View Full Version : Head torques

08-22-2011, 12:00 PM
...What should I be torquing the head to on a HC 1098, its probably close to 14:1?


08-22-2011, 02:13 PM
If youíre running 14 to 1 C/R you should be using more than your standard studs and nuts. I would recommend ARP with that much compression. Itís obviously your running this engine on the track, to much C/R for the street.

08-22-2011, 02:48 PM
...Yes to both, but need a recommend #.

08-22-2011, 03:11 PM
When I'm using ARP head studs, I pull to 50lb-ft with just a little motor oil on the threads. Same for "drill points" or "22's". Be sure to use good washers and nuts. If using roller rockers, might need to narrow the washers and nuts a little to clear the edge of rocker body.

I toss the stock 948 or 1098 studs or shorten them down to 3/4" above the coarse end and use them for a top clutch slave cylinder locating "peg". I use only the bottom bolt on the slave.

Mike Miller

08-22-2011, 03:30 PM
If you use the ARP studs, tighten them according to the manufacturer's recommendations. They give you very detailed information on this. Their procedure is based on keeping the stud comfortably within its elastic region, so fatigue is minimal. Making them tighter won't help anything, and is more likely to weaken them.

08-22-2011, 08:10 PM
Whoot, 14 to 1. Haven't seen numbers like that since the 60s.

08-22-2011, 10:20 PM
Where do you buy FUEL? :wall:

Hap Waldrop
08-23-2011, 06:50 AM
Where do you buy FUEL? :wall:

At the race track, I doubt it is 14 to 1 on the street, I guessing a race car. And 14 to 1 in a 1098 takes domed pistons to there. Mike is spot on with the 50 foot pounds.

Hap Waldrop
08-23-2011, 06:54 AM
Whoot, 14 to 1. Haven't seen numbers like that since the 60s.

Ah Jack for a 948 race engine, that would be consider low compression ratio, the norm for the fast SCCA guys was 16 to 1, and is advisable not to stand too close to them when running , so you don't get hit the face with part of the crankshaft :smile: