align bore / new head studs

jtkkz · 01-08-2007, 07:36 PM

In the process of rebuilding my motor, engine has been taken apart, everything inside the motor are in excellent shape.

Original motor was 2.7 134,000 miles

Is align bore and new head studs advisable to replace and do?

afterburn 549 · 01-08-2007, 08:12 PM

there is a bunch of little things that needs to be done to a 2.7..oil mod, stud inserts, cyl deck ht,. Send it to a known shop that deals with these on a reg basis

casperlabs · 01-12-2007, 10:41 AM

Most 2.7's had 5 blade fans and thermal reactors in their history.
The extra heat resulted in much more rapid distortion of the magnesium case across the cylinder spigots. Lay a true straight edge across the three holes on each side and check for an air gap (bridge effect) on center rim with a feeler gauge. Not uncommon to find .015 gap. This is easy to surface on the mill while KEENSERTING the stud holes (MUST DO!). No hand/eyeball
insert jobs, you will never get 24 perfectly straight. Premium studs/nuts like our kit will go a long way to keeping this engine problem free and oil tight.

Bill Ryan
Casper Labs, Inc.

Bobboloo · Bobboloo's Garage

If the case is pre-77' then it can benefit from the oil bypass mod.

As mentioned above. Inserts (timesert, casesaver etc.) are a good idea. Decking.

The case should have the line bore verified. You can do this yourself with plasti-gauge and a good set of bearings. More than likely it will need the line bore. The bore in the 2.7 cases tend to distort into an oval shape. I've rebuilt a 2.4T before that didn't need line boring but every 2.7 case I've seen has needed it. Not saying that yours does but chances are more than likely that it will so either take it to a shop or check it yourself.

My personal opinion but I think a Dilivar type stud is a good idea for magnesium cases when aluminum alloy type cylinders are used. (2.4Ts for example used iron cylinders and consequently didn't need a Dilivar type stud.)

jtkkz · 01-14-2007, 04:37 PM

my 74 carrera 2.7 came with mahle cylinders/pistons and a 11 blade fan
came with steel studs, but not dilivar

we will be doing all the necessary mods, line bore, etc..

thanks for replying,

casperlabs · 01-14-2007, 06:34 PM

I should have mentioned that if this engine is intended for the street (more thermal cycles) you need to consider a couple more items if you really want to get long life. Oil does a disproportionate amount of cooling on air vs. water cooled engines. Magnesium's creep strength drops faster with temperature than alum., so your 7R case really needs help here if you want to control distortion after all the upgrades. The 2.7 is infamous for cyl. head nuts that are found finger tight or loose after 50K miles (due to the all alum. cylinders and the softer mag. case combo). Installing the OEM nuts will not fix this unless you can find a threadlocker that will live at 500 deg. F cylinder head temps! Using all metal locknuts on your studs is a far better solution. Lastly, a lot of 2.7s heads had really rough machining on the washer surface under the nuts. This tends to wear down over time and relax nut torque. It only takes a few seconds to dress this down with a really sharp spot face tool or end mill.

Bill Ryan
Casper Labs, Inc.