Questions: Intake Port Carbon Deposit

[kevin_fisher2.0]

A few quick questions for the forum. Currently the engine in my 1969 911T 2.0 is out for a new clutch, carb rebuild and oil leak fixes.

- After removing the carbs/intake manifolds, I inspected the intake ports. Numbers 2-6 look clean as a whistle while port #1 has a consistent, thin layer of carbonization. Is it a burnt valve, bad seat, bad guide? Recommended next steps? Can this be identified without significant engine disassembly? I checked and all valves are properly adjusted (0.004 in.)
- Fuel line replating; the plating (zinc, cad?) from the metal line that supplies both carbs has worn off; is it OK for the new plating to cover the inside diameter as well as the outside diameter or do I need to block this off with some fittings during the plating process?
- Points; my Marelli distributor still has points and the engine is equipped with a PermaTune ignition box; should I take the next step and install a Pertronix electronic ignition kit on the distributor?
- Ignition coil refresh; OK to mask the top and repaint the coil housing? Alternatively, can coils be powder coated?
- Intake manifolds; what material are these black painted items? Can these be bead blasted and powder coated? Or should they be paint stripped and resprayed using rattle can?

Here's a 'progress' image.

[304065]

1. Who knows, could be a jet problem or a bad guide, how far down are you planning to go?

2) Do you mean the line up on the shock crossmember? The plating process involves an acid dip to completely degrease the part and remove old coatings-- it's not perfect but it should help clean inside. Electroplating doesn't work very well on the inside of tubes for some reason, so I wouldn't expect it to plate internally, but it might. Just make sure there is no rust.

3) Can you get a Pertronix for a Marelli? I thought only Bosch. Anyway, I would be the other way around-- keep the points and check the Permatune, they often go bad, including the old ones. A new MSD works great or the OE Bosch CDI is a time-proven winner. The Pertronix is claimed by many to eliminate points bounce and spark scatter.

4) Painting coil OK. Powdercoating not OK, the heat will destroy the coil. You probably have a Permatune coil anyway so don't bust your pick if you're going to change to MSD or Bosch.

5) The manifolds are magnesium, covered in a black epoxy finish. Are they in poor condition? Removing the coating is VERY difficult and you are likely to find corrosion in the magnesium substrate.

Good luck and keep the photos coming!

[cgarr]

Which side is your breather hose connected too? I bet its just oil making it look like that and not actually exhaust carbon..

[kevin_fisher2.0]

Originally Posted by 304065

1. Who knows, could be a jet problem or a bad guide, how far down are you planning to go?

2) Do you mean the line up on the shock crossmember? The plating process involves an acid dip to completely degrease the part and remove old coatings-- it's not perfect but it should help clean inside. Electroplating doesn't work very well on the inside of tubes for some reason, so I wouldn't expect it to plate internally, but it might. Just make sure there is no rust.

3) Can you get a Pertronix for a Marelli? I thought only Bosch. Anyway, I would be the other way around-- keep the points and check the Permatune, they often go bad, including the old ones. A new MSD works great or the OE Bosch CDI is a time-proven winner. The Pertronix is claimed by many to eliminate points bounce and spark scatter.

4) Painting coil OK. Powdercoating not OK, the heat will destroy the coil. You probably have a Permatune coil anyway so don't bust your pick if you're going to change to MSD or Bosch.

5) The manifolds are magnesium, covered in a black epoxy finish. Are they in poor condition? Removing the coating is VERY difficult and you are likely to find corrosion in the magnesium substrate.

Good luck and keep the photos coming!

This is about as far down as I'd like to go right now. With the engine performing well before its removal and a limited budget my goal is to clean things up, stop some oil leaks, replace the clutch, paint the engine compartment and re-install.

Yes, the line that runs along the crossmember. It's pretty clean but I'll plan to cap it during replating anyways (along with making sure no rust particles are inside.

Looks like you're right about the Marelli elec. ignition parts availability. I'll stick with points for now.

Yes, manifolds are in poor condition. I'll post a few photos. They need to be stripped and recoated. One needs to be rewelded. Anyone know someone who can weld Mg in SoCal? How about the epoxy finish; is there a specialty shop for this? Anything wrong with painting them with glossy, black Wurth enamel?

[kevin_fisher2.0]

Originally Posted by cgarr

Which side is your breather hose connected too? I bet its just oil making it look like that and not actually exhaust carbon..

Breather hose is on the other side. This intake port has no external tube connection.

Also, the breathers on the other side, 4 and 6, are connected to each other. I'm assuming this move by the previous owner is OK.

[kevin_fisher2.0]

Afew more questions for the group:

- Intake manifolds: See photos per comments above.

- Timing Chain covers: Can these be cleaned with Scotchbrite and degreaser? I did a test patch and it appears that these are actually too abrasive leaving scratch/streak marks. Any recommendations?
- Oil tank: I will have it flushed and repaint with high-temp 500 degree paint. Do these need pressure testing?
- Casting/stamping codes. What do these various numbers mean? Dates?

[304065]

Kevin,

See those stiffening ribs on the mainfolds? that tells you they are the later style. If you look on the side you should see the part revision number, probably 1R. That means they are fairly cheap and widely available from all the junked 911T motors-- $100-150 a set in today's market.

If you want the flange welded up, send to Ollies in Lake Havasu, they can fix you up. Will certainly be cheaper, but given the stressed nature of the flange I would rather have a new set.

The numbers all mean things-- particularly the case parting number -

[kevin_fisher2.0]

Thanks for all the help so far. Another question... The fan shroud bolt closest to the oil cooler broke off into the cam housing. While drilling it out I drilled all the way through the 6-mm bolt into a recess.

Any reason to be concerned about this or the metal shavings that could've fallen in? I can't think of a reason why this area would be exposed to oil or bearings but just wanted to ask?

Next question: my trusty bolt extractor snapped off while trying to extract. Best next step? Employ a titanium drill bit?