Performance Timing Table Chevy 5.7 Liter TBI ECM 1227747

[dave w]

Below is a .pdf document showing a performance timing table I've used on dozens of stock or nearly stock Chevy 5.7 Liter TBI engine using the 1227747 ECM. I strongly recommend Adjusting the VE Table when making any changes to the timing table! Use at your own risk!

dave w

[EagleMark]

Ahhhhh? You built that in a mask/XDF that does not take out the "SA - Spark Bias - Main"

So if someone add's that table to my $42 XDF it will be 9.84* to much!

[dave w]

Ahhhhh? You built that in a mask/XDF that does not take out the "SA - Spark Bias - Main"

So if someone add's that table to my $42 XDF it will be 9.84* to much!

Below are a couple screen shots showing the same timing table, one with the $42 TunerPro website .xdf and Marks V5.9.2 .xdf.

dave w

[EagleMark]

[tolow4phathoes]

Sorry not trying to be a noob haha. But If I add that table to the bin I have downloaded from this website which happens to be the ones you guys mention. My tables should look like the first pic? And if using the bin from tunerpro website it should look like the second pic?

[EagleMark]

Bin is the same. The issue is the XDF from this website automatically removes the Spark Bias so what you see in spark Advance table is actual timing. Not timing with 9.84 degrees added to it. (if small block, if big block there is no bias so any XDF will show actual timing)

[Fast355]

Below is a .pdf document showing a performance timing table I've used on dozens of stock or nearly stock Chevy 5.7 Liter TBI engine using the 1227747 ECM. I strongly recommend Adjusting the VE Table when making any changes to the timing table! Use at your own risk!

dave w

Not doubting you have used those values with suucess but in my heavy van I saw good results with more initial timing and a quicker advance curve and less total timing.

[EagleMark]

And a little lightener car would be better with more, depending on heads. Even a big heavy truck can be totally different if it has some tall gears! So it's only a guideline. Watch your knock sensor counts!

But I gotta add a little warning for those finding this and not taking into consideration some other adders to spark!

First is "SA - Max RPM for Spark Slope" which adds timing after the 3600 RPM because that is as high as the Spark Advance table goes in these 7747 $42 ECM. So say a stock ADSU chip adds 5.05 degreees per thousand but it only adds to "SA - Max RPM for Spark Slope" 4200 RPM so that's about 2.5* which it no longer needs with a table like this.

Then there's "SA - PE Spark Added" which will add up to 4.92* which is no longer needed... or can be played with.

What I'm getting at is with Dave Spark Advance table total at WOT of 31.99 + the Spark Slope of 2.5 + the PE spark of 4.92 you could end up with 39.41 total advance by 4200 RPM! Which is to much for any street vehicle on pump gas!

Watch your knock sensor counts!

[dave w]

I saw good results with more initial timing and a quicker advance curve and less total timing.

Stock camshaft?

dave w

[Fast355]

Stock camshaft?

dave w

Yes, the stock GM "395" roller camshaft. However the engine was 8.75:1 and had piston oil cooling jets. I had 1.6:1 full roller rockers and doug thorley tri-y headers on it along with an edelbrock 3704.

[dave w]

Yes, the stock GM "395" roller camshaft. However the engine was 8.75:1 and had piston oil cooling jets. I had 1.6:1 full roller rockers and doug thorley tri-y headers on it along with an edelbrock 3704.

Thanks for the reply. Good information to know when setting up the timing table. Most all stock TBI motors (light pickups) have very mild flat tappet camshafts with a lift of .351 / .386 (very likely to be the lowest lift cam GM used in the Chevy 5.7 liter engine). The timing table I posted works great with stock flat tapped TBI camshaft I describe. The "395" cam mentioned, (if I'm remembering correctly) has a lift of .414 / .431. If I'm remembering correctly the .414 / .431 roller camshaft was used in the "Police" TBI 5.7 liter in the early 90's. In all fairness, camshaft comparison is not exactly apples vs. apples (roller vs. flat tappet vs. lift profile).


dave w

[Fast355]

Thanks for the reply. Good information to know when setting up the timing table. Most all stock TBI motors (light pickups) have very mild flat tappet camshafts with a lift of .351 / .386 (very likely to be the lowest lift cam GM used in the Chevy 5.7 liter engine). The timing table I posted works great with stock flat tapped TBI camshaft I describe. The "395" cam mentioned, (if I'm remembering correctly) has a lift of .414 / .431. If I'm remembering correctly the .414 / .431 roller camshaft was used in the "Police" TBI 5.7 liter in the early 90's. In all fairness, camshaft comparison is not exactly apples vs. apples (roller vs. flat tappet vs. lift profile).


dave w

Dave,

Not sure where you got your cam info from, but only the B/D-car roller cam engines had that small of a cam. They had the "155" peanut roller cam in them. The police cam is the "156" and is the same as a L98 TPI 350. I have pulled apart numerous TBI 350 engines that had the "929" cam in them. .383/.401" lift and 193/204 duration, 108 ICL on a 112 LSA.

[dave w]

Dave,

Not sure where you got your cam info from, but only the B/D-car roller cam engines had that small of a cam. They had the "155" peanut roller cam in them. The police cam is the "156" and is the same as a L98 TPI 350. I have pulled apart numerous TBI 350 engines that had the "929" cam in them. .383/.401" lift and 193/204 duration, 108 ICL on a 112 LSA.

Fast,
The pic below is some of the information I have on SBC camshafts. Is the information in the pic correct?

dave w

[buddrow]

Ok, bear with me here if you will.

1. Are those cam specs cam lift or valve lift?
2. Mark, just out of curiosity what is "too high" for knock counts? my stock asdu runs about 20-40 on average. Conversely my buddies truck ive been tuning on, with the asdu bin had knock counts running ramped at idle not to mention on a drive. Ill try to log some this weekend and share with you. I did get it to idle steady and improved driveability over the asdu with the modded chip. need to lean out the low end a little but over all it runs reasonably well. I know there is still more there being a 383cu. in. though.

Happy Tuning,

Buddrow

[dave w]

Are those cam specs cam lift or valve lift?

Figures below the "Lift @1.5" are valve lift, using 1.5 ratio rocker arms. Cam lift multiplied by rocker arm ratio = valve lift.

dave w