Camshaft Position Retard.

[ZR2_350]

I have a s10 with a 5.7L Vortec in it. i was told by a friend of mine that i should make sure that the CPR should be set to 0*, i logged my truck while idling( having other problems and can't drive it right now) and it is showing that my retard is at 102*...

I'm almot positive that the distributor is in right, or atleast not 103* off. For that matter i don't see how it would even start with it that far off.

Could someone tell me if this is a direct correlation with how the dizzy was put in, and perhaps what i can do to get it to 0*.

I've driven the truck and it doesn't stumble or feel like it is missing at all, while logging there aren't any misfires either.

I've attached the log file for those interested.

[Taz]

Hello ZR2 350,

I don’t do Vortec tuning, and am definitely not an expert on this platform. I am reasonably certain that Camshaft Position Retard, when measured by a scan tool, is not accurate below about 1200 RPMs.

Trying logging CPR again, with the engine speed at or above 1200 RPM throughout the duration of the log. I also believe CPR tolerance is between 0 and 2 degrees.

Again, not my area of expertise ….


Regards,
Taz

[ZR2_350]

Hey thanks Taz,

I went and checked it out, it didn't change things though. However i did turn the distributor and it got closer. I ran out if movement so i only got it down to 19 or so.

I am confused on this, does that mean i have the distributor in too far advanced? Retarded? I am thinking that it's advanced since the computer is trying to retard the timing. Since i had to turn the distributor all the way clockwise, i would have to realign the distributor with the rotor farther ahead than before? or am i looking at this backwards? LOL...

[Taz]

As I understand it, the CPR exercise is to confirm the CMP and CKP are synchronized. At this point you should confirm alignment / synchronization of components.

Was the camshaft or timing chain / gears replaced ? If so, confirm the alignment marks of these components are properly oriented.

I take it the distributor was removed at some point. You will need to confirm its installation - by locating TDC compression stroke on cylinder #1 - then confirming distributor orientation.

It is very easy to be “off” by a tooth or two on the above components …


Regards,
Taz

[ZR2_350]

This is a fresh rebuild with about 4k miles on it. I just recently had to replace the head gasket (don't ask, long story LOL..).

Upon the initial install i did not have EFI Live so i can't be positive that it was or was not happening prior.

I'm positive the timing set was installed properly.

I will double check the distributor and go from there, Thanks Taz.

Is there anything that stands out that you can see in the log i posted?

Thanks.


I would of posted this in the Vortec specific section, but for some reason i was not seeing it. Mods can move according...

[ChipsByAl]

You need to retard the distributor. Loosen the clamp, take off the cap, slowly lift the distributor and turn the rotor back over to the next tooth. Have an assistant spin the engine over while you gently push the distributor back down to the intake.
Al

[ZR2_350]

Thanks, I've gotten it to -11.xx degrees now. I went one tooth too far, but at least i am on the right track. I can't believe how smooth and free revving it is, not to mention it idles way better now. I appreciate the help.

[nevinsb]

Welcome fellow s10'r. Glad you got it sorted out. Didn't you have a check engine light from the distributor being that far off?

[ZR2_350]

Surprisingly enough i didn't have a 1345 code. That probably wouldn't of helped me any anyway. EFI Live is what helped.. that and the friend who told me about it.

[tokymon]

if you're still runing a black box pcm search "411 pcm" it well worth the upgrade

[ZR2_350]

Yeah, i got lucky with my truck when it comes to tuning. My truck came stock with the 0411. I do have a buddy that has a 97 fs that has the black box i've been trying to convince to make the change.