head torque and compression

Derek May · Post by **Derek May** » Mon Mar 11, 2002 11:19 pm

I'm putting an engine from a '78 into my Van. Engine was pulled from a running Van, has very little oil, but is very dirty so its not been cleaned up to hide the oil. I'm aiming to do as little fiddling around as possible, but may change my mind...

Questions:

1) I've measured 150 ft/lbs or compression, the book says up to 135 ft/lbs. Any ideas on this?

2) I checked the head bolts, which the book says should be torqued to 23 ft/lbs, but they are at 50. 23 doesn't seem very tight, but it is aluminum. Is 50 overtight? Should I back them off to proper torque or leave well enough alone?

thanks.

rich2481 · Post by **rich2481** » Tue Mar 12, 2002 7:02 am

I do mine to 25, why were they at 50?? how did you test that ( I figure retorqued?? )

would think at 50 pounds the studs would have pulled out of block

Pillow · Post by **Pillow** » Tue Mar 12, 2002 9:49 am

50 is way too tight. Once the engine heats up the expansion causes the head studs to hold firmer.

I am sure people have gotten away with 50+ before, but I would not risk it.

------------------
Adrian Pillow
'66 VW Westfalia - "Biscuit"
'79 Porsche 911 SC - "Cochese"

Bob Ingman · Post by **Bob Ingman** » Tue Mar 12, 2002 9:57 am

Derek, as far as the compression reading is concerned there are several ways this is possible.
Most readings are based on a test of about six revolutions. If you go more compression readings will rise. Also the heads (my personal theory) may well have been flycut as a cleanup measure.This will bump the compression up.Anyway you cant complain it the comp is high across the board with no low holes. All the better. Big bore (96s) will also bump compression. Sounds as if you have come across a good long block.
Be sure your torque wrench is calibrated accurately. Then torque to specs. However if you`ve had no problems as a result by now its unlikely that you will but to be sure go by the book. In case you take it into a warm climate the stress could result in pulled studs. Good luck. Bob

Derek May · Post by **Derek May** » Tue Mar 12, 2002 9:35 pm

Ya, my reaction was similar when I saw the head bolts were at 50. Didn't seem right.

The engine is used, but new to me, and Bob is correct, for a used engine its a very nice unit. Its been sitting 4 months unattended and the oil was at top, there is very little evidence of oil leaks.

I tested the torque on the head bolts by turning the torque wrench until the nuts cracked. No movement until 50 on all nuts, so its pretty clear that they were torqued to that degree. I suspect a prior owner just cranked them up to what seemed "tight", as 23 foot pounds does not FEEL tight.

I'll loosen them, and retorque to 25.

How do I calibrate the torque wrench? I have not reason to believe its off, but how does one cheque that?

Regarding compression, I had the engine and tranny out when checking, and connected the starter to bump it over. If I bumped it once, it got about 110 lbs. I bumped it until the compression wouldn't go any higher, and this was about 6 bumps. I got 150. I checked this on 2 gauges, so it seems right.

thanks as always for the suggestions.

Pillow · Post by **Pillow** » Wed Mar 13, 2002 8:25 am

>How do I calibrate the torque wrench? I have not reason to believe its off, but how does one cheque that?<

I like to use the old skul "pointer" style for light duty stuff because they are much less likely to get out of calibration. On the heavy duty stuff I use a "clicker" style.

Figure for heavy use if you are off a couple pounds it is no big deal.

Most of the clicker style are much more accurate than people give them credit for. I think you can have Sears calibrate them for a fee???

------------------
Adrian Pillow
'66 VW Westfalia - "Biscuit"
'79 Porsche 911 SC - "Cochese"

rich2481 · Post by **rich2481** » Wed Mar 13, 2002 8:40 am

my 2 cents, my dad is a weekend wrencher too so I just use his and mine once in awhile to check they are within a pound so I say it is good, maybe you can borrow one from someone just to try out,

Derek May · Post by **Derek May** » Wed Mar 13, 2002 1:18 pm

My torque wrench is the pointer kind, always kept carefully in its original box, with the styrofoam packing, placed carefully in a drawer.

I can't conceive of any reason it would be out of whack.

Bob Ingman · Post by **Bob Ingman** » Wed Mar 13, 2002 2:06 pm

Derek, you`re probably fine on your torque wrench.It could be that a thread sealant such a loctite is binding the threads to a release pressure of #50. Either way it would be a good idea to retorque for personal satisfaction. The matter of torquing is sometimes over rated other than a need for uniformity. However in the case of VW cylinder head studs it is important . The old magnesium type one cases were nortorious for pulling head studs in hot running conditions if OVER torqued. Under torque them and you soon have oil and compression leaks.
A good T-4 long block is a find indeed. You`ve done well. Protect your investment. Good luck. Bob Ingman

Derek May · Post by **Derek May** » Wed Mar 13, 2002 9:54 pm

Well, I'll update everyone when everything is put together. The tranny seems to have good synchromesh, so I'm hoping the $700.00 all in for the rusty tub with good mechanical is going to work out well.

And I've got three big bins of spare parts from fuel pump to mirrors to an almost complete BA6.

Derek May · Post by **Derek May** » Tue Apr 02, 2002 12:07 am

Well, solved the high compression riddle.

I decided to pull the heads and look inside. I found that there was a lot of carbonization, either too rich or oil?? Enough deposited stuff to perhaps increase compression.

Spent some time with some Gunk and cleaned up the cylinders, pistons and heads, then got the heads done -- new exhaust valve, clean up, reseating and lapping. All stock, and good price at $200 cdn.

I polished the top of the cylinders on a sheet of glass with lapping compound, then lapped the cylinders into the heads. What a way to spend a day! No wonder most shops just put in the aluminum ring.

Hard to tell when enough was enough with the equipment I have. I'm sure someone has a way to measure, but I just looked to see that the head metal was affeced all the way around, then went another 10 minutes or so and called it done.

Put in new rings, left the bottom end alone, replaced some key seals, particularly pushrod tubes.

Going to torque heads to 25 ft/lbs, and put some blue locktight on the threads for comfort.

Hope all the works out. Hasn't cost all that much, and goal is a reliable good runner that doesn't leak oil.

Pablo · Post by **Pablo** » Tue Apr 02, 2002 6:57 am

Why on earth would you put locktite on head nuts? You're asking for big trouble when it's time to take the heads off. You're better off putting anti-seize. JMHO

Paul

rich2481 · Post by **rich2481** » Tue Apr 02, 2002 7:04 am

Lapping in cylinders, valves and such is what I would call a great weekend. I never have lapped the tops of cylinders though always wire brushed. Sounds like you got a deal on that tub Derek

Rich

my two cents, I wouldnt bother with the loctite, blue doesnt have good heat properties and I certainly woudl not use red
if you are worried about them spend a couple dollars and get locker nuts

david thomas · Post by **david thomas** » Sun Apr 14, 2002 5:54 pm

if your heads are still off, its a good idea to run a die over the threads to clean them up. i do this as a matter of course with engines i build. the reason is that thelower 4 ( usually encased in oil so no problems) will tighten up tighter than the upper 4 (exposed and usually rusty), due to crap on the threads. i dont normally loctite the head bolts, just torque to 25 ft lbs. everybody does this, you wont have problems of nuts coming undone.

Derek May · Post by **Derek May** » Sun Apr 14, 2002 6:39 pm

I did clean up the threads.

the lapping ... well that was a full weekend of fun.

heads are on. The blue locktite, well can't hurt. And it keeps rust out of threads so it actually helps gettings stuff apart later on, in my opinion. Blue, not red. Red would be very bad.

Just about ready to put the engine in. I'm very sick and tired of cleaning up engine tin these days.