I'm considering purchasing a car advertised on this site. The engine however is not complete. All there is of the motor is the original YW block, crank and #16 heads. How difficult would it be to source the remaining parts to restore the engine to as close to original as possible?
I am thinking a crate engine would be a better option short term, but at some stage I would like to get the 400 back in the car. Any thoughts greatly appreciated.

The internals of a 400 HO are the same as the internals of a standard 400.

The cam, carburetion, and distributor curve vary from year to year and auto to manual.

Bolt on accessories are mostly identical. Check the AMA specs on this site, and the sales brochure powertrain section, to note any differences.

Purchasing the correct numbered carburetor and distributor can be a lengthy and expensive search. Some carbs and distributors were also used on the standard 400 configuration and are more common.

If the numbers matching block is already .060" over or has badly rusted cylinders or is cracked or damaged, a generic rebuilt Pontiac engine may be a reasonable compromise. Pontiac does not have "crate" motors.

The 400HO carb and intake manifold for automatic is the same as the 400, so it will be much easier to find. A reproduction cam is readily available. The 400HO had a different valve train. I haven't looked into how hard it would be to find matching parts, but as Vikki said, its not necessary- a 400 valvetrain will fit just as well. The longbranches are not there so that will be an exhausting search, but you can always use the RARE reproduction manifolds unless/until you find originals.
I agree regarding the crate- better to put a cheap 350 or similar Pontiac in there temporarily.
For research on the 400HO automatic, check out JimC's site:
JimC2002 400HO automatic

Thanks for your help guys. I was looking at engines from Buttler Performance. Certainly not a cheap alternative. Are the engines they produce just aftermarket reproductions with no affiliation to Pontiac?

my ho has forged crank, pistons and rods they are all stock originals. another difference is the rod and main bearings are heavy duty and the valve train is also. the valves have duel springs instead of standard single springs on a standard 400 4 bbl. camshaft are also a larger duration and lift. than a stock. h.o also has factory headers the standard does not.

68n 400 h.o 4 spd posi numbers matching

Back to the books...



All 1968 Pontiacs other than 250 1 bbl have dual valve springs. That includes the 400 4 bbl.

YW has the same cam (9779067) as YT and WZ.
It uses the same cylinder heads as YT, WZ, and WQ.
It uses the same distributor as YT.
It uses the same intake as YT, WZ and WQ.
It uses the same block casting 9790071 as YT, WZ and WQ.
It uses the same crankshaft 9795480 as YT, WZ, and WQ.
It uses the same main bearing package as YT, WZ, and WQ.

The difference is the long branch manifolds for the auto 400 H.O.

Where did you get your info?

Capri, the engines put together by Butler Performance are usually Pontiac Blocks and Heads. They also make high end engines using a variety of parts from Edelbrock, Eagle, Scat, and others. They know what they're doing.

You also may want to check with Marcel at SD Performance.

I found it by working on pontiacs and owned them for 28 years and rebuilding them. . sure the yt parts will bolt on and work and the springs will work but why is it rated at 335 and not all others execpt the ra 1 and 2? by the way still underated. its not just the exhaust that helped it. and why was it an extra cost option? if the engineers built the ra's with a cast cranks, cheap bearings and the same valve train as a regular engine why are they rated at a different hp and rev limit? and if all motors are the same than why are there different casting numbers and block codes? if you wiped out the part numbers then sure they are all the same visually? and why put high performance parts on a 1 bbl engine when it was originally designed for low performance? what sets high performance engines from others is the quality built into the parts that are engineered for racing and street durability.

The valvetrain parts in an HO are the same as the standard engine. Standard 400 parts are the same parts where specified as such. The auto HO and auto Ram Air were not the same as the manual trans version, they did up the cam in most of the manual trans high performance engines.

The early '60s "Armasteel" and later nodular cranks are not "forged" cranks. They are cast iron, but are a different composition using spheroid graphite iron (nodular) or pearlitic malleable iron (Armasteel).

Ram Air IV was a performance engine. It had a lot of components that differed from the stock '69 400/HO/RAIII.



The same rods were used too, until Pontiac came out with SD rods later. There weren't "Ram Air" rods and "2 bbl" rods.

It's always hard to keep things constructive after someone asserts their personal experience of XX years etc. Since it makes it a personal argument and is taken personal when you continue to debate the point. lol

Please understand that there is a desire to keep the facts straight only. I'm glad Vikki is tactful =)

One example of parts lacking uniqueness that always cracked me up is the intake. Pontiac used the same qjet design and part number on the 350 as they did the 428 and 400! Good or bad most of the stuff is generic no matter what the designation was. Too bad they were all cast rods in our first gens instead of all forged!

It is unfortunate that this discussion took root within an unrelated thread (buying a car). But getting accurate information out is crucial; I almost removed some original parts from my first Firebird because I was told they were "not correct" or "not original".

Cast rods or not (dubbed Armasteel, no less), have you ever had one break during normal use? They do seem pretty tough.

I have a "Ram Air III" intake for sale...

I agree that only the facts matter, and the Pontiac Parts Manual is pretty hard to argue with.
It was not my intention to foster hearsay as opposed to facts when I said the valvetrain is different. While I didn't look up the parts, I did have it from a pretty reliable source- JimC2002, who had mentioned a few times in these forums that GM advised him to use straight 30 weight to avoid clacking at cold startup- specifically because of his 400HO engine. (Jim's Post) I was pretty sure I had heard someone else mention the springs and lifters were different, but if the part numbers are the same, I agree that that should remain the record unless or until documentation can prove otherwise.

The Parts Index offers only replacement part information. While a copy of the '67, '68 or '69 Parts Index would be an excellent resource for the corresponding year car, it would not take into account running model year changes such as dash vent balls etc.

The later (mine is '73) copies of the Parts Index offer replacement part information that often reflects revised or reissued parts. Sometimes the part numbers have been altered from the original, but sometimes the part number is the same and the part changes in some way that is not deemed sufficient to create a new listing. So the Parts Index in itself is insufficient documentation.

The A.M.A. specifications for the model year were published prior to model release. That allowed for service manual providers and other publications to analyze and compare data. The A.M.A. specifications also do not have 100% accurate information as to the date of manufacture.

Assembly manuals have some excellent data, including part or process change dates. However, I am not aware of any '67 or '68 Firebird assembly manuals in circulation.

Dealer service and sales bulletins are an excellent resource. But it is necessary to store them sequentially and keep complete sets as one can supercede another. Other than this site, I do not have access to a set of service bulletins for '68, and do not have '67 or '69.

And the final item is physical inspection. I have several sets of heads, some rebuilt, many original, from 350s and 400s. All have dual valve springs. I can't fathom someone taking a set of stock 350 2 bbl heads with press in studs and going through the trouble of installing dual valve springs without making other changes. And the existence of the dual valve springs is supported by the A.M.A. specifications.

There are of course still unexplained mysteries, such as why my '71 YS block is factory drilled and tapped for 4 bolt center caps. Or why a block I sold, from a 400 2bbl Bonneville, also was drilled and tapped for 4 bolt center caps. None of the "regular" 400s were ever delivered with 4 bolt caps. GM would not have drilled and tapped those blocks if they were not for potential use in a vehicle that would require them. After all, machining operations cost money.

"Bird Glass" has been bandied about as a huge mystery. It's no mystery. It took a bit of cooperative input from members here with and without 'bird glass and the answer was quickly found. Documenting every detail of every unmolested car would greatly increase our knowledgebase. Kurt S. and the CRG group have done an excellent job, there is no reason that we could not research, review and publish a comparable set of information for Firebirds. That is why I took the added time and expense of plastic media blasting over any other type on the '68 restoration, it revealed previously hidden writing on the firewall that I would never have known existed otherwise.

Correct fan on a Ram Air...why was the four blade fan standard equipment? Did it perhaps have to do with stiffness and stability at high rpm, as it was the same fan specified for the OHC-6? The standard 400 non A/C fan was a 5 blade flex fan. At high rpm, it flattens out. Unfortunately the reasons for the selection are not given, but the A.M.A. specs give the usage.