About the head bolts on the A15(with A14 H72 head). The smaller diameter head bolt which goes in the center is smaller in diameter on its body(lenght)...but the thread is the same as the rest of the bolts, right? or else I messed up, because I cleaned all the threads in the block with the tap # 10 X 1.50
I think the threads are and must be the same, otherwise this bolt would not torque the same as the rest, but I want to double check before final assembly. I can not find any info on the exact size for the bolts, not even the dealer knows.
Jaime.

Yes, you got it right -- the threads are the same. Just the body diameter slims down in the middle of the bolt.

This seems like an important issue, does anyone have an example of each, so they could take a photo and publish it here for reference?

Chris.

Quote:

This bolt you refer to forms part of an oil gallery which supplies oil to the rocker gear. It is important that you put the bolt back in the right place otherwise your engine will come to an untimely end.

Benny

Cool, thanks for the piece of mind, for a moment I thought that I might had messed up the thread and enlarged it, but it is the same thread, I suspected it(after I tapped all block bolt housings)... but should had been more carefull, I could had messed up if it was not the same size.I just forgot about it, got carried away with my new Craftsman Die n Tap set, and started having fun. Do not worry guys, I will make sure I reposition it in the right place, I cleaned the bolts too with a die,and the new bolts I bought, I will keep them for my performance rebuilt after smog(july), the car will be exempted from smog forever, so I will rebuilt the A15 to monstrous specs, and even in the event I use the L20(610's) later on, the A15 will go to the rallye ute. The bolts I got, I ordered for the A15, but after checking with my catalog, I got GX super bolts, I know that because my nismo catalog says GX stronger bolts have a number 13 stamped on the head of each bolt, which is the case with this set.No reason to use them now, this is a stock engine with a 32/36 Weber, but after a more compression build, they will come in handy. Dattodude, I will take pictures, so I will post them when developed, I will photograph both bolts for reference.

Anyone know if ARP makes head/main studs or rod bolts for A engines?

Yes, they do. The search box should show up some links.

I have Arp cylider head bolts in my A15.

Here is picture of those:http://www.sunpoint.net/~finndatsun/arp.jpg

Arp bolts are really good, I have used 1.5 bar boost in my A15, Twin dellortos, Garret T25.

I have payen standard head gasget.

Here is picture of my engine:http://www.sunpoint.net/~finndatsun/a15t.jpg

Finn, that is a very impressive looking A15!

Thanks for the help finn!