Virgin engine builder!

[marco]

I aquired an engine a while ago (it was cheap!) it's an Ad code engine based on an as21 case with an alleged low mileage. It was a vw recon engine (has vw stamp with 'recycled' symbol on it. It has all genuine vw crank etc
Bearings showed some sign of wear so putting new ones in.
Now, I have weighed the conrods and they're all way out, at least 14 grams between lowest weight and next one up! I was lead to believe that the engine was a vw built unit, the previous owner couldn't remember if short or long block.
Question is why would there be such a difference?
And is it critical?
Just want to build a budget engine that doesn't leak, and gets us from the lakes to devon / cornwall every summer!
Thanks in advance, and apologise for the waffling

 

[mr scoops]

I am surprised they are that far out!
I have a spare set of VW rods in the garage from stripping an engine.
I'll weight them and see what they come in at.

 

[marco]

Yeah, exactly my concern! I expected a few grams, maybe 5 max!

 

[marco]

Don't really want to build it back up if it's going to rattle itself to pieces!

 

[mr scoops]

Ok, I'll weigh the rods I've got this evening.

 

[marco]

Actual weight of all four!!
1 - 656g
2 - 641g
3 - 644g
4 - 630g

 

[atafonso]

Vw tolerance was 5g max, they had a few different rod weights but always matched their sets within a max of 5g from each other. They had some paint marks to differentiate them, but by now the paint is gone.
Do not assemble it this way as it will bring inbalance and make your engine not only vibrate slightly but also accelerate the wear.
26g is a lot! You have two rods from the same group and the other two are from two different groups. The solution is to either get another matched set, or ask around for loose rods, then hopefully you can find two of the 640ish group.
Abel

 

[marco]

Thanks Abel, you confirm my fears! The case and crank need sorting too, there is play in the thrust bearing saddle, so a thrust cut is required. So this cheap rebuild is fast becoming anything but!!!

 

[atafonso]

You can ask as many questions as you want, i can help you no probs
If you want, i can PM my number and we can talk through whatsapp, it will be quicker.
Abel