, but put 250 miles on it at least. At first when I was wot, I though the black trim up front that says camaro was flapping in the wind. Then one day I was doing pulls with other cars and it sounded like marbles being rattled... it was the same noise, but constantly through the rpms.

I also noticed this sound in a situation like yours. When my tc locks up at 39 mph my rpms drop to 1300. With 3.27's and a big cam if I give it more than 10% throttle it'll ping. It can pull as much as 6*. This weekend I'm ganna raise lock up to 45+ mph so the rpm drop isn't as low so I can put load on the car and not get ping.

I used seafoam one time through the brake booster. People say it doesn't work at all, but it cleaned a lot of oil off my spark plugs. My intake was oily before the procedure, but I never checked afterwards since the kr was gone. I also ran a husky filter to catch any oil being sucked into the intake.

I tried mopar combustion chamber cleaner. It's safer than seafoam. It is an actual spray you spray into the pcv hose. It coats the walls of the top end. I popped my intake tube off and it had attached to all surfaces. Something to think about considering the above pic.

redtan

iTrader: (5)

You don't really, but to me it sounds like you are getting false knock due to the sensors picking up some sort of sound that may sound like actual engine knock. 18* and still pulling timing is odd. I would check around the engine compartment and see if anything is loose or banging on other components. Check the exhaust, steering knuckle, behind the engine etc.

Do not desensitize the sensors in the tune, that's not the right way to go about it. You want to find out where the knock is coming from before you start doing that. But even then, you still want those to be on and working properly incase there is true knock inside the cylinders.

rcwilbur

Yea. I didn't think desensitizing the sensors was right--it just destroys the protection you would otherwise have.

I will look around the engine compartment, but I think everything is in order. The valve train makes significantly more noise than the stock valve train. I noticed more noise when I added the LG Street headers, but the heads and cam added even more noise. I guess the higher lift and stronger springs makes it noisier, especially echoing through the LG headers.

Thanks again for your help.

rcwilbur

These engines apparently are know for burning oil. Is the Husky Filter something that local auto stores sell?

JakeFusion

iTrader: (7)

26-28 is generally where the timing falls with an all aluminum setup. Is your 5.3 iron? If so, you might only be able to run 23-24.

I would have cleaned the pistons before reinstalling the heads. And run an oil catch can to keep oil out of the intake tract.

flattusmaximus78

iTrader: (1)

Home depot or lowes will carry it for about $15 or so. Get some 3/8th tranny line with some brass fittings. One side connects to the pcv, flows through the filter then into the intake port behind the tb.

rcwilbur

Thanks. It is an aluminum block. That is the problem being new to all this and doing it without anyone who has experience. I wondered about the pistons, but then just proceeded ahead because I thought it must be normal.

I know otherwise now and am trying to correct it and hopefully get timing somewhere near where it should be. I'm going to try the sea foam procedure I saw posted here. I hope that removes the carbon buildup and corrects the issues.

I am going to install some kind of oil catch can as you suggest. Thanks.

rcwilbur

Thanks.

JakeFusion

iTrader: (7)

Negative on sea foam. I wouldn't do that ****.