Decisions...sometimes I hate them...

[RustyRed]

Thinking about eventually doing something to the motor in the Trans Am.

403 in it is running fine but 175 horsepower from the factory sucks. It's getting a little tired but not worried it's going to grenade on me anytime in the near future.

My options are pay a couple grand and get a running 455 from someone I know in San Antonio...even comes with the ceramic coated headers...pretty much everything minus the carb. He's building a track engine and has reasonably low miles / age on it. Could for the most part drop it in and go.

or option two is I have a line on some recently rebuilt 7a heads that someone I know was running on their 403. Matched with the right cam, etc it would probably double my horsepower.

I hate decisions....my only hesitation on the 455 is making darn sure both it and the ac will fit under the hood.

However, if I went with either option I bet I'd be able to catch a PT Cruiser :steer

 

[midpack]

Well, if $$$'s no consideration and in the end I wanted to keep as much of the originality of the car intact, I'd go the 455 route... Do you think the block is that much bigger that your accessories won't fit somehow?

 

[rollinsmoke65]

Is the 455 an Olds also, or is it a Pontiac. The 403 gets a bad rap from a lot of people, but it can actually be quite a good motor with a good amount of torque. You could upgrade your 403 for a lot less money then the 455 is going to cost I'm sure. Basically get some heads and bump your compression up some, put in a mild cam and good free flowing exhaust, and the car will feel like a whole new beast. If it is a weekend warrior car I would also recommend possibly a gear change to 3.23 or even 3.42's.

 

[Fst Blk]

Drop a late model Silverado 5.3 in it along with the trans, wiring harness, and computer. You get good tuneability and fuel mileage. Plus, they were near 300 horse stock. A little work and you could have a bruiser. That's my plan if I ever run across the right 67-8 firebird.
Bill

 

[lethal289]

put a ford in it and call it done.

 

[RustyRed]

Well, if $$$'s no consideration and in the end I wanted to keep as much of the originality of the car intact, I'd go the 455 route... Do you think the block is that much bigger that your accessories won't fit somehow?

The 403 is the numbers matching block.

Even if I went the 455 route, I would keep the 403 on a stand just in case anyone ever wanted it. I personally don't care about a car being all original but some folks do.

I really think with the early 70's 350 heads and a few other minor changes you can make a good weekend cruiser motor out of the 403.

I'd have to pull it apart first but I would imagine the 403 would not require an abundance of machine work, it's not burning oil or anything.

Some of the mid 70's model TA's came with a 455. I have seen pictures of a guy that fit one in a car like mine. However, the 455 is a little wider at the intake and I've heard of potential problems if you have the ac box on the passenger side firewall. I know the guy that has one installed said he had to cut off the ends of some of his front suspension bolts, etc. I've also heard you have the potential for some modifications to get the shaker to fit because a 455 sits up a little taller. It's a pretty tight fit at any rate but it is doable.

 

[RustyRed]

Is the 455 an Olds also, or is it a Pontiac. The 403 gets a bad rap from a lot of people, but it can actually be quite a good motor with a good amount of torque. You could upgrade your 403 for a lot less money then the 455 is going to cost I'm sure. Basically get some heads and bump your compression up some, put in a mild cam and good free flowing exhaust, and the car will feel like a whole new beast. If it is a weekend warrior car I would also recommend possibly a gear change to 3.23 or even 3.42's.

I think the 455 is an Olds.

I was thinking the same thing on the gears but I'd probably stick with 3.23's.

My Mustang is running 3.55's and makes it a real pain to drive on the freeway...not to mention my gas mileage sucks. I don't really mind because most of my driving is light to light and the Mustang is a blast to drive as long as you aren't going 70+ down the freeway.

 

[dodgestang]

ls1

 

[RustyRed]

Decided to go with different heads / cam / intake on the 403.

I went last night and picked up the heads, intake and cam. Been super busy so I was surprised the guy hadn't sold them yet. On the plus, I got a better deal via waiting, LOL!

Came with the rollers, push rods, etc. Also threw in some valve covers...not sure I'll end up using the covers but good to place on the heads for now to help keep dust off of them.

At some point I'll get around to doing something with the 403. First thing I have to figure out is what sort of shape the lower end is in. If it's in good shape might not have to do much to it other than clean up and install the "new" parts and move on.

Pictures attached just so I don't have to see that God forsaken mankini picture, LOL!

 

[stangg]

There are a few 403 builds discussed in the Pontiac Trans-AM High Performance Handbook if you want something to read over. The copy I have was published in '81, so not sure if there are better builds outlined elsewhere.

 

[RustyRed]

There are a few 403 builds discussed in the Pontiac Trans-AM High Performance Handbook if you want something to read over. The copy I have was published in '81, so not sure if there are better builds outlined elsewhere.

There are one or two websites that address the subject but yeah, I'd be interested in reading it.

A local motor guy I know (Herb...built Dne's motor and mine in the Mustang) had some ideas I need to discuss with him as well....he builds a lot of Pontiac motors after getting in good with the local pontiac / firebird club of some sort or other. What I'll probably eventually do is pull the motor out and take the heads off, the oil pan off, etc and see if we can figure out what the deal is with the bottom end and make decisions from there. If the motor is out for a while it gives me time to clean up the engine bay.

Forgot to get the specs on the cam but the guy is going to send them to me tonight. From what I gathered it's a mild street cam similar in nature to what I am running in the Mustang.

Before I tackle the motor in the TA though...I am going to drop the gas tank out, patch up one small spot in the trunk then install new leaf springs / bushings. I've been changing out all the locks but almost done with that. I've done one door the trunk and the glove box and only have one more door to go. The key cylinder on the driver's side crapped out on me so I ended up replacing all of them since I wanted one key to operate all the locks.

I am going to tackle the motor however before I tackle paint and a few things that need attention on the interior.