ARP 202-5402 head stud measurements taken!

[jt15833]

got a chance to install the head studs and take some measurements tonight.interesting stuff.

units are mmWP = water pump stud, the only one in question

distance from block surface to top of studWP = 102.72Others = 95.55

So our water pump stud sits roughly 7mm higher than the rest. Heres numbers that matter. From here out the only stud we are talking about is the WP, since the rest are assumed to work, or else this would be useless. Pinching theorem.

Distance from block surface to bottom of ARP nut, fully threaded on the top of stud (no head in place yet)-78.05

Distance from bottom of headbolt washer perch (in the head) to the head mating surface-77.49

Thickness of ARP washer2.99 (3 nominally)

Ok so there it is, we essentially have 80.48 mm of material above the block surface, and the threads begin 78.05 mm above the block. With a headgasket there will be even more margin.

For me this is still very close for comfort, but unless there is 2mm + of metal compression (noooooooo way) it should work with this ARP hardware, and no double / beefy washer.

Here's a pick with a different way of interpreting the numbers.

[r34 gtr]

Just tightening down that one on my car with the stock ARP washer I had a little play in it. When I used one washer on all the studs, the head gasket leaked in that spot. I mean, it could well work for you, but I tried it and it didn't work.

[jt15833]

I feel ya I am even still thinking of using 2 washers or getting a special super washer made at work, same inner and out dia. as my arp hardware but 5-10mm in height just because of what you speak of.

But I will try it first without, just looking at the stud and head installed, because it's hard to argue with numbers. It should work... 77.5 mm of cast aluminum head material to torque down to 80ft-lb's with less than 75mm of clamping length (bottom of torqued nut - washer - headgasket).

Also for using 2 washers if you use stock one as the lower, it's covered from the lifter by the perch. The arp's are smaller and not only fit around the stud tighter, they also don't have as large outer diameter to contact the lifter.

I threw my last felpro away, I was going to measure it's thickness. Anyone know this roughly for a fully compressed HG?

Did your #1 cyl. leak on compression test r34?

[HighwayStar22]

Random, but just to make sure I'm clear, this is when you are using the SR20 Main stud kit from ARP correct?

I have the CA18DET specific head stud kit from ARP. I searched and searched but don't see anything on this type. Just the SR main stud-to CA head stud topics.

*edit* I'll check my part number tonight. I didn't see that in the title. doh!

[r34 gtr]

I had no problems with compression, but the oil passage right next to the stud didn't seal properly, and it leaked oil out the side until I went back in and sorted it out. Now it leaks out of the front main seal. CRY!!

Just so its clear, those two lifters I showed you pictures of were from the exhaust side, from the #1 cyl.

It also should be mentioned I was running a Nismo 1.2mm MLS head gasket.