Right now I have a 390 with exhaust manifolds. I have to take them off to replace an exhaust leak at the block, and was considering putting headers on the block while I am at it. What performance changes will I see with headers instead of manifolds, and is it worth it? Also I have heard it is hard to keep headers from leaking, is this true?

This might be an elementary question, but I want to make the right decision. Thanks!

 

yes its worth it. the changes you were wandering about include better fuel mileage and an increase in hp. but yea its worth it. and they can be problematic to keep from leaking but just use new good bolts to start off with and you should be fine

 

Headers are lighter than those cast manifolds, a little increase in HP, cause it opens up your exhaust sys. Keep in mind you might have to do quite a bit of exhaust pipe rerouting, depending if they are inside the frame exit, or fenderwell exit headers.

I have a inside the frame set on a 78 F150 4x4 351M auto, was a PITA to get the exhaust to route without it hanging lower than my trans cross member.
And on occasion my front DS will contact them.

Used some fenderwell exit ones on my 79 F250 4x4 400 4 spd, and love the easy hook up of the exhaust. Had to trim my inner metal fenderwell a bit, and remember either set will produce ALOT more heat under the hood.

As far a leak problem, I got some thick header gackets from Jeffs Bronco Graveyard, a bit pricy, but they AWESOME. I have had no problems with leaks at all.

I took the oppertunity to upgrade my attachment hardware to grade 8, and IMO use those, not sure what they are called (2 pieced little teethed lock washers) from Fastenal.

Now for the BIG issue, you must LUBE LUBE LUBE those old exhaust bolts. Its a major pain when you break one. I have broke 3 on the pass side, 2 on dvs side on the a 77, and 2 pass 1 dvs on the 79.

Repaired without taking off head, LOTS of patiance and drilling, easyout, tap, helicoli ect..... It can be done and there are benifits, just LUBE those bolts like crazy.

Also be ready to remove and reroute your dip stick depending on what engine and brake lines from master cyl, proportional valve. On my 79 I removed those items for installation and rerouted them back thru the header tube gaps.

One more thing when you are ready to install the gaskets make sure you have NO lube grease at on your hands it will cause you to burn up those new gaskets, I found that out the hard way.

Sorry so long just wanted to help you out, best of luck.

 

I just installed long tube headers on my 73F100. The hardest part of the job was getting the 3 broken manifold bolts drilled out and retapped. I would recommend that before you even attempt to crack the top bolts, you heat up the manifold around the bolt with a torch. The bottom ones came out no problem and without applying any heat.

 

Thanks a lot for this advice. Would you say, after all is said and done, that the headers are worth it over the manifolds?

 

I tryed it both ways, hot and cold. Seemed to me to get better results cold, plus you do not have to worry about burning yourself on a hot exhaust manifold.

The mount bolts only go thru the exhaust manifold, they thread into the head itself. If you lube the heck outa them and then use the "heat m up tecnhique" you risk catching something on fire. So use caution if you go that route.

Like I said if you can LUBE (PB-Blaster or Sea Foam Deep Creep) the hell outa them for a few days, hard to do it its your daily driver, I think you will have better results.

To lube it, I use a straw tip, like comes with WD-40 and spray around the area between the head and exhaust manifold. Lube Lube Lube worked for me, oughta work for you.

Bottom line, answer to your question, yes header's are worth it. But depending on your application they might be hard to find. I use and will use again Hedeman IMO, good enough for what I need.

I run headers to 5" open stacks and "hell yea it's loud" but its a trail rig only, I have some cheap bolt on inline glass packs if needed, but I like it open and loud.

Am planning on putting a set of fenderwell exit one's on the blue truck, 460 4spd when I get a little time.

 

I went with the cheap Dynomax headers and Thrush muffler package from Summit. I did have to tweak them a bit to get around my manual steering box. All things said and done, it is worth the 1-2 days of screwing around. The truck sounds great and it breaths the way it was meant to be.

 

Congrats on the upgrade, how about a pic.

 

It's not much to look at, but here you go.

 

I've had success using Percy's ''Dead Soft'' Header Gaskets, kinda pricey at 40 bucks a pair (for FE's anyway) but never had one leak or blowout on me.

 

That eng compartment is cleaner than mine, looks good. Are the fenderwell exit?

 

Nope...they come out just above the crossmember.

 

Will the headers off of a 460 fit onto a 390? They are both the same block, right?

 

No. They are NOT the same block. 390 is from the FE family, 460 is from the 385 series.

 

I know, an old post I just ordered a set of these from Jeg's. This 76 F250 390 4x4 has never had headers. I sure hope it's worth it. For years I've read FE's had a breathing problem. I just hope, for the money and labor, that it has a seat of the pants difference in power, and mayby a little fuel mileage to boot.

PS: converting from the stock intake\exhaust manifolds to eldelbrock intake and carb, hedman headers, and hopefully a cam combo that Josh recommends..