455 swap

[tommytpk]

Just in the planning phase of this, but I want to replace the 260 in my 1979 Cutlass, and I thought I may as well go big if I'm going to do the work.

A few questions:
- what year(s) 455 should I be looking for? Or does it not matter, as long as it has performance head/intake?
- any fitment problems?
- will accessories bolt up? I have working AC and would like to keep it
- th400 or 2004r?

Would love to get some opinions from anyone who's done the swap!

Thanks!
Tom

 

[Qdub24]

Which 455; Buick, Olds, or Pontiac?
200-4R will require some strengthening
May be a tight fit with a/c box; easier to drop in as a short block, then bolt heads on

 

[MrSony]

If there are clearance issues, it takes all of about 20 minutes to saw out a hole in the box and fiberglass it in to make an indent. When my 350 comes back out I'll be doing that very thing as the passenger vc touches the box.

 

[dr78442]

If you're talking about an Olds 455 there is no cutting required if you use stock valve covers. In my experience it is much easier to drop the engine in assembled. I attached a picture of my 78 with an Olds 455. Visit my build thread for more details. Good luck

 

[oldsmobile joe]

i dropped a stock '73 olds 455 into my 79 calais after pulling the 260 out. no clearance problems at all. a/c box, steering shaft, have plenty of room. p/s pump bolts right up. used the stock motor mounts, clutch fan and shroud. I'm using reproduction 442 w30 exh manifolds with custom pipes. i had to modify the a/c bracket, the one that mounts to the head by flattening the bend and redrilling two holes. still have the same a/c compressor and hoses.
the alt bracket either needs to be for a 455 or needs to be spaced up where it bolts to the p/s pump, its the outer bracket with the adjustment slots. the only thing you should be careful of is the intake. a 455 is an inch taller than a 260,307,330,350 and 403. so hood clearance becomes an issue depending on intake, carb and air cleaner used.

 

[Canon_Mutant]

As Oldsmobile Joe says, on my '87 I have to live with a 2" tall x 14" diameter, drop style, open element, chrome breather [pant pant, damn, a few more adjectives describing that breather I might have had to take a break] until I get my custom dual snorkel done that I am fabbing up. Of course, given my age and health, I have been changing my stupid electric antenna for 2 months now so take "fabbing my dual snorkel" with a grain of salt. Still, the big block swap is well worth it though and do NOT worry about having to muck with headers unless you are just going to the drag strip. Though my BB is not stock, I am running WZ manifolds too and cannot begin to get the power I am making to the ground. Now, I am in the process of ordering parts to hopefully change that but headers are a PITA and only worth while IMO when you are going to the strip.

Some say higher nickle F blocks with C heads were the best but, trust me, you will feel all the wonderful torque in a stock later and lower HP 455 or with whatever you can get your hands on if it is built right?

Especially combined with a 3.73 posi out back, I would prefer the 200-4R over the 400 but you will need an Art Carr, Bowtie [I chose the stage 3], or other similarly built model to stand up to all of this new wonderful torque. There are plenty of rebuild kits available to get you there cheaper IF AND ONLY IF you have a transmission shop you can trust. I learned this the hard way before I bit the bullet and just got a Bowtie model and even then they forgot to put the retainer clip on the front seal required on performance built higher pressure transmissions which blew out at 75mph and had the transmission empty and scarred before I could even get it shut down but, with a reputable company, they just sent me another transmission with apologies.

Good luck with your project.

 

[olds307 and 403]

Get a completely stock 73-76 455 from a big car, you will need trans as well, you TH200 will NOT last! Your A/C brackets will not fit, did the 78 have the R4 compressor? If so the brackets will need lengthened and welded. A better more direct bolt in is an Olds 350 or 403. The 68-76 350's were very durable motors. The 73-76 350 had less power but seemed to last even longer. Even the nylon coated cam gears were in OK shape. If you add dual exhaust you will gain 75 HP and torque over your 260 with a smogger 350 and your current TH200 transmission may hold up if you adjust the TV cable properly for a little while.

 

[tommytpk]

Thanks for all the great replies. Yes, I was thinking Olds 455, and I've seen a couple of local blocks, needing rebuild, for about $500, complete. I would use the short valve covers and a drop air cleaner, and would like to retain the A/C; not sure what compressor is in there. I don't have a bottomless budget, but I would have to shop out the engine and transmission rebuilds, I've been burned on used stuff in the past, and I'm not that interested in doing anything twice anymore!

Keeping a close eye out for any parts that could help (2004r, 8.5), probably will do the rear first, since I already have the shocks/springs/sway bar/hitch to tighten up the back end.