Headers to 2.5" Ramhorns

[cleszkie]

Well, I finally got fed up with dealing with my headers. I could never get them to stay leak free for very long at the heads, and the crappy ball and socket "gasketless" collector connnections never sealed due to the ball portion continually crushing down when you tried to tighten it (Hedman headers). It was always a PITA to change spark plugs, and it was hard to route the plug wires without one or more of them getting cooked. The last straw was when I resorted to wrapping the top 3 inches of the the two inner header tubes on each side with a header wrap to protect my plug wires. Well, the cheapo headers couldn't handle this. The wrap prevented the headers from dissipating the heat, and the tube on my #6 cylinder blew out a quarter size hole under the wrap while I was accelerating on the freeway (after being wrapped for about 2 years). When I removed the wrap from the other side, the two inner tubes were all heat deformed and as brittle as glass! Now I know why wrapping headers voids most warrantees. Sure, most of these problems could be fixed with a real set of high quality headers, thick aluminum gaskets, and anti-loosening fasterners, but I have had my fill, and don't have the money for ceramic coated Doug Thorleys.

So to make an already long story a little bit longer, I ordered up a set of 2.5" ramhorns (Dorman Corvette knock-offs for $78 each), cut of the accessory flanges with my angle grinder, bolted them up, spliced in the required exhaust tubing to mate up with the back end of my exhaust system, easily put in the plugs, rerouted the plug wires to the dizzy and fired it up. No leaks, quieter exhaust tone from under the hood, and the peace of mind that they wont blow out - priceless. Sure, they may not flow as well as the headers, but from what I've read, they should flow well enough for the HP I'm making. I seriously recommend this "upgrade" to anyone running a set of leaking cheapo headers. I can supply the GM part numbers for the OEM manifolds (more expensive when new), and the Dorman part numbers if anyone is interested.

I got this idea from this board. Yet another reason why I love this board so much!

[Mike C]

Great mod! I did the same thing on mine. My butt-o-meter suggested more low end torque and at least same HP. I have a little cam, though. Crane 266, about same as a Comp 260. I also went to 2 1/2" exhaust at the same time up from 2 1/4".

I've got a 4x4 '86 dually with a big block that someone put 2 wheel drive headers on and had to pull the front driveshaft. Me thinks manifolds are going on there as well.

[jaros44sr]

Nice upgrade, did you use brass nuts on your flange studs? Are you going with or without gaskets between the head and exhaust manifold?

[cleszkie]

Jaros44sr - The Dorman ramhorns come with studs, washers, lock washers, pinch nuts, and manifold donut gaskets. I used one washer, one lock washer, and a pinch nut on each of the studs with a dab of anti-seize. What is the benefit of using brass nuts? Do they resist corrosion better?

The instructions that came with the manifolds suggested that they be installed without gaskets between the manifold and head for optimum sealing. However, I was not certain that my heads were perfectly flat to mate to the manifolds, so I used the Felpro semi-metal gaskets for a stock application (part #MS 9275 B).

BTW, the Dorman part numbers are 674-504 and 674-503 for the right and left manifolds.

[67_C-30]

I quit running headers on anything but a racecar long ago because of this. There are some headers out there that will seal up, but they are expensive and still cumbersome to work around. I think you'll love your ramhorns!

[project 67 sub]

thats what i plan on putting on my burb..... hate my d@#N cheap a$$ leaky mr gasket brand headers

[jaros44sr]

Originally Posted by cleszkie

Jaros44sr - The Dorman ramhorns come with studs, washers, lock washers, pinch nuts, and manifold donut gaskets. I used one washer, one lock washer, and a pinch nut on each of the studs with a dab of anti-seize. What is the benefit of using brass nuts? Do they resist corrosion better?

The instructions that came with the manifolds suggested that they be installed without gaskets between the manifold and head for optimum sealing. However, I was not certain that my heads were perfectly flat to mate to the manifolds, so I used the Felpro semi-metal gaskets for a stock application (part #MS 9275 B).

BTW, the Dorman part numbers are 674-504 and 674-503 for the right and left manifolds.

The brass won't oxidize, so it will allow you to unscrew the nut by hand once you break it loose, anti-sieze is a must, higher temp one preferred. If you have long studs this can be an advantage, hard to get a wrench in there. Racket wrench may work. Gaskets, no gaskets is an ongoing debate, I just use a copper shield spray on...if there is no gasket there it can't blow out, but as you state, surfaces have to be flat

JMO but lock washers are useless, since when they get hot, they lose their tension, locking tabs are better cause they maintain proper torque, and I'm sure that this is why you will blow a gasket in the first place. Hot and cold cycles back out the bolt

Simple check is to put a strait edge on the heads, look for light, use a flashlite

[Yukon Jack]

Did your ramhorns have the heat tubes that kind of run diagonal near the bottom of the collector?

I've heard some people drill them out and fill the hole. Just curious to see what you did. I've got a pair ready to be installed but I painted them before seeing that maybe I should have removed that heat tube.

[Critter]

I have a whole list of guys that I want to read this post. I have been preaching this same idea to local "gear heads" for years with few people actually listening to me. I got fed up with cheap headers about ten years ago and started ripping them off of all the old junk I had. Like everyone else has said, you can spend a grand and get something that won't leak, but on a street/trail truck it just isn't worth it in my opinion. Now, when I finally build my 12 second street legal swb truck...that might be a different story.

[jaros44sr]

Originally Posted by Yukon Jack

Did your ramhorns have the heat tubes that kind of run diagonal near the bottom of the collector?

I've heard some people drill them out and fill the hole. Just curious to see what you did. I've got a pair ready to be installed but I painted them before seeing that maybe I should have removed that heat tube.

Drilled and knocked out tube...do it now, because A it will rust out, and 2, you'll have to pull the manifold to tap the bottom hole. Maybe you will have clearance to tap it with the manifold mounted, but it could be difficult

Now that I think about, once I knocked out the tube, the hole was just the rite size to be tapped for a 1/8" NPT

[fun in dirt]

Y'all have convienced me to go this route too!

So are the vettes the only thing that had manifolds like this or is there others I can seek out in the junkyard too?

[see ten]

I've always ran manifolds instead of headers myself! The ramhorns are supposed to have excellent flow as well.

On a side note, I thought the Hedmans were supposed to be good headers. Were yours the thinner uncoated ones or the thicker gauge headers?

[cleszkie]

Yukon Jack - Only the passenger side manifold came with the heat tube. I left it in, but after reading what Jaros44sr said about it rusting out eventually, I think I will be drilling it out and filling it.

See Ten - I think I must have had the thinner, uncoated headers. They came in a black primer. Under $200 for the set from Summit. It was the heat wrap that destroyed them, but the ball and socket collector connection should never be used on a thin gauge header because it just crushes down like a crush sleeve everytime you tighten it, or when the motor moves on its mounts.

[LUV2XCLR8]

WOW, great mod

(*I had Headman Elites w/ ball flanges & mine
never leaked, but I may have had a good pair)

[70rs/ss]

You can order two of the rights or lefts, as the vette ramhorns are a straight dump and will work on either side, so if you remember which one has the tube in it, buy two of the other side and you will not have any issues with tapping anything??

[Blazer1970]

Originally Posted by 70rs/ss

You can order two of the rights or lefts, as the vette ramhorns are a straight dump and will work on either side, so if you remember which one has the tube in it, buy two of the other side and you will not have any issues with tapping anything??

yup

[Mike C]

Speedway Motors sells a high flow "rams horn" style manifold. $300 I think for the cast iron, and $400 for the cast stainless. That's a pair.

[Skirkpat]

Good move, you wont regret that.

[72freak]

I have had many many automobiles and I am normally a slow learner...BUT......after 1 pair of headers 20 years ago I have never bought another set and I dont plan on it either. Good move!!!

[Critter]

Originally Posted by 70rs/ss

You can order two of the rights or lefts, as the vette ramhorns are a straight dump and will work on either side, so if you remember which one has the tube in it, buy two of the other side and you will not have any issues with tapping anything??

So which side DOESN'T have the tube??? So I will know which to order next time I need some.

[jaros44sr]

the side that has the flange cast into it has the tube, the cast flange is for mounting the generater/ alternater...so get the other side

[vtblazer]

Welcome to the 2.5 club.

Watch those center plug boots, they like to burn through.

[jaros44sr]

Originally Posted by lks dcvn

I got lucky and got a set from JC Whitney for [drumroll please] - $75 shipped.

If you go to the JC Whitney website and then do a search for item #674503 - it will come back with the corvette 2.5" center dump ram horn - I tried to order 4, but they shipped 2 and then told me they were discontinued after that.

I got them and they are the Dorman set with all the mounting hardware in the boxes...

They are going on my Dad's truck when I get it out of storage for the winter (April).

That is quite the deal, didn't know Whitney was still in business

[cleszkie]

Thought I would update my ramhorn install with one last bit of info. As was pointed out, the center plug boots like to burn after a while. So to combat this problem, I installed a set of the stock metal plug shields. Bought them new through a local aftermarket shop. Super easy install - the shields bolt to existing tapped holes in the block below the heads. Took about 20 minutes to install. $20 for the set of four shields. Hopefully they work, because they look alot better than a bunch of silver heat wrap on the plug wires in my opinion.

[jaros44sr]

Originally Posted by cleszkie

Thought I would update my ramhorn install with one last bit of info. As was pointed out, the center plug boots like to burn after a while. So to combat this problem, I installed a set of the stock metal plug shields. Bought them new through a local aftermarket shop. Super easy install - the shields bolt to existing tapped holes in the block below the heads. Took about 20 minutes to install. $20 for the set of four shields. Hopefully they work, because they look alot better than a bunch of silver heat wrap on the plug wires in my opinion.

Got pics.? Welcome to the 2.5" club as VT put it