Im new to this form and had some questions not sure if this is the right spot to post but ill give it a shot. Iv got a 73 ventura and it currently has the pontiac 350 in it but hopfully not for long i found a 455 that the guy is willing to sell very cheep not sure what year yet but i plan on taking my time and building it the right way regardless. My question is has anybody here done a 455 swap in this type of car before, if so do you have any tips,tricks,or sugestions before i take on this challenge.I allready know i need subframe connectors and front disk brakes any info on a good place to find that stuff would be nice to but if not i weld for an living and can make the connectors probly not the brakes though . And im assuming that since this is a pontiac site i wont get the whole "just drop a 350 chevy in it" thing, if i want to drop a 350 chevy motor in something its gunna be a chevy.

I might be wrong and Frosty or Justa6 can chime in on my mistakes but the 350 and 455 are the same dimension blocks. So this will be a bolt in application for that. I would upgrade the trans or at least the torque converter to handle the added fun. For brakes I believe they use the same spindles as the Nova, Chevelle and Camaro so upgrading them should be a snap.

I use Summit for all of my stuff or Amazon if I cannot find it on Summit

The swap should bolt right in like Notallthere said. I would look for a 455 torque converter to use with your 350 trans. (maybe the guy your buying it from will throw it in??) Headers would solve your exhaust probs. (finding the right stock exhaust might be a pain.) Pontiac in a Pontiac....keep it real. I'm partial to Jeg's, but check Summit for prices....INCLUDING shipping cost. They vary alot between the 2. Good Luck.

Everything that notallthere and JUSTA6 said is correct. Externally, all Pontiac motors are the same except the 301/265 that came out in the late 70s and early 80s. So a 350 Pontiac has the same external dimensions as a 455 Pontiac, the only difference is the bore and stroke of the motor. So it should be a bolt in but the torque differential will create the need for a new torque converter, perhaps a tranny upgrade and the subframe connectors. The only other pitfall with a 455 into a Ventura is the age of the 455. The 455 came out in 1970, by the mid-70s Pontiac had made a slight change in motor mounts from two holes to three. So check your motor mounts and blocks of your 455 and 350. You may need a different motor mounts for the engine.

One word of caution on header selection. Pontiac made two basic styles of exhaust ports- D-shape and round/oval. So knowing which heads you are running is good thing to know when trying to get matching exhaust gaskets and headers for your car. The head numbers are cast into the heads and are easy to read. 98, 66, 7M4, etc. Doug's Headers is one of the most popular maker of headers for Pontiacs. So shop around as JUSTA6 suggests.

Look at Nova/Camaro subframe connectors and front disk brake options. The 1st gen Camaros were based on the Chevy II/Novas. That carried over into the 2nd gens too. So many X-body/F-body front suspension components interchange. Parts that fit a Nova should also fit the Ventura, Apollo, and Omega, key word here is should. Do your homework. Shop around and ask questions of these potential suppliers - will these fit a '73 Ventura? It most cases, it should - be certain though and ask before you shell out your hard earned money.

Thanks for all the info its gunna help me alot, but now the only problem is i went to get it from my buddy and he sold it to someone else even though i said i had the money in hand but i still need the breaks and subframe connectors and keep my eyes open for another one.

oh that sucks.

Some "buddy" he is

Well it stinks that he sold it out from under you, still there are plenty of 400s and 455s out there. Keep looking and keep doing your homework. You can still buy and install your sub-frame connectors and brake upgrades in anticipation of the 455. You can also nore and stroke a 400 with aftermarket parts too. So unless you have to have a block with 455 stamped on the side, you have options.