TRANS AM 455 OLDS Vs TRANS AM 403

[Manning713]

OLDSMOBILE WINS !!

[PQXLR]

@Manning713 With eight car lenghts for a spot !

[caudice]

also if anyone needs to buy a set of 7A heads for their 403 i got a set that were recently ported with the stud holes already drilled out for the 403 block

[Dhoylandrules84]

i got an issue of performance pontiac that compares the 76 transam 455 to an 81 trans am with a 305 chevy and also have popular mechanics repair manual from the year 1976 itself (seriously) that lists all cars horsepower ratings that say in 76 the 455 had only 200 horse, same with 75, and it was 250 in 74 with the exception of the Sd455 which had 290 horse from 310 because of a milder cam. excuse my horrible grammer but i believe those are right. Anyone else have anything different?

[madmike90]

you're thinking of the PONTIAC 455. the engine in this video is the olds 455 which is an animal of a motor. some cars with the olds 455 had in the upwards of 400 hp stock.

[4rlorenti]

290HP to the wheels right?

[thisroomistripin]

all you need to make the 403 wake up is heads from a olds 350 between the years 68-72 cus of the compression and drill the head bolts to a 1/2 inch and put a bigger cam and your ready to go... my cam and heads are coming in the mail

[caudice]

@thisroomistripin yeah but you need to drill coolant holes too. i was going to do that but new pistons are a better choice because the valves on the stock heads are also bigger

[caudice]

@caudice yeah thats what i did. i actually bought heads and ended up getting pistons too and now i have the heads just sitting around. but the heads are way cheaper than new pistons

[Dhoylandrules84]

I got a 403 in my 79 trans am and im really surprised it kepted up with the 455 that well. Its actually not bad motor ,but you gotta really do some work to them to get them going. However, if this a mostely stock late 70s 455 than i could see why it was close as they only had at one point 200 hp in 75 and 76

[SanFran90]

@dhoylandrules84: Net. Actual hp in those cars was somewhere around 250 stock in '76.

[camirocz]

@SanFran90 no it wasnt it was 200 gross in 76

[bloozelover]

the slower one has the 403 im guessing

[bbjornson]

which one is the 403 and which one is the 455