Need alt, fan & housing education.

[millarg]

I have the alt etc dissembled to be sandblasted and wanted to enquire of proper distance between fan blade and housing.

At some point under previous ownership my 78SC suffered rear end trauma, fan housing still shows evidence.

I have always thought that the blade was too small - as best I can measure it is 9" diameter, whereas the ID of the housing appears to be just over 9.5" meaning a 5/16-3/8 gap between blade and housing.

The housing part # is 930.106.102.OR
Can't find part number on fan - it has 11 blades & doesn't appear to have been butchered in any way

Alternator is A14N11, 14V 75A

Any suggestions appreciated,

Thanks in advance, Glen

[Justin@Athens]

Don't sand blast it, use soda or glass. It is an aluminum/magnesium alloy that will pit fairly easily. Then powder coat it.

The fan housing on my '89 fits much more closely (1/16" gap). I can't comment on the specs for your SC.

Good luck.

[Bob Kontak]

My experience is that sandblasting these parts then powder coat will deliver a very shiny finish. I would not do a thing to the alternator itself.

Not arguing with Justin, just stating my experience.

[masraum]

You absolutely have an issue. It's my understanding that you need the very close fit between the fan and housing to get the appropriate cooling. The fit should be very close, definitely not 1/4" per blade.

[Bob Kontak]

Here is an older link. Does not indicate what year SC the 930 106 102 OR is from.

WTB Fan Housing

The US PET (parts diagram) does not agree with the number of your housing. You may have a ROW car and I do not have access to the ROW catalog in my garage. I can confirm later.

I have a feeling your housing is "ok" but you fan is too small. 1/4 inch wall gap is too small. There has to be threads about differences in fans housing and diameters. I will dig into this later down in the "man cave" as I just found out my matching number 930/16 81SC engine has a mag fan housing from a 74 (fan fits great though). Not the end of the world but would like to understand if there are major differences.

[Bob Kontak]

OK - Found a thread that says the 78-89 fans were 226mm and all other 930/911 fans were 245mm.

245mm = 9.645 inches
226mm = 8.897 inches

I bet you have a later SC housing with the original fan.

Engine cooling fan

[boyt911sc]

Originally Posted by Justin@Athens

Don't sand blast it, use soda or glass. It is an aluminum/magnesium alloy that will pit fairly easily. Then powder coat it.

The fan housing on my '89 fits much more closely (1/16" gap). I can't comment on the specs for your SC.

Good luck.

Justin,

What's the reason for not using sand but OK with glass beads? I don't get it. Please advise. Thanks.

Tony

[GaryR]

Glass beads are much finer than standard (1/4 grit) Black Beauty sandblast sand. Finish is much smoother, takes a lot less material off, won't expose pits in the aluminum casting.

[Bob Kontak]

All sandblasted at a powder coating factory. Did get some powder coating on some of the gasket surfaces that had to be removed but came out nice.

I glass beaded my pistons. I have read where that was a no-no but still holding together.



Here is a better pic

[Bob Kontak]

Originally Posted by GaryR

won't expose pits in the aluminum casting.

This makes sense. I did have some ugly pits in my shroud. Sandblasting just made them a wee bit bigger.

[masterdave]

What are soda and glass blasting, I have been thinking about doing this for some time but wanted to do it my self (was considering sand blasting), I have a lot of time on my hands this winter and was going to do it. Has any one done it them selves and have any advice. Or should I just have it done some where, what would an estimate for just the fan and fan housing be?

[Bob Kontak]

Glass beads are not as sharp as sand - more globe like and are not as abrasive. If I remember, the globules explode upon impact absorbing some of the impact. Finish is smoother than sand. I am not sure - the other guys will know - but I think soda blasting is less abrasive than glass beading. People also use walnut shells ground into a powder for a blasting media as well. Sand is cheap - other stuff is many times more expensive.

Depends on what you want to clean up and what pressure you will be using. If you have a home compressor and you will be pumping out 90psi, sandblasting will be ok for the panel under the rear or front bumper or spot repair, engine sheet metal, etc. An industrial setup could warp a body panel. Common sense applies.

Google search is your friend http://abdeburr.com/catalogue.aspx?Cat=2&SubCat=7&gclid=CNyWiemf9qsCFYLsKgodMAmApQ

Coal slag looks pretty nasty.

[masterdave]

I have a fairly hefty home compressor, i think it can get it up to a solid 120psi or around there. I dont mind cleaning up stuff if it means I can do the job that much cheaper. I will most likely start a thread for all this when the date gets closer, but thank you for all the info.

[ivangene]

WOW @ pics...some parts were meant to be plain looking...those look like a circus clown


(sorry its an opinion)

[Bob Kontak]

No prob. The red is a little orange in the pic. By the time you get everything back in place with CIS and throw a little grime in, the only thing you can really see is the fan and part of the chain housing covers. It actually looks pretty sedated and clean.

Here is a pic of black and red with yellow. The carbs make you forget about the clown colors, though.



I could deal with this clown car:

[ivangene]

Wow bob, that's way nicer than the parts looked in the yard.... my hats off to one beautiful motor

[KTL]

Originally Posted by millarg

I have the alt etc dissembled to be sandblasted and wanted to enquire of proper distance between fan blade and housing.

At some point under previous ownership my 78SC suffered rear end trauma, fan housing still shows evidence.

I have always thought that the blade was too small - as best I can measure it is 9" diameter, whereas the ID of the housing appears to be just over 9.5" meaning a 5/16-3/8 gap between blade and housing.

The housing part # is 930.106.102.OR
Can't find part number on fan - it has 11 blades & doesn't appear to have been butchered in any way

Alternator is A14N11, 14V 75A

Any suggestions appreciated,

Thanks in advance, Glen

Glen,

Having just gone thru part numbers and casting numbers for various fans (to change my '79 226mm fan to a suitable 245mm fan & housing) I can assure you that the 930.106.102.0R fan housing casting number is the casting for a '80-'83 3.0L SC or '78-'89 3.3L Turbo 245mm fan housing.

How about you post a picture of your fan laid in the housing and we can make a better assessment as to whether the fan fits properly or not. Sounds like the guys have it right- 226mm fan inside 245mm housing.

Originally Posted by Bob Kontak

OK - Found a thread that says the 78-89 fans were 226mm and all other 930/911 fans were 245mm.

245mm = 9.645 inches
226mm = 8.897 inches

I bet you have a later SC housing with the original fan.

Engine cooling fan

Slight typo by Bob. It should say 78-79 fans are 226mm. However the non racing 226mm and 245mm fan housings have the same outer diameter. Meaning, regardless of fan size, the OD of the housing is the same and therefore the plastic (or fiberglass) engine shrouds have the same arched opening for the fan housing. However the inside diameter of the fan housing is obviously different for 226mm and 245mm fans and that sounds like the problem.

Here's a great bit of information provided by Tom Butler (tom1394racing) on the forums.




edit for correcting my statements about the casting number- '80-83 3.0L SC and 78-89 3.3L Turbo engines

[Bob Kontak]

Nice job Kevin.

My Typo in post #6 was not so slight really - but it was a typo. At least I put the link in.

[KTL]

No worries Bob. I had to edit/correct myself as you can see. I originally misspoke, saying that the 930 102 0R was the 226mm housing!

Great looking engine bay by the way. Excellent job plumbing the fuel and also mounting the ignition boards. I had my single board on the wall like that and struggle with getting to the dials for adjustment. I'm going to give the Clewett mount a try (places them between the carbs atop the engine). Got any pics of your oil tank install? Send me a PM if you don't mind, to keep from going off topic with responses here.

Thanks,
Kevin

[Tippy]

Glass beading tore up my fan and the housing!

I just did it a week ago.

I used medium grit.