HEADER DIFFERENces?

[Guest 1977Datsun]

I'm sorry if this was already posted, either im stupid or the search engine doesnt get what i ask for

 

I want a pair of headers

 

So what is the difference between the 3-2 header and the 6-1

 

If the only difference is the 6-1 is only for manuals then sorry i wasted ur time

[Hugh]

The flow characteristics of the 6-3-1 will be smoother than those of the 6-1. It has to do with turbulence in the collector.

 

The difference is usually very little in HP terms. However, those with smoother transistions are considered to be better.

[johnc]

For a basically stock internals engine (cam, pistons, etc.) there's no difference. Purchase the header that you feel looks the best and fits the best.

[Guest 1977Datsun]

Will both of them fit the same or will the 6-1 require that i "bash" the floor pan up an inch? Special modifications are annoying

[JMortensen]

The MSA or AZC 6-1 fit with no mods to the floor on my 70. However I did have to weld on the flange because there simply wasn't enough metal around #6 port to seal (that made me very angry), and I hate the way the tubes are crimped on it. I actually "ported" the header a little bit before I stuck it on it was so bad.

 

The 6-2-1 that MSA sells is also pretty dang crappy as I recall. Nissan Comp header is very good, but then you have to bash the floor in IIRC.

[olie05]

I'm also looking into buying a header, the one on my previous engine was a pacesetter POS. Never buying that again. What is the consensus on best fitment? Jon, you said the msa 6-2-1 is also a POS? That was probably the one I would get because they advertise a "thick flange," something the pacesetter lacked (it required spacers). So has anyone else had problems with the MSA header?

[JMortensen]

The MSA 6-1 has close to the "right" length runners. The 6-2-1 has primaries that are shorter than ideal according to How to Modify. When I was building up my car the first time around my roommate had a 6-2-1 header that he was going to give me, and I remember thinking I'd be better off buying the 6-1. It's been a long time (this was like 8 years ago) so I don't really remember what it was about it that I didn't like. I think it was the primary length and the fact that were obviously not equal IIRC.

 

On the MSA 6-1 I had to grind down my Mikuni manifold to the right thickness so that the manifolds would seal with the normal washers. I seem to remember not having to do that with SU's, but again, its been so long it's hard to say for sure.

 

The Nissan Comp is perfect lengthwise, you get your choice of primary size, and it is relatively expensive, and then you have to make your Y pipe or run duals all the way back.

[technicalninja]

MSA 6 to 1 square ports require grinding and welding to fit properly. Do not buy a coated one as my last customer did. You want to solve the fitment issues and then have it coated. His header required very careful mods to work.

All (not just MSA) square ports I have messed with required some fitment work as none of them cleared the stock port exits. Most exhibited port infringment at the roof of the port which is the very worst spot for performance (port velocity and flow is greatest at roof of port).

I have never worked with a Nisimo or Nissan Comp as their price was very high. I have heard that they are much better on fitting.

Besides it's fitment short comings I like the MSA header. It does have thick flanges (makes welding easier) Its runners are close to the same length. The collector doesn't hang down (my customer had to send his first header back as its flange was welded at an incorrect angle/Motorsport did take care of him). They are reasonable as to price and available.

One the other hand, All round port headers (even the old rusty ones I have retrieved from junkyards) have fit perfectly. They haven't needed any porting or grinding work at all. Sadly for me I prefer square port heads and have to deal with poor header fitment on most of my builds.

The square ports also usually have trouble with sealing area at #4 and #6 cylinder. This is were the gasket will blow.

I believe a square port just bolted on with out port matching will actually reduce power over the stock manifold (which fits pretty good).

During full engine builds I take the bare head (no valves), bolt the header and intake manifold to it, and then inspect port match with a bend-a-light and a small mirror. The stock manifolds have much less port infringment that the square port headers. Usually they have none and if they do they have plenty of meat on them which allows port matching.

 

For the original question- 6-2-1, 6-1 will not have a noticable difference between them. They probably won't make a noticable difference over a stock manifold (below 200hp) and will probably leak more.

Both designs are available and although I have had to modify the headers to fit the head I have not had to modify the body to make any fit properly.

I might suggest a stock manifold (if yours is still good-77/78 manifolds were thick and sturdy and didn't have the warping issues as the ZX manifolds). Get the MSA exhaust adaptor and their 2.5 inch exhaust kit.

This set up will be fine for 200 maybe 225 hp and not leak. The exhaust kit can also be a pain but it is nice, has clean mandrel bends and is priced well. I usually get the aluminized version. This kit has always needed the slip fittings opened up a little to make it work. Harbor Freight Tube expander was like 10 dollars and works great.

 

Hope this helps

[Guest rick458]

What about the MONZA header from Victoria Brithish?

any fitment probs? they can come coated