Timing chain set

[Denalibro76]

Replacing the timing chain set on my 2003 Yukon with the LQ4. Is it just a 1 pole reluctor?

 

[OR VietVet]

Are you doing the oil pump at same time?

 

[Denalibro76]

Are you doing the oil pump at same time?

Yes. Full rebuild. There is a strong possibility that I will have to go oversize on the bore. Haven’t pulled the motor yet. Can anyone chime in if I can go up to the 6.2 pistons and not change the heads? Currently a stock LQ4.

 

[Doubeleive]

@iamdub @swathdiver @randeez

 

[OR VietVet]

Why are you rebuilding? More cost effective to do a 6.0 swap?

 

[iamdub]

Replacing the timing chain set on my 2003 Yukon with the LQ4. Is it just a 1 pole reluctor?

Yes, it has a 1x reluctor on the cam.

 

[Denalibro76]

Why are you rebuilding? More cost effective to do a 6.0 swap?

The engine has 240k miles on it. Already have new BTR valve train and truck norris cam. Didn’t want to go buy another motor not knowing the condition of that one. If I rebuild mine I know what i have and the satisfaction of the process .

 

[iamdub]

Yes. Full rebuild. There is a strong possibility that I will have to go oversize on the bore. Haven’t pulled the motor yet. Can anyone chime in if I can go up to the 6.2 pistons and not change the heads? Currently a stock LQ4.

Boring the LQ4 to 4.065" isn't unheard of, but it's kinda sketchy. Also, there are two different blocks and one of the differences is thicker walls. The block differences may have coincided with the change from iron to aluminum heads. It's been years since I've researched all this. It's probably okay in a truck engine kept at stockish RPM and power levels. If it needs boring, I'd keep it at .030" and get off-the-shelf overbore pistons. Them 317s will work fine. I'd recommend shaving them while they're off for a fresh and flat surface and to bump up the CR a little for some extra pep while still being 87 octane friendly.

 

[Denalibro76]

Boring the LQ4 to 4.065" isn't unheard of, but it's kinda sketchy. Also, there are two different blocks and one of the differences is thicker walls. The block differences may have coincided with the change from iron to aluminum heads. It's been years since I've researched all this. It's probably okay in a truck engine kept at stockish RPM and power levels. If it needs boring, I'd keep it at .030" and get off-the-shelf overbore pistons. Them 317s will work fine. I'd recommend shaving them while they're off for a fresh and flat surface and to bump up the CR a little for some extra pep while still being 87 octane friendly.

Ok thanks!! Yeah I don’t like sketchy so I’ll probably just step it up a little . Maybe I’ll get really lucky and I won’t have to at all. Be nice to not have to spring for new pistons but I’ll most likely have to.

 

[RAMurphy]

As @iamdub already mentioned I wouldn't go above 4.03 if you need to increase bore. The engine I'm building is bored to 4.03 although I believe you could go higher (up to 6.2) based on my research. Whoever will do your machine work could give you better insight.