What timing gear set for Vortec engine 350 block 880 / 5.7GXi?

[bollerwagon]

I would like to replace the timing gear on the Volvo Penta 5.7GXi I´m building. I am using a old GS engine block, but the part numbers of the parts seem to be identical:

3856114 cam shaft sprocket
3852685 chain
3852690 crank shaft sprocket

On the cam sprocket I took off the GS it says 12552129 but the small one does not have a number.

Summit recommended these two:
- Cloyes Street True Roller Timing Sets 9-1157
- Chevrolet Performance Timing Chain Sets NAL-12371043

But last time I asked them I got a CLO-C-3023X and that does not fit at all. So I would like to verify with you guys. I want it to be as stock as possible.

 

[Scott Danforth]

I ran a comp cam double roller set. there literally are about 200 different sets that fit and will work for an SBC.

the stock timing set is the cheapest thing that GM could stuff in the motor from either Mahle or Melling (both supply GM). I personally prefer to spend a little more on the timing set and the oil pump than what was "stock"

Ignore what VP has listed for the GM truck motor. get a timing set for a GM V8 truck motor

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Find CHEVROLET 5.7L/350 Chevy small block Gen I Cloyes Gear Timing Chain and Gear Sets COMP Cams Brand, MAHLE Original Brand, Melling Brand, Summit Racing Brand and get Free Shipping on Orders Over $109 at Summit Racing!

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Is your block align bored? if so, you need an undersized set.
you dont need billet
recommend double roller (less wear over time)

 

[bollerwagon]

I understand and agree to your idea of "oversizing" things. This is why I purchased the double roller (that doesn´t fit). But since the engine ran well the first 30 years with the single and cheap stock part, I thought that would be fine for the next 30 years.

The list you provided does also contain my CLO-C-3023X that has a sprocket that does not fit on the cam. How can I filter for the ones that work with my engine?

the block (and pistons) are .020 bored, but why would the timing be any different?

 

[bollerwagon]

I see GM offers only one timing set: Single Roller Timing Chain Kit
this is the same set that summit suggested with the part number 12371043.
If this is indeed the stock truck part, then the mappung of the GM and the Volvo Penta part numbers would be like this
chain GM part number 14088783 -> VP part number 3852685
crank sprocket GM part number 14088784 -> VP part number3852690
cam sprocket GM part number 12552129 -> VP part number 3856114

can anyone confirm?

 

[Scott Danforth]

Explain how it doesn't fit your cam

 

[bollerwagon]

Explain how it doesn't fit your cam

The diameter of the hole in the middle of the cam sprocket is smaller and the diameter where the holes for the screws are is also smaller on the Vortec cam sprocket.

I also have a AQ271C (pre vortec) in parts here, there the CLO-C-3023X with the larger diameter fits well. Maybe Vortec and pre-Vortec have camshafts with a different fit?

 

[bollerwagon]

The difference seems to be the cam side:
- flat tappet -> bigger diameter on holes of the cam sprocket
- roller tappet -> smaller diameter

Called Cloyes today, the guy gave me two options

• Cloyes Street True Roller Timing Sets 9-1157​

• Cloyes Original Race True Roller Timing Sets 9-3157​

9-3157 seems to be better material​