Headers to 2.5" Ramhorns

[LostMy65]

Ok, I found the answer:

Originally Posted by smbrouss70

Mine came in yesterday! Dorman 674504 is what you want, if you don't want the heat tubes.

Also this thread:
http://67-72chevytrucks.com/vboard/s...d.php?t=404828

The left (Driver's side) doesn't have the 'heat tube'

[LostMy65]

RockAuto has them for $47.79 for either the DOR-674-504 or DOR-674-503.
They add $8 each for shipping.

Amazon has the 504s for 55.94 with free shipping.

but if you got two rights from amazon, you could have two 503s to your doorstep for $98.40

[mcmlxix]

another alternative....
http://www.jegs.com/i/Wysco/938/MA035RAW/10002/-1

[72freak]

I just did a set on my 69. Engine in stock V8 possition. They really look nice. I got the ones with no brackets or heat tube holes. I also did extensive research to find a set of plug wires that were long enough to wire it correctly from the bottom without having to buy 2 sets or make them. It turned out nice. Ill take a picture to day of the completed engine bay.

[TonyJohnson]

Where'd you get those collector tubes? Are they just standard header type?

[badpeanut]

Originally Posted by 72freak

I just did a set on my 69. Engine in stock V8 possition. They really look nice. I got the ones with no brackets or heat tube holes. I also did extensive research to find a set of plug wires that were long enough to wire it correctly from the bottom without having to buy 2 sets or make them. It turned out nice. Ill take a picture to day of the completed engine bay.

Details please on your exhaust pipes!

Any clearance issues to the starter (and is it the stock full size starter)?

[72freak]

Originally Posted by badpeanut

Details please on your exhaust pipes!

Any clearance issues to the starter (and is it the stock full size starter)?

Normal 2.5 straight runs just like any other dual exhaust with 40 series. No issues. The common myth that there are clearance issues with x-members with the engine in the v-8 position or clearance issues with stock starters is just that...a myth!. I have noticed I will probably need to make a shield for where the exhaust pipe comes close to the front right brake line where it wraps around the frame...its a little close.

Originally Posted by TonyJohnson

Where'd you get those collector tubes? Are they just standard header type?

Yes...collectors welded on to pre bent 2.5 pipe. I told/showed my muffler guy what I wanted and he made them for me. I had 2 sets made exactly the same for the next project.

[drunkbus]

Originally Posted by badpeanut

Details please on your exhaust pipes!

Any clearance issues to the starter (and is it the stock full size starter)?

It was a tight fit to the starter on mine but there is room to make it happen. I ran heat wrap for the first few feet on both sides since it is so close to the starter and transmission cooler lines and the oil filter on the other side.

[Effeckt]

Originally Posted by mcmlxix

another alternative....
http://www.jegs.com/i/Wysco/938/MA035RAW/10002/-1

Still available on amazon for $55 each shipped currently also.

[TonyJohnson]

Cool...

[rsavage]

Nice "unmod". I'm a firm believer in stock exhaust manifolds for a variety of reasons looks, ease of plug access, less heat in the truck, easier on the starter, etc. With the center dump ram horns, the wires were designed to run underneath along the block and up to the plugs with 90 degree angle boots. Cylinders 1,3 and 2,4 actually come up through in-between the block and motor mount. Run like that with the stock heat shields, they shouldn't burn. One other note, if you are keeping your truck stock, I don't believe that the heat stove sheet metal will fit over the 2 1/2 " exhaust manifolds - you would have to stick with the 2".

[Green Monster]

Originally Posted by Gyrine

I've had 2 1/2 Ram's horns on a 72 Blazer for 15 years.

For those of you with an HEI ignition who want to run factory type plug wires, get a set of plug wires for a 1975 Corvette. That was the first year of HEI and they still utilized Ram's horns manifolds. You can still find the back of the block looms and the looms that bolt to an oil pan bolt. With factory heat shields, your wires will not burn.

Great tip suggesting 75 Corvette plug wires. Thanks.

Originally Posted by rsavage

Nice "unmod". I'm a firm believer in stock exhaust manifolds for a variety of reasons looks, ease of plug access, less heat in the truck, easier on the starter, etc. With the center dump ram horns, the wires were designed to run underneath along the block and up to the plugs with 90 degree angle boots. Cylinders 1,3 and 2,4 actually come up through in-between the block and motor mount. Run like that with the stock heat shields, they shouldn't burn. One other note, if you are keeping your truck stock, I don't believe that the heat stove sheet metal will fit over the 2 1/2 " exhaust manifolds - you would have to stick with the 2".

Great info here in this old thread but I haven't seen anyone in this thread using a heat stove with the 2.5" center dump ram horn exhaust manifold? What's the best option here for retaining stock appearance while maintaining original function of the intake for cold starts?

Does anyone have experience using the 76-80 Corvette heat stove with 2.5" ram horn manifolds?
https://www.southerncarparts.com/c3-...ield-assy.html


They look similar to original stoves but will our stock heat riser and air cleaner work with the Corvette heat stove?


Also, can 57-79 Corvette spark plugs shields be used?
https://www.southerncarparts.com/195...block-4pc.html

[PDXk5]

Green Monster,
I don’t know for sure if it will work/fit but that is exactly what I am (was) planning to do when I get my engine rebuilt.

Hopefully someone has done this and can confirm this for us!

I am also going to have the ram horns ceramic coated inside and out to reduce engine bay heat. Unrelated, was thinking on having the master cylinder ceramic coated to match so they will look like bare cast iron but not rust.

[Green Monster]

PDXk5- A ceramic coating in a cast iron color on the manifolds and master cylinder will have a nice look for sure.

Yesterday, a pair of Assault Racing 2.5" straight dump ramhorns with black ceramic coating inside and out from Assault Racing showed up at my front door. They were inexpensive ($200) and came with gaskets and all mounting hardware in the photo. Cast iron color was my first choice but black and silver are the only colors offered in ceramic coating, that I could find. The manifolds appear to be two RH (passenger side) manifolds, which is a good thing since there is no ports to drill out, tap and fill as Jim (Jaros44sr) shared he did with his LH manifolds.

https://www.assaultracing.com/item/1...?category=8107

The new repo stove and spark plug shields I posted earlier seem like they would fit, function and look close to factory correct.

If no one can confirm they won't work then I'll pick up a set and go from there. I need to find out what hardware I'll need for the shields and stoves.

[Effeckt]

So reading through this thread, I began wondering if you all would recommend getting the 2.5 ram horns over the factory ram horns? I recently found the factory 2" ram horns that already dump out at an angle in my garage. The PO put headers on my Blazer but I have an exhaust leak so I'm wanting to redo the whole system now. Would the extra .5" be worth while getting the Corvette horns or should I stick with the ones I've got?

[rsavage]

They are 25% larger so they will flow better. Probably wouldn't notice on a stock engine. Your Blazer is a 4WD. 4WD used the straight down center dump whereas 2WD uses the angled. I am not sure whether or not you would run into clearance issues with the angled dumps because I have never tried it. Perhaps someone else can tell you.

[Mike C]

Originally Posted by rsavage

They are 25% larger so they will flow better.

It is a 25% larger diameter, but that is not what makes the difference.

If the exit is the largest restriction, the 2" manifolds have a 1 x 1 x pi=3.14 sq inch opening. The 2 1/2" manifolds have a 1.25 x 1.25 x pi=4.9 sq inch opening. That is a 4.9/3.14=1.6 times as much so a 60% increase in area which should have a huge impact on the ability to flow.

My opinion is just about any performance level can benefit with the 'vette manifolds.

On my truck the "butt-o-meter" said they made more low speed torque than the headers they replaced with no loss on the top end. But it has a little cam, 210 @ .050. This is not a fair apples and apples comparison because the headers had 2 1/4" exhaust with some Turbo King mufflers while the manifolds got 2 1/2" pipe with Dynomax Hemi turbos.

Regardless, one of the best mods ever IMO. Good power with low noise and no maintenance.

[Cap'n Hook]

Does anyone know if the Dorman 674-504 lefts will fit Vortec heads? I've got a nice big hole started on the #2 cylinder and I'm tired of the leaking flanges!

[jaros44sr]

Originally Posted by Cap'n Hook

Does anyone know if the Dorman 674-504 lefts will fit Vortec heads? I've got a nice big hole started on the #2 cylinder and I'm tired of the leaking flanges!

Yep, got them on mine! If it has the molded in boss, you can cut it off with an angle grinder and a cutoff wheel.

Thing is, if you run the heat sheilds, you might have a problem with mounting them up. The Vortec heads are about 1/2" taller

Main question is...do you run gaskets or not...big debate floating around the boards. I don't, I am just using copper shield. Also, I think the factory locking plates will work best to mount your manifolds, no more loose bolts that create leaks

Don't forget you need a new intake, although they make a dual pattern bolt, for the early intakes, the runners are about 3/8" short for the earlier intakes

[Effeckt]

So I am finally getting around to looking into getting these. I don't love the alternator mount but don't really have the means/tools to remove it. Is there a set that will fit without the alternator mount? Like the 674-501? I'm guessing not or there would be more talk about them. Would there be any figment issues if I just left the alternator mount on them?
Posted via Mobile Device

[jaros44sr]

Originally Posted by Effeckt

So I am finally getting around to looking into getting these. I don't love the alternator mount but don't really have the means/tools to remove it. Is there a set that will fit without the alternator mount? Like the 674-501? I'm guessing not or there would be more talk about them. Would there be any figment issues if I just left the alternator mount on them?
Posted via Mobile Device

Depends on which ones you buy, when i bought mine, i had to buy the same manifold for the right and left side. So, with that being said, the alt. mount will be located at the back of the engine on one side. And it does hit the firewall, so in my case i had to cut it off.

It was really easy to cut with a angle grinder, and a cutoff wheel

[SeventyOne]

Originally Posted by Effeckt

So I am finally getting around to looking into getting these. I don't love the alternator mount but don't really have the means/tools to remove it. Is there a set that will fit without the alternator mount? Like the 674-501? I'm guessing not or there would be more talk about them. Would there be any figment issues if I just left the alternator mount on them?
Posted via Mobile Device

Got a buddy with a grinder? It literally takes 20 minutes per manifold to remove the bracket and "sculpt" the metal to look right. Then hit it with some manifold paint.

[jaros44sr]

Originally Posted by Effeckt

So I am finally getting around to looking into getting these. I don't love the alternator mount but don't really have the means/tools to remove it. Is there a set that will fit without the alternator mount? Like the 674-501? I'm guessing not or there would be more talk about them. Would there be any figment issues if I just left the alternator mount on them?
Posted via Mobile Device

Might be a good time to start a tool collection, really not much money if you go to harbor freight. Just a thought, but an angle grinder with a cut off wheel went thru it like a hot knife through butter...

BTW, nice looking truck!

[Heavy Evy]

Not to brag but I picked up a used original set locally for 30 bucks! They're going on my truck ASAP since they didn't clear on my Nova. How do you guys like the dormans?
Posted via Mobile Device

[Effeckt]

Thanks Jaros! Time to really start investing in this thing. It's not running properly right now, so I'm working on that now and these manifolds are part of the process. The plan is to use my tax return next year to get some color on it as well. I have some tools but not a ton of power tools. I have a buddy that likely will have one. If it's that easy then time to make a trip to his place!