From bad to worse

[Joe Ricard]

Got the motor pulled and disassembled as far as I dare. Heads, flywheel, etc. Put all the tin in a box will be spending some lunch hours in the sandblaster all week.

My worse fears were realized when the clutch came out and it was GLAZED with oil. not form the rear main but the transaxle input shaft. What options are there in performance clutches?

That Phft Phft was comming from a pulled exhaust stud. Got to schmooze my welder buddy. Not to leave out the valve job buddy. What kind of port work should I do? I was thinking of port match and remove any casting marks ie. very light. What about the combuston chambers?
Speaking of Heads. there wasn't any sealing rings between the cylinders and heads. Do I need them? (not euro pistons) darn it.

[paulhagedorn]

As far as performance clutches...you can get a 911 clutch from the early cars that will fit...it has a couple more springs around the clutch. Or you could get some special clutch...i am sure there are some out there.

Porting...I know if the intake chambers are too smooth, it isn't a good thing...at least for some cars. The expert on that will probably say something eventually...

[Ron Meier]

Your pulled exhaust stud should be fixed via helicoil - very stable & very good. Can be done with handtools.

Port match your intake manifold & heads - no ridges. Further porting of intake and exhaust is done to increase flow and volume. Intake left "rough" to maintain fuel/air emulsion mix - exhaust can be "polished" for better exhaust flow.

If you not experienced - pay someone.

Combution chamber - cc so that all are equal - no sharp edges.

No sealing rings - ok - it's all metal to metal anyway. Sealing rings are used a shims to set compression ratio. You probably have slightly higher compression without them.

Anybody else have opinions?

[Joe Ricard]

Thanks never had sealing rings in any of my type 1's. I built up a 1915 cc bug motor that would really scream. I have ported the heads on it and it wasn't to hard as long as you don't get carried away.
Sat there in garage last night just staring at the pistons and cylingers. Trying to rationalized pulling the whole darn thing apart and do a balance job too.
HEY IT'S ONLY MONEY AND TIME, THERE WILL BE MORE OF EACH TOMORROW.

[Jim Smolka]

Joe,

Check out this months issue of Grassroots Motors Sports Magazine. They have an interesting article on rebuilding a 2.0 motor and the porting and polishing they did.

[Joe Ricard]

Jim, so incase I don't get this issue in time or what ever could you give me a run down. Man now I have another MB to surf, doesn't look like I will ever get anywork done.

[Dave at Pelican Parts]

I think they took the porting too far in GRM. They make good power, sure--but I think they've sacrificed some longevity for it. I could be wrong; time will tell. The five-angle valve job is cool, but won't last as long as the stock three-angle one. A full-on "venturi grind" would probably flow a little bit better, but would wear down even quicker.

Don't take much (if any!) material from the short side of the exhaust port. There isn't enough there as is, particularly on a 2.0 head, and taking more away doesn't do much for the flow. But it does lead to easier cracking.

If you want the GRM issue, I think you can get a free one by surfing to http://www.grassrootsmotorsports.com and checking around.

GRM is a good magazine if you're into autocrossing, time trialing, or wheel-to-wheel stuff. And Pelican Parts is a sponsor of theirs!

--DD

[Joe Ricard]

Well now that I learned that flat top pistons are the euro ones well, Thats what I got. Pulled the valves out today only to find dual valve springs. Looks like someone tried to put together a hot rod.
Pullled a piston and cylinder apart, found the oil ring with a the gap at the bottom!!!! Both compression ring gaps were in the lower 1/3 rd of the piston???
Every motor I have built was completely the opposite. The only markings on the piston face is 93.87 and + no arrow nothing else.
So now that I am this far I looked into the case and did not see any evidence of balancing. Are 914 rods that well made? no marks on the crank either. Tought I would get the flywheel surfaced and then have all rotating pieces balanced just for good measure.
Getting ready to order parts

[Conrad W Peden]

From what i understand all type 4 rods are the same. The only diff between bus and 914 is that 914 rods are chosen more carefully, they are all closer to the same weight.

At, least on the 1.7.

[Ron Meier]

The 1.7/1.8 rods are the same, except for the size of the balance pad on the small end of the rod. They are marked "021" and "022" respectively.

2.0 rods are completely different - smaller big end and no balance pad on the small end. Marked "039".

Matching rods consists of:
1. Length, measured from centerline of big end to the centerline of the small end should be the same.
2. Static balance consists of making the big ends and small ends weigh the same (you grind material to achieve this). Requires use of a fixture and scale.
3. Rod material is the same.
4. Replacement of stock rods bolts with higher tensile strength bolts is major improvement.
5. Polishing rod beams (remove casting marks) makes them less prone to cracks (and helps shed oil).
6. Shot peening slightly increases tensile strength of rod beam.

If you really want a set of well made, balanced & blueprinted rods - go aftermarket (Carillo, etc), but your gonna PAY for them.

[DSPTurtle]

Lemme make sure I got this right.... if I take a set of rods and "polish" them they will be better than the orignal casting??? This sounds like a job for the dremel. Do you polish the whole thing? just one side? I am going to static balance them myself and get someone to do a dynamic but this sounds like a fun and cheap way to spend an evening. Someone please let me know if I should under no circumstances do this.
Thanks

[Ron Meier]

When I say polish, I don't mean to attempt a bright finish. Just remove the forging marks so that the beam is smooth. This can be done with a belt sander. This is done prior to static balance.

You can "smooth" the entire beam with your dremel. You're not actually removing significant material. Rough surfaces tend to attract and hold oil - this adds to "parasitic drag" (read lost horespower).

Shot peening after all this work, compacts the surface molecules and lessens probabilites of rod beam failure at elevated rpms.

Oh! Before you install the rods, bake them in your oven at 400 to 450 degrees for a couple of hours prior to installation (let them cool of course). This procedure is called "stress relieving".

The same thing (except for shot peening and baking) goes for the crankshaft too! Smooth the casting on the counter weights for less parasitic drag.

Just old racing tricks where stock components are used.

Anybody else have any opinions?

[DSPTurtle]

Okay, so I don't "need" to polish but if I do I can expect some slight improvement. What if they are polished to a mirror like finish? This would seem to potentially significantly reduce the drag as the rods moves. The sand cast finish just does not seem as if it is conducive to smooth slicing through oil and air. Will this inhibit the splash that is used to coat the piston with oil. If I provide a set of polished rods would anyone be willing to do a quantitative test (or has one already been done?) Sorry for hopping onto your post Joe!!! Hope the blower fan is working for you.
JB

[Joe Ricard]

You bring up some interesting points but I really don't think this could be quantified. Because you would have to do a dyno run prior to. Then change just that and run another one. To get a motor back together excatly the way it was??? probably not. You will get more power from a good tune up. Probably the best bang for the buck.
The blower motor as you can see is the least of problems as you can see by all my posts. Had clear windows for two days!!!
Just for kicks I wieghed the fly wheel . Yup it's been lightened too! 14lbs. Getting it surfaced today.
All header pipes are screwed up. the triangle brackets are bent from to much torque. two of them are ripped through the pipe wall. SSI exchangers so working a package deal with my welder buddy.

[DSPTurtle]

I figured I woudl give it the day but no one has answered. Has anyone ever polished the rods. Maybe Jake will give us some input. I have almost finished one rod...not too hard and pretty relaxing but should I expect anything over it?

[914GOD]

Well, I haven't ever polished a rod and wouldn't want to comment on if it would make a difference or not (in regards to oil).

However, polishing the rods will increase the fatigue strength (not the tensile strength) of the rods. Fatigue is surface initiated (almost always) and as such is improved by removing imperfections in the surface. This means VERY smooth. Of course, anything helps. The fatigue strength can also be improved by producing a residual compressive layer on the surface of the part. This compressive layer means that the part will have to undergo a higher tensile stress before the surface of the part is subjected to stresses high enough to initiate a crack. This compressive stress is caused by shot-peening. So these changes will make your rods less likely to break.

That being said, I have never heard of breaking a rod on a nearly stock motor. That is, unless something else was very wrong. If that is really a problem then I would polish, otherwise I think it would be a waste of time.

Out of curiosity, has anyone had rod breakage issues with a near stock type IV?

Sean