I just received the rebuilt 2.0l heads from the machinist. After the rebuild I asked and paid for him to cc one of the combustion chambers. When I picked it up, he wasn't around, but I noticed that he painted on the head 120 cc. I called him today and verified that 120 cc was the correct volume. This seems very large to me, is it correct? If not, why? They forgot to install the spark plug? Depending on the responses, I was planning to bring the head back to the machinist and have him verify the volume.

BTW, the pic shows the spark plug I just installed.

Click to view attachment

-- Rob

120cc total? 60cc per?

Question. Just one cylinder? When I do them, the customer wants to be assured that all cylinders have the same volumes with the plugs installed. I've done 356 and 911 heads but never 914/4 heads. The answers will be interesting.

Good Luck

That's my first thought as well.. No matter what is said here you will have to confirm his thinking with him.. but 60cc is per cylinder is possible 120 cc each is just wrong or there is an assumption he meant per cylider when he meant per cylinder head.. at 120cc per cylinder you compression ratiois approx 4+-?/1 whihc is about half of factory so .. there is your measure..

... my last cc was 55 per cylinder or so I can't remeber exaclty and they were fly cut first more so than I can see in your picture so my money is on 60 per cylinder..

Thanks for the responses. I'll let everyone know tomorrow after I get back from the machinist.

This is my thought also..

-- Rob

Betcha he measured from the wrong spot. You need a disc that sits inside the bore to correctly measure volume.

Here's my disc.

Interesting observation. So if I measured the diameter/radius and the thickness of the extra section and subtract it from the 120cc I should get a better idea of what the combustion chamber volume.

-- Rob

The difference between 60 and 120 is... well, 100% Pretty broad difference. You could easily find out which it is without being exact. Put 60cc of fluid in one combustion chamber and see if it will fill it or require another 60cc.

It's prbably cheap enough to have all of the CC's done anyway though. Might be your best bet.

What fluid is used?

-- Rob

Anything. The lower the surface tension the better, but anything will work. I used power steering fluid for awhile.

I used some model fuel as it is red, like PS fluid. Something other than clear is best.

Food coloring in rubbing alcohol I believe is pretty standard. Don't quote me on that though. I can't remember what I had for lunch yesterday.

Rob,

Who did the heads? Someone local?

When I did mine they were 61 cc`s

United Speed World, recommended by Fisher Buggies.

-- Rob

Mine where 53, 54, 55 and 55. They were done recently is the only reason that is still in my head this AM.......

....Yes I agree, and its almost self cleaning.(dependant on amount of dye).

I wouldn't bother cc'ing those heads until they are flycut. Stevie Wonder could see that they need it!
Don't want to be a PIA, but those used exhaust valves are hollow time bombs! I would assume that the valve springs are also used. If my assumptions are correct the combined age of your 8 spring and 8 valves would be 544years old, if they are off a 76 model!

It also seems likely that the valve seats have not been replaced either. They have a nasty habit of falling out when you need them most (when the engine is running). Especially true of the intake seats. And I can't tell you how many times heads have landed in my shop with a destroyed chamber from a dropped seat and the customer says " I just had a valve job done". For what ever reason (and I think I know why, but don't feel like going into it) the likelyhood of a dropped seat goes way up with these heads after seat work is performed, especially if new guides were installed.
I hate to be the one to breeak it to you, you still need a lot of work to have a reliable pair of trust-worthy 2.0 914 heads! And the thing is, the castings appear to be in good condition. I'd sure hate to see another pair of otherwise nice 2.0 heads get chewed up.

USED sodium filled exhaust valves! SWEET!

I wonder if he knew that during the valve grinding procedure (If he even ground them) that the valves could explode??

I think I'd be double checking ALL that work including the valve job, guide/stem clearance, flycut etc, etc, etc

WOW.

Thanks to everyone that posted with their suggestions. I have ordered a new set of exhaust non-sodium filled valves. I'm going to cc the chambers myself after the new valves are installed.

I had someone remove one of the valves. Based on the photo any other suggestions?

Click to view attachment

-- Rob

What is fly cut and how is it done? Should the machine shop have done that for watson, or is it something people normally do at home?

Flycutting is a machining process to make a surface flat. It is done on a milling machine which goes into the head to remove a small amount of material in the cylindrical area that receive the cylinders.

The flat surface guarantees a good seal with the cylinders- if the ends of the cylinder are flat.

Ken

................. ...........He may be too young to know "steve wonder"....the machinest.or even the other less well known "stevie wonder"....

You can see the ring worn into the head by the cylinders. This needs to be removed for proper sealing.

Here is a Len Hoffman flycut.

Thanks for the photo Mark. I'll discuss this with the machinist. I'm assuming that the valves need to come out before the chambers are fly cut, correct?

-- Rob

It can be done with the valves in. Rob I don't think this guy did anything other than reassemble and CC the heads. It is clear they were not flycut AT ALL. This guy needs to be told that ALL chambers must be flycut, and the measurements for each chamber MUST be equal. If not you will

A: have cylinders that won't seal properly because one is taller than the other

B: have an unbalanced engine because one head has a different volume then the other.

This is a set of bug heads I had a quick skimming done on. Original motor and they needed a total of .010 taken off to even up all of the chambers. No I didn't get them spotless clean Didn't even remove the valves Just a quick cut to get a good seal

Man I love the way those things shine! I recently (this week) refined my flycutting tooling even further. The new finish is even more spectacular.

Ask your machinist how tight he holds his trammel tolerances (how perpendicular the milling machine quil is to the table) if the quil isn't trammelled properly the two flycut surfaces will not be on the same plane and the cylinders will not seal properly. I regulary trammel my quil and hold a tolerance of .00001". This takes a lot of effort and is not typical of most automotive machine shops.

The close-up photo reveals that your head may have been welded. Based on what I can see in that photo I would bet the intake seats have not been replaced (look closely at the photo of the head that I did and you can see the new seats O.D. is out there slightly more than the O.E. seats in relation to the valve diameter).

It is well established that not replacing the valve seats on 2.0 914 heads at this point in there life is playing Russian roulette with your engine, even if they haven't had weld work done. But weld work not followed by replacing the seats is crazy. If money is the issue I recommend putting the heads aside until you can have them built properly.

Well, I have the heads back from the machinist. I took everyone's advise and tried to follow thru. I ordered new intake valves from PP and had the machinist fly cut the combustion chambers. We also discussed how he came up with 120cc. He had his 'assistant' cc the heads and yes, he placed the plexiglass on top insted of the recessed area. When I got them back I also made my own plexiglass, used rubbing alcohol and red food coloring and vaseline to seal the liquid. We both got 61cc for each chamber.

Here's the pics... Thanks again from everyone's suggestions.

Click to view attachment

Click to view attachment

-- Rob

If that chamber is 61cc it's the largest flycut chamber I've ever seen!

Should be 50 something... Lessen you buildin' one a them turbo jobbies... But that would be stooopid since everyone knows you can't turbo a Type IV!

So, I should remeasure it again? I'll check it tomorrow, again... Thanks for checking up on me.

-- Rob

Oh...you can turbo a Type IV... its a 914 you can't turbo.

My bug (T4 conversion) heads are 62cc and they are opened up and the valves are unshrouded for 102's