# Exhaust port "D" ???



## fredyG (Apr 18, 2012)

I started to disassambly my 1968 400 HO engine rusted and frized. As any restored should do, the first thing is to "discover" what type of engine, gearbox, VIN, trans, etc. the car came with. Lockily being my GTO a one owner, the car is 100% original (matching numbers) as I will post the pictures. but the question is, looking at the picture, Is that port a exhaust D port or an oval port, this is because I don't know which type of heads the engine came with. When overhauld the engine, which pistons I'm going to use in relation with compression, flow, cc, etc. I'm posting a sequence of matching numbers, (vin, engine s/n, gear box), and a rusted exhaust HO manifold.


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## BearGFR (Aug 25, 2008)

Those are D port heads, and if those are the original exhaust manifolds you've got something special there. Those are what are referred to as the 'ram air' exhaust manifolds. I'm going to attach some images to this email that will show you where to get the important numbers from in order to correctly ID what you've got there.
You need (in this order)
block date code
block casting number
block "engine" code (2 character code)
cylinder head date code(s)
cylinder head casting numbers

Bear


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## fredyG (Apr 18, 2012)

*D ports*

Thank you for your reply. In my desassambly process I'm taking photos of every step to document the vehicle numbers. (Just for the record). Since this is my first experience with Pontiac I have a lot to learn. And yes, the car is totaly original and a one owner. I've place "somewere" pictures of the maniforl, but I'll do it againg. Today I took more of the heads, block and manifolds. Any info at all, I'll very much apreciate. By the way, Cliff Ruggles the person that wrote the book about Rochester carbs. told me that my QuadraJet carb was from a 1969 Ram Air Aut Trans. very extrange! See the pictures and tell me what you know. Thank you


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## 68greengoat (Sep 15, 2005)

Cliff is spot on about the carb..... Imagine that!

I believe the block casting is a 9790071 combined with the WS makes it an HO block. Hilited is what the carb number should be:

1968	400	360 HP	WS	M	10.75	068	16	1-4	*7028267* HO Block Casting # 9790071

The center exhaust port on the heads should be #16.


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## fredyG (Apr 18, 2012)

How do you translate # 16 ?? Explain me something. When I search for replacement pistons I found 8.0:1 ; 7.5:1, etc. Low compresion. Where does the "extra" CR comes from ?? to obtain a published CR of 10.75:1 ??


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## 68greengoat (Sep 15, 2005)

Small combustion chambers. #16 heads are approx 72cc. With the stock pistons the cr is around 10.75. In order to run on today's premium you need to get the cr down to 9.5. A good way to accomplish that is to run dished pistons. I've read a good rule of thumb is, 94 octane/9.4cr.


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## BearGFR (Aug 25, 2008)

Ok, from the photos...
The date code on the block appears to be A129, correct? (I couldn't tell for sure from the photo if the last digit was a "9" or an "8"). If it's a "9" that means it was cast January 12, 1969 - making it a year model 1969 block. (A128 would mean January 12, 1968 - year model 1968). 9790071 is a 400 - some had 2-bolt mains, some had 4-bolt mains depending on the application. 
The "WS" indicates (if year model 1968) 400-HO GTO - 4 speed, 2-bolt mains, or if model year 1969 it would be a 400 Ram Air III - GTO - 4 speed, 2-bolt mains (but if 1969 the casting number for WS RA-III should be 9792506, not 9790071, so hopefully that block date code is really an "8").
The head date code, B068, indicates February 6, 1968 - again model year 1968. For 1968 HO the tops of the center exhaust ports should have "16" on them.


Ok, compression ratio. First of all, don't go by the factory published specs for compression ratio. The published specs were based on an engine that had been "blueprinted" - i.e. everything machined to minimum/maximum (whichever was most advantageous) factory "blueprint" engineering specs. Such a block would have been zero-decked, the heads milled so that the chamber sizes were at the engineering blueprint minimum - and would have been 10.75:1 compression. The engines that rolled off the assembly line wouldn't have been zero-decked (probably closer to .020 down) and the heads would have been "about" the nominal chamber size of 72 cc's - and would have had a compression ratio of around 9.8- 9.9:1 That's one of the reasons an NHRA class-legal "stock car" is so much faster/quicker than it's street-legal counterpart. Its engine has been built to 'factory blueprint specs'.

To be 'safe' with a factory (or factory spec) cam on today's gas (93 octane) you'll want to aim for a compression ratio of less than 9.5:1 ---- probably around 9.3:1. On a "nominal" 400 (stock bore, stroke, .020 deck clearance, .045 head gasket, 6 cc's in the piston valve reliefs, 72 cc chambers (ALWAYS measure them!) ) I'd recommend swapping the pistons out for a set with an additional dish in them such that their total dish volume including the valve pockets is around 12-13 cc's.

Especially on a street engine, pushing compression ratio to the limit doesn't help power enough to justify the risk (in my opinion). On my 461 that's making over 500 HP, the difference between 9.5:1 and 10.0:1 would only be worth about 8 HP, everything else being equal.

Bear


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## fredyG (Apr 18, 2012)

*New major problem !!*

Thank you Bear, but look at the pictures. This is what I found when I took off the heads, that's why the engine was friezed !!  There is no piston in # 3 (almost) and # 1 well ... but look at the heads, when I put them up side down, the admission valve just fell. Do you think the heads can be save ?? That's my concern. Today, will continue disassambling the heads and will see what I find. More picts. tonight


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## the65gto (Oct 9, 2008)

I should take a pill and a nap after looking at those pictures . Here is the standard Pontiac cylinder numbering:lol:


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## BearGFR (Aug 25, 2008)

Oh my.... 

I wouldn't try to make predictions about whether or not it can be saved just from photos. My recommendation is to get it all apart, cleaned up, maybe take it to a machine shop and have everything cleaned/hot tanked and checked for cracks, then see what you've got to work with. If that truly is the original engine (did you verify that date code on the block? I'm curious..) then it's worth going to more effort to save it.

Bear


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## fredyG (Apr 18, 2012)

This are the photos I took today, after cleaning. Piston # 4 is there (second from right) I think the block can be saved, eventhought the cylinder wall are very corroted. But the heads.... , after cleaning a little, 3 valves heads came off by them selve by corrosion, the valve seats.... thank you very much, you don't see them. Tomorrow I'm taking apart the crankshaft (if I can) and start hitting with a piece of wood the pistons to see if I can take them off. being pretty sure that's the original engine, I must save the heads. Of course , the logical move is to go to the milling shop summerge the heads and block in acid, reedo valve seats and guides, new valves, etc and mill the cylinder heads the minimun possible. lets see what we get. Here are the "today pictures"' be in touch. any recomendation, be free to say it. TYou


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## ALKYGTO (Mar 29, 2010)

Wow, you have a project my friend. I'd invest in a case of PB blaster and soak that mother down. Hopefully that will help in disassembly.

Heads should be saveable IMO unless they are cracked. Block may or may not need to be sleeved depending on the level of corrosion. 

And as others have said....Good Luck! :cheers


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## Thrillseeker (Oct 16, 2012)

Wow, did someone use that as a salt water boat anchor? Lots of WD-40 and a good soaking at the machine shop should get it apart and clean. I hope the block and heads are salvageable. Good luck and keep us posted.


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## fredyG (Apr 18, 2012)

*Engine Parts Supplier*

While I'm taking my engine to the milling shop, I'm starting to search for new parts (Engine Master rebuilding kit) including valves. Members, who do you recommend that have and sell good quality parts ? I need "almost" the complete engine. I'll like TRW, Comp Cams, Federal Mogul, Milodon, etc. One notch up stock engine and run with 95 oct. "Happy" Street use. Any good idea ??? Summit ?? Thank you


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## BearGFR (Aug 25, 2008)

My recommendation? Call Jim at Central Virginia Machine. That's where I bought the huge majority of my parts.

Bear


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## fredyG (Apr 18, 2012)

*latest Pictures*

Thank you BearGFR, I got in Central Virginia M. web page and saw their products. probably I'll get in touch with them, but I whant my engine Original Specs plus bolt on stuff (aluminum manifold, Headers) and a modern cam. hear are some pictures of the work done yesterday. I manage to "extract" 5 pistons, but they were really jammed. I had to hit them really hard with a steel bar from under and to the pinston pin. I smashed them but they were no good anyway. Here are sone pictures. By the way, the crank is in excellent condition. keep in touch


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## BearGFR (Aug 25, 2008)

Just rememeber, this is a Pontiac - not a chevy. They're worlds apart in what works on them and how to make power with them. By far the lion's share of information you'll run into especially from large vendors will be people who try to treat them the same as the bow ties ---- that's a mistake. That's why I steered you towards Jim at CVMS. He builds more than just Pontiacs at his engine shop, so he's not 'blind' to other makes, but when it comes to the Indian he knows his stuff - for sure. 

For example, why are you interested in an aluminum manifold?

Bear


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## fredyG (Apr 18, 2012)

*Pistons damages / water passages*

Bear. This is how the pistons had to be taken off (the 3 mouseketeer) (see photo), but the cylinders are find. Todat if I have the time, is the turn of the heads. I am worried about the block water passages. The upper water passages or are close or have really small holes (rust obstructed ??) This doesnt look right to me, but I am not familiar with Pontiac blocks. What do you see here ??? Crank is fine. Why aluminum intake manifold ?? because of weight and efficiency. Standard manifolds (series production) design by factory are never as efficient as special purpose design. If I'm not going 100% original, why use heavy weight components ? For instance, my right exhaust manifold has a hole because of rust (there ia a photo in upper thread), I'm going to headers, less weight and more efficiency. I'm not going to any track, this is for the pleasure of driving a "happy" GTO. keep in touch and advise


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## fredyG (Apr 18, 2012)

*Here comes the Pictures*

This pictures completemts the above thread


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## BearGFR (Aug 25, 2008)

Reason I asked 'why aluminum' --- the fact is, no aftermarket manifold will perform as well on a street Pontiac than a cleaned up, port-matched factory cast iron manifold. The notion that after-market aluminum will always be 'better' is what I call "Chevy thinking". True, it will save you some weight, but that's it. In terms of torque and power in the street Pontiac rpm range (5200 and below), that fancy aluminum manifold is going to cost you power, not make it. This fact has been proven time and time again through actual testing. Fact is, Pontiac didn't gain its reputation 'back in the day' because the factory engineers were idiots. Pontiacs are torque engines, and it comes on early in the rpm range - nothing feeds that better than a clean dual plane intake and that's just reality.
It's the same reason they don't need (or like) a lot of gear to be quick. My 69, at about 4000 lbs. race weight, has a best e.t. so far of 11.86 @ 113 - that's on pump gase, with 3.50 gears and running the trans in Drive - and it shifting at 5000 rpm. I can drive the car anywhere I want, and do.

As far as the water passages in your block, don't panic yet. For whatever reason, I know that there are passages in the heads that meet with blind passages in the block - do sime internet searches, grab some books, and look at other blocks. You'll probably find that you're not as bad off as you think.

I run headers on my car too, but honestly unless you're trying to get every last bit of performance out of the engine it's very hard to beat the manifolds like you have. For about the cost of a good quality set of ceramic coated headers you could have a reproduction set of those manifolds from Ram Air Restorations - "most" of the performance and none of the fitment/clearance/longevity of headers. Your choice on that deal.

Bear


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