Hi, I would appreciate anyone's opinion on this. I own a 67 bird convertible daily driver. Right now it has a chevy 350 in it and 350 TH tranny. My bearing are worn so it is just a matter of time to replace or repair. I would like to return it to a pontiac engine and am interested in maybe a 350 HO, so I wouldn't have to change out the transmission. Although the idea of a 400 would be cool too. But I have also heard that the chevy 350 is a cheaper engine to modify with better results. I guess I would like about 325hp when I am done, any thoughts. Thanks Kevin

Car's already got a Chevy. So it will be substantially cheaper and easier to keep it that way. It is cheaper to modify. I do not agree you'd get better results...that all depends on the recipe used for the build and the quality of the build. Pontiacs are stout motors...stronger than Chebby's when done right.

Purists will hate you if you put in another Chevy.

Returning it to all Pontiac will cost substantially more money, and depending on the car you MIGHT get some of that money back in increased value. Since it'll still be non-numbers-matching and non-original, you might not. These cars just don't have that much monetary value except for a few concourse and true original examples of specific models.

Your car, your choice. Do what makes you happy.

You seem to be under the impression that 350 chevy and 350 pontiacs are interchangable motors. They are not. There are alot of differences. That's why crazy says it will cost you alot more. Because you will have to gather alot of stuff to go back. You will be much happier(my opinion) if you do and 325hp is easy to achieve even with a fairly stock 350 Pontiac motor and you will have alot more torq. Of course you're likely to spend more money on tires but such is life owning a Firebird.

might as well just go with "modern' technology...buy a cheap LS1 ..get twice the MPG

The cost of a 350 HO (true 350 block code and 65 cc #48 350 HO heads) will be high as well as the cost of building a 350. Machining costs will be the same, pistons, rings will be a little more expensive.

The more cost effective solution is a 400 with 77-82 cc heads or 72 cc heads. If use 72 cc heads, Speed Pro/TRW has a piston that will keep your CR to around 9.1-9.6.

If you go the 350 HO route..find a 350 block that has the cylinder walls chamfered for valve clearance. Find a pair of 670 Pontiac heads. Use the 068 cam grind (or Comp Cams regrind)

What would be cool? a 350 HO with the 670 heads (which incidentally are the best low lift head and the only closed chamber Pontiac head) with fuel injection.

That would be interesting.

If time isn't a factor, you could easily search Craigslist and the boards for a block, pistons...etc and come under budget.

One piece of advice? Spend the money up front for the block parts and machining. Get the best bearings, rods, pistons and rings. That mentality will "bulletproof" your bottom end..After that, you have the flexibility to tinker with exhaust, heads, intakes...etc. IMO, the block and prep is paramount.

It is sad but true since you can get a new GM crate engine for under $2000.
Cant do all the machine work and parts for that cost on a pontiac engine.

Interested in knowing who has a 325 hp turnkey crate engine for $2k

Unless I am severly mistaken (happens more and more these days) the TH350 trans sitting behind the Chevy block will not mount to the Pontiac block without and adapter plate.

Good point.

I put the 290 Hp longblock from GM in a car was $1680 for the longblock. Customer already had intake, carb...etc
Cant build a 350 Pontiac for that.

Thanks, it's good to get opinions from you guys, I have some time to think this through. I would love to go back to pontiac but I am concerned about the $. At least a new engine and tranny ( I think) plus I heard motor mounts may be different if I switched over, although wouldn't mind more torque and becoming a purist.

Yea, 350 tranny, might not fit behind a pontiac block, but a bigger TH400 would and you can normally find those that arent too pricy that will fit behind a 400! Hope you can find something that isnt too pricy and restore that machine to pontiac! Granted, it cost a little more to a lot more for a Pontiac engine, depending on what you are trying to do with the engine.

TH350 and TH400 are the same thing/same fit...there is no difference.

Simply put you'd need to buy Buick/Olds/Pontiac bellhousing versions of either tranny if you're bolting it to a Pontiac block, and you buy Chevy version of either tranny if you're bolting it to a Chevy block. OR...you us an adapter plate to do the conversion if you're trying to mix/match a BOP engine/trans with a Chevy engine/trans.

Exactly my point, but why spend the money on something to adapt a 350 tranny to a pontiac, when you can buy a pontiac 400 that bolts to a pontiac without a conversion and have a much better and stronger tranny for little price!!!

ah..now I understand where you're coming from. But...not to get too far off topic, but for purposes of this discussion and owner's intended power output I feel that's a point of debate. I frankly prefer the TH350 over the TH400. When built properly (very inexpensive and easy to do) the TH350 can be built to handle substantial HP & torque, and with it being lighter in weight with much less rotating mass it is more efficient and allows more HP to get through it to the ground. TH400's waste HP.

Given 2 identical cars, if properly set up, the TH350 car will be slightly quicker and faster than the TH400 car...and will get better fuel mileage. Both will have equal service life and handle the abuse equally well...AGAIN only if properly built and set up, maybe to a max of 600-ish horsepower.

Indeed in pure stock form the TH400 is stronger than the TH350. And the TH400 can be built to handle MORE than 600 hp...where that's approaching the limits of what a TH350 can be built to handle.

I run a TH350 behind my 400 engine F-bird...I dumped the TH400 by choice...

Also need the correct trans crossmember and shorter driveshaft and detent switch if you go with a T400

You put a longblock in...

OK...from where did you buy this?

You compared $2000 in machining and parts and (still wouldn't be complete) versus your solution...a $1700 GM crate engine.

YOU CAN NOT BUY A GM (I said GM) crate engine, turnkey for $2000.

I worked at a machine shop for 10 years...I only built Pontiac engines as they came in.

Your assertion in grossly skewed on both aspects...the cost for building a Pontiac block (sans hard parts) versus a "GM crate engine"

I also have an uncle who works at the Willow Run GM warehouse and have kept up on the GM crate engine prices.

Point?

For $3500 plus/minus $500 you can source and build a complete 350 block with heads, machining, parts...etc.

Now we come to this mystical "GM" crate engine. Is it a GM crate engine warrantied and built by GM or is it a reconditioned longblock, sans $1500-2000 in additional parts and costs?

Just because it is a GM block with GM heads does NOT make it a GM crate engine. As defined, a GM crate engine in not a reman, is not a second, and for the most part, it's apples to apples.

Engine was new from the GM dealer with a 24 month warranty.

The base 290hp crate engine costs $2003 now. That's "dealer net".
Everything except flywheel/pulleys/exhaust mans.
Most dealers sell at 10%-20% over do to competition.
Not a bad deal.
GM also offers "power packages" for same engine up to 360hp, but price go's way up of course.

Some GM dealers buy mixed truck loads at a time and get extra 5%-15% discount, then sell to other GM dealers who don't what and/or cant stock'm do to space. Usually at cost with no shipping.

Or opt for the 350 HO/330hp. Also complete less flywheel/pulleys/exh mans.
Dealer net on it is only $4731 LOL!