TR4/4A TR4A long intake manifold on a TR3A?

[karls59tr]

Anyone running the long intake manifold on their 3? I know that some do this for racing applications under the theory that it would give better engine breathing. Then I've heard that the stock log manifold is more effective and there is no advantage? Wouldn't the long manifold be advantageous with a mild street cam and header?

 

[TexasKnucklehead]

My (TR3) engine has the TR4 intake, and HS6 carbs. My body is not yet back on, but I'm pretty sure you'll need to change the stock H6, with HS6, or it will not fit. Even with the swap, I'm planning to use a smaller air filter, because the stock filters will not fit. I have a stock cam and manifold and no idea if there will be any advantage -aside from any possible advantage of the center pull throttle. I also made a heat shield for the plastic jets on the HS6.

 

[TRMark]

There is an article about this by Ken Gillanders at the Triumph Register of Southern California website. Click on H6 vs. HS6

 

[Mychael]

I have the TR4 intake on my car with the stock TR3 carbs and airfilters. It fits (just) you can have issues with the filters interferring with the inner wing.

 

[karls59tr]

I saw a picture today of a TR3 motor with Stromberg carbs and the long runner 4A intake manifold. There was a hose coming off the center junction of the manifold that ran over to the right side of he motor but I could not make out what it was connected to? What is it's purpose?

 

[CJD]

Probably a positive crankcase ventilation valve. The later TR4 had to stop using the TR3 road draft tube to meet emissions standards.

 

[Hamish Racing]

Karl
I ran the later inlet manifold and the longer H6 carbs with short intake trumpets and they fitted
I do have the harder engine mounts that stop excessive engine rocking.

i later upgraded to full radius intakes on the carbs.
worked well for me

 

[karls59tr]

What confused me was in the picture I saw he had the hose coming out of the intake manifold center passage (some of them...not sure wether 4 or 4A they have an outlet on the center piece that connects the two halves of the manifold together) If it was for blow by as John suggested why would he not have the hose coming out of the valve cover instead of the intake manifold??? Wish I could post a pic.

 

[billspohn]

The flow on the long runner intakes is better, but yes, you have to watch your inner fender clearances.

I used one and a half TR4A intakes to create a much improved intake for a triple carb set up on my MGC.

 

[karls59tr]

 

[Hamish Racing]

What confused me was in the picture I saw he had the hose coming out of the intake manifold center passage (some of them...not sure wether 4 or 4A they have an outlet on the center piece that connects the two halves of the manifold together) If it was for blow by as John suggested why would he not have the hose coming out of the valve cover instead of the intake manifold??? Wish I could post a pic.

Karl
its either the PCV valve cover breather system that “sucks” the valve cover vapours into the intake manifold to be burnt. As CJD says.
see borrowed picture

or

its a vacuum pipe to make a brake servo work. That you can see in Billspohn picture .

 

[karls59tr]

I see what you are saying. Just looking at the photo of the way your car is set up.....picture the hose coming off "your" intake manifold and looping over the valve cover and down to the ground?

 

[Hamish Racing]

No pipe on the intake manifold should be “open”. It’ll ruin the running, the fuel air mixture etc
even the dizzy vacuum advance should be sealed on the manifold if not used and that’s a very small hole …….. or should be

 

[karls59tr]

That's what I thought. It did not make sense the way he had it set up.

 

[mctriumph]

Karl , longer runners are for better torque which is usually not an issue on a 3 if the cam is NOT
crazy as crap. The main issue with the old manifold is that the factory did a terrible job of
port matching.# 1 #2 #4 all perfect in every manifold I have ever seen.BUT not #3 it is way off.
If you do nothings else on a Tr3 match up the ports! Number 3 is off centered by over 2 mm.
It is also good at this time to work the splitters to make them more like the tr4a manifold does.
these tricks make the old log work well for 99% of non race cars.
Mad dog

 

[karls59tr]

Karl , longer runners are for better torque which is usually not an issue on a 3 if the cam is NOT
crazy as crap. The main issue with the old manifold is that the factory did a terrible job of
port matching.# 1 #2 #4 all perfect in every manifold I have ever seen.BUT not #3 it is way off.
If you do nothings else on a Tr3 match up the ports! Number 3 is off centered by over 2 mm.
It is also good at this time to work the splitters to make them more like the tr4a manifold does.
these tricks make the old log work well for 99% of non race cars.
Mad dog

That's good to know about the no.3 port. I have been running a 4A intake manifold for years. Mild street cam. While we are on the subject.....Can you think of any reason why all of a sudden the intake manifold and plugs would turn black with carbon? Would a blown intake gasket or a loose intake manifold bolt cause this? (I noticed this when I pulled the head off). This happened around the same time the cylinder head gasket blew. How are the two things related?

 

[Jerry]

TR4 intake on TR3 engine with HD6 carbs. Works well!

 

[mctriumph]

Karl the head gasket can do this .High pressure exhaust gasses can escape into the intake
causing misfire and carbon deposits.
I have never double checked the alignment of the ports on a Tr4a intake, You might do.
Mad dog