1972 Porsche 911 with ZZ4 and 930 Trans

Hello All,

My name is Ryan and after a long search made the jump into a 911 Outlaw that has some cosmetic work that needs to be done. I’ve owned and driven a number of fast vehicles - Dodge Viper, Corvette FRC, Ducati 1198, KTM RC8R, and the mighty F/A-18A-D. Unfortunately I never had time to do anything but drive them. Below is my long term project and I’ll likely need some of your assistance along the way.

First, I need to remove the carb spacer so I can get the air filter assembly lower so I can install a grill over the deck. Will that cause any significant performance degradation? The car is currently putting out 325 RWHP at a weight of approximately 2,300 lbs. Additionally, if removal of the spacer doesn’t provide enough overhead capacity, are there any other air filter assemblies that may be attached to the sides vice directly above the carburetor? 

Thanks

I dont think you'll notice anything objectionable even if you lose a couple hp with that type of power to weight ratio.  It looks like there may be some slightly shorter air filter assemblies out there vs what you have, but finding the shortest one is usually something of a PITA because some bases will interfere with some carburetors and not with others. 

looks beautiful

Looks so clean and crisp in white. Love it! 

B&M has been making a low profile filter that draws from the sides for years. It looks like Holley has a newer version that might be even more low profile now. Linky

The biggest reason for the non metalic spacer is to prevent heat soak in the carb. It may be perfectly OK to remove in your application, but be consious of the fact that most carbed V8s have them. The extra runner length may improve power, but will you notice it? You will notice if you get hot start problems that were previously absent though!

Ron, thanks! I’ll look into that. There is a ton of space in the bay to the sides, just not fore and aft.

Turner, if that is the case, what height spacer is typically sufficient to prevent heat soak? I’m certain a 911 Turbo deck lid would fit over everything, but I much prefer the RSR ducktail look if I can make it work and not sacrifice drivability.

There are so many factors that determine the effectiveness of a carb spacer that I don't even have a rule of thumb.  I usually play with spacers on the dyno as kind of a last step and sometimes they make an improvement and sometimes they don't.  The only time I've seen them make a really big change is when the combination is really miss-matched in the first place so I wouldn't worry about removing it for performance reasons in your application. 

As other have mentioned heat transfer could be an issue.  The thermal break can be helpful but you don't necessarily need a thick spacer.  My Camaro would boil the fuel in the float bowls while the car sat in the paddock between races before I added the aluminum heat shield under the carb.

Love the 911 by the way.

I second the thin heat shield, some 60's GM products came with a stainless version, they were absolutely necessary. 

In reply to BarrettRC8 :

I would make a thin stainless one as described by akylekoz. Make it as long and wide as you can without fouling anything else, and around .040 inch thick. Paper gaskets both sides. APE's experience says it should be enough.

The air filter you currently have, I believe, is not very well respected at all and actually blamed for engine fires.  What I might consider is a carb hat like you would use to boost a carb, only run it to a tube and a remove mounted cone filter ala K&N.

My 2 cents, take it for what it's worth.

So my gameplan is to maybe this weekend purchase the Spectre 9834 listed below. It is 1.9" compared to the Edelbrock air filter assembly that is currently on the engine which is 3". And if I'm lucky I'll be able to get some aluminum sheet with small holes stamped out of them and fab up a grill, which, with a spacer along the edge of the decklid may allow just enough clearance. If not, I'll go ahead and take out the spacer, add paper filters and a stainless heathshield and I should be good.

I'm not super optimistic that I'll get it all done as we're celebrating my daughter's first birthday and will have a fair number of people in town. But the first step is to make a plan!

Thanks all. 

https://www.spectreperformance.com/search/product.aspx?prod=9834#specifications

You definitely don’t need that stack of spacers.  You need to check the clearance above the choke horn and the air cleaner.  I’d recommend a drop base round air filter like the ones that came on the C3 Corvette.  The C3 probably had the least carb to hood clearance of any production car.

Maj, 

Is like to go that route as it seems easiest, but if you look at the photo, overall clearance isn’t really the issue, it is the clearance at the aft end of the decklid.

There are also 'heat isolator gaskets' for carbs that are just a thicker carb gasket, with that and a different filter might get it dropped enough.

https://www.amazon.com/Edelbrock-9266-Heat-Insulator-Gasket/dp/B00062YBPM

I kind of like the suggestion of a round, drop base air cleaner, with a K&N filter lid for a top to let it breath better.  Some 3/4" tall round filter plus a filter lid perhaps.

Pres, thank you for the head's up regarding the air filter - I bought the car as is, so it wasn't a choice I made. Regarding a round, drop base air filter - Unfortunately it won't fit because it is so close to where the rear decklid closes, even with removing the spacer. In the box I fashioned up to represent the dimensions of the dual plenum Spectrum product I listed above, even with a front to aft measurement of 8", it is still to tall at 1.9" (with the spacer still on.)

I actually like how the above product would look - Somewhat similar what the turbo 911s look like under the hood. Can anyone see any issues with that setup and two cone filters? The pictures below reflects roughly what it'd look like albeit with the additional 1" spacer still installed.

If that were mine I'd be tempted to fabricate a stainless steel wire cloth (aka wire mesh) replacement for the vent.  Cut, grind, bondo and sand some MDF into the shape you need to clear everything and then from the cloth over the form.  Depending on what cloth you get you might not even need a form.

APEowner,

Apologies for my ignorance, but I can't really understand or picture what you're describing - I'm completely open to all suggestions though. Do you mean creating a duct that feeds directly to the grill? Or just fabricating a completely custom intake? 

Any chance you have a youtube link or webpage talking about it? I'll try to do some research on my own.

Thanks!

Was able to get the spacer removed last week and installed a dual intake Spectre. Just barely clears the deck but a much improved look resulted.

Spent yesterday removing and reinstalling the driver seat which was incredibly painful due to the very small space under the seat to get to the bolts. The previous owner must have been 6’5” because the car drives so much better now that I can properly reach the pedals without consciously thinking how deeply I have to press in the clutch!

Now, for the next project - I have the old tachometer, but it’s not installed. Any idea/guidance/reading material I might browse to get an idea of how to install this thing and make it read correctly on a “now “ V8 vice the original flat 6?

Here are a few pictures from yesterday.

This hat from a late model cadillac. $9 at the pick a part. It can oriented in nearly any position. K&N generic filter and aluminum tubing.

20180912_174010_resized by Ben Modified, on Flickr" />

Thanks Ben, got that issue sorted, and the car actually starts and runs better now. But I need to keep in mind I can find parts there.

Now, for the next project - I have the old tachometer, but it’s not installed. Any idea/guidance/reading material I might browse to get an idea of how to install this thing and make it read correctly on a “now “ V8 vice the original flat 6?

http://ashlocktech.com/

super cool car by the way. 

In reply to 914 :

914, 

I saw that over on Pelican Parts and was considering picking it up and seeing if it solved the issue. Unfortunately a number of the other gauges aren't working - Speedometer, voltage, oil press/temp, fuel level, clock, etc... The only two that work are a rigged water temperature gauge and the oil pressure gauge. 

I'm considering selling the original gauges and going with aftermarket like the below and making a custom fabricated cluster. Do you foresee any problems with getting those gauges to work? I think the only tricky part might be the speedometer since the transmission is not essentially a Chevrolet like the rest of powertrain. 

https://www.ebay.com/itm/112363728521?ViewItem=&item=112363728521

In reply to BarrettRC8 :

If you go with custom gauges, keep in mind that there are a fair amount of GPS-based speedometers out there; that would eliminate the need for a transmission-driven speedo.

As far as building a custom cluster goes, I say do it!!!

In reply to BarrettRC8 :

No idea what is involved in getting all the other gauges to work but shouldn’t be too complicated. I do agree that a gps based speedo would be the easiest to work with though. I like the night lighting the gauges you are looking at use.

On my V8 914 I plan on using that tach adapter. I am still running the stock transaxle so the speedo is still connected like a stock 4 cylinder.