307 to 455 in a 1987 442. Should I??

[FE3X CLONE]

Personally I think the 455 is the better choice. My posts above were just to try and point out a few pitfals.

I've built both and had both in two different street cars. Both cars had the same transmission and same rear gear.

My 455 was pretty much stock, no porting on the heads, no headers, etc.

It ran a best of 13.9@99mph before I pulled it out.

The 403 we built for my brother's '81 wasn't too radical either however it did have a larger camshaft, better intake, headers, and better flowing heads.

His has run a best of 13.2@101mph or so.

However the 455 engine I had was much more fun to drive on the street. I had a 2200 stall converter instead of the 3000 stall behind the 403 which makes a world of difference in the overal feel and streetabilty of the two engines.

I'd venture to say that if you did two builds, one was a 403 capable of 12 second ET's and a 455 capable of the same, the 455 would be a much more street friendly daily driver engine.

The two engines really didn't have that much different fuel economy either. 12-14mpg average.

 

[dan2286]

The reason I wanted the 455 was because I had a sweet deal on a running,smoke free engine. But if a 403 is more streetable then I start to wonder. Is a olds 403 the same as a Pontiac 403? Is there any difference at all. Also would this be a better fit when it comes to the a/c and heater box? Would this be a better choice or should I stick with a 455. This is not my everyday car so gas mileage is not a issue. Thanks for the help.

If it's a good deal, then buy it! If you don't decide to go with it, you can always sell it and probably make money off of it.

 

[OldsThunder]

The reason I wanted the 455 was because I had a sweet deal on a running,smoke free engine. But if a 403 is more streetable then I start to wonder. Is a olds 403 the same as a Pontiac 403? Is there any difference at all. Also would this be a better fit when it comes to the a/c and heater box? Would this be a better choice or should I stick with a 455. This is not my everyday car so gas mileage is not a issue. Thanks for the help.

If it's a good deal, then buy it! If you don't decide to go with it, you can always sell it and probably make money off of it.

do you plan on just sticking in the motor or do you think you might change cams? or heads? what are the heads that are on it now ? alot of them came with j heads but not all "c" or "b" 4 barrel heads are a good upgrade but "b" heads for the older gas.

 

[skooterace]

I had read on another site that some trans ams came with the olds 403 in it. I don't personally know if this is true or not but if you know where a donor is at that could be the same. I ran a 403 bone stock out of a 77 delta 88 and it really woke my car up compared to the swirl-port 307. But since it was stock (and I drove it hard) it is now due for a rebuild. I'm currently looking for a set of 350 heads to wake it up when I get my body work done... So if it were me I would go the 403 route to keep the weight down, and keep the stock handleing characteristics.

 

[GP403]

I had read on another site that some trans ams came with the olds 403 in it.

The 6.6 T/A from '77-'79 *could* have been an Olds 403 instead of a Pontiac 400. For sure if its got a stick its a Pontiac, there was never a 403-stick combo from the factory... check this out: http://www.78ta.com/enginecodes.php

 

[joe_padavano]

Is a olds 403 the same as a Pontiac 403? Is there any difference at all.

Two completely different engines. And the Pontiac is a 400, not a 403.

Actually, Pontiac used the Olds-sourced 403 in the Trans Am and full size cars in the 1977-79 model years. Many people think this is a Pontiac motor just because it's bolted into a Pontiac car, but in fact it's an Olds 403. There were probably more 403s installed in Pontiacs than in Oldsmobiles in those years.

 

[OldsThunder]

I had read on another site that some trans ams came with the olds 403 in it. I don't personally know if this is true or not but if you know where a donor is at that could be the same. I ran a 403 bone stock out of a 77 delta 88 and it really woke my car up compared to the swirl-port 307. But since it was stock (and I drove it hard) it is now due for a rebuild. I'm currently looking for a set of 350 heads to wake it up when I get my body work done... So if it were me I would go the 403 route to keep the weight down, and keep the stock handleing characteristics.

a real good set of heads to get for the 403 would be a set of # 5 and # 7 heads not the 5a heads just 5

 

[dogsht]

http://www.robertpowersmotorsports.com Bob ran 12.3 at 110mph and got 15mpg before his was stolen. Pump gas reliable streetable no spray and way more fun to drive than a sb.
http://www.cardomain.com/ride/1381227/1 ... tral-mn-us Dwight's ran 12.0 at 112 mph and gotten 20 hwy. Again pump gas reliable streetable no spray and way fun to drive

 

[1badchevy]

If the deals good, and the cars not gonna be a daily driver then dont hesitate. Im looking for a cheap one myself for the 84 Delta 88. The only thing is your gonna need a th400 cause the 200 wont hold a week even to a stock 455

 

[dogsht]

Box stock with some abuse no the 200-4r will sooner or later give out. The th400 is the cheap route & ideal for a drag car etc. But leaves a lot of goodies on the table for a hot street build. My built 200-4r held up well to my 570 torque 509. But over 500 torque additionally needs billet forward drum/shaft and needs to be done by a shop with s track record of successful hi performance use 200-4Rs.