About this time last year I concluded that I wanted to rebuild the motor in my 914. It is a salvage title 1.7 D-Jet FI whose engine was tired but had recently undergone a cosmetic revovation that had gone pretty well and I wanted to finish the conversion to a "sports" car. There were three things I wanted to accomplish when undertaking the rebuild:

1) Give the car some "oomph" that was severely lacking. It looked like a sports car but because of the motor did not run like one.
2) Increase the MPG. With the price of gas and the miserable milage I was getting on the car (and rumors of 30 MPG motors) I wanted to get better than the 13 MPG I was getting.
3) Eliminate the oil leaks that was marking everywhere the car stopped - even if it was for only a couple minutes.

I had a spare 1.8L block and decided to increase the ouput to 1911 by adding 96 mm P&C's. Along with a new cam,Webers and heads redone by Len Hoffman I thought I could accomplish my objectives on a reasonable budget.

First thing I did was purchase Jake's video and watch it 20 times. The rebuild and assembly went pretty well over the Winter. Replaced all of the recommended pieces and parts - bearings, cam gear, etc. Used the 86 cam from WebCam and Webers from Jake. The one thing I did (which in retrospect may have been a mistake) was purchase the 96 mm P&C's from eBay. My understanding is they are made in China. One neighborhood Porsche wrench said he has had no bad experiences with the parts so I thought I would take a chance. The other "bad" thing I did during assembly was I did not disassemble and fully inspect the P&C's when they arrived. The pistons arrived assembled into the cylinders and despite recommandations to the contrary I only removed one of the pistons and inspected the rings. This one cylinder seemed good and because of my anxiousness to get it together I left the remainder assembled and put them on the motor as shipped?? As I would find out this proved to be a bad idea.

After I got the motor assembled it started up as planned - using the adjustments that came with the Webers. The throttle and carb linkage provided a very quick throttle and the motor seemed very strong - especially compared to the old motor. I drove it fairly easy at first and with little direction on engine break-in was not sure how to treat it. One other mistake that may have led to my current issues was that I had way too much oil in the crank case.

Shortly after getting the motor running the oil leaks started. It is still difficult to see where it is coming from but the leaks are no better than they were before the rebuild. (Strike 1 !) It looks like it is coming from both ends of the crank seals and possibly the oil cooler. A bit is coming from the head covers but none is coming from the oil return tubes or the cylinder/case seal.

The encouraging part of the rebuild was the new found power that I uncovered in this motor! The car had some serious torque and ran like a "bat out of hell"! I was really excited about the car not just looking like a sports car and running like one now. I assumed the slight smoking of the motor was only temporary

The next issue was the noted MPG - I was only getting 12 MPG I adjusted the carbs but that only increased the milage to about 15-16 MPG. After suspecting the rings are not sealing I performed a leak down test over the last couple weeks and it is not good. The only percieved leakage is coming inside the crank case. The leak down cold was more than 20% and hot was between 12-15%. This has initiated an effort to tear into the motor again and check the rings.

The question at this point is what I will find? Will I need to replace the rings or the complete P&C's (which I will consider if it will fix my problem?). Can I get away with re-honing the cylinders - or is this a no no?

This is disappointing given it is the peak of the driving season here in NE Ohio - and too hot to do any serious wrenching. I have just put the car up on jack stands this morning and will be digging in over the next couple days.

Stay tuned!!!

Vance make every effort to sort out your tuning issues before tearing the engine down. If you re-hone your cylinders (probably all you'll need to do along with new rings) and put the same carbs on with the same rich condition, you will likely have the same problem. Plus if you get the tuning adjusted properly the rings may seat, that just depends on how much damage they have received. the rings won't seal without oil. If the fuel is leaned out perhaps they will seal again. You can always squirt some oil in the spark plug holes prior to performing the leakdown. If the leak decreases that is a good sign.

Tell us how your carbs are set-up. We may be able to spot your problem right away.

Good question on how the carbs are set-up? I did a test where I ran the car on the freeway and then shut it down and took pics of the spark plugs - I iwll attach. I went through the carb adjustment process about 20 times with several different explanations on how to do it. WHen it came time to adjust the idle mixture mine did not respond the same way as the articles outlined. My next step was to take to my wrench and have him monitor the exhaust while we adjusted - does this make sense or is there a better way?

BTW - I have about 900 miles on the rebuilt motor.

Wow!! That's rich! What size jets and venturies are you running?

The electrode looks like it was cleaning up, does look fat. Around town with carbs

mine runs a little leaner. About the color of coffee with 1/2 a cream added. I run

mine a little fat because it gets so hot here.

What fuel preasure is your regulator set at?

The fuel pressure is set at 3.5 psi if I remember correctly.

I am not sure on the venturis and jets but purchased them from Jake. He was told all the data on the motor and supposedly provided jetting that would match the motor. I may have some documentation that was provided with the carbs - let me check.

Now the 4-5 slider crapped out in my tranny so been running w/o 4th gear? WOW- when we say projects I did not realize it would last the remainder of my life!

welcome to the world of 914"s

Sorry for the problems Vance, but that is the world of 914's! They are so much fun to drive becasue you have to work so hard for it.

If it wasn't for my 914, my jackstands would just float away!

You are running way to rich.
It can be fixed.
Lets get the carbs right first.

I am still concerned that you only took apart one set of pistons and rings before you built the motor. You have no way of knowing if the rings where gapped correctly, and no way of knowing if the rings were lined up or not....that is a variable that I personally would not leave alone at this point.

This particular variable could make you chase your tail for a long time.
From the one plug you show, its not oil, its fuel...so that is a good sign so far...its just a configuration issue.

Check your PM for how to figure out the jets and venturis.
Post the results here.
If you cant figure it out, shoot me a pm and I will get a picture or two that should help..
Before you ask for the picture, search here under McMarks posts...he has a great picture of the carbs broken down..its here somewhere.

We will need to get Len involved if he did your heads. (he knows how they are built)
Where did you get the camshaft? If its from Jake, and the heads are from Len, these two guys probably can save you loads of time...I bet they have built this exact combination and car help with jetting.
If not, we can walk you through it...its not rocket science.
The carbs/cam/heads all will dictate what you need to do.
This combination is what dictates the jets and venturis.

Smaller venturis will make it run a bit leaner.
Its odd, but it speeds up the airflow.
This statement is not blanket...its in combination with the heads and camshaft profile...so we will need those also.

If you do need to swap jets and venturis, I have had great luck with aircooled.net.
They have a database of known jetting.
They also swap jets and vents till you get it right..so you dont have to keep buying more and more stuff. Just send back the ones that dont work, get a new set.

Rich

No "supposedly" about it.. Remember- there are many variables that impact enrichment. I cannot tune an engine I haven't designed and built as well as one that I have. I jet people's engines from 2,000 miles away all the time with great results.

My jet sizes were defaults, if the temperature rises in summer you'll need to accomodate for that and I can't do that for you. You must learn as I did, by doing it.


Also, had that engine been at idle for any period of time before the plug was pulled? if so thats the answer to why it appears so rich, more than likely.

Also, have you adjusted the mixture control screws for YOUR engine to operate best? drive the car down the road @ 70 MPH and shut it down, never allowing it to idle, then p[ull a plug on the side of the road and take a pic.

BTW- 3.5 PSI is ttoo much for a weber carb, I run no more than 3 PSI and that .5 psi does make a difference to the super sensitive needles/seats in the Weber carb.

And.. What are you running for exhaust? Timing? retarded timing can make an engine seem rich due to the delayed burn of the charge.

I am good, but not a Magician.

The above pic shows the plug after driving 65 and shutting down. This is the pics of the plugs after removing motor. I alos did a leak down test on teh cold engine while I was pulling the plugs and they were mostly 35% (#2, 3 and 4) while #1 was 20-25%? Sounds like piston/ring issues?

Cylinder #4
Click to view attachment

Cylinder #3
Click to view attachment

Cylinder #2
Click to view attachment

Cylinder #1
Click to view attachment

Cylinder 4 has issues, bad intake valve guide, or fuched up rings more than likely. Tear it down. Have fun

Cylinders 2 couldn't be running better, cylinder 1 isn't far behind it but I do see signs of detonation on the porcelain...

The carbs seem to be tuned fairly well, they can't make up for a mechanical issue. Based on this I think my armchair tuning from 1K miles away is pretty damn good.

Cylinder 4 has issues, bad intake valve guide, or fuched up rings more than likely. Tear it down. Have fun

Cylinders 2 couldn't be running better, cylinder 1 isn't far behind it but I do see signs of detonation on the porcelain...

The carbs seem to be tuned fairly well, they can't make up for a mechanical issue. Based on this I think my armchair tuning from 1K miles away is pretty damn good.

Thanks Jake! I will redo the leak down to see if I hear any leaking through the carbs to confirm it is the rings.

Stay tuned for more pics of the tear down!

Some background reading to get you up to speed.

Basic Jetting discussion.
http://www.aircooled.net/gnrlsite/resource...les/jetting.htm

Pistons, cylinders, rings discussion
http://www.aircooled.net/gnrlsite/resource...cles/pcrops.htm

Weber tech book (buy this)
http://images.google.com/imgres?imgurl=htt...l%3Den%26sa%3DN

Parts breakdown of the Weber carb
http://www.redlineweber.com/html/Tech/40-4...s_breakdown.htm

PLEASE LOOK...take specific note of parts 47-50
47 is the main jet
48 is the emulsion tube
49 is the air correction jet
50 is the jet holder extension

These parts are all pressed together and will come apart with gently twisting...
You have not taken them apart, so you cant answer the question of what air correction jet you have.

In this assembly you will find three numbers.
Mains, air correction, and emulsion tube numbers.
these number are marked on each item 47, 48, and 49.


Rich

soooo???

Rich

Here is a pic of the intake valve on the #2 cylinder. What do you think?

Looks like I am getting some leakage around the seam around the main seal - and ideas on how to seal?

Vince knowing that you have new valve guides, I'd say you are pumping oil into the chambers and up into the intake ports. Your rings aren't seated. Look at how far up the port the residue runs.

It does not look like the residue run up the ports.

How should I clean them up before re-assembling?

Your heads are fine.
Take them off and do ana analysis of the rings.

You need to replace the front main seal. That typically happens when you rebuilt a motor.

Rich

Got the # 1 and 3 cylinders removed. Included a pic of the cylinder tops. Took a bunch. Let me know which ones you want and I iwll include some of my observations:

1. Cylinder #1 had both ring gaps at 6:00 position (worst possible?)
2. #3 had ring gaps at 1:00 and 5:00
3. Piston sidewalls show some level of scuffing, but nothing the untrained eye would be concerned with.
4. The cylinder walls still showed cross hatching marks.

Any other areas I should take a look at and provide comments of include a pic of?

Thanks!

Here is piston #1 - could they have been aligned any worse? Does the top of the piston tell the story?

The front seal was damaged during install. It is torn on the OD at the case parting line.

I'd be happy to inspect the pistons, cylinders and rings if they were bought from my store to see what the story really is. I'll do this for free.

Judging from the fact that all the oil is at the bottom of the piston, I'd say its an oil control issue and the oil is puddling in the cylinders.

I've got the Weber tech manual by Bob Tomlinson. It has some great info. You might want to see if you can get your hands on a copy. Main and a/c jets aren't the only things that affect mpg. Venturi size, emulsion tubes, idle jets, etc. There's lots of charts and graphs in the book to get you close. An EGA is a good tool to have too. I've got an old Heathkit unit that has payed for itself 100 times over.

How can I tell if cylinder walls are glazed and need rehoned?