My Conversion Project, Question on Engine Break-In Options

[Cap'n Krusty]

Not to rain on the parade, but with S pistons and Solex cams, you have a high compression E. Looking at 130-140 HP, tops, especially with carbs. Good luck with the fuel ............ I had a 2.4S based Solex cammed motor in my bus for 10+ years. Fun motor. In the 37 years I've been working on 911 engines (and for a 3 or 4 years, we did a minimum of one a week), I've NEVER timed them with the tensioners installed. In fact, I don't see how you could. If it were OK to do so, the manual would be written differently.

The Cap'n

[Ericv1]

Not to rain on the parade, but with S pistons and Solex cams, you have a high compression E. Looking at 130-140 HP, tops, especially with carbs. Good luck with the fuel ............ I had a 2.4S based Solex cammed motor in my bus for 10+ years. Fun motor. In the 37 years I've been working on 911 engines (and for a 3 or 4 years, we did a minimum of one a week), I've NEVER timed them with the tensioners installed. In fact, I don't see how you could. If it were OK to do so, the manual would be written differently.

The Cap'n

So, what do you use to clamp down on the idler arm? I used a vice grips and it was in the way when I went to intall the tensioner. Then without losing tension, I switched to a channel lock thinking it had a slimmer profile but I still could not get the tensioner installed without it slacking. That's when I lost grip and the chain slacked. I was able to intall both tensioners and start the process over. It was a little more difficult because the left side did not have as much room to remove the nut. I was able to position the pin in the correct setting and torque down the nut. From what I understand, cam timing is about repeatable results. I was able to get the same results through 12 rotations of the engine. Just curious, thanks.

[ArtechnikA]

...I used a vice grips and it was in the way when I went to intall the tensioner. Then without losing tension,...

The timing is a fine adjustment (like a vernier) on the position of the cam relative to the position of the crank (via the intermediate shaft). Coarse adjustment is set by the links in the chain.

You set the initial timing, put in the pin to hold it there, and YOU ARE DONE on that side. There's no 'maintaining tension' to it - the tensioner acts on the 'slack' side of the chain that does not affect timing. Unless you somehow manage to slip a whole tooth on the chain, your timing does not change.

You tension one side, establish the cam position, pin it, do the other side, pin it, install tensioners and re-verify.

[jmill]

Curious why you went with solex cams? With the IDS carbs and S pistons I would think you could seriously benefit switching to the S cams. Low end would suffer but you'd get another 50 hp on the top easy. Does it have a CW crank? Couldn't really tell from the post. I've seen T,E and S mentioned.

[PRS914-6]

I'm a little concerned for you.....

1. Did you put a straightedge across the top of the case to make sure that it was flat with no warpage?

2. Did you check the length of the cylinders? One shorter than the others?

If the case has warpage or the bad cylinder was jumping up and down and wore the top of the cylinder (making it shorter) it won't matter if the heads are flat it will happen again.

I find it odd that a couple of thousands head warpage would cause a head gasket blow out in 500 miles. I have pulled motors down that were warped way worse than that with no issue. In fact my 3.6 was warped .010 on one head with no leakage. I would look a little deeper, something else may be wrong.....

[Ericv1]

...I used a vice grips and it was in the way when I went to intall the tensioner. Then without losing tension,...

The timing is a fine adjustment (like a vernier) on the position of the cam relative to the position of the crank (via the intermediate shaft). Coarse adjustment is set by the links in the chain.

You set the initial timing, put in the pin to hold it there, and YOU ARE DONE on that side. There's no 'maintaining tension' to it - the tensioner acts on the 'slack' side of the chain that does not affect timing. Unless you somehow manage to slip a whole tooth on the chain, your timing does not change.

You tension one side, establish the cam position, pin it, do the other side, pin it, install tensioners and re-verify.

That makes a lot of sense. I thought you had to maintain tension throughout the whole process. I ended up installing the tensioners and setting the timing with them in. I was able to set to the correct spec, but it was more difficult torquing down the left side cam nut. Thanks.

[Ericv1]

I'm a little concerned for you.....

1. Did you put a straightedge across the top of the case to make sure that it was flat with no warpage?

2. Did you check the length of the cylinders? One shorter than the others?

If the case has warpage or the bad cylinder was jumping up and down and wore the top of the cylinder (making it shorter) it won't matter if the heads are flat it will happen again.

I find it odd that a couple of thousands head warpage would cause a head gasket blow out in 500 miles. I have pulled motors down that were warped way worse than that with no issue. In fact my 3.6 was warped .010 on one head with no leakage. I would look a little deeper, something else may be wrong.....

I did not check the case. The cylinders were checked the same time the heads were in the shop on the recommendation of the machinist.

[Ericv1]

I've been busy this past month. I pulled apart the left side on the advice of PRS914-6 to make sure the case was level and flat. I put a straight edge on it and it was fine. At least I know that it's right and it only cost me $30 in seals. I got the engine together and worked on cleaning up the engine compartment. The hell hole was in great shape. It appears it's been replaced before along with the engine shelf. The only way I knew was that they did not grind down the welds. Smythe auto parts mixes spray paint and it's local. They were able to mix my color code and I painted it up. I put a couple coats of clear on it to make it look pretty. My next step will be to drill the holes for the oil tank and mount it. Then, I'll put the engine in and replace the fuel pump. I bought a CB rotary that should work well with the carbs. Here's some pictures of my progess to this point.

[Ericv1]

I got some more work done this weekend. I was able to install the oil tank. It was a tight fit. I was able to tilt it at an angle and gentley nudge it in. I had to cut out the support bracket for the blower from the heating system because I could not install the oil filter with it there. I was also able to clean up some surface rust on the bottom of the engine shelf and get it painted. I had to put a dehumidifier in the garage to keep the humidity under 50%. Those of you who live on the west coast don't have that problem but it'll rust a car fairly quickly. Here's a picture of the oil tank. Next I'll work on cleaning and replacing the main transmission drive seal. It is 36 years old and leaking and a cheap "while your in there" project.

[J P Stein]

Curious why you went with solex cams? With the IDS carbs and S pistons I would think you could seriously benefit switching to the S cams. Low end would suffer but you'd get another 50 hp on the top easy. Does it have a CW crank? Couldn't really tell from the post. I've seen T,E and S mentioned.

I am a serious fan of the Solex cams. There is more hp to be had with the S cams but with a drivability loss.....they are too peaky, IMO.

In my 2.7 I get excellent torque from 3500 to 5000 rpms.....over 200 ft/lbs and "tuning issues" with the carbs are minimal. The hp drops off about 6300 from a peak of around 230.......still well over 200 at 6800. The S cams get peak torque at 5000 rpms.....no thanks. With the exception of the P/Cs (10.5:1 Mahles) this is a "no trick shit" build using all Porsche parts.

[Ericv1]

Curious why you went with solex cams? With the IDS carbs and S pistons I would think you could seriously benefit switching to the S cams. Low end would suffer but you'd get another 50 hp on the top easy. Does it have a CW crank? Couldn't really tell from the post. I've seen T,E and S mentioned.

I am a serious fan of the Solex cams. There is more hp to be had with the S cams but with a drivability loss.....they are too peaky, IMO.

In my 2.7 I get excellent torque from 3500 to 5000 rpms.....over 200 ft/lbs and "tuning issues" with the carbs are minimal. The hp drops off about 6300 from a peak of around 230.......still well over 200 at 6800. The S cams get peak torque at 5000 rpms.....no thanks. With the exception of the P/Cs (10.5:1 Mahles) this is a "no trick shit" build using all Porsche parts.

I agree. Ultimately, I want a nice driveable street car with more torque and horsepower than I get from the present motor. Plus, I've always wanted to build a six conversion. If I can get 140hp with 160 ft/lbs of torque, I'll be a happy camper. When I drive my car now, it rarely operates above 5,000 rpms. Most of my driving is between 3,000 and 4,500.

[J P Stein]

After torquing down the heads & cam tower, the cams should turn freely (finger pressure) in their bores. Any of the many surfaces being a different height will cause a bind at some point in the rotation. This is the last of many checks for parallel.

That said, whenever a mag case comes down, it's wise to have the case spigots decked & squared. Those cases are noodles but if the above was done you should be good to go.

[Ericv1]

So I was working on the engine harness today and had a few questions. I thought it would be easy to switch the pins in the plug to the configuration in DR 914's book but was mistaken. I have all of the plugs labeled but there are a couple of wires that I need ID'd. The first is a black wire with a purple stripe that that runs from the plug to the dizzy and then goes to the CDS unit. In appendix II of How to convert your 914-4 to a 914-6, I think this is the wire to the control unit. Is this correct?
The second wire is blue with a yellow stripe that goes to terminal 15 on the coil. Is this the wire for the tach?
And finally, I have four wires for the Alternator (B+, DF, D-, and D+/61). The book does not describe where these wires fit on the plug. Any help would be appreciated from the wiring Gurus. The wiring harness is from a 70T and it's a 69 2.0. Thanks.

[ArtechnikA]

Black wire purple tracer is tach.
'the control unit' ? wazzat ?
Terminal 15 is 'coil' positive - that'd be from the CDI ignition box.
Make sure you have a CDI "coil" (not really a coil with CDI...).

[Ericv1]

Black wire purple tracer is tach.
'the control unit' ? wazzat ?
Terminal 15 is 'coil' positive - that'd be from the CDI ignition box.
Make sure you have a CDI "coil" (not really a coil with CDI...).

Thanks Rich. " The Control Unit" in this case is the CDI box. That's how Dr. 914 describes it in his conversion book. The system I have is an exact transplant from a 70T I had running last summer. So, it should work if I wire it correctly. So , terminal 15 is the CDI signal. Where do I connect the four alternator wires? It doesn't really describe where those pins go in his book. Thanks, Eric

[ArtechnikA]

...terminal 15 is the CDI signal. Where do I connect the four alternator wires?...

Let's clarify the CDI thing because the terminology is important (Bosch CDI boxes are expensive...) Be careful about use of the word 'signal' ...

the Bosch 3-wire CDI box has 3 connections (duh...). Ground is easy and not one of the 3 connections... It takes switched +12 from the ignition switch for power. It takes the points-closing "signal" from the distributor - and that may in fact be the black/purple. Then the high-voltage (~300V) output pulse returns to the "coil." I'm pretty sure that's your green/yellow.

(The black/purple then goes forward to run the tach.)

As for the alternator - this is why I consider the alternator harness part of the car, not part of the engine ;-) ...

I believe colors and pin assignments are shown on the 911 wiring diagram (in color) and the Art Zapf 914.6 big color wiring diagram - both of which I have but can't get to this morning. Let me look for/through those tonight and this weekend.

If someone else has the information right at hand - go ahead and post it here...

Especially since I do not have a relay board I can reference...

[Ericv1]

...terminal 15 is the CDI signal. Where do I connect the four alternator wires?...

Let's clarify the CDI thing because the terminology is important (Bosch CDI boxes are expensive...) Be careful about use of the word 'signal' ...

the Bosch 3-wire CDI box has 3 connections (duh...). Ground is easy and not one of the 3 connections... It takes switched +12 from the ignition switch for power. It takes the points-closing "signal" from the distributor - and that may in fact be the black/purple. Then the high-voltage (~300V) output pulse returns to the "coil." I'm pretty sure that's your green/yellow.

(The black/purple then goes forward to run the tach.)

As for the alternator - this is why I consider the alternator harness part of the car, not part of the engine ;-) ...

I believe colors and pin assignments are shown on the 911 wiring diagram (in color) and the Art Zapf 914.6 big color wiring diagram - both of which I have but can't get to this morning. Let me look for/through those tonight and this weekend.

If someone else has the information right at hand - go ahead and post it here...

Especially since I do not have a relay board I can reference...

Thanks for the information. I can at least get the rear plug setup correctly. I'm interested to see how the alternator will be wired in. Obviously the the voltage regulator on the relay board has to play a part. I have the 911 haynes manual and it's pretty usless in this detail. I'll try to search for the Art Zapt 914.6 diagram when I get home.

[jt914-6]

The battery + wire goes to the battery +. See pic for the wires that go to the regulator. The D+, D-, and DF go to the regulator. I did away with my relay board and simply pluged in the wires from the alt. to the regulator direct....Regulator is #4.

[Ericv1]

The battery + wire goes to the battery +. See pic for the wires that go to the regulator. The D+, D-, and DF go to the regulator. I did away with my relay board and simply pluged in the wires from the alt. to the regulator direct....Regulator is #4.

I just found that diagram under "914-6 Wiring" from a couple of years ago. It makes so much sense now. I can wire the alternator pins directly to the alternator wiring harness on the relay board and be done with it. My final question is: Can I wire the blue wire from the alternator (the one that works the light on the dash) to the corresponding receptacle on the main wiring harness? Thanks for your help.

[jt914-6]

Connect the blue alt. guage light wire to the D+ wire at the regulator and it should work.....mine does.....