Hello everyone, I have a 1974 455 engine that i would like to add more power to but nothing crazy just a mild build. Bear with me I dont know much on building engines so i don’t really know where to start but I’ve read that the J heads have bad compression and best to be replaced by #5 #7 heads or maybe aftermarket? Installing long tube flowmaster headers? Should I keep or replace Qjet carb? Should i replace the intake manifold? …So if anyone can recommend by what should I start with and what I should avoid. Thanks

 

Your options are limited because of the low compression, and most likely truly cast crank.
But headers/dual exhaust, a Performer intake along with a well done tune will make a noticeable difference.
In addition most times a gear change helps too.
Best of luck in your project.

 

The #5 and #7 are SBO heads which have smaller ports then even your J heads. Problem is your 40cc dish pistons. Even if Edelbrock release the 68cc version of their head, with Felpro head gaskets, you will only be at 8.6 to 1. What do you want to do want to do with this 455?

 

What is the engine going in? What’s the rest of the combination? What are your performance goals? What’s the budget?

My advice: build the short block correctly, regardless of the budget. Don’t cheap out on the pistons and rods, make sure your machinist is familiar with Oldsmobile engines, or won’t argue with your build specifications. While any competent machinist can machine the parts, performance Oldsmobile engines like different tolerances than the typical Chevy/ford engines. What works for those engines isnt ideal for a Oldsmobile.

If you HAVE to cut corners, cheap out on the heads. It’s far easier to install better heads later with the engine still in the car, but that only an option if the bottom end stays together long enough to save the money for upgrades.

 

Its going in a numbers matching ‘74 442 undergoing a frame off restoration. I’m trying to go with a stock look engine bay but would like to bump the numbers up a bit, would like to add some hooker comp headers, and maybe add edelbrock aluminum heads that needs an aftermarket manifold fi fit correctly. I’m not in a hurry to do anything since the bodywork will take some time so I want to study the best setup for an engine and how much i can get from a power to value ratio.

 

Engine budget?

 

The bottom end has to be able to support any serious modification.
This is a good read and will help you understand the specific challenges of building an Oldsmobile big block.

 

what Oldsmobile heads should I look for? And are what changes are needed to install, the edelbrock head which need and edelbrock intake manifold to fit. Im trying to reduce smog restrictions and get it close to older model 455s

 

Alll the other stock BB heads flow similar and have around a 82cc chamber size except the rare D heads. The Edelbrock heads and Performer manifold should bolt on. The new heads even have clearance for a mechanical fuel pump like the Robmc fuel pump. The Procomp heads will also work as well. Figure out what compression, cam, converter and rear gear you comfortable with before you decide on a combo. Also what octane do you plan on running?

 

So other BB heads wont make quite a difference, regarding fuel its either 95 or 98 only options available where i live

 

Where do you live that has such high octane fuel 95 and 98.
In Canada we have 89 to 94 Max
I think it's similar in most US States.

 

Europe and other regions of the world use a pure RON rating method to calculate an octane number. For the same fuel the US methodology would yield lower numbers.

 

Correct, by about 6 numbers.

 

Again, budget and expectations for that budget?

 

Yeah 91 non ethanol is our Premium in most of Saskatchewan. We used have it somewhat local, not anymore. So he has 89 to 92 in our ratings, sounds like he can build a healthy motor.