The passenger-side exhaust manifold on my 352 has a monsterous crack (2"+) running down the merge point, the leak is quite loud and very annoying even for short periods. Any recommendations on headers, hi-temp coated preferred? I'm on a budget, does Dynomax make something to fit my '66 F250?

 

If you really want headers, someone here might be able to help. If you want to stop the noise, cheaply, take it to a machine shop and for about 20 bucks, they can repair it for you.

 

Would headers be more trouble then they are worth?

 

Unless you are running your truck engine over 4000 rpms (racing) there is no reason to install headers. IMHO
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In the cool still quiet of night, you can hear chevies rusting away.

 

Just out of curiosity, why do you say if you are going to run over 4000 RPM?

 

Charles, There is a long standing discussion about the sorry flow of the log manifolds on the FE engine, and mostly on the passenger side. The HP guys want headers and 4 barrel carbs on everything. After falling for that side of the debate, I rebuilt a 352 and installed a Performer alu. intake & cam, a 1406 4 barrel carb, and Hooker Hi-comp headers. I have a 2.75 rear gear. I wanted some mpg and power. I had an old worn out 390 in another truck that would run circles around this truck. It was a plain jane 2 barrel log manifolds, 3.00 rear, other than dual exhaust nothing special.

I never run my truck over 4000 rpms, even standing on it the most I have seen on the tach is 4200 when it shifted into hi gear, but mostly it operates in the 2200-2600 rpm range. 3600 rpms and all of the numbers on the speedo are used.

So I contend you build your engine on how it will be used. If you are racing your truck and will be turning 5500-6500 rpms you need the best air flow that you can get, but one running 2200-3000 rpms just doesn't benefit from the extra $700.00 or so that the extras cost.

I have a new 390 still on the engine stand with ported & polished heads 2 barrel carb. and the log manifolds. A strong base engine is better than one with hundreds of dollars of bolt ons that burn up starters and just don't add that much. all IMHO of course
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In the cool still quiet of night, you can hear chevies rusting away.

 

OK John I am going to bust your bubble. The reason that your 390 beat the 352 is becuase of several reason's. First, gear ratio that is behind the 390. The 2.75 to 1 with your 352 is way too tall for the bennifits of the headers, manifold, and carb. If the gearing was changed to the say 3.50 you would see a differance. But then again you are comparing apples to oranges when you have 38 cid between the 2 engines. The added stroke of the 390 make it a torque monster while the 352 can handle a higher rpm range then the 390 (shorter stroke). The main differance of the headers is to promote better exhaust flow over stock manifolds. So there take that. :P

 

Just sand the cracked area clean and fix it with JB Weld. Follow their directions and the noise will be gone.
PS. tuned long tube headers will increase torque!!

 

Thanks Mark, you boys got a lot more to do to bust my bubble. I certianly know the 390 is a much better engine. When I started with the 352 it had a 3.25 behind it. I couldn't see where the carb and headers did much of anything for the fresh engine. I wanted to build a highway cruser that worked best at 65 mph. not a drag truck. My truck runs 95% of the time empty.

I just splained why most trucks used that way don't need headers and 4 barrels. It will run about as good and can get better mpg with the 2 barrel.
Bubble still strong.
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In the cool still quiet of night, you can hear chevies rusting away.

 

Take some wrenches, a propane torch, a can of PB Blaster and go to the junk yard, remove the right manifold from any Ford pickup with a FE motor. Closley inspect the manifold for corrosion, and cracks on the ears (where the bolts go through). After finding a good manifold have it resurfaced, install new studs. Start your truck and get the engine to operating temprature. Carefully loosen the top manifold bolts. Use lots of PB Blaster, and heat the head with the torch if the bolts are really rusted. Remove the old gasket, clean the head with acetone and reinstall the re-conditioned manifold. Torque the bolts to 10 FP. Tighten from the center bolts out.
William in Atlanta

 

Would anyone believe I gave 12$ for a set of headers in reasonably good shape for my 352 at a local swap meet?

 

 

OK. After reading everyones suggestions, first let me say that getting all the bolts out from an old, tired, rusted but running good 352 is tricky-and not easy.

The best thing to do is to spend a couple of days applying some penetrating oil-and then start by going one bolt at a time and first tighten it a hair and then back it off a fraction and then back and forth and make sure you keep applying more oil.

But-the suggestion to use JB Weld seems easy as a fast / quick fix. Will it work?

Hey-whats a broken / cracked exhaust manifold sound like? Knocking noise too?

I have 2 cracks. Sounds like valve knock and if you jump on it it sounds like a bubble machine.......but at idle it goes tick, tick tick!

 

I had one on a '68 Chevelle one time...think "Pro Stock" and you'll have an idea.

 

headers are cheap, basic sets run $150 new. and the single biggest power killer on an FE is the exhaust logs. its not that they are particulary restrictive, its that they don't allow clean pulse flow and scavanging. replacing them with a cheap set of headers will improve your gas milage and power at normal driving rpms.

if you have a technical mind for this stuff, this site is a good read. http://www.nsxprime.com/FAQ/Miscella...austtheory.htm