crusadersflank7

Hey everybody first off i'd like to say hi to everyone im new to the forum. My uncle gave me a 1975 olds 88 royale last year as a graduation present, the car was handed down to him from my grandfather who was the second owner. Anyways to my first of probably many questions to come: the exhaust system is all rusted out so i decided i'm going to re do the whole thing from the headers down but i can't find any for the car. Everywhere i go they say they wont fit the convertible and i wouldn't be surprised if this question has been answered or not yet but would most of these headers actually be compatible with my car? thanks for any help!

rocketraider

The 71-75 convertible and coupe/sedan are no different underneath. That's their way of saying they don't know if it fits, and they don't want to deal with a return on parts that don't fit.

I'd be more concerned about finding a set of headers that fit at all.

An option is to get a set of W and Z factory exhaust manifolds. They were used on 71-74 full-size Olds with factory dual exhaust and thanks to being used on 442, they are being reproduced if you can't find a good used set.

To do this job right you also need a 71-74 transmission crossmember that has the double humps for exhaust clearance. A 75-76 crossmember is set up for catalytic converter single exhaust and you'll have to flatten the left pipe where it crosses under it.

Welcome BTW.

76 Regency

Hey and welcome to the forum! Rule # 1 about joining is that you have to post pictures!

Which engine does your Royale have? the 350 or 455? I'm not sure about headers but there are dual exhaust manifolds you can upgrade to which will really improve the performance but they are specific per engine.

Where are you located?

76 Regency

Good call on the crossmember Raider....almost forgot!

Am I right that the 350 uses different manifolds than the 455? I've only had 455's but I'm pretty sure they're different, right?

crusadersflank7

it's a 350 and im located in chicago, i'll get some picks up as soon as it gets a little warmer out and i can uncover my car

rocketraider

There may be a little port mismatch between a 350 and 455 exhaust manifold but my parts book shows 350s and 455s using the same part numbers thruout early 70s depending on year and chassis application.

To use your existing 350 manifolds with dual exhaust you'll have to get some type of blank-off plate for the crossover port on the RH manifold. The 75-later exit angle is different than earlier years to accommodate the catalytic converter (which you may run into some chin music over removing it depending on where you are- some places won't issue any type of inspection sticker if it's not there). The LH should be pretty much the same for them all. Make friends with a good pipe bender and he should be able to do you a nice clean job.

I'm told that headers for 73-77 Cutlass will work on the 71-76 big car, but I can't say for sure. Any more I think headers are more of a PITA than they're worth.

crusadersflank7

looks like i have it all going in my favor right now because from research that i've done the headers for the cutlass would work, because my car is older than 20 years it doesn't have to go through emissions testing or anything like it in illlinois, and my uncle who is going to be assisting me on this car is actually a good pipe bender, thanks for all the help you guys are very prompt, again like i said i'll begin posting pics as soon as possible