Unfortunately, the washers weren't included by mistake in the ARP HG kit I ordered. Now in a pinch. Wondering if I can use these grade 8 washer's I found at NAPA?

 

Washer is used to distribute the clamping force and protect the aluminum, so that washer should be fine. In this case the thickness is more important than the grade.

 

Yes, I'm concerned about the thickness. After a massive two hours of Google searching, I can't find the thickness of the washers - they are 3/16 which I believe means M10 but can't find any more info. Do any of the experts on here know the specs? Based on the ARP kit stock photos, the ARP washers look thicker than what I found today at NAPA.

 

Why not contact the company that sold you the kit and get them to send the washers or a whole new kit? I know that will take time.

 

In a pinch the washers could be doubled up. I would do that only if I had no other choice, or if we were at the race track getting ready for the final. The thickness helps distribute to force over a wider area. Once the gasket seals, there is nothing more to worry about.

Some local hardware stores have a good selection of heavy duty washers and such, but takes time searching... inside diameter, outside diameter, thickness... and the clock is ticking, especially after google time. Google helped me find this: 3/16 inch is just shy of 5mm. 3/8 inch is a bit less than 10mm (M10). I might order some washers from McMaster-Carr if I had time, but that would still leave the original supplier as the best option.

 

Yep, that is what I ended up doing... It was a matter of it taking time

 

Yes, it was a matter of wanting to take advantage of the time that I'd had carved out to work on the car. Frustrated with the original supplier; however, they did make it right and the washers eventually found their way to me although lost quite a good chunk of time

Thank you for all the expert thoughts/advice