Guys, I wanted to take a few minutes to post and let you know the final outcome of my 1.6 build and the effects of ARP head studs.
As you may remember, 6 mos ago, I installed the studs and fired the engine (dry) to get some heat into it, and then allowed it to cool completely down to retorque the studs.
This startup sequence allowed the head to expand and compress the head gasket, and I had lost over 30% of the torque values within the first 5-10 minutes of start up - which highlights two things:
First, those studs were doing their job. The bi-directional clamping forces of the studs allowed for the direct compression of the gasket - versus expansion of the cyl head and stock bolts - wherein the bolts (as I understand it) lose torque over the first 1000 miles, which is when the mfg's retorque is recommended.
Second, as noted above, such a quick drop in values would not have been observed when using the stretch bolts, which are uni-directional clamping devices subject to expansion in synch with the aluminum cylinder head and, depending on driving styles, could IMHO render the 1000 mile spec arbitrary and possibly reduce longevity of the sealed surfaces - though I don't have any data to support it. Maybe others can chime in and share their thoughts and experiences on this subject using comparative data. Nevertheless, I am very happy with my decision to use the studs and will keep you posted on long term performance.
Once the head studs were returqued, to 110 ft. lbs. and ran over the next several months, it was apparent the studs were doing their job, with no erosion of torque values and all cylinders checking in at 475-485 psi - with zero fluid leaks.
I will in the near future check the torque values of the studs, just for insurance, but I'm pleased to share that I am more than happy with the ARP studs, and the next step up in this build will be the addition of a Giles Performance injector pump, which I ordered this past week.
Again, just thought you guys might want to know members experiences, and I highly recommend the upgrade to studs for the 1.6.
One other thing for the Mods:
I had posted a technical article on "how to" install a marine fuel sending unit in the MK1's for those having problems finding new (cheap) replacment sending units, but I don't see it listed in the "Tech Tips" forum. Can I move the post, or can you assist with having it moved ?
I'm happy to report the conversion to the "marine grade" fuel sending unit I posted is working better than the original units, since the float operates on the vertical plane - instead of the pivoting arm. It's extremely accurate and works great with the factory gauge.
I've also recently upgraded the throttle linkage on my injector pump to eliminate the factory stuff, including the rubber bushing which I've had trouble locating. I will post photos and details on the conversion, and I'm happy to report is work (and looks) much cleaner than the factory stuff. In fact, if "pimping" your injector pump with underhood glitz appeals to you, then you'll like this upgrade.
Thanks for site !
David