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70ra455 · 10-02-2006, 08:35 PM

I have a '70 455 with Ram Air manifolds. What is the standard size of the inlets/outlets for the mufflers? I'm having a set of reproduction VOE mufflers made. The switches will come out later. By next spring maybe?

Thanks for your help.

70ra455 · 10-04-2006, 01:15 PM

Nobody can help on this one?

Silver Judge · 10-04-2006, 08:28 PM

Don't know about size for sure, I'd guess 2.25 inches
You should look into the stuff Jim Hand has for this, I think he's already made reproductions of these available, likely easier for you then having them custom made.

JLHarper · 10-04-2006, 09:19 PM

Did you add the RA manifolds for performance gains over the D ports? How did they do?

I have a 70 RA455 driver and bought PYPES set with RA manifold reproductions. My standards were missing with headers in place and havent put these on yet.

70ra455 · 10-06-2006, 01:02 PM

It's Jim who's making the mufflers and I just wanted to know the inlet/outlet sizes for standard 455 with Ram Air Manifolds. I'm shocked that nobody knows this on this board. Very strange.

JL - I didn't add the manifolds they supposedly came with the car which is an original 4spd 455 with Ram Air. There has been heavy discussion about this and most people fall on the "they didn't come with" camp but Gary Cave says they did and his 29K original convertible supposedly has them too. Mine is a convert with 4spd and Gary's has automatic. As for performance gains I've never compared with anything else but the '70 Ram Air manifolds are D-port too unlike the '71 or '72 which are round ported.

Held for Ransom · 10-07-2006, 12:43 AM

It was 2-1/4" inlet and outlet for the RA mufflers.

70ra455 · 10-07-2006, 06:24 AM

Thanks Held ... that's what I needed. Greatly appreciated. It's amazing how much you know about these cars. You're truly a treasure trove of information. Thanks for sharing.

Ron Landis · 10-07-2006, 10:50 AM

Quote:

Originally Posted by 70ra455

Thanks Held ... that's what I needed. Greatly appreciated. It's amazing how much you know about these cars. You're truly a treasure trove of information. Thanks for sharing.

...he had to look it up!!! lol There is a wealth of info on these boards and they have never let me down. Just gotta ask the right person. My thanx to all that contribute. Ron

JLHarper · 10-08-2006, 03:00 PM

70ra455
My 455 RA Auto car was missing original exhaust also but upon asking on here and there told that they were supposed to be D ports.
Knowing the history on Caves 455 car (low and original owner from what I read) I might be looking for wrong manifolds. If I might ask...Did you have multiple replies that would say the same for the correct ones being RA manifolds instead of D ports?

70ra455 · 10-09-2006, 09:25 AM

As I said in my earlier post most people fell in the "it came with logs" camp. The person I purchased this car from claimed that it came with the RA manifolds and then Gary Cave's comments (according to this board) were that his 29K mile 455 Ram Air Convertible had RA manifolds and that they were original to the car.

Soooo ... in the end I've got my car the RA manifolds and they'll stay on!

Oh yeah JL ... just a note .... I believe both RA and standard manifolds in '70 were D-Ports. The only round ports in '70 were RA4 manifolds. In '71 the 455 HO came with round ports.

TJH · 10-12-2006, 03:28 PM

There seems to be a bit of confusion here. I am positive that the RA STYLE manifolds on the 455 were D-port. As in, the same as what was used on the RAIII.
Pontiac most certainly did NOT put round-port RA (RAIV-type) manifolds on a D-port engine.

Lloyd-TX · 12:21 PM

Quote:

Originally Posted by Held for Ransom

It was 2-1/4" inlet and outlet for the RA mufflers.

Mike - I hate to tell you but you're incorrect about the muffler inlet size.

ALL '70-'72 A-body dual exhaust mufflers had 2" ID inlets. Even on the Ram Air III/IV and HO cars. The head pipes were 2 1/4" OD right up to the muffler inlet, and then necked down to 2" OD to fit into the muffler inlet.

I still have a pair of NOS '70-'72 RA III/IV/455HO A-body head pipes in my stash which are necked down to 2" at the muffler. PN's 478607 & 478609.

Interestingly, ALL '70-'72 GTO's did indeed have 2 1/4" ID muffler outlets and tailpipes. Never have figured out why the engineers didn't spec 2 1/4" muffler inlets???

Lloyd-TX · 10-17-2006, 12:19 PM

One additional comment - regardless what anyone has heard, all 1970 455 GTO's were OEM equipped with "log" exhaust manifolds. Doesn't matter whether it was a plain GTO, or Ram Air equipped, or a Judge, TH400 or 4 speed.

Held for Ransom · 10-17-2006, 04:52 PM

Well, I did measure some original headpipes and they were 2-1/4", that's why it took so long to answer. Muffler was missing and I made an assumption. Truely sorry if I was wrong.

Lloyd-TX · 10-17-2006, 06:09 PM

Quote:

Originally Posted by Held for Ransom

Well, I did measure some original headpipes and they were 2-1/4", that's why it took so long to answer. Muffler was missing and I made an assumption. Truely sorry if I was wrong.

Hey, no big deal Mike.

The necked-down ends of those pipes you measured had obviously been cut off before you got 'em.

I'd still like to know why the engineers did not spec 2 1/4" muffler inlets on the RA/HO cars!

JLHarper · 10-18-2006, 10:13 AM

Sorry, I call the standards exhaust manns D ports from old habit of looking for many years for parts.

Now Ive heard two decent answers to what came on my 70 455 RA GTO...standard or RA exhaust mannifolds, but still dont know 100%...lol!

Lloyd-TX · 10-18-2006, 10:21 AM

Quote:

Originally Posted by JLHarper

Sorry, I call the standards exhaust manns D ports from old habit of looking for many years for parts.

Now Ive heard two decent answers to what came on my 70 455 RA GTO...standard or RA exhaust mannifolds, but still dont know 100%...lol!

Rocky Rotella and Roger (oPh) need to chime in about this. With their extensive knowledge and experience, whatever they can add would tell the tale.

Rocky Rotella · 10-18-2006, 12:27 PM

Standard log manifolds were definitely used on the '70 455 H.O. engines.

Though I don't have an answer confirmed by Pontiac engineering, I'm sure the log manifolds were used because the 455 H.O. was available in A, B, and G-body cars. Though the RA manifolds may "fit" the B and G chassis, long branch manifolds were used on these models in previous years (ex 428 H.O.). So to simplify production and increase engine availability to several models, standard log manifolds were substituted.

Rocky Rotella · 10-18-2006, 12:32 PM

One clarification. It isn't Jim Hand who is reproducing the VOE mufflers, it's his son Tom that is.

Lloyd-TX · 10-18-2006, 12:48 PM

Quote:

Originally Posted by Rocky Rotella

Standard log manifolds were definitely used on the '70 455 H.O. engines.

Though I don't have an answer confirmed by Pontiac engineering, I'm sure the log manifolds were used because the 455 H.O. was available in A, B, and G-body cars. Though the RA manifolds may "fit" the B and G chassis, long branch manifolds were used on these models in previous years (ex 428 H.O.). So to simplify production and increase engine availability to several models, standard log manifolds were substituted.

Thanks Rocky!

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