428 swsp
 

I’m buying a 428 for my 69 Firebird. I’m going to swap it in for my 350. I’m trying to process the pieces.
I’m hoping for some “don’t forget”

428 is complete running engine w all accessories.

My list:
Wiring change from points to HEI.
Using my ps pump so all plumbed.
Throttle connection to quadrajet. Had 2bb
Tranny kick down?
I’m redoing exhaust. Need to replace 1 exhaust manifold on 428.
My th350 is going in for refresh plus shift kit (?)
My 8.2 rear end will need updating. Eaton posi? Thinking 3.42 gears?
Doing new radiator. Hopefully fan shroud fits 428 fan.
Replacing motor mounts.
Not sure about gauges. I have basic idiot lights now.
Fuel lines? Hoping existing will be adequate? 428 has mechanical pump.

So many different discussions here that I can deal with separately. But what am I missing?

All good. Plan for a TH400 when that effort is running. Plan for 3/8 steel fuel lines. Hope you have POSI highway gearing.

If your keeping the TB350 than most of all it needs the kick down cable to be in the proper start off position with the throttle closed.

Your stock fuel line size is good for a stock 428 provided that all the rubber connections are good and not dry rotting.
A mechanical fuel pump finds it far easier to suck air than fuel.

It should not be hard to turn up another exh manifold unless it’s a 428 HO motor.

Have you heard this motor run?

Even if so I would pull the pan to clean it out.

Look at the oil pump screen ,

Replace the timing chain if need be, and most importantly look at a few bearings.

You don’t want to kill a hard to find 428 motor and especially if it’s a non 1969 two bbl motor which will then have 4 bolt mains.

The block codes for the low per 2 bolt main motors are YL, YH, XE and XJ.


With auto trans and if you do not run slicks if you ever go to the strip the 8.2 should hold up behind a 428 provided it’s not going south already.

If your 8.2 currently has 2.73 rear gears I think you will need a spacer for the ring gear to step up to 3.42 gears.

Save the Distributor swap for dead last .
Get the motor and trans working right with the old points set up that way you have one less potential problem to confound you.

Also be sure that the HEI you go with has vacuum advance.

The 428 already has HEI. It is YH code. Reported to be rebuilt. Polished crank. 20 over. 46 Heads updated. Mild cam upgrade (blue runner?) unsure of details. Saw video of running. Sounded solid. Price is very good so figure it’s probably worth the risk since other option is spending a bunch of money on my 350.

The gain in torque from 80 more cubic inches will be eye opening. You will need 3/8" fuel lines/hoses from tank to carb. Seems like 350 Pontiac engines may be 5/16" Need to verify that. Yes a TV cable will need to be rigged up for the Q-jet., I good running 428 will tax a turbo 350 pretty hard. That's why the factory didn't build them that way. 350 will need some updated, improved parts to last lots of hard use. Will be fine if you don't drive it hard all the time. 428 is a favorite stock Pontiac engine size. A great combination of torque and a little RPM. Do you happen to know what the 428 engine has for connecting rods? Stock rods, properly prepared, should be limited to 5200 RPM.

Just wanted to point out that the TH350 does not require that the kickdown cable be attached to the carburetor. It will shift and function just fine without the cable, you only lose the ability to automatically downshift at full throttle, (which you can do manually instead). The TH350 does not have or require a TV cable like some later overdrive transmissions.

As others have said ck engine before installing,pull pan,timing chain,oil pump, hd shaft. I'd also pull your gas tank. Ck cleanliness esp the sock. Just making sure you have good fuel flow. One less headache with engine change to frustrate you. Been there ugh!

The 2brl throttle cable is likely too short for the 4 brl carb/intake, requiring a 4brl throttle cable. This was the case on my 69 Lemans.

Yes. I’m planning on dropping the tank. Fuel gauge quit a couple years ago. Bad ground I think. But will check and maybe replace pick up while there. Probably original.

All 1969 Firebirds already come with a 3/8” chassis fuel line, even if it was 5/16” which it’s not you’d be okay.

Kick down cable not necessary as already stated above.

HEI may interfere with the firewall on early Firebirds so be aware that you may need to get out the big hammer if you’re set on using it.

The exhaust manifolds on your 350 will work fine on your 428. Pontiac didn’t put larger standard log exhaust manifolds on larger displacement engines, 350 / 400 / 428 / 455 are all the same.

I have a Tri-Power 421 HO (bored to 429.7 cubes) in my ‘64 Le Mans with the original 5/16” fuel line and a Carter M6907 mechanical fuel pump and it’s fine, new sending unit and sock in the tank.

I pulled some nice log exhaust manifolds off of a 326 Le Mans in the junkyard, I used them on my 421 installation. Same manifolds a 389 GTO used.

I run a completely stock TH350 trans (kick down cable deleted) and it’s fine behind my 421 that probably makes 350 horsepower. I do have a 13” Continental converter that gives it some added performance when I hammer it on occasion.

It has a ‘71 Olds 8.5 corporate 10-bolt (way stronger than the 8.2) with a factory posi and 3.08 gears, it a great street and highway gear. A 3.42 rear end gear would be tiresome on highway trips, even 3.23s aren’t that great.

Consider a swap to an early X-body 8.5 that has the same spring perch width / location as your 8.2, year range 1968 - 1974 if I’m remembering correctly.

With those small valve #46 heads your TB350 should hold up ok.