[Steve Shively]

I bought my 1968 Firebird 400 HO in October of 1983. Through the ups and downs I have held onto the car. After getting PHS docs on it in the early 2000's I began gathering correct code & casting parts to take it back to original as possible. Original drivetrain was long gone from the car when I bought it.

I tore the car down to an empty shell and finally have it running again. A minor accident did some damage, can easily be repaired. Currently has a 1974 455, stock bore & bottom end, 4X low compression heads. M-20 Muncie, 3.55 rear.

Been thinking: since original drivetrain is long gone, being truly original is not possible. At this point I am thinking of selling off all the bits I have collected. I have all the major parts to build a 400 HO engine.

Something to ponder.

[Steve Shively]

From when I first bought it...

[Steve Shively]

Another pic of it....

[JLMounce]

How do you want to use the car? If it's resale value you're after, I'd continue the search for proper date coded drivetrain parts.

If all you're looking for is a cool hotrod to have fun with it, being 100% original doesn't matter in my mind. What matters is it being reliable enough for the activities you want to partake in. It's a '68 Firebird after all, even as a 400HO, it's not an investment grade car, so getting big money out of it is never going to be a reality.

I'd decide what you actually want to do with the car, the sell the items (if any) that don't contribute to that goal.

[jhein]

Well, it's never going to be a numbers matching car. To make it numbers/parts correct could be done but at what cost and what purpose? For resale? To win a show? For resale, probably not worth it. And it doesn't sound like your planning on selling the car anyway. Winning local shows would be a fine goal if that's what you're into. Otherwise, I'd just make it the best possible driver you can for your use. Myself, I prefer a stealth restomod type of car.

[Steve Shively]

I want to enjoy driving it. Too much money has been spent to not enjoy it. The parts are going nowhere at this point. One mod I thought about is EFI. Probably when I do a head swap on the 455, find a set of 6X-4 heads, roller cam.

[Scarebird]

I would sell the HO stuff and get a pair of Eddy round port heads and run that on the 455.

[indymanjoe]

drive it and enjoy it! efi is a waste of effort in my Opinion. keep it simple and reliable.

[b-man]

It would be fun to experience how an original 400 HO 4-speed 1968 Firebird performs.

If you strive to build it as factory correct as is practical then you’ll have a nice fast car that’s reliable as well. Date codes and such aren’t important really.

Sometimes it can be rewarding to resurrect a classic high performance car and see what it would have been like to drive one exactly as delivered back in the day.

I did exactly that with a 421 HO engine. Even though my ‘64 Le Mans convertible was never factory equipped with a 421 HO I wanted to experience the feel of one that’s unmodified. Other than adjusting the compression ratio to work in harmony with today’s fuels it’s just as the factory would have built it.

Stock can be satisfying, especially with a Pontiac High Output engine.

A 455 is a nice powerful engine but the 400 HO is better suited for a manual transmission in a lightweight Firebird. The 400 won’t blow the tires off as easy and rev a little higher, a recipe for fun.

[694.1]

Build that 400. That way you have a spare for the next Pontiac

[b-man]

A 400 HO 4-speed drivetrain even if it’s not the ‘born with’ one will still garner more interest and bring more money if you should ever decide to sell it than a generic 455/6X combo.

Not to mention the 3.55 gears are much better matched to a 400.

There’s really no good reason not to make use of the 400 HO pieces you’ve gone to the trouble of searching up all these years.

[Steve Shively]

Originally Posted by b-man

It would be fun to experience how an original 400 HO 4-speed 1968 Firebird performs.

If you strive to build it as factory correct as is practical then you’ll have a nice fast car that’s reliable as well. Date codes and such aren’t important really.

Sometimes it can be rewarding to resurrect a classic high performance car and see what it would have been like to drive one exactly as delivered back in the day.

I did exactly that with a 421 HO engine. Even though my ‘64 Le Mans convertible was never factory equipped with a 421 HO I wanted to experience the feel of one that’s unmodified. Other than adjusting the compression ratio to work in harmony with today’s fuels it’s just as the factory would have built it.

Stock can be satisfying, especially with a Pontiac High Output engine.

A 455 is a nice powerful engine but the 400 HO is better suited for a manual transmission in a lightweight Firebird. The 400 won’t blow the tires off as easy and rev a little higher, a recipe for fun.

I bought my WQ block from you!

[b-man]

Originally Posted by Steve Shively

I bought my WQ block from you!

Yes, of course I remember.

That was about 12 years ago.

[77 TRASHCAN]

Make me a deal on the 455..........

[unruhjonny]

if you are at a cross roads with parts, please take this into consideration;

A 455 will be relatively easy to sell;
A RUNNING 455 should be SUPER easy to sell.

I agree that an original 400HO car will likely garner more market interest, and better money with a 400 (with period parts on it) vs a later 455.

Now, honestly forget the idea of chasing date codes - I can see from your posts, this is something you are not interested in, and that's totally fair.
If you already have a 400, and if already you have "all the major parts to build a 400 HO engine", why not get that engine built, do a swap, then sell the 455 - as well as any other remaining parts.

At the risk of repeating myself;
Enjoy the car as-is while getting machine work done;
Maybe even find a buyer who will put a deposit on your 455 while the car is together and running - then only hand off the 455, when you pull it to swap in the 400.

[Drag Star Le Mans]

unruhjonny just gave you the best advice on your situation. Mostly drive and enjoy the car. My GTO is not worth a resto so I'm just going to drive and enjoy it as is.

[Bill S]

I have had my 67 Firebird since 1980 and had the same thoughts years ago. At first I was going to make it a 400 clone. I picked up a correct 400, M20 and 3.26 geared rear axle with traction bars. Then in the early 1990s, I read Jim Hands HPP article "Street Fightin Ponchos". Changed direction and went with a 1970 455. Put on the correct 67 unique intake manifold.

Go with what floats your boat. For me, mine is still a Pontiac engine from a similar era, but stronger performance than a perfect original 400 with more torque for fun. I can understand the "feel good" effect of a perfectly restored number matching car. But a clone or what I think of mine, a period correct mild mod makes me happy. Headers are the oblivious visual mod. How many non-Pontiac enthusiast could tell a 400 from a 455, and know enough to check for the "mountain / lug"? Its still a real Pontiac engine. I have a Cliff R. Quadrajet, reproduction ram air pan setup, front griller hockey sticks and original donor car 400 hood, upper and lower baffles. I built my car for me, and do not care what it is worth on the market. Not selling after 44 years.

[Steve Shively]

b-man has a good thought, I have the major components to do a 400 HO build. But drop compression into the mid 9's to run pump gas, good internals, including forged rods & pistons. The 455 can serve me in the meantime. Still needs painted & repairs from a mishap putting on the trailer. I have a good friend & mechanic who has been my overseer of my build, he will be my engine builder, with my hands all over it.

Appreciate all the comments, keep them coming!

[locomotivebreath]

I have a slightly warmed over 400 in my 68 GTO - all factory parts except the oversized RA manifolds, small roller set up with 230cfm 16s . Factory 68 Qjet , M20 , 3.90s . It rips and easily gets 14mpg , doesn’t run hot , manages 10.0.1 on 93 & isn’t temperamental - EFI is cool but my Qjet is as responsive as any of my modern cars . Instead of efi , I bought vintage air !

[Steve Shively]

I do agree that a change in gear ratio would be a good idea, something around 3.08-3.23 would be best. Picked up a set of 6X-4 heads to use on the 455 along the line next year. The bottom end is a stock , no ARP rod bolts to add strength, so cam will not be too wild. I want it to run strong and be right in it's power range. Would need to find an 68-9 8.2 rear end to build, then I could set the 3:55 posi aside until the 400 HO is built. I have two cranks to choose from (one is really nice shape) for the 400, it will get good forged rods & pistons, Built right. Future projects!