Dweed777

I am having the engine rebuilt. It will be a summer street car. Will hardly ever race the car. Which would be better Headers or Exhaust manifold? What are the pros/cons of each?

JMD

Headers will all but universally make your car run better, but manifolds worked fine for every classic mustang ever built from the factory (that I am aware of anyway). Headers will make a difference on power output, but the difference will be much less on a stock engine vs. a performance engine.

As an example, headers on an otherwise stock engine might bring 10 or maybe 15 HP, the right headers on a high performance might bring as much as 4 times that or more, because this engine NEEDS headers in order for everything else to work right.

"Good" headers paired with good gaskets are trouble free for the most part, no real down side, cheap headers and/or cheap gaskets can be a pain in the ***.

I am a fan of "mid length" headers for these cars, especially if the car is dropped. I had briefly worked with a pair of long tubes for the 66, for me they just took up way too much space in the classic Mustang so we went with mid length even before we started the car.

If you want to stay close to stock and/or you want to save a few bucks, manifolds will be fine.

Headers go on most of my V-8s, but not all of them.

Starfury

Headers will definitely flow better, but exhaust manifolds will be less maintenance (won't blow gaskets), cheaper, and produce less heat in the engine compartment.

IMO, it depends on what kind of motor you're building. If it's a 350hp fire breathing 289, give it headers. If it's a mild build, you might be better off with a set of hi-po manifolds.

Dweed777

I am puting a rebuilt 302.

So if I am puting in a high end rebuilt engine use headers? If it is a Stock 302 just use manifold?

Also JMD, I am repainting the engine compartment. Do I use Edge primer then Semi gloss finish?

JMD

IMO, there is no real down side to good headers, if headers wont break your budget I will recommend what we used, Headman ceramic coated mid-length. IMO these are a good value, providing good performance at a price that wont bust the bank. I will say that Hookers and some other brands might be better, but it seems like better comes at a really high price.

Frankly, for a stock rebuild, manifolds are fine, but is seems like everyone starts with the upgrades sooner or later, you might just junp ahead of the curve a little and go with some headers from the get go.

As far as the paint goes, if you are locked into spray bombs, clean, sand, and follow up with a thin coat of primer, lightly sand, retouch your sand throughs with primer, lightly sand and spray with semi-gloss.

Give yourself at least a day before working in the engine compartment for the paint to dry so you won't mark it up.

With spray bombs it is really, really, important to keep your coats (and OVERALL COVERAGE) as thin as practical (really as thin as possible) while allowing a final coat thick enough to flow out, (look good and shiny). Keep your primer THIN.

Use a self etching primer if you go to bare metal, SEM sells a nice self etch primer, it should be available at auto paint stores. http://sem.ws/Catalog.asp?prod=139

If you can/will spray with a paint gun this changes everything.

You can use a self etching primer, it may marginally help with bare metal, here is what I would do.

Sand the crap out of the metal, coat with self etch on bare metal, followed by a coat od 2K primer, sand with 180, another coat of 2K, followed by sand with 320, then a semi gloss paint.

You can get by with more primer for a better surface with catalyzed/activated materials, faster sanding and top coating too.

With catalyzed materials this can be done in one day for stuff under the hood.

synthartist69

I hated the headers that were on my 65. They leaked all the time, they were in the way, and it got really hot under the hood. They were on a slightly modified 289.

I went with thee HIPO manifolds. It feels like I lost about 5% to 10% of my upper end power but gained some torque. The HIPO manifolds look great, never leak, and are easy to install and work around. Good luck!

nba1341

I like my headmen headers but had to get some little spark plug wire sleeves becuase they burned cylinder 4 and 8 got there wires burned through from them. Only had to replace the gaskets once in the last 5 years.

Dweed777

I am having a friend use a spray gun. It is bare metal. I have already sanded it also. I was going to use 2 coats of etching primer then 2 coats of either semi gloss or the other (forget the name of the paint).

Will that turn out looking good?

JMD

If the metal is good and straight it will look good, you only want to use a single thin coat of the etch primer, not much at all, it is actually better if if it is translucent, it does not build well.



Then follow with a 2K surfacer and sand smooth with 320 for a better finish, although you can skip this step if you don't have big sand scratches, but it usually always improves the finished product.

rst08tierney

+1 on the headmens

I have a 289 with power steering and went with MSD wires. Its tight but the bottoms of the sockets can be bent at any angle to help

The headmens do take up a bunch of room take a look