manifold interchangability

Will later model (1986) 258 intake and exhaust manifolds fit an intermediate 258 (1974)? The most I can come up with is that the gaskets have different model numbers. That doesn't necessarily mean it wont work.

 

Yes they will work. I did a similar setup on my old 258. Beware there are some differences in the manifolds. Later ones have egr so you need to use both or plug some holes. Later exhaust manifolds have an O2 sensor port. Later intakes have a cooling passage in them, although I think you can just run with it unhooked. I recall there are also differences in throttle linkage. Also some bolt hole locations for accessories on the front of the intake are different.

However I got mine to work so its possible.

Kevo

 

Same here. I put 1985 CJ-5 manifolds on my '77 truck. Had to notch the power steering bracket, but they fit otherwise. Throttle linkage is different; works fine if you get the later bracket and rod with the manifold and use the later throttle cable. Uses an electric carb preheater instead of the exhaust flap, so unless you rig a relay, you have a longer warmup time.



Easy to route the heater water through the manifold. I'd only bypass it if you live where it's warm year-round.

 

Thanks for the replies. I have access to some newer manifolds that I would like to use. I seem to recall somebody mentioning that they are an improvement over the older designs.

The main reason I want to use them is to be able to ditch the adapter on my Weber. I've got a single barrel intake manifold, currently.

I already have an EGR valve so that isn't a problem. I don't have power steering, so that shouldn't be a problem. I also want the O2 sensor. I'll use that for carb tuning.

Is the carb preheater always on or is there a temp switch that cuts it off once the engine warms up?

 

On my truck, it's never on. I have the MC 2100 you see in the picture, and the lack of it doesn't seem to matter. On the original vehicle, I'd expect it's only on until the engine warms up. Warming helps to vaporize the fuel, improving cold weather starts. Once the coolant warms up (and heats the manifold), it would not be needed.

I don't know that the aluminum intake manifold is an improvement over the cast iron 2V manifold (probably is - I've read that it is), but the exhaust manifold is much smoother - no more right angle bends.

The manifold also has two threaded holes for your CTO switches, if you should choose to move them there.