Exhaust Manifold questions

[Revmohr]

Greetings all; first time poster. Am in the process of having my recently-purchased Stag engine rebuilt (LHD, LE21694, 1973) after finally getting a car I wanted back in 1976. Mike Coffey (Stagparts USA/terrific fellow), and Phil Lamberti (SWU machine shop) are taking care of me, so I'm lucky to have their expertise. Only have one question while the engine is out: Am having a new SS exhaust system put in, and just curious as to whether I should opt for the Rimmer Bros SS Sports Tubular Exhaust manifolds, or is that just cosmetic overkill. Also, if I stick with the original cast-iron manifolds, has anyone used the ceramic heat tape/wrapped the manifolds? Again, have no personal experience with either, so if anyone has opinions as to performance enhancing/consistency of the exhaust flow, or heat reduction, I'm all ears.

Always glad to read the incredible wealth of advice on this site, and can't wait to get my car back and actually drive her!

Steve

[DJT]

Welcome, Steve.

I fitted tubular manifolds a few years ago. Engine seemed to rev better and sound better, but that might just be me justifying the expense.....

Note that most of the UK Stag suppliers sell the same SS exhaust manifolds, made by Phoenix Exhausts, Devon. It might be worth comparing prices as there is often quite a difference. Best to fit them whilst the engine is out, as fitting them with the engine in situ is a PITA, unless the heads are off.

[Revmohr]

Thanks for the input- I have to think the flow is better, and I'd really like to do this "right" the first time, since its easier now with the motor out. Purchased Stagweber's cooling tank kit as well- just trying to head off problems (car will be a "driver" , versus show car, so it's all about practicality/reliability/etc)

[Phil S]

I agree the engine seems to rev more freely with the Phoenix manifold, I had mine ceramic coated inside and out to contain the heat in the manifold, but ouch, the coating was more than the steel work

[sujitroy]

The manifolds available need work to fit on a lhd stag. From something ISTR Flying Farmer said, they don't make much difference in performance to a stock Stag.
Sujit

[trunt]

The manifolds available need work to fit on a lhd stag. From something ISTR Flying Farmer said, they don't make much difference in performance to a stock Stag.
Sujit

I think the consensus is that without work on the inlet manifold they do not give much in the way of gains, but if the inlet manifolds are improved then they will provide some extra gains.

I wondered what work you feel they need? The latest versions clearly say that they are ok for LHD except when air conditioning is installed.

Terry

[PJB]

Another vote for the headers. Ceramic coated. Less heat. Much quicker cool down.

[Revmohr]

Verdict seems to be about a “51/49 you pick it” proposition. Possible improvements in performance, but may take $$ and fabrication work to fit (car originally had A/c, but it was non functioning and I’m yanking it out....

My other thought was how long do original manifolds last/ cracking issues. Motor only had 440000 miles prior to this rebuild- they look clean/ok

Again, appreciate all the input!

[Revmohr]

Maybe another piece of helpful info for votes:
Original carbs are gone; replaced by Holley 4bbl

[flying farmer]

I started a thread about performance tuning the Stag engine about 5 years ago. If you have a lot of hours to spare then use the search facility to find it

There are lots of rolling road results that confused the hell out of me but did give some general trends

The general conclusion I arrived at was that the tubular manifolds give quite a boost to bottom and mid range torque on a generally standard engine. The Holley conversion makes a slight difference at the top end but it isn't a large gain as the inlet manifold is massively restrictive.

Power wise the tubulars will generally lift the power back to the factory figures which are a touch on the generous side. Watch out for the balance pipe where it enters the main pipes just before the silencers. On my stainless Stag system it protruded into the pipes sufficiently to significantly restrict the flow.

While the engine is in bits the short side of the inlet ports need smoothing out as there is often a massive step in the casting.

Neil

[trunt]

I am yet to see any confirmation in the LHD fit, but here is a pic of the latest version of Phoenix Left hand side headers that claim to fit LHD without Aircon

Wait a few months and I'll tell you if thats true!


header2.JPG
headers1.JPG

[jbuckl]

Never really wanted to put tubular headers on my stag, but didn’t like the rusty look or flaky painted look. Linished the iron & got a light grey vitreous enamel finish, which has lasted well.

[Revmohr]

You gentlemen are great; this forum is a huge help to a novice like myself, in the US. (I do fly to London a lot however, and will gladly trade pints for Stag hints!)

[mjheathcote]

UNTITLED-SCANNED-238.JPG The phoenix manifolds are so crude in comparison to my 'Mike the pipe' (deceased) manifolds that are properly formed.

[Jonat127]

If you are doing your whole engine and you want to do it properly then may I suggest you also change the water pump for either an electric one or an external belt driven one.
sorry I'm off topic a bit but couldn't help responding to your "do it properly" comment


stands back and waits for debate to start