[Scott McDonald]

Weekend past, my cousin and I started dismantling the GT engine. Nothing was tight that we put on wrench. Manifolds, carb, fuel pump, timing cover...

As we removed the head (at least this was relatively tight), we saw where someone before had removed the head from the gasket & applied copious amounts of black RTV around the front two large openings. I was wondering why water was leaking from the head.

As I look into the burned-valve head, I see what appears to be burnt chunks of RTV silicone caked, in around the springs of the top of the head.

The leaks continue down around the timing cover. After a call to OGTS, I now have on order a complete bottom-end gasket set, and new 2.0 valves.

The head is going to a shop to be hot tanked, magna fluxed, install new valves and seats.

Some questions:

Should the head be milled? I've read possibly .050" from a post by Rally Bob.

Can anyone give me the low-down on removing the oil pan?

Any pointers on regasketing the head? I saw where it is recommended to punch a couple 3/4" holes @ the #2 area for better coolant flow.

What about the valve cover gasket?

Thanks everyone,

Scot

 

[Old Hippie]

Most shops (that want a good rep) will check your head for true and let you know if it needs a trim or nor.
ALWAYS! replace gaskets. No if's, and's or but's! Especially head gaskets.
But, I'm that way and that's my 2c's.

 

[Paul]

Scott,

You probably should have ordered a FULL gasket set. I know it costs more $$. Bob L (RallyBob) has posted some fairly specific information about valve pocket and bowl work that should go along with the 42 mm Intake valves from a 2.0. The best low buck combo of valve sizes is the Intakes from a 2.0 and std Exhaust from a 1.9. Remove 1/4 inch of height from the Intake valve guide protrusion, round it over and blend the valve seat into the bowl area. The exhaust needs very little. With everything bolted up, the exhasut outflows the intake on a stock 1.9. The ports on the manifold side need very little if any work.

Head milling... .050" milled from the head combined with the larger 42 mm Intake valves will raise you compression about one full point (1.0). Not a bad thing. When the head is milled, slack is given to the timing chain. When the tensioner takes up the slack the cam timing is retarded by 2 degrees for every .025" milled. This MUST be adjusted back by some means or else you will lose almost all that you gained from the compression increase. There are several threads discussing this, for example using offset bushing from a small block chevy.

Double check the size of the holes to add to the head gasket. The picture shows 3/8 holes.

Removing the oil pan is pretty straight forward.

Good luck
Paul

 

[Scott McDonald]

Oh, for what it's worth, it was just this order that I got a bottom end gasket set. I have received all the rest of the engine gaskets. It was only after looking closely that we realized the lower gaskets needed replacing.

3/8"-got it. I typed the wrong size (I have copied the original image as a resource as well).

As far as the valves, I figured I might should just go and replace all with 2.0l. I thought I would get all the potential problems corrected before I change cams. As I'm with the understanding tensioners need changing, and probably other parts likewise. I will definately look into the mods to correct timing retardation. Also, I do not believe I am of the skill level to blend bowls and cut valve guide protrusion-Hopefully I can find someone who knows that they can do this competantly.

I was reading a shop manual that stated I had to brace the engine to remove the oil pan. I didn't know if that is the only way, as it appears difficult, and not at all straightforward. Thanks for the help.

Oh BTW this is going into a port-matched intake from a 32/36. Hopefully through the head with the 2.0l valves and out through a 4 into 1 header and either 2" or 2.25" exhaust. Probably the latter, as I hope to do some further mods as $ will allow.

 

[Scott McDonald]

Bowl blending? Any pointers?

The 2.0 intake valves look to be a close fit, while the 2.0 exhaust do not. I think I'll relap the 1.9l exhaust valves. Does anyone need them? I'm willing to trade-out.

Also, how would one "blend the bowls" as previously discussed?

 

[Paul]

Scott,

The instruction I was given for the 2.0 Intakes was to reduce the height of the intake valve guide protrusion by about 1/4 inch and round it over. As far as bowl blending... There is a rather large ridge of material that sticks out into the port immediately behind the valve seat. Once the new seat has been established, that material can be removed, carefully! The 42mm valve is not big enough to allow for all of the ridge to be removed. So the point is to remove the portion that sticks out past the seat and blend/radius the remaining ridge's back side into the port. Articles I've read about "Pocket Porting" say to address any sharp edges or changes in curvature along the short side radius, as well as along the roof. Remember, on the intake side, you don't want to polish anything. Actually, after you have smoothed things out, you need to roughen it back up. I used 80 grit sanding rolls, but 36 is better. The roughness helps keep the fuel in suspension.

There are tid bits of information packed away in several older threads. Search for them and study them several times. Don't be shy about private emailing the posts author for more information.

Good Luck
Paul

 

[petrieopel]

Head bolts

Can anyone tell me if head bolts can be reused when rebuilding an engine? If new ones are needed, are there stronger aftermarket bolts to be used?
Thanks, Trent

 

[Scott McDonald]

I reused my headbolts.

 

[Old Hippie]

On older cars w/ cast iron heads, it was common to reuse the existing head bolts. On newer designs w/ alum heads, a "softer"-type bolt is used that allows it to stretch as its torqed. I believe this was to protect the head (which is very high dollar) from over-stress.

 

[petrieopel]

head bolts

I'm running 12 to 1 compression and would like to be sure I don't break a head bolt.
Thanks, Trent

 

[tomking]

What I recall RalleyBobs advice being was that you can reuse the 12 point bolts but not the allen head bolts. The 12 point bolts are 12.9 grade while the others are a lesser grade and are to be used only once.

 

[petrieopel]

head bolts

Can you tell me if Opel used both type bolts on their engines or are the 12 point an aftermarket bolt? Are the 12 point available to buy somewhere?
Thanks, Trent

 

[tomking]

I am sure you can buy bolts from OGTS. My local bolt store has the 12.9 grade in the allen head type. I suspect your local industrial bolt specialty shop will too.

 

[GTJIM (R.I.P.)]

Bolt Grades

Opel used special 12 point cap screws rated as 12.9 metric hi-tensile grade.
If you try to use conventional "Allen Head" six sided hole cap screws make very sure they are the same grade - 12.9 will be stamped on the heads either under the knurl or beside the hex hole. Also make sure you get high quality name brand cap screws and not some knock-off copy. If you canot get the original type of 12 points then some four cylinder Fords also used 12 point metric Head bolts 9don't know if they are the same size though).

The use of ARP type studs is an attractive idea until you try and get the nuts and hardened washers on down beside the camshaft! However if you perseve it is possible to get both head and main cap studs that fit some of the Japanese engines and eventually get them fitted - so I am told.
Not sure exactly which engines they come from but it just goes to show that the rice Boys are not a complete waste of time.

 

[RallyBob]

All the 1.9's imported into the US had the higher-grade head bolts. I've only seen the lesser-grade head bolts on newer 2.2 and 2.4 engines.

For the main caps, I have ordered off-the-shelf socket cap screws that are 12.9 grade from Metric and Multistandard Components. But be aware they're taller than the OEM bolts, and you will need to grind the bottom of the timing cover for clearance. I've also had ARP make main studs in the past.....they need to be cut down in front as well for the timing cover, and the cover ground away a bit too.

For head bolts, I had some custom ARP external 12-point bolts made many years ago. Very nice stuff, but pricey, and you can't remove the cam with the bolts in place, so to swap a cam the head must be removed and the gasket replaced. Overkill unless you are running mega-rpms or nitrous or turbocharging.

Bob

 

[petrieopel]

Head Bolts

Thankyou all for your information and knowledge.
Thanks, Trent

 

[GTJIM (R.I.P.)]

All the 1.9's imported into the US had the higher-grade head bolts. I've only seen the lesser-grade head bolts on newer 2.2 and 2.4 engines.
Bob

Apparently some engineering "genius" worked out that if lower tensile bolts are torqued to their yeild point more consistent clamping is obtained in automated assembly. So the modern head bolts are 'oncers' which cannot be reused as they have been stretched right up to thier yeild point and are kaput!

I know it sometimes goes against the grain to reuse old bolts but the old bolts are of higher tensile strenth than the new ones - so we have to make a choice.

With the Mains it is always possible to use the best two original bolts on the front main cap which should be the lightest loaded anyway and just stud the other mains if we must.

Have you ever had original main or head bolts "let go" on you , Bob?

 

[RallyBob]

Have you ever had original main or head bolts "let go" on you , Bob?

Never. I've seen plenty of threads strip out in the block for the head bolts, but that was rust-related. I've also seen stretched head bolts (.080" longer!), but that was from a racer who insisted that if 72 ft lbs of torque was good, then 100 must be better!

Bob