TR2/3/3A TR3A VS TR4 Long Tube inlet manifold

[BobbyO]

Are there any advantages/disadvantages to using a TR4 long tube inlet manifold on a TR3 engine with H6 carbs or should I use the shorter TR3 inlet manifold?

 

[Geo Hahn]

...using a TR4 long tube inlet manifold on a TR3 engine with H6 carbs...

Is there enough room to do that? I honestly do not know, but would have thought something would hit the inner wing.

 

[BobbyO]

The long tube inlet manifold is 3/8 inch bigger than a standard TR3 inlet manifold. I suspect there's a good possibility the air cleaner would hit the inner wing. Part of why I asked the question.

 

[Marvin Gruber]

If you use the original air filters I believe they will hit or be very close. Let use know how it works if you do it. I have a TR4 engine I plan to use in a TR3. I will be changing out the front mounting plate.
Marv

 

[TR-3rg]

Hi,
I have the setup you are asking about. My 3a has the small port 4a head in it so I wanted the matching 4a intake. I use the H6 carbs that came with the car. Heres what I found:

1. Stock air filters will hit the fender well. I made a set of filters with tapered K&N filters. I offset them vertically about 1". I have about 1/4" fender clearance. Adjusting the fwd carb jet nut is a pain.
2. The stock throttle linkages binds up. My manifold is about .62" longer than the 3a manifold. I also think the mounting angle is different. I went to a cable.

The HS6 carbs would fit a lot easier. The H6 carb is 5.5" long, I think the HS6 is somewhere in the 4" range. I installed a header at the same time I swapped intakes so I did not get a direct comparison. It does run well.

Good Luck, Roy

 

[BobbyO]

Seems like a lot of work for not much, if any, benefit. Think I'll go with the stock TR3 inlet manifold. Thanks.

 

[karls59tr]

I've been running a 4A manifold on my 3A for years. I mounted the round mesh and foam air filters. I had to push the bottom of the front filter in slightly for clearance. I didn't notice any fouling on the throttle linkage but I'd be interested in seeing a picture of the cable set up. I believe the 4A intake would be advantageous for better engine breathing.

 

[Simon TR4a]

Kastner says the 4a inlet manifold flows significantly better, but how much improvement you would get on a stock engine I do not know.

 

[Don Elliott]

For a late TR3A I restored where the owner had a long TR4 intake manifold, I had to use very thin air filters but they are not fully circular. There is a flat that I adjusted so the filters fit on. But the owner felt that the engine was not getting enough air flow through the thinner filters hence lower output power.

I also saw a photo where someone had taken a 5 pound hammer and bashed his inner fender about 2 inches so that the common air filters would fit without hitting to inner fender.