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Bunch of questions

12-01-2009, 05:56 PM
Ok so I have a 71 firbird I am going to fix up, I recently yanked the 350 that was in it out wich was actually a 74 engine so it wasn't original anyway. well I came across a pontiac 400 in my barn I'm going to go thru and drop in it but I'm having trouble figuring out exactly what I've got.
The engine numbers are 9799914 , 400 , GM-5 D N , the heads say d280 , D N , 8 8. so the engine is a 400 small block correct? and any Idea what the heads are? I have another set of head that's number are HO74. the transmissions plate says Turbo Hydro Matic seriel PR-69 11991 is this a turbo 400 tranny?

I'm the first to admit I am a retard when it comes to crap like this :P anyway any advice on parts ect I'm going to tear the engine down rebuild it new intake , cam , headers carb , roller rockers ect btu not looking to invest a shit load of money just wanna beef it up and get it running good so if you could suggest some parts shift kits stall converters cams header rockers ect that are good and decent price I would be thankfull as well as what you think I should do.

Also let me know were to look for numbers at on anything and I will find em.

12-02-2009, 08:46 AM
Our resident Poncho expert MrPBody should kick in here, just hold on he knows these cars forward and back.

12-02-2009, 02:15 PM

Thanks for the segway... (:-


The block casting number indicates a '67-'69 400 Pontiac. No, it is NOT a "400 small block". A 400 SB is a Chevrolet engine. The ONLY thing these two engines have in common is the bore and stroke. NO parts interchange. The Pontiac is a unique design to Pontiac cars through '79. To identify EXACTLY which 400 it is, we need the two-digit "code" stamped into the front pad, passenger's side, next to the water pump housing. That code will tell us what car it came in and what the factory "rating" was.

The date code on the heads (H280) indicates Aug 28, 1970, BUT, there are other numbers on the heads for ID. On the center exhaust ports, where they protrude from the head, there are two or three large numbers cast in. For a '70 model, the "good" ones are 12, 13 and 64. This assumes they're not "Ram Air" heads, which have a different exhaust outlet configuration (round ports instead of "d" ports). That casting would be a "614".

The first thing to do is get Jim Hand's "How to Build Max-performance Pontiac V8s" published by SA Designs. This is the only CURRENT study of the ol' Injun. Many questions are answered in detail, in there. Some good porting and other performance info is there, too. It IS 5 years old now, so some of it is already obsolete.

Cams, headers, rockers, etc., are pretty much the "same" (in principle, NOT part numbers) as any other.

Welcome to the upper crust of GM performance. Ignore the "buzzing" in your ear from the Chevy boys, that will tell you it "can't be done" or "You gotta use a Chevy 'cuz a Pontiac won't run..." or any of that. The Pontiac is among the BEST street-performance engine families out there. Afterall, GTO didn't get a reputation for LOSING... (:- Truth is, you build it right (using a Pontiac-specific approach), and the Chevy boys will HATE you! That IS our "job", BEAT Chevys!!!

Once we've established exactly what you have to work with, mainly the heads, as the 400 block is a good one, we'll get to specifics as far as brand names, sizes, etc. It's completely realistic to build a 600 HP driver with a 400 Pontiac as a "base". With a lower budget, though, 450-500 is also quite "doable".


12-02-2009, 02:34 PM
Thanx for the info and I will head out there and see if I can find the numbers, btw I need to post up some photos of the 70 GTO convertable I have sitting out here, it's not mine or it wouldn't be rotting away I need to find out all the details on it for sure for my aunt but I've been told it's 1 of like 200 made, just a damn shame she won't sell it.

12-02-2009, 03:35 PM
Ok so after taking the waterpump off realizing I didn't need to lol block # is 0539431 and Y S under that.

The HO74 heads number is 50
The 400's heads are 13
and one of the other pontiac engines I have sitting around is 17
I think I may have 4 pontiac blocks if not more sitting around I really need to go thru all my engines.

I don't know if this matters but it had a metal tag on it I assume is from a shop that worked on it in the past that says , Stock No. A 1885 rebuilt engine power-pak

12-02-2009, 08:45 PM
One place you might want to call is Butler Performance which does Pontiac engines only.Plus when the heads are done, have them replaced with hardened valve seats instead of the soft seats.With soft seats,you have pour in a bottle of lead additive in the gas tank everytime you fill the gas tank up.1975 was the first year for hard valve seats.

12-03-2009, 08:58 AM
YS is a 350-horse 400, GTO w/auto trans (TH400). If there are 5 mounting holes drilled and tapped on each side, it'a '70 block. If there are 2, it's a '69. Either way, it's a GOOD one. Steps will be required to lower the static compression to 9.5:1 (or lower), considered the practical limit for 93 octane. A simple "dish" in thge piston will suffice.

Get "the book"!!!

We (CVMS) buy parts from Butler when we can't get specific stuff through "normal" channels. They offer some trinkets unavailable elsewhere. They're the "highest profile" Pontiac shop, and have an excellent reputation in their business practices. I always enjoy my conversations with Jim when I call. We've bought two crank forgings from them in the last month or so. At one time, they were the "power leaders", too. They've fallen a bit behind in that arena over the last 4 or 5 years, though (not in volume of powerful engines, in the "max power" pursuit). Their attempts at making a twin-turbo, electronically controlled Top Alcohol engine has hit many obstacles which they haven't yet overcome. I have no doubt, David (Butler) can figure it out, though. We went the "old school" route of a Roots supercharger and Enderle mechanical injection for Dirty Bird (current Pontiac record* holder, 6.52@213.7). There are several other high-end Pontiac projects nearing completion, including one REAL nitro F/C, so we figure our record* (it's been over a year, though, Dirty Bird is "on top") won't stand for much longer. Kauffman Racing is another high-profile, "high-end" Pontiac shop. They offer a very good aluminum "D-port" head. Read as much as you can before doing business with them. Reports are "mixed". Make your own choices.

* The word "record" refers only to a "traditional" Pontiac V8-powered car


Unless there's already seat "recession", Pontiacs don't generally require "hard" seats. If the engine is going to pull a load, or use low-octane (87) fuel, do lots of mountain driving, or other low-RPM/high-stress applications, hard seats ARE recommended. But unlike small blocks of the era, they don't "automatically" need them. Also, '72 was the first year Pontiac used "induction-hardened" seats. EPA had a requirement for EGR for '72. At least one manufacturer wasn't "ready" (Chrysler...) so EPA moved it out to '73. GM used induction-hardening for all EGR-equipped engines. Some of the small blocks had such poor metalurgy, it didn't always "work"...

The way we build performance engines today, the valve grind is such that unless the hard-use conditions apply, the seats and valves "live" just fine. There IS power to be gained, though, by using the right seats, "profiled" in a "venturi" form. Higher revving performance engines wouldn't fall into the "hard use" category in this regard.


12-03-2009, 09:35 AM
Any older car 1974 and down use soft seats.If the the lead additive is not added,the valve guides will wear out too.Most engine builders probally recomend changing the soft seats to hard seats.Plus Butler performance does recomend a differant brand plug.I know a guy that bought a set of modified Edelbrock heads from them and was told to install NJK plugs instead of AC delcos because the AC delcos do not work very well with the heads.

12-03-2009, 01:21 PM
NGK is quite popular among performance guys today. So is Autolite. We use either Autolite or Champion in E-heads. The main reason is the parts store next door stocks them. We've found no appreciable difference in performance, as long as the heat range is correct. With today's unleaded fuel, plug "life" is not an issue. Now, in a high compression RACE engine, other factors are certainly to be considered, but that's outside the "scope" of this thread.

Your statement about "hard seats" is more "folklore" than engineering reality. My experience has shown clearly, what I posted. And it is not an "opinion" that GM started induction-hardening seats in '72. EGR is what severely increases exhaust temperature, causing the problems with the seats, not the catalyst ('75-up). It's the "lean mixture" EGR creates. When we cut the seats, we can definitley tell the difference between the intake and exhaust seats in 7K3, 4X, etc.

I remember in the mid-'70s, many machine shops were telling people they HAD to have bronze guides for unleaded. Not so at all. We use iron guides today, until total valve lift exceeds .520" (Pontiacs, as they have a shallower valve angle [14 deg] than small blocks [23]). The "side-loading" of the guide is the issue, not the fuel. For small blocks, .500" is the "line". There ARE "hardened" iron guides available, too, but we don't use them. GM's LS-x engines have iron guides in aluminum heads... No factory head I can think of has bronze guides, of any "make". Even the legendary L-88 aluminum heads had iron guides from Chevrolet.

This is all for clarity, not controversy.



12-03-2009, 01:53 PM
Thanx for all the info btw I ended up finding another set of pontiac heads 64's would those be better then the 13's?
I called a local shop in woodland ca today to get price range on head work the guy asked what the heads were off of I said pontiac 400 he asked if it was a 6 cyl ... I hung up called another shop lol.

12-04-2009, 08:27 AM
64s are like "hen's teeth" today. At about 84 CCs, they are ideal for a 9.5:1 400. They're quite valuable to the collector crowd, as they're the only casting that was on '70 GTO 455 cars. 13s with a small "dish" in the piston are every bit as "good" a place to start.

Good call on hanging up... (:- It amazes me how the "younger set" isn't versed in older engines. When I was a young man (early '70s), it was VERY important that I knew the flat-head Fords, the early '50s OHV Olds, Packard V8s, 216 and 235 Chevys, etc. Most of these were already "gone", but knowing A) they existed and B) how to repair them was a necessary part of my job.

Vic Hubbard Speed and Marine used to be in Oakland or Walnut Creek (memory is the 2nd thing that goes..). He was THE Pontiac "guy" in that area in the '70s. If he's still around, he can probably point you to a good shop that will KNOW the Pontiac.

Woodland, huh? I used to work for the man that owned Woodland Rent-All. He had stores in Vallejo (where I was), Fairfield, Vacaville, and Auburn. NICE area! Haven't been there in many years, though. I was a member of The Brotherhood of Streetracers, Vallejo Chapter!!! My GTO was the only non-Chevy in the chapter, and it was the KING of the street-legal cars among them. They hated me... (:-


12-04-2009, 11:20 AM
Nice so now I'm caught between build up this 400 and you also said the 64 heads are rare or sell them to a collecter and build a different 400? meh I'll figure it out.
I actually live in a town called rumsy ca on an organic farm of my family's it's down highway 16 in capay valley really nice place.
My aunts brother was a really big GTO / pontiac guy he passed away but it's his stuff I'm using to build up my firebird and it's his poor old goat that's rotting away :(

12-04-2009, 01:27 PM
A 400 is a 400 is a 400... By that I mean, the block/crank combos aren't any different until you get to the mid-'75 models. Even then, everything "fits", just the block is thinner and not as tough and the cranks aren't made from "nodfular" iron, but plain-cast.

If you HAVE the 64s, by all means, USE THEM! Good heads. Just right for a "flat top" piston in a 400.


06-16-2013, 10:36 AM
I was thinking 1970 #12 heads were off a Ram Air III Engine Automatic Trans and the #13 were off a RA III Manual transmission?I may have it backwards since it's been a while since I've ran the numbers on that year?Either way I've got a pair of 1970 #12 RA heads I plan on putting on a '69 GTO WS block.

You mentioned Your using parts from Your Cousins collection....was the 400 engine out of the 1970 GTO?

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