Head bolt torque for 2.5

**Little Jon** · 12-03-2013, 10:04 PM

What is the torque spec for 2.5 litre heads?

I did about 38 foot pounds. both sides had a little leak, tightened them down again, with 2-3 more ftlb's and one side stopped, the other still has a small leak.. Just trying to see what everyone is doing for them.

**patchesII** · 12-03-2013, 10:40 PM

I use 34-35 on o ring heads. If you have a leak at 38 you need to find whats causing it cause its not lack of torque. Much more and you'll start pulling threads

**baja200merk** · 12-03-2013, 10:47 PM

Wrenches vary way too much to say threads will pull at XX.

Is it leaking out or in?

**Dave Strong** · 12-04-2013, 01:16 AM

Gasket heads, good clean threads, clean bolts, light oil on threads, grease on washers, 40lbft should be fine.

Dave

**HStream1** · 12-04-2013, 06:00 AM

I've torqued them at 35 for gosh knows how long. And if the deck and heads are flat It should not leak at all at 35.

**tux974** · 12-04-2013, 06:27 AM

I was taught on gasket heads, 30 first round and finish with 35. You should be OK at 38 gaskets being new and of course both surfaces being right. If it was leaking or had an issue before you replaced them I would definitely get them checked by a good machinist!
I have also seen a hand mild sharpening stone used to lightly clean the matting surfaces.
The newer heads with built in washer have the torque spec casted on them, 30lbs.

**patchesII** · 12-04-2013, 07:00 AM

Just for the record I wasn't saying they would pull at XX torque but I simply thought he should take a close look at all the components before just increasing torque till they sealed.

**rev.ronnie** · 12-04-2013, 07:05 AM

Originally Posted by Little Jon

What is the torque spec for 2.5 litre heads?

I did about 38 foot pounds. both sides had a little leak, tightened them down again, with 2-3 more ftlb's and one side stopped, the other still has a small leak.. Just trying to see what everyone is doing for them.

If you are using the correct lube on your fasteners and getting what should be accurate torque, something is wrong. Obviously, first thing to check is head flatness and RA finish. Too rough and they will never seal.

Be aware that if someone cut them on a small machine like a Bridgeport, using a small diameter cutter and too much head tilt to avoid back cutting, they may never seal. They could be concave cut like a water ski. It can be done on such a machine, but only by a operator who knows the correct procedure.

I cut them to a 20-30 RA finish. My larger machine has a 13" wheel head and less than .001" tilt. Never had one leak or had an issue @ 35- 38# install torque.

**Jay Smith** · 12-04-2013, 06:44 PM

+1..... I torque at 35 FT lbs on ALL heads O ring and garloc never had issues. If you have a leak look for surface imperfections...OR gasket issues, a new gasket on flat heads and deck should seal fine at almost any torque.. I find after cutting litterly thousands of heads any fly cutter that's larger than the head by 1 or so inches has worked fine cut on my "little" machine ( J Head Bridgeport ) or any quality milling machine, I've cut a zillion never had a leak just gotta know how to set up, it ain't rocket science......Jay

**TEXAS20225** · 12-04-2013, 06:51 PM

i agree i also torq at 35 all heads something aint right

ive one round torqued at 25 and have heads not leak ever if all is flat

**DonChicho** · 12-04-2013, 07:44 PM

I torqued at 32 lbs. Never had any Problem !!!!

**rev.ronnie** · 12-04-2013, 09:04 PM

Originally Posted by Jay Smith

+1..... I torque at 35 FT lbs on ALL heads O ring and garloc never had issues. If you have a leak look for surface imperfections...OR gasket issues, a new gasket on flat heads and deck should seal fine at almost any torque.. I find after cutting litterly thousands of heads any fly cutter that's larger than the head by 1 or so inches has worked fine cut on my "little" machine ( J Head Bridgeport ) or any quality milling machine, I've cut a zillion never had a leak just gotta know how to set up, it ain't rocket science......Jay

Like I said, knowing the correct procedure and machine set up and it's nuts on. I know guys who sucessfully cut them on a table top mill.

I've had to re-cut heads that were done on a mill with a 3" shell mill and about .005 tilt to the head. Not so good.