Hello, i'm swapping out my 6cyl for a 428 and would like to know what I need? Do I need to do anything with the steering? What about the springs, the car is a sprint and I read they are already heavy duty. Will I need different mounts for a bigger readiator or will the one's I have work? I also bought a M20 4spd from a 73 firebird with a 26 spline, will an 11in clutch to fit a 68 400 be what I need or what size? Thanks for any advice you can give, I want to drive her this summer.

Sad to see a real sprint bite the dust. You will need new springs as the 428 motor is much heavier than the OHC. You will need a new rad for more cooling but should just bolt up. An 11 inch clutch will fit a V8 bell housing but it's hard to remove the bellhousing in the tunnel with the 11 inch (from experience). 10.4" ought to work OK. Older Muncies were 10 spline so be sure you get the right clutch disc.

Save the Sprint, swap your car.

Sounds mean spirited, I know, but Sprints are both rare and becoming ever more collectible. They're also fun to drive.

I'd swap a generic V-8 'bird for a Sprint 'bird of the same condition.

might need to swap gas tanks for a bigger one.

What about the steering? any other concerns?

Lots of different parts, steering, charging, suspension, driveshaft, shifting, cooling, frame mounts, wiring harnesses, throttle linkage, shift linkage, exhaust and many more parts.

And if you are doing mix-n-match it gets more interesting.

Sounds overwhelming. I already have to much into the motor and tranny to quit. As far as the steering what will I need in order to put the 428 in? My motor builder has the mounts and thinks the driveshaft is the same, is he wrong? As far as supension, I just need V8 springs, correct??? For the tranny, I have the rods and will just swap the shifter if it fits. What will be different about the charging? Thanks for the help

I believe the Pitman arm is different. Your builder may be right on the driveshaft. I would do the springs last to see where it sits with the ones you have. This is an easy conversion for a mechanic. No big deal. Set him loose and see what 'snags' you run into. There will not be many....

it sounds like yellowbird has the way to go swap the car for another v-8 car and keep that a sprint even if it is not a #s matching one. just a thought

IMO The car will be worth more with the V-8 than a wrong 6. So what's the point in keeping it a 6 if he wants an 8? LOL He asked HOW to do it, not IF he should do it.

I didn't see anything about a "wrong 6" except your post, Jim.

My point is that Sprints are rare and have a collectibility of their own besides being a kick to drive; 350 2 bbl cars which would be a drop in are plentiful. So why spend extra time and money and take a scarce car out of circulation to make it not numbers matching?

If you never drove a good running Sprint with either a modern overdrive trans or a manual trans, try it. The two speed auto wasn't a good match since it had no first gear ratio, but even then my '66 Le Mans was a blast to drive anywhere. But since the 200-4R bolts right in, there is no reason to suffer. There is a reason John DeLorean was so strongly supportive of that engine.

The post just before mine insinuated it was not numbers matching. Maybe that was a guess or inside info...

I've had a few 6's and I'm definitely not cutting them down at all. My opinion is that a non numbers matching v-8 car is worth more than a non numbers matching 6 car.

And he did ask How not If. And then after all the good advice he still wants to switch... let him go and switch it! Let's help him do it. And if it is/was numbers matching...keep all the parts. This is a bolt-in conversion.... It will not hurt the value if it's wrench reversible.

Thanks Fbody69, although it is a numbers matching motor and 3spd tranny I still want to switch it. I will keep all the original parts just incase. I thank everyone for there advice but I still have way to much invested in the switch to stop, so I still seek advice from the first gen gods.

I did not know if it was a matching #s car or not I was just thinking it would be a lot easyer if the car that was started with was a V8 car to start with with all the part changes that are needed. I would think the sprint car would be a good swap for a good car to stuff the 428 in but you guys know more then I would anyhow

My only input is..

I'm sure the OHC 6 is fun to drive, but I bet putting your foot into a nicely built 428 will be even "funner".

The "world" isn't going to offer you anymore for a pristine numbers matching OHC 6, sure a few here might but I didn't see anyone making you any offers for it either, so it's just "in theory"...

So if "in theory" the OHC 6 is rare and that valuable, all of us would be off the charts since our cars were actually the upgrade to the Camaro and few were sold in comparrison. But "in reality" we seem condemded to being the step child of the Camaro (and GTO for that matter).

I vote to build that car/428 for all you got! Good luck!!

I have a 350 2bbl car with a 400 in it. I have no problems with non matching cars. I also have two numbers matching 400 birds, and briefly had a 455 bird which started as a 400 car.

OHC came out the gate late, and with a bad rap because of Chevy's anemic 6. Then PMD made the bad move of continuing the two speed auto with the engine in the sporty Firebird. So Pontiac takes some of the blame for not giving customers what they really wanted, but they still sold a load of 6 cylinders, mostly 1 bbl. A Sprint Cammer is a bird of a different sort. No, you won't likely be smoking up the tires as with a 428, but in typical around town driving the Sprint is very responsive. Some people like them. Some have never driven one.

Yes, JM, I would consider a trade for a generic 350 car for an equivalent numbers matching Sprint car. I'd also offer to buy before any changes were made. As I said, I like the Sprint. I've shopped a few of them, and when the right one comes along I'll own another.

hehe, get a grip Vik.. you have how many cars? That is not normal girl..

if I had a half dozen birds to humor me, sure I'd probably be out to save the OHC6 because I've "been there done that" and already achieved what he is trying to accomplish.

I'm just being pratical...

The more I see and learn about the Sprint cars the more I like them and want one. A #'s matching would be too cool!!
From threads/photos posted here There is just something real nice about the way the motor sits in the engine bay.

Do I love my Bird...sure but realistically cars like mine ,400 non-matching, are not all that hard to find.

If I was only going to own one bird, it may or may not be a Sprint. I don't think I could select just one car that could satisfy every need I place on one. I want excessive displays of power and a car that will easily make a coast to coast trip loaded up with luggage. I want sharp handling, and a good ride. I don't have much opportunity to really open up an engine around here any more, it's far too built up, but even on my way to work I have the half mile to one mile stoplight runs. And a cammer is pulling hard before my 400 even starts to really breathe.

All these things could easily be filled by one new performance car, but that's not what I want. I like the old beasts for their honesty and simplicity. They are what they are, and I understand them. And they are not so common as they once were, though around here I see more Firebirds than Camaros.

I need at least two play cars, and a Sprint could easily be one of them. Now, roof or not...?

But anyhow, since I have nothing else to contribute to the swap, I'll bow out.

Color me the Mr. T of Lake Forest then.

If you like attention at a car show, show up with a sprint Firebird or LeMans. The Pontiac guys will be hovering around like flies.

And that's the truth. And then you get a lot more respect when that little Quadrajet-topped six speaks up!