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Headers/exhaust manifolds for 4 cyl TR with Webers

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Darrell_Walker

Darrell_Walker

Jedi Knight
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I'm installing DCOEs on my TR4A this winter. The car currently has a set of 4-2 (and 1 with the y-pipe) headers, mostly for looks (purchased from Moss). My engine is mildly warmed up (270 degree cam, ~9.5 compression).

I got my new intake manifold for the Webers, but they won't mount with the header as-is. Some of it could be solved by grinding the headers and/or the intake. I'd rather not grind the header because it is ceramic-coated, but some of the areas of the intake are already thin where I would have to grid. But even if I solve that, it looks like the front bend of the header tube will hit the intake.

I did some basic fitting with my stock exhaust manifold, and it looks like that will work without any mods. I'll have to bolt it up to the head just to be sure. So my question is, do headers buy much with a mildly warmed up engine? Or is there another source of headers that might fit better? I have seen a 4-1 header, but I heard somewhere that the 4-2-1 was better (and that is what the stock 4A manifold does).
 
Re: Headers/exhaust manifolds for 4 cyl TR with We

Welcome Darrell ,another Triumph person with web feet.sorry,don't own a 4 so I'm clueless on that,or as some might think on all.
 
IMO, the headers will buy you more than the DCOEs will. ISTR Kas Kastner said basically the same thing.
 
TR3driver said:
IMO, the headers will buy you more than the DCOEs will. ISTR Kas Kastner said basically the same thing.
Click to expand...

Thanks. Do you recall if he said anything about the various styles of headers? Somewhere I seem to recall that the 4-2-1 was better, at least in some application, but I can't find any reference at the moment.

Anyway, I did a bit more fitting with the stock exhaust manifold, and it has issues as well. It seems that the elbows from the center two exhaust ports interfere with the intakes (the current header does that on the front port). The stock intake comes up at more of an angle, where the weber intake is nearly straight out. So if anyone knows of a header that is known to work with the TWM weber intake, please let me know!

Thanks,
Darrell
 
Darrell_Walker said:
Thanks. Do you recall if he said anything about the various styles of headers?
Click to expand...
For racing, Kas said long primary tubes directly into a single collector made more power at the top end.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Somewhere I seem to recall that the 4-2-1 was better, at least in some application, but I can't find any reference at the moment.[/QUOTE]The 4-2-1 is supposed to work better for the street, as it gives you a broader power peak. Recommended to me by Ken Gillanders at BFE.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]So if anyone knows of a header that is known to work with the TWM weber intake, please let me know! [/QUOTE]Sorry, can't help you there. I thought the old el-cheapo ones sold by JCW would work, but when I sold my last one to a friend, he said he had to dent the tubes to make it fit.
 
Happy day! I just got a new manifold set (Cannon, instead of the TWM), and everything fits!

Anyway, here is what I've discovered in all of this:

TWM manifold, stock TR4A exhaust, won't work
Cannon manifold, stock TR4A exhaust, will work

TWM manifold, 4-2-1 header (from Moss), probably could work with mods
Cannon manifold, 4-2-1 header (from Moss), works with no mods!

I believe that the 4-2-1 header from Moss would work if the tube for cyl #1 was moved down on the mounting flange. It sits much higher (on my copy) than the rear. Since the tube is much larger than the opening in the head, there is room to move it around.

Anyway, I'm happy.....
 
I saw the reference to the TWM intake manifold on a TR4 and thought this is where I need to ask my question. In fitting the manifold to the head and Weber 40DCOE's I notice that the diameter of the manifold on both ends is noticeably larger the carburetor throat or the head intake ports. Is this common on the intake systems you've worked with? There are also some casting edges in the mainfold air flow path that need to be smoothed in my opinion; I am considering building a metalic sleeve that fits in each of the four tubes to produce a better match at both junctions. I figure it will work the way it is but it's not right. What have your experiences been and what has worked for you if you've worked with this situation?

Thanks, Stan

1967 TR4A hardtail
 
Hi Stan,

I didn't do any port matching when I had the Webers installed (I've since sold them and installed the Moss supercharger kit).

-Darrell
 
Stan, I would take a closer look at the manifold; it may be the wrong one for your car. When I first installed my DCOE webbers I had vacuum leaks around the intake's and head. It turned out I had the wrong intake's. The one's I'm using are TWM's #2041's and they fit perfect.
 
I saw the reference to the TWM intake manifold on a TR4 and thought this is where I need to ask my question. In fitting the manifold to the head and Weber 40DCOE's I notice that the diameter of the manifold on both ends is noticeably larger the carburetor throat or the head intake ports. Is this common on the intake systems you've worked with? There are also some casting edges in the mainfold air flow path that need to be smoothed in my opinion; I am considering building a metalic sleeve that fits in each of the four tubes to produce a better match at both junctions. I figure it will work the way it is but it's not right. What have your experiences been and what has worked for you if you've worked with this situation?
Click to expand...

It should be port matched at the head for this scenario. A larger step from the carburetor to the manifold, while not ideal, is not the end of the world and might help with some reversion issues if one has an aftermarket cam with too much duration.

As for headers, it depends. For street cars, I don't know if it makes much difference. Most TR racers are running a Stahl or a stainless Stahl copy. I would imagine the primaries are probably on the larger side for a street car. Some more ambitious are using custom set-ups designed for their particular combination of engine parts. Primary length and diameter is a function of rpm, VE %, EGTs (temperature changes harmonic wave speed), displacement, and camshaft duration. For a street car it doesn't matter to take it that far, but on a full out race motor, you bet it makes a difference (as do Webers).

Most problems with DCOEs is just poor tuning. The real good carb wizards, while always being a rare bunch, are getting rarer as they're dying off. I know of race cars that start easier than most street cars and have air fuel ratios that are flat enough that the dyno shop owner (who tunes modern fuel injected cars) was very impressed. It's rare they have to make a jet-change at the track as well, maybe one size due to a a big swing in temperatures and/or elevation. Of course, it takes dyno tuning and someone who really knows what they're doing (I'm not that guy lol).
 
Hey all.... to revive an old thread....

I picked up a DCOE kit from Pierce Manifolds and these TWM manifolds don't fit worth a **** with the factory exhaust manifold. I called them and they were very nice about it but didn't really have much to say besides that they should fit.

I'm at the point now where I'm ready to get a tubular manifold if that's what's going to make this thing fit, but I don't want to take another chance on something that I don't really care to invest in at this moment.


Is there anyone out there that has successfully fit the TWM manifolds with a stock manifold?
 
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