I am replacing the 403 with a 455 in my 1978 Delta 88 Holiday Coupe replacing the 350 Trans with a 400 ... looking for advice as far as what what motor mounts / trans mount to use ... also I will be replacing the factory floor shifter with an aftermarket (car has a console - factory shifter is junk ) any suggestions on a shifter that will replace the factory unit ? And last but not least what transmission crossmember should I use ?

THX

 

Use the motor mounts already in the car - which are the 2328 mounts. Use W/Z manifolds.
A few 403 Ninety Eights did come from the factory with a TH400. The problem is that unlike the earlier cars, you can't just slide the crossmember backwards. The TH400/200-4R crossmember is physically different from the TH350 crossmember. The good news is that you can get 200-4R crossmembers for the 1977-1990 B-body cars pretty easily.

 

Thank you for your input

 

my brother had a 78 98 ls with a 403 and a th400 but wasn't it actually called a th375?

 

Likely, but the TH400-based TH375 still used the same case as every other TH400, so the crossmember would still be correct.

 

Just a little note here that the only factory double hump crossmember for the B or C body would be the SS Impala unit, but it would probably need modification. Pretty sure aftermarket ones exist too.

 

Unfortunately, the SS crossmember is for a 700R4. All the 77-96 crossmembers vary by transmission. You can't just slide it back.

 

I know if you change the motor you must change the springs or the car will sit flat in the front. You need to take into account the weight difference of what you're taking out and what you're putting in. The 403 is more than powerful enough, you can barely stop the car as it is much less handle more power. You will need to stiffen up your suspension but expect to find yourself wrapped around a pole or in a ditch or possibly hitting another car. These cars weren't designed to handle that much engine in such a light car. The *** end is way to light to handle the power of an unleashed 455 gas guzzler. Food for thought!

 

The 455 is only about 50-75 lb heavier than the small block. Use an aluminum intake and the difference is even less. I have personally weighed a bare windowed 403 block and a bare 455 block. The 403 was 170 lbs, the 455 was exactly 200 lbs. You don't need to change the springs.

 

Thanks for your concerns / input , I was calculating the 455 being 100 lbs heavier then the 403 , the 400 trans I'm installing 15 lbs heavier then the 350 trans that came with the car ....My build includes replacing the iron 4A heads with Speedmaster aluminum heads my guess is they're 60 lbs lighter , replacing the iron factory intake with Edelbrock RPM , I would guess 25 lbs savings , removing the factory catalytic convertor (very heavy) but installing dual exhaust / headers probably no weight savings there .... the car may be slightly heavier maybe 25lbs
As far as the brakes the car has power front disc brakes / 11" rear drums I plan replacing the pads / rotors / rear shoes with brakes made of modern materials . Even with the stock brakes the car stopped on a Dime - gave back change so I do not anticipate any issues there .
I special ordered the car in 1978 when I was a mechanic at an Olds dealer with - 403 / heavy duty suspension / posi / heavy duty cooling system / Holiday Coupe / buckets / floor shifter .....
The car was a blast to drive - handled surprisingly well for what it is .... spun a bearing 30yrs ago and the car's been sitting has 40K miles ... the engine is at the machine shop , the trans has been rebuilt .. am hoping the get it together before the snow flies - wish me luck.

 

I plan on doing a 455 swap in my 78 Delta 88...I would love to see pictures of your car and your build along the way!

 

The build is on hold till warmer weather kicks in ... I will be posting pics. / parts list should be back on track by April....

 

It amazes me how somebody can come on here and in their second post tell us things we didn't know. I guess in the thousands of posts or tens of thousands of posts we don't seem to know very much.

 

I am looking forward to watching someone else do this.

Re: 11" rear drums - is this the factory setup ?

What kind of rear end is in the car? I have a Buick 8.5" rear end with 11" brakes (that I pulled from...a Lesabre, I think)in my '77 Pace Car - but I had to drill the axles for a 4.75" bolt circle.

What kind of wheels do you have on the car?

Enquiring minds -

BrianA in Houston

 

The 1977-1985 Deltas could have come with one of two brake systems. The base system was 10.75" front rotors, 9.5x2.0 rear drum brakes, and the 5x4.75" wheel bolt pattern. Cars with HD suspension and brakes (taxi, police, and some 403 cars) came with the 12" front rotors, 11.0x2.0 rear drum brakes, and the 5x5" wheel bolt pattern.

 

/Threadwhore

I would give my...well, a lot...to find a 77-85 Olds B- or C-Body "police" speedometer ("Certified", +85 MPH). Do you think that thing exists in this universe?

/Threadwhore OFF

 

I special ordered my Delta in '78 with 403" V-8 / Heavy duty cooling system / Heavy duty suspension / posi. rear / yes the the 11" drum brakes came from the factory possibly standard with the 403 don't remember ..... not sure what the bolt circle on the wheels are but do know they are different than the pattern that came with Deltas that had the V-6 , 260 , 350 engines ..... I currently have the stock steel wheels but will be replacing them down the road with aftermarket wheels so I will need to get that info.

 

I plan on going a little wild on my build Southside Machine QA1 and a complete Wilwood brake setup the car will be of stock appearance for the most part inside and out but will be a wolf in sheeps clothing is what some may say...just want to show you my project she's rust free besides a few freckles and some patina on the body....did you ever get any pictures of your car for us yet?

 

Here's my pathetic story sewer pipe from the house to the street had " a belly " in it which means there is a dip in the piping going to the street and the original pipes where installed 2 feet lower then normal sewer back-up into the house ....it's cheaper to run new drain pipe from the house to the street still cost $11K + ouch , obviously has put a hold on the Olds build for a few months !!!

Note to anyone reading this - there is Insurance ( which I did not have ) available that covers this , offered by the local reginal water department I hear costs $70 pr year , you might want to check into it and save yourselves a painful experience .

I like the wheels on your Delta - appear to be Ralley style - give your car a nice stance ... What Size wheel / tire did you go with ?