[hgiv]

The 350HO build is essentially what most 350 builds end up being. Time and money are certainly a factor when doing any specific restoration/build, but if I had a choice between a "real" 350HO car and a car with a 400, all else being equal... i'm going for the 350HO. They are somewhat rare and just cool. Now in that same thought I would not spend a lot more money on a 350HO. I would simply be drawn to it... and prefer it to a vanilla 400. How much more might I spend, all else being equal and without looking up real value, a couple grand maybe. It just seems like in the Firebird world people care more about big engines than low numbers models. Obviously 69TA excluded, and some early gen 2s. You just don't see Firebird guys looking up how many were midnight green with an auto and AC and saying "its one of only 250" blah blah.

[thews]

Originally Posted by hgiv

The 350HO build is essentially what most 350 builds end up being. Time and money are certainly a factor when doing any specific restoration/build, but if I had a choice between a "real" 350HO car and a car with a 400, all else being equal... i'm going for the 350HO. They are somewhat rare and just cool. Now in that same thought I would not spend a lot more money on a 350HO. I would simply be drawn to it... and prefer it to a vanilla 400. How much more might I spend, all else being equal and without looking up real value, a couple grand maybe. It just seems like in the Firebird world people care more about big engines than low numbers models. Obviously 69TA excluded, and some early gen 2s. You just don't see Firebird guys looking up how many were midnight green with an auto and AC and saying "its one of only 250" blah blah.

The problem with low production numbers is PHS doesn't break them down like the Martini Ford data. One of my 69 350HO's is originally Champagne with a green interior and green convertible top. It's been rumored that there were only 112 69 350HO converts, but there's no way to prove that, or the color options. If that were true, I'd bet $1000 this is a one-of-one car. The people that say "one of 250" are just estimating.

[thews]

Originally Posted by ponyakr

"... 70 RA #62 heads..."

I've always heard that the #62 heads were used on '69 model year engines, and that #12 heads were used on '70 model year D-port RA engines.
.

You are correct, the #62's are 69 heads. They are supposed to be automatic heads, but I had a bone stock numbers matching 69 400 with #62's and it was a stick car in 1996. I wrote to Pete McCarthy asking about it and he wrote me back stating he has seen #62's on stick cars. 69 350HO heads are #48 for sure.

The 69 and 70 D port "RAIII" heads are the same 72cc D port heads. #62, #48, #12 and #13 are the exact same head. Outside of the stamped numbers, they are all put on 350HP engines. Does anyone disagree that those 4 head numbers are different in any way?

[hgiv]

Some very late 69 and all 1970 350 birds wore #11 heads. Slightly larger chambers than the 1969 #47. Too bad really. 350s non HO, started with 1968 #17 heads. Which was a great flowing head which cc’d generally below 80. The 69’ brought the #47. Lucky to get under 80cc. The #11 heads were all Well over 80. And the 350 which could have lived up to its potential began the slide into vanilla.

[mysticmissle]

Swing an a miss. Comes back as standard 350 2 barrel auto console rally 2s remote mirror delux wheel. Nothing special. I’ll post phs Monday. Too hard from phone. Thanks for your input fellas.
Pm for parts I think I going to let it go. If it sits here it’s going to be another race car and I already have 2

[hgiv]

Nothing special? That’s my car! Lol

[mysticmissle]

Lol come get it

[hgiv]

No I mean that is the car I have!😜

[rdl]

Originally Posted by thews

The 69... D port "RAIII" heads are the same 72cc D port heads. #62, #48.... Does anyone disagree that those ... head numbers are different in any way?

I’ll take some of this on for ‘69. There have been longer threads on this topic over the years with many anecdotal claims. It was a pit conversation at the Pure Stock Drags too. Finding true virgin heads for inspection is part of the reason for a lack of real evidence. On 400 platforms one common observation is that the heads were matched to the cam (generally aligning with the transmission). #62 heads were used with the 067 cam, and #48 heads were used with the 068 (also 744 In GTO) cam. The 067 generates greater cylinder pressure warranting less static compression to ward off pre-detonation). The 72cc chambers were more consistently reported on #48 heads used on these 400 applications. The #62 heads more often spec’ at closer to 75cc. The #48 head used on the 350HO spec’s closer to 66cc. They are used regardless of transmission selection on this platform. No one has definitely claimed evidence (other than chamber size) of a distinguishing mark to identify those heads from the other 400 platform #48 heads. This isn’t gospel but hope it helps.

[mgarblik]

Originally Posted by mysticmissle

Swing an a miss. Comes back as standard 350 2 barrel auto console rally 2s remote mirror delux wheel. Nothing special. I’ll post phs Monday. Too hard from phone. Thanks for your input fellas.
Pm for parts I think I going to let it go. If it sits here it’s going to be another race car and I already have 2

Well, no old Pontiac is nothing special with the brand dead for ten years

now. But I understand where your coming from. From the few pics it looks like a TON of good parts to help other projects along and your doing a good thing for the hobby. Good luck passing it along. BTW, when growing up the mailman delivered mail for several years with a 68 red Firebird 350 HO. I remember it like yesterday. Used to stand at the end of the driveway waiting for that beauty to rumble by with the mail. It was a manual trans to boot!

[Shiny]

Originally Posted by rdl

...Finding true virgin heads for inspection is part of the reason for a lack of real evidence. On 400 platforms one common observation is that the heads were matched to the cam (generally aligning with the transmission). #62 heads were used with the 067 cam, and #48 heads were used with the 068 (also 744 In GTO) cam. The 067 generates greater cylinder pressure warranting less static compression to ward off pre-detonation). The 72cc chambers were more consistently reported on #48 heads used on these 400 applications. The #62 heads more often spec’ at closer to 75cc. The #48 head used on the 350HO spec’s closer to 66cc. They are used regardless of transmission selection on this platform. No one has definitely claimed evidence (other than chamber size) of a distinguishing mark to identify those heads from the other 400 platform #48 heads. This isn’t gospel but hope it helps.

This is an interesting summary, thank you.

I had read here about the #48 for 350HO had smaller volume yet was indistinguishable from #48 for 400. I don't remember reading about the correlation between the other head volumes and cam. That is good insight.

I'm baffled, however, why there isn't an "engineering" or "design" history that clarifies chamber volume for each head. If Pontiac was tailoring these heads by cc to match cams/applications I would expect the head designs would clearly specify intended chamber volume.

Do the original design documents (ie drawings, specs) not contain the allowable range of chamber volume? Very odd to me they would manufacture two versions of #48 and not have a traceable mark or stamp to distinguish... Are the original engineering documents available anywhere or are they lost?

[thews]

Originally Posted by rdl

I’ll take some of this on for ‘69. There have been longer threads on this topic over the years with many anecdotal claims. It was a pit conversation at the Pure Stock Drags too. Finding true virgin heads for inspection is part of the reason for a lack of real evidence. On 400 platforms one common observation is that the heads were matched to the cam (generally aligning with the transmission). #62 heads were used with the 067 cam, and #48 heads were used with the 068 (also 744 In GTO) cam. The 067 generates greater cylinder pressure warranting less static compression to ward off pre-detonation). The 72cc chambers were more consistently reported on #48 heads used on these 400 applications. The #62 heads more often spec’ at closer to 75cc. The #48 head used on the 350HO spec’s closer to 66cc. They are used regardless of transmission selection on this platform. No one has definitely claimed evidence (other than chamber size) of a distinguishing mark to identify those heads from the other 400 platform #48 heads. This isn’t gospel but hope it helps.

I've heard this before about the #48 350HO head being 66cc, but also that it's simply not true. The rumor has it that a standard set of #48's would be milled down to 66cc. If that were true, then there would pretty much have to be some distinguishing mark to differentiate them on an assembly line from a set that wasn't milled. There would also be a procedure somewhere to define this. The only real difference IMO is the head gaskets between a 350 and a 400. Real 350 head gaskets are difficult to find and the opening for the piston is smaller than a 400 gasket. Parts places sell them as interchangeable, but that's what killed my 350 HO in the car I bought it from. I listed that data in a 350 thread in another forum a long time ago.

[rdl]

Rocky Rotella addresses the issue of the markings on a 350 #48 head in his book (a great resource by the way!). There are some who believe there are examples of the head with an ‘X’ stamped on the exhaust port. No compelling proof exists to support its consistent use.

[hgiv]

And of course there is the fact that Pontiac heads are notorious for not being the “correct” volume. Most are at least 5cc bigger than advertised. 350 heads seem to particularly suffer from this. I don’t know about HO heads but good luck finding 1969 #47 that isn’t 80. It happens but MANY are.

[mysticmissle]

This will be in the classified section later today. availabe in various configurations all will need parts, time and money. If a board member wants this it will be 2300. I will put it on market place and see what happens and them maybe ebay after that. There ae some crazy people there, looking at THews posts. If it doesnt sell, I will keep it and dream of a RA1 tribute at somepoint. Thanks

[Rocky Rotella]

Where the No. 48 head is concerned, I had a chance to closely inspect a '69 350 HO that hadn't been apart since the day it was assembled at Pontiac.

During the rebuild, I was able to cc the heads myself in my garage and they measured exactly 66 cc. They'd been hot tanked and were completely bare (not yet machined), and I couldn't find a single marking on them anywhere that might suggest they were a variation of the standard No. 48. That doesn't suggest that Pontiac didn't produce a larger chambered No. 48 for 400 applications as we've heard they exist, but I can say with absolute certainty, the 48 heads I looked at were 66 cc.

[Shiny]

Anyone?

"Are the original engineering documents available anywhere or are they lost?"


I'm just curious about how GM managed the design and release of head drawings to the foundry and/or manufacturing operations.

[maxepr]

Great thread guys, I have a 69 350 HO stick car survivor in the garage. I also picked up a 350 HO stick engine as a spare was kind of close by. Ill have to go out and look at it now. If I do have the spare engine rebuilt I will now cc it for my own curiosity. By the way I do drive the HO car a lot its a blast..

[rdl]

Originally Posted by Shiny

"Are the original engineering documents available anywhere or are they lost?"

That would be a hobby treasure trove if they could be found and collated into a binder. Maybe they’re on Oak Island? 😄

[thews]

Originally Posted by rdl

That would be a hobby treasure trove if they could be found and collated into a binder. Maybe they’re on Oak Island? 😄

My opinion on the 350HO is based on marketing. I don't think Pontiac wanted the 350HO to compete too closely to the 400. With the 400 HP rating dumbed down at 350 and the 350HO at 330HP. If Pontiac installed the long branch headers on the 350HO it would be even closer.

One interesting tidbit about the 69 350HO is that there isn't any distinguishing marks externally to tell the world it's a 350HO. The 67 and 68 had stripes, but not the 69. It was designed as a sleeper.

The 350HO engine I have is a stick with #48 heads. It came with the date codes all matching and even the original carb. I'll pull it out of storage soon and cc the heads. This engine came from Canada and has a Chevy stamp along with the Pontiac stamp. Maybe the 66cc head was a Canada thing?