TR4/4A Radiator Duct Cowl Shroud

[RJS]

Hi All

I am curious if anyone has installed one of the metal TR4A ducts available from either Moss or Goodparts? If so, how is the fit - especially snug-up to the radiator itself?

Years ago I had the fiberboard model. Subsequently swapped that for a black ABS plastic one from Vicky Brit (when they were still around). I like this one except it is not very deep and it leaves a good 2" to 3" gap before it meets the radiator. As such, I can't help but wonder how much air is escaping up over/around the radiator vs going through it.

Thanks
Bob

 

[Rockie51]

I have the Goodparts one. Excellent fit, right up to the radiator. We have just done an 8000km trip to Western Australia with some hot (35c) days. The car ran perfectly sitting on normal on the temperature gauge and the oil pressure seems to stay a bit higher than previously. I have an electric fan and no engine fan.

 

[RJS]

Rockie
Thanks for the reply. 8K km - quite the long trip. I am envious. I have heard similar that the Goodparts rad duct is an excellent fit and rather easy to install since it comes in three pieces. I reached out to Richard Good about having it powder coated in black (as you know, it comes in polished stainless steel). But, he said it would take months to arrange and would be prohibitively expensive to do it as a one-off.

Would you be able to do me a favor and measure the depth of the top of the duct - from the front of the valance where it mounts, measuring backwards towards the rad?

Thanks so much and Happy New Year everyone!

Bob
PS: I hale from Connecticut in the USA but, was fortunate enough to visit WA back in March of 1991. One of the most beautiful places I've even been - a true diamond in the rough

 

[malbaby]

Bob,
I have made shrouds for two of my cars...One piece shrouds from alloy sheet...Making it in one piece is tedious work...Used small rubber extrusions on the ends of the shroud where it touches the radiator...Threaded rod across the lower sides to keep them firm against the rad.

 

[Rockie51]

Rockie
Thanks for the reply. 8K km - quite the long trip. I am envious. I have heard similar that the Goodparts rad duct is an excellent fit and rather easy to install since it comes in three pieces. I reached out to Richard Good about having it powder coated in black (as you know, it comes in polished stainless steel). But, he said it would take months to arrange and would be prohibitively expensive to do it as a one-off.

Would you be able to do me a favor and measure the depth of the top of the duct - from the front of the valance where it mounts, measuring backwards towards the rad?

Thanks so much and Happy New Year everyone!

Bob
PS: I hale from Connecticut in the USA but, was fortunate enough to visit WA back in March of 1991. One of the most beautiful places I've even been - a true diamond in the rough

Hi Bob
It is not easy to get an exact measurement because I have the wiring loom running across the top of the duct against the front panel. The best I can get is 250mm. The duct is 245mm wide. The screws holding the duct do dual duty holding the plastic wiring loops. It is very well sealed against the radiator on 3 sides and against the front valance. It was very easy to install. I have a standard radiator.

We have visited the US twice with the first time being in 1980 when my brother was living in Tucson. We did a trip around Arizona, Utah, Nevada and California. The national Parks were spectacular. The second visit was in 2006 to New York. Different sort of scenery.

Let us know what you choose.

Rockie

 

[mctriumph]

This is IMHO a case of over thinking a non problem .
I have always taken the cardboard original shroud (new) and urethaned the interior, Then
after fitting, painted the exterior black .Fits well ,looks nice , lasts forever.(now that it s water proofed).
If you wanted to get wild why not Titanium?? or Kaydex ??
The shroud was never the problem the fan has always been. Adapt the Tr6 or Tr7 fan to the hub.
Mad dog

 

[RJS]

Hi Bob
It is not easy to get an exact measurement because I have the wiring loom running across the top of the duct against the front panel. The best I can get is 250mm. The duct is 245mm wide. The screws holding the duct do dual duty holding the plastic wiring loops. It is very well sealed against the radiator on 3 sides and against the front valance. It was very easy to install. I have a standard radiator.

We have visited the US twice with the first time being in 1980 when my brother was living in Tucson. We did a trip around Arizona, Utah, Nevada and California. The national Parks were spectacular. The second visit was in 2006 to New York. Different sort of scenery.

Let us know what you choose.

Rockie

Rockie,
Thanks and will do. It may be a while however. It is our winter (freezing temps with bone chilling wind today) and car is laid-up until April 1st. This is my time of year when I research projects for the coming summer. But, greatly appreciate you sharing that info
Bob
PS: I work in NYC but my oldest lives in New Mexico. Agree, two entirely different worlds!

 

[RJS]

This is IMHO a case of over thinking a non problem .
I have always taken the cardboard original shroud (new) and urethaned the interior, Then
after fitting, painted the exterior black .Fits well ,looks nice , lasts forever.(now that it s water proofed).
If you wanted to get wild why not Titanium?? or Kaydex ??
The shroud was never the problem the fan has always been. Adapt the Tr6 or Tr7 fan to the hub.
Mad dog

Hi Mad dog

I don't disagree. Too much time on my hands I am afraid. To your point, I have def read your prior posts on TR6 and TR7 fans. In fact, I have a TR6 8-blade fan in the basement (with a TR3 hub if I need it). And I literally just purchased a used TR6 13-blade fan and adaptor off eBay (for US$25). Will test them both in the spring to see which fits better and which moves more air.

TBH my car does not overheat. My only issue is occasional fuel percolation in the carb float bowls but only on the worst of days when sitting dead stop idling in traffic when ambient is >80*F. Naturally, this only ever occurs when I decide to take the Mrs. along. I am looking into:
-Checking my ignition timing. If not advanced enough, exhaust manifold temps will be higher. I have not checked this in 15+ years and believe I am still at the factory 4* BTDC static. Might be able to push that out to 8* to 10* BTDC and see what effect that has on manifold temps
-Ensure I am running fresh "summer blend" fuel. Winter blend fuel has a higher RVP to aide cold weather starting but, results in lower boiling temp.
-Replacing stock/ original TR4A fan to move more air in the engine compartment
-Last, consider fabricating my own removable carb heat shield which can be fitted only in the worst heat of the summer - otherwise stored in the boot.

All the best for 2025 gentlemen

Bob

 

[mctriumph]

The 13 bladed fans (tr6 or 7) move over 100% more air through the radiator. The "flaw" in the cooling
system was always getting air through the radiator . Its thick as a brick.
Mad dog

 

[Rockie51]

Hi Mad dog

I don't disagree. Too much time on my hands I am afraid. To your point, I have def read your prior posts on TR6 and TR7 fans. In fact, I have a TR6 8-blade fan in the basement (with a TR3 hub if I need it). And I literally just purchased a used TR6 13-blade fan and adaptor off eBay (for US$25). Will test them both in the spring to see which fits better and which moves more air.

TBH my car does not overheat. My only issue is occasional fuel percolation in the carb float bowls but only on the worst of days when sitting dead stop idling in traffic when ambient is >80*F. Naturally, this only ever occurs when I decide to take the Mrs. along. I am looking into:
-Checking my ignition timing. If not advanced enough, exhaust manifold temps will be higher. I have not checked this in 15+ years and believe I am still at the factory 4* BTDC static. Might be able to push that out to 8* to 10* BTDC and see what effect that has on manifold temps
-Ensure I am running fresh "summer blend" fuel. Winter blend fuel has a higher RVP to aide cold weather starting but, results in lower boiling temp.
-Replacing stock/ original TR4A fan to move more air in the engine compartment
-Last, consider fabricating my own removable carb heat shield which can be fitted only in the worst heat of the summer - otherwise stored in the boot.

All the best for 2025 gentlemen

Bob

Hi Bob
My car came from the US as a LHD and did not have either the fan or the extension on which to mount it. It did have a large electric fan mounted in front of the radiator. In the process of the rebuild (and conversion to RHD) I had the radiator rebuilt and added a thermo switch to the header tank. This was a Mitsubishi part I believe and is set to cut in at 85c. A later mod was to move the fan behind the radiator. The car has never overheated in 20 years on the road including 3 trips across the Nullarbor Plain. It is 38c here today and we took the car to the Triumph New Year breakfast in stop-start traffic. No problem.

I fitted a new cardboard shroud when I rebuilt the car. It was a lousy fit letting air around both sides of the radiator and finishing about 3 inches below the top of the radiator. The Goodparts one directs all the air through and finishes at the top of the radiator. Highly recommended.

Rockie

 

[RJS]

Got it, great info Rockie. Really appreciate it. Pretty much sold me on the GoodParts duct. But, still curious anyone's feedback on the metal duct option from Moss.

I am envious of your Triumph New Year's breakfast meet up. We are 0*C today with a gusting 35mph wind. Hope you enjoyed it. I won't be seeing my TR4A for another three months.

As an aside, my 13-blade TR6 fan arrived yesterday. So now I have both an 8-blade (yellow) and the 13-blade (red). I was thinking a good winter project would be to set up a rig where I can take comparative measurements of various fans using a cheapo anemometer from Amazon. I've seen them as low as US$30 for a hand-held one. I think they are useful to HVAC technicians, windsurfers and drone pilots...and now Triumph geeks like me.

Bob

 

[TR Tom]

Hi Mad dog

I don't disagree. Too much time on my hands I am afraid. To your point, I have def read your prior posts on TR6 and TR7 fans. In fact, I have a TR6 8-blade fan in the basement (with a TR3 hub if I need it). And I literally just purchased a used TR6 13-blade fan and adaptor off eBay (for US$25). Will test them both in the spring to see which fits better and which moves more air.

TBH my car does not overheat. My only issue is occasional fuel percolation in the carb float bowls but only on the worst of days when sitting dead stop idling in traffic when ambient is >80*F. Naturally, this only ever occurs when I decide to take the Mrs. along. I am looking into:
-Checking my ignition timing. If not advanced enough, exhaust manifold temps will be higher. I have not checked this in 15+ years and believe I am still at the factory 4* BTDC static. Might be able to push that out to 8* to 10* BTDC and see what effect that has on manifold temps
-Ensure I am running fresh "summer blend" fuel. Winter blend fuel has a higher RVP to aide cold weather starting but, results in lower boiling temp.
-Replacing stock/ original TR4A fan to move more air in the engine compartment
-Last, consider fabricating my own removable carb heat shield which can be fitted only in the worst heat of the summer - otherwise stored in the boot.

All the best for 2025 gentlemen

Bob

Good to know they are now making the metal shrouds for the TR4, always liked the ones I saw on TR6’s.

As far as fuel percolation, I insulated my fuel line from the pump all the way to the carbs. Also installed an ARE carb heat shield. It’s a nicely made product, and I even added some DynoMat to it for added insulation. For a fan, I use the one from Macy’s Garage, seems to work well.

The real secret weapon against engine compartment heat though, is to just reach over and pop the bonnet release. That one inch gap at the back of the hood lets all that accumulated heat flow right out!

Summers around here regularly top 100*, and with these modifications I’ve not had problems for many years.
Tom

 

[Rod-H]

3 pieces of thin aluminum sheet (available on amazon) and it is easy enough to make your own. Use a CAD system to design it (Cardboard Aided Design) to make a pattern. Bend the top piece so the edges go over the top of the two side pieces so you can put screws it to attach it.
Not overly difficult. Unless you in a part of the world where you can't get aluminum, they only sell that al-looo-minnny-umm stuff, then you may have issues
Rod

 

[mctriumph]

If it's over 100 deg and you are NOT in a pub with a pint, may the Lord have mercy!!
Mad dog

 

[RJS]

Good to know they are now making the metal shrouds for the TR4, always liked the ones I saw on TR6’s.

As far as fuel percolation, I insulated my fuel line from the pump all the way to the carbs. Also installed an ARE carb heat shield. It’s a nicely made product, and I even added some DynoMat to it for added insulation. For a fan, I use the one from Macy’s Garage, seems to work well.

The real secret weapon against engine compartment heat though, is to just reach over and pop the bonnet release. That one inch gap at the back of the hood lets all that accumulated heat flow right out!

Summers around here regularly top 100*, and with these modifications I’ve not had problems for many years.
Tom

Tom,
Great idea popping the hood latch if you are stuck in stopped traffic. I am sure when you are done you can simply reach around the windshield stanchion, lift and drop to re-latch it once traffic is moving again.
Additionally, I was thinking you could pull the high idle/choke nob a bit, increasing idle to 1200rpm before engaging the chokes. My car idles at 650rpm so that would increase both fan and water pump speed - which I think would help.
Bob

 

[RJS]

3 pieces of thin aluminum sheet (available on amazon) and it is easy enough to make your own. Use a CAD system to design it (Cardboard Aided Design) to make a pattern. Bend the top piece so the edges go over the top of the two side pieces so you can put screws it to attach it.
Not overly difficult. Unless you in a part of the world where you can't get aluminum, they only sell that al-looo-minnny-umm stuff, then you may have issues
Rod

Rod
I'm certainly game to try and fab my own. Two quick questions for you:
1) what gauge or thickness aluminum should I look for?
2) how best would I cut or trim the aluminum sheets to make clean cuts and not warp the aluminum?
Bob

 

[bammons]

Here is a picture of the Moss unit. As you can see it does not come to the top of the radiator. It fits fine and I have no overheating issues but that may be more of a function of where I live and I avoid heavy traffic. I have the tropical fan option that came with the car. Bruce Edit; well it says my picture file is too big

 

[RJS]

Here is a picture of the Moss unit. As you can see it does not come to the top of the radiator. It fits fine and I have no overheating issues but that may be more of a function of where I live and I avoid heavy traffic. I have the tropical fan option that came with the car. Bruce Edit; well it says my picture file is too big

Bruce
Would love to see that photo. Give it another go?
Thx
Bob

 

[bammons]

I figured out how to reduce the picture. Bruce

 

[Rod-H]

I'm certainly game to try and fab my own. Two quick questions for you:
1) what gauge or thickness aluminum should I look for?
2) how best would I cut or trim the aluminum sheets to make clean cuts and not warp the aluminum?
Bob

Hi Bob: I used .060" aluminum and a band saw to cut it. The top piece was straight with a bend toward the radiator. The 2 side pieces were made to fold over the top piece (in a vice with a rubber mallet) I used rags on the jaws of the vice. I drilled holes through the top and side pieces and put nut inserts in the top piece.
I used a dual action sander to smooth the edges in various grits.

Note: mine is different due to what yours will look like due to having a different radiator, but the concept is the same.

R