alluminum exhaust manifolds?

[ethyl]

I just repowered my 67 18 classic and am wondering if I should replace the iron manifolds with alluminum ones. Any feedback will be apreciated, thanks..

[Trueser]

GLM Alum are a good deal.

[gold-n-rod]

Sorry to be blunt, but based on this and your other post, you need to learn to work the search function.

You will find all kinds of answers to your questions.

Good luck...... and welcome.:wink:

[BigGrizzly]

I have stated my case several times. I deal with only what I deem the best bang for the buck. That is not always the cheapest. There is more involved than just more ponies and less weight. For instance, I have seen the same HP on the Dyno with more fuel being used on one type of exhaust Vs. another. There is also fit and finish, warranty, and the people you deal with. I won't bad mouth any one at this time. Stainless makes a lot of what every one else sells. Most of these companies are just outlets for others.
If you want to play the

[boatnut]

I have stated my case several times. I deal with only what I deem the best bang for the buck. That is not always the cheapest. There is more involved than just more ponies and less weight. For instance, I have seen the same HP on the Dyno with more fuel being used on one type of exhaust Vs. another. There is also fit and finish, warranty, and the people you deal with. I won't bad mouth any one at this time. Stainless makes a lot of what every one else sells. Most of these companies are just outlets for others.
If you want to play the
Hey Griz, I have read your posts many times and have the most respect for your advice -- we will soon be going through a '69 Classic and will be staying with a small block Ford, we now have the original H&M aluminum manifolds but are concerned that they are 38 years old (I heliarc'd a couple of places where the exhaust was eroding the aluminum about 20 years ago) and are thinking of updating to ??? What do you suggest, I cannot tell from your post? I agree on cheapest not always being the best choice. Our motor will be more optimized for reliability not max HP. Ed

[BigGrizzly]

First as much as I like original H&M, they just don't work and cause real problems as do all logs on high horse power engines. I don't just mean horse power loss but valve problems. The fact that you have a Ford the exhaust is limited. I have a 351 Cleveland which is a real issue, but not impossible. In your case I would find a center rise manifolds from a PCM -master craft etc ot thoes nice Astrailian SS ones which work real well and look good too. I used to have a picture of them but can't find it. I believe Moody- Blue was using them as well as a couple others on the board that I have sent props to. I have not done Dyno tests on these, but they are similar on the inside of the SS marine. They use them in Australian sprint boats.

[boatnut]

Thanks, I'll look for the Aussie manifolds when we get started on this. The restoration of the 18 keeps slipping on the schedule due to other priorities. The boat looks beautiful so just engine work would simplify the effort but the gas tank risk has us planning to remove the deck also which makes a big project out of it. The only engine trouble I've had has been burnt valves or cracked heads in valve seat area three times and always on the cylinders near the rear of the boat ---I thought it was due to cooling water hot spots but it may have been associated with the log manifolds?? The 302 (other than heads/valves) and the Volvo 250 (other than a u-joint and a lower seal) have been bullet proof --for 38 years. I've owned the boat since 1971. Do the Aussie manifolds require relocating the thru-hull exhaust outlets? I assume they are low enough to fit under the hatch.

[Sweet little 16]

on a 351 w they( hiteks) do not fit under the hatch i believe the deck height is higher on a 351w than a 302 there are also issues with clearance on the valve covers and spark plug access

[f_inscreenname]

I assume they are low enough to fit under the hatch.
Those Aussies are high. On a 351W (which is even bigger then a 302) you may have some issues.
Here is set on my old Mopar 360.
http://www.supernova19.com/3abd3aa0.jpg

http://www.supernova19.com/386e8ee0.jpg

[BigGrizzly]

As for the valve problem and heads, you are correct. They cause hot spots in the cylinders. I will bet every engine problem was the same valve or the one on the other side. Just for information the cars had the same issues. This is the real reason that Ford changed the exhaust on the 5.0 engines. Unfortunately it took me two short blocks to find this out.