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Posted by: defianty Aug 29 2017, 10:57 AM

The engine I have for my six conversion is a 3.0 and was rebuilt and used as a spare for a guy who had an original RS. The engine was used whilst the RS engine was rebuilt. Once thing led to another and he only covered 1,000 miles with the 3.0 before the RS was complete.

The 3.0 had PMOs and I bought them with the engine. When I collected the engine all of the ancillaries were boxed separately and only today, almost a year later, when trying out the carbs for size I thought to myself - "Those look tall!"

Amongst the paper work I can see the 'Tall' manifolds were ordered and a quick google has revealed that these are going to be too tall for a 914, they measure 100mm. To big?

I'd speak to PMO themselves but I'm not sure how they'd be as I'm not the original owner. That and I don't know how to send a fax in 2017!

Posted by: mepstein Aug 29 2017, 11:37 AM

PMO doesnt care who buys from them, origional owner or current owner.

Posted by: brant Aug 29 2017, 11:43 AM

honestly don't know if they will be too tall

they sell both tall and short
I actually run tall on a 2.0/6 race car with the engine lid on
but the height of your motor mount will likely determine if that works or not in your situation

the talls are great for small displacement motors when you are trying to fight an inversion problem and very aggressive cam shafts

I don't think they will be as important on a big bore 3.0 and you will probably notice no loss or problems if you do have to revert to the short version

Posted by: gms Aug 29 2017, 11:54 AM

On an original 914/6 I had to run the short air cleaners (911 Air conditioner K&N)
If you have a -6 conversion your engine height will vary.
I was not aware of a short intake made by PMO...if you find one please report back.
The original Porsche carb manifolds will most likely require a a spacer to block off the injector cut out on the head and probably need to be bored to match the intake port.

Posted by: Lucky9146 Aug 29 2017, 12:07 PM

QUOTE(defianty @ Aug 29 2017, 09:57 AM)

The engine I have for my six conversion is a 3.0 and was rebuilt and used as a spare for a guy who had an original RS. The engine was used whilst the RS engine was rebuilt. Once thing led to another and he only covered 1,000 miles with the 3.0 before the RS was complete.

The 3.0 had PMOs and I bought them with the engine. When I collected the engine all of the ancillaries were boxed separately and only today, almost a year later, when trying out the carbs for size I thought to myself - "Those look tall!"

Amongst the paper work I can see the 'Tall' manifolds were ordered and a quick google has revealed that these are going to be too tall for a 914, they measure 100mm. To big?

I'd speak to PMO themselves but I'm not sure how they'd be as I'm not the original owner. That and I don't know how to send a fax in 2017!

Richard at PMO is pretty cool. I will send you a PM. And thanks for weighing in on my thread as I have been following you as well.

Posted by: Lucky9146 Aug 29 2017, 12:12 PM

You need to run longer studs in the heads for the PMO's they should have come with the manifolds.

Posted by: Lucky9146 Aug 29 2017, 12:19 PM

QUOTE(gms @ Aug 29 2017, 10:54 AM)

On an original 914/6 I had to run the short air cleaners (911 Air conditioner K&N)
If you have a -6 conversion your engine height will vary.
I was not aware of a short intake made by PMO...if you find one please report back.
The original Porsche carb manifolds will most likely require a a spacer to block off the injector cut out on the head and probably need to be bored to match the intake port.

I just posted pictures and info on the short PMO on my thread today.

"Finishing a 914-6 GT Conversion Project"
Sorry I don't know how to paste in the link. Dammit

Richard at PMO actually calls it a "standard height" but it is shorter for sure than the talls.

Posted by: defianty Aug 29 2017, 12:43 PM

QUOTE(gms @ Aug 29 2017, 06:54 PM)

On an original 914/6 I had to run the short air cleaners (911 Air conditioner K&N)
If you have a -6 conversion your engine height will vary.
I was not aware of a short intake made by PMO...if you find one please report back.
The original Porsche carb manifolds will most likely require a a spacer to block off the injector cut out on the head and probably need to be bored to match the intake port.

Probably not a short one exactly more like just a standard height as Lucky9146 has just bought.

QUOTE(Lucky9146 @ Aug 29 2017, 07:12 PM)

You need to run longer studs in the heads for the PMO's they should have come with the manifolds.

Thanks Lucky9146, the carbs were just resting on top of the threads in the picture and not pushed down. I think there's plenty of thread there.

Posted by: burton73 Aug 29 2017, 01:17 PM

PMO46 - 3.0

Bob B

Posted by: defianty Aug 29 2017, 01:36 PM

Thanks burton, I think that confirms it. Mine are a lot taller than that.

Posted by: gms Aug 29 2017, 02:03 PM

I did not know those shorter PMO intakes even existed...learn something new every day!

Posted by: porschetub Aug 29 2017, 02:27 PM

Pretty sure there will be clearance issues,when I was running K&Ns I had minimal body clearance @ the alloy top cover,not sure about the rain hats ?.
Mine are stock Porsche manifolds they are roughly 60mm high, I now have stock aircleaner on and I had to relocate one hold down clip on the RH side rear due lack of room at the bulkhead.
Great point about conversions,my motor is a little lower than it should be and I have altered the front mount once already.
Seem to remember Larmo (Lawrence ) mentioning PMO manifold height with his build...maybe he will chime in and comment ?
Good luck.

Posted by: Mark Henry Aug 29 2017, 02:35 PM

You will likely have rain hat clearance issues on the right side for a '74-up conversion.

The charcoal canister has a raised boss and stud, for sure you will have to cut the stud off.
My stock manifolds have a 3/16" aluminum spacer and a 1/4" phenolic spacer, plus two extra gaskets. I barely have a 1/8" clearance between the rainhat and boss with the stud cut off.

I see you have a '73, so you may not have this issue as your canister is up front at the tank, so hopefully no boss on the rear firewall.

Posted by: forrestkhaag Aug 31 2017, 06:21 PM

The good news is that early conversions to 3.0 with Webers and PMO intakes / not talls / fits fine with K&Ns / and the noise at 6 or 7K is something to deal with no matter what the intake system is.

I have no spacers between the heads and intakes and run 3 standard gasket sets between heads intakes and filter bases / no leaks there.

Sidebar: Note the cool flexible perfect fitting carbon fiber "tin" set I made.... Not to worry about flexing and bending when installing or temoving the engine... just pops into place and the rubber from Mark fits perfectly... off topic.... oops

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