[Baron Von Zeppelin]

Originally Posted by "QUICK-SILVER"

The 68 400 will need adapters to go in the 79 bird.
Like this..
https://butlerperformance.com/i-2462...tegory:1393557

Good heads up on those adapter brackets. Must have items.
He also will need a replacement shaker scoop and breather pan from an original 77-79 400 Pontiac TA.
Olds 403 TA stuff is offset.

I will start by pulling the passenger side head next week at some point and see what I have.

I understand what you mean. Can only pull 1 at a time, and see how good or bad of shape you are in on the "worst side". I hope you can salvage on the cheapside. And just re-do both heads with new gaskets.

You can check for bent rod / compromised piston with a dial indicator on the deck surface after head is off. Thats about all you can do, and cross your fingers. Or tear the whole thing down. Sometimes you just have to roll the stones and go for the easy button.

Edelbrock Aluminum heads are cheap for Olds compared to Pontiac, is what someone was referring to with that suggestion. Worth comparing just to know the best way to spend before getting too deep into the stock heads. Free shipping and ready to run from places like Summit and Jegs - maybe eBay.

I'd want that 403 out of my life if it was my car.
But that is very very bias and prejudice

I'm thinking the 403 cars came with THM350 tranny, not THM400
Not an issue, just a side note.

If it wasn't a special keeper car, i'd probably try to reconcile with the 403 Olds.

[i4abuygto]

Thanks for your comments. I will further investigate when I get the opportunity. I want to at least pull the head(s) while the engine is in the car and see what I have. Maybe upgrade the heads to higher compression if I stay with the 403. At the very least, repair what I have in the 403, if it is reasonable in cost, and shelf the engine as it is the original.

I'm thinking the 403 cars came with THM350 tranny, not THM400
Not an issue, just a side note.

At some point in the cars life the original automatic transmission was replaced with the current THM400. I do have an option to transplant a M21 Muncie 4-speed if that would bring more value. I do enjoy driving a stick better but the expense in adding pedals, linkages and frame pivot points makes it almost not worth the effort and expense.

Is there any resale value in staying with the original motor or is there more value with the available Pontiac 400 that I have. The Pontiac 400 is newly redone with all new components and extensive headwork - it has a performance cam for automatic transmission - should dyno around 400hp.

Is an automatic or manual more desirable for resale.

Seems like most here think I should go with the Pontiac 400 - I should have all the brackets needed.

Good heads up on those adapter brackets. Must have items.
He also will need a replacement shaker scoop and breather pan from an original 77-79 400 Pontiac TA.
Olds 403 TA stuff is offset.

As far as the shaker scoop- |When I purchased the car, it was not on center so I had to realign it anyway with the aftermarket carb that is on the 403 currently. I will do that again when/if I transplant the Pontiac 400. I can unfasten the scoop from the pan cover and realign to the new carb location, if needed.

[Grand73Am]

Originally Posted by i4abuygto

As far as the shaker scoop- |When I purchased the car, it was not on center so I had to realign it anyway with the aftermarket carb that is on the 403 currently. I will do that again when/if I transplant the Pontiac 400. I can unfasten the scoop from the pan cover and realign to the new carb location, if needed.

It's not just the centering of the air cleaner base that would need to be done. They are also different heights. The 403 engine is shorter, sits lower, than a 400, so the 403 shaker adapter plate(that's on the bottom of the scoop) is about 1/2" taller than a 400 plate. And the 403 air cleaner base sits up about 1" more than a 400 base. So, the 403 shaker assembly overall is about 1.5" too tall when sitting on a 400 engine to be able to fit under the hood. It would take some cutting and welding to shorten everything so it would work on a 400.

[Baron Von Zeppelin]

Some guys just mount the shaker to the hood and use an aftermarket breather after doing a 403 removal. Its cheaper and looks cheap - but its done to a lot of modified cars. Depends on what you're after and what kind of originality you want to maintain.
Big Builds usually have little to no choice.

Forget all about being able to modify the 403 shaker set-up to fit in a stock manner with a Non-Olds engine.
it don't be gunna work no mo for all the time and trouble it would take to modify each piece.
If you go there, you'll see

All the other questions depend on what you value your parts at.
If around Zero - you can't get hurt.
Long story-short , if you aren't keeping the car, let the next guy pick his own upgrades and mods.
All you'll do is lose money and parts when you go to sell.

Consider how much money the last guy lost when he sold you the car.

Most everyone here would almost instantly swap the 400 you have if they planned to keep the car. On the other hand, they would all patch the 403 back up if they knew they were going to be selling it soon or within a couple few years.
You'll just be giving your engine away.

Now if its a really sweet cream puff with deluxe interior and in excellent condition inside and out, the variables change quite a bit.
At that parameter, you might could break even or gain a little - if you value your engine at around $3000 or less.

[Ben M.]

Originally Posted by i4abuygto

Is there any resale value in staying with the original motor or is there more value with the available Pontiac 400 that I have. The Pontiac 400 is newly redone with all new components and extensive headwork - it has a performance cam for automatic transmission - should dyno around 400hp.

As BVZ says, unless it's a super nice original car that is well equipped and in fabulous shape, the 403 vs. 400 swap does not hurt the value. The collectors that care about numbers matching are going to go after the low mileage garage kept originals (sub-30k mile cars). Anyone who beats you up on price when you go to sell over it having a correct appearing and well performing 400 (with shaker mounted right, etc) vs. having the "original" lo-po 403 block is only doing it to get the price down and money off of you, not because they truly give a damn about the original engine.