L Backdate Heater Duct/Disty clearance problem, help!

[AZAirCooled]

Anybody else have a problem with distributor cap clearance after installing the left back dating heater duct? Solutions, suggestions, explainations?

I have a 1976 911S with a 1981 3.0 motor. Bought the duct from our host and the part discription said some adjustment with a hammer is required, ok. I have a Bosch cap and new SS Buru wires. My engine cover is green. The disty cap won't quite line up and snap into place for interferance from one spark plug wire boot (mm's off?).

So far I've used a hammer to align the duct holes and installed the duct. I've used a hammer on the duct to creat a slight dent where the boot contacts it. I even slightly razor bladed a very thin angle off the boot (not the wire, didn't go thru).

The interferance is very slight but if I could get a little more "dent" in the duct (it was very hard to get the one I have) I think I might have a problem adjusting the timing.

?

[MysticLlama]

It takes a pretty big clearancing.

John Walker actually cuts a section out there and welds in a new piece to create the necessary clearance, I think there have to be pictures on here somewhere.

[AZAirCooled]

Thanks Rob.

[john walker's workshop]

here's a link to the mod. John Walker's magical hand (heater duct)

[boyt911sc]

Originally Posted by AZAirCooled

Anybody else have a problem with distributor cap clearance after installing the left back dating heater duct? Solutions, suggestions, explainations?

I have a 1976 911S with a 1981 3.0 motor. Bought the duct from our host and the part discription said some adjustment with a hammer is required, ok. I have a Bosch cap and new SS Buru wires. My engine cover is green. The disty cap won't quite line up and snap into place for interferance from one spark plug wire boot (mm's off?).

So far I've used a hammer to align the duct holes and installed the duct. I've used a hammer on the duct to creat a slight dent where the boot contacts it. I even slightly razor bladed a very thin angle off the boot (not the wire, didn't go thru).

The interferance is very slight but if I could get a little more "dent" in the duct (it was very hard to get the one I have) I think I might have a problem adjusting the timing.

?

AZ,

It would take some effort to make the right indentation on the metal duct (driverside) by using a ball peen hammer to get a good clearance from the distributor body. Short of cutting and welding, making the indentation is the next best procedure I found for creating the necessary clearance. It is a simple and easy conversion. I've done this metal sheet conversion project atleast half a dozen times in the past and very satisfied with the results.

Tony

[AZAirCooled]

Tony,

It sounds so simple to make an indentation with a ball peen hammer. I spent a lot of time beating the hell out of the spot that needs the clearance will many implements of distruction including a ball peen hammer. But I produced very little relief (not enough).

Can you give me any details on the "procedure" or "tricks" you used to make the indentation? Today I'm going to try using a torch to heat the spot during the ball peen hammer beating.

What a bummer, I had planned on spending the weekend driving the Targa around with the top out in 72 degree weather, but instead I am fabricating sheet metal!

I thought I bought an R&R part, not a core for a fabricated one!

[AZAirCooled]

Thanks guys, Bob

[AZAirCooled]

John Walker's modification looks very nice.

John, how much does your shop charge for the modification?

[Rot 911]

Heat and hammer method: Heater Duct Modification

[john walker's workshop]

the main problem with the ballpeen method is that the duct gets all out of shape where it mounts to the fan housing.

[VaSteve]

Originally Posted by AZAirCooled

Tony,

It sounds so simple to make an indentation with a ball peen hammer. I spent a lot of time beating the hell out of the spot that needs the clearance will many implements of distruction including a ball peen hammer. But I produced very little relief (not enough).

Can you give me any details on the "procedure" or "tricks" you used to make the indentation? Today I'm going to try using a torch to heat the spot during the ball peen hammer beating.

What a bummer, I had planned on spending the weekend driving the Targa around with the top out in 72 degree weather, but instead I am fabricating sheet metal!

I thought I bought an R&R part, not a core for a fabricated one!

Yes, heat it and beat it!!! I thought I had done my enough on the workbench until I put it back on the car. When I realized the dist cap was cockeyed, I pulled it off, heated it with a propane torch and beat the hell out of it some more. The heat really makes it a lot easier. You really need to knock it in pretty good for the clearance.


Oh and it's like 34 degrees here and super windy, so you can take your 72 degrees and stick it.

[boyt911sc]

Originally Posted by AZAirCooled

Tony,

It sounds so simple to make an indentation with a ball peen hammer. I spent a lot of time beating the hell out of the spot that needs the clearance will many implements of distruction including a ball peen hammer. But I produced very little relief (not enough).

Can you give me any details on the "procedure" or "tricks" you used to make the indentation? Today I'm going to try using a torch to heat the spot during the ball peen hammer beating.

What a bummer, I had planned on spending the weekend driving the Targa around with the top out in 72 degree weather, but instead I am fabricating sheet metal!

I thought I bought an R&R part, not a core for a fabricated one!

AZ,

I sold about a dozen sets in the past and if the buyer wanted more space for the distributor body, I made them for free. It looks daunting at first but after you have tried it once, the next are easy. The trick is to start at the center where you want the most curvature. Start at the edge where the resistance to deformation is greatest!!!!! This is some sort of 'creative art'. As a matter of fact, I'll try to do one today or tomorrow. Got to finish the X'mas tree first today and will post my art work.


The duct at the upper most left is for the turbo and looks very similar to JW's duct works.

Tony

[AZAirCooled]

I'm a blacksmith now!

Kurt thanks. I wish I had searced this forum better before I started the project. Your method is what I ultimately did. It's done and looks great. The first attempts were off the car without heat. It was difficult, gave poor results, and as John mentioned, moved the mounting holes back out of alignment again (I had to "tap" on the sheetmetal around the holes to mount it the first time). With the disty cap almost on I scratched the duct where it needed to go in. I used a realy long screw driver to hold all wires & disty away from the duct. Then I alternated between heating up a spot to glow red using a torch and using the round end of the ball peen hammer to shape the duct. The paint or powder coat on the part smoked but I was VERY mindful of the locatation of the torch flame at ALL times and was by the open garage door. I had a bucket of water and a fire extinguiser near by. I recogize that this was not the safest approach and do not recommend that anyone compromise on safety. I am not a fabricator or mechanic, just a self taught DIY'er. After I was done I scuffed the damaged area with 400 gret sand paper, wiped with paint prep degreaser, and used a sponge brush to paint the area to minimize rust. My engine bay is not beautiful yet so whenever I need to pull the engine I plan to detail the engine and bay and will prep and spray the duct then.

If time and mony are not a concern, I would have John modify the part if his shop still performs the service. There is a link in this thread showing his beautifully modded part next to a stock one.

It's a beautiful day and I gotta go drive the Targa now! Woo Hoo! Here is a great website for checking the weather before you take out your beloved car, The Aviation Weather Report and Forecast - Wind Speed, Temperature, Wind Direction, Precipitation Forecast
You do not need to set up an account or log in. Just use the "Get Locations" pull down menu, twice, to get to the town nearest you. It is an aviation website for pilots so it predicts all aspects of weather in your area, by the hour! Oh, my bad, it's going to be 74 today! Heh, heh,heh, I love this town! Yes, the top is out!!

Thanks for the support guys!

Bob
76 911S Targa 3.0