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TR4 Bonnet hits carbureteur


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here are mine measurements, maybe it helps to solve the issue.....

if you compare the pic's whit the crossbar's your carbs are much higher then the carbs from Marco and mine. 

the end of the inlet-manifold is about 10cm below the crossbar  and the brass nut on the carb just touche the crossbar.

regards

Marcel.

 

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Edited by Quicksilver
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My setup is exactly the same as Quicksilver’s: H6 carburetors, as in TR4, and the longer TR4A manifold. The dash pot covers are approx 4-5 cm higher than the rocker arm cover, and, with the bonnet closed, they are a bit past the highest point of the bonnet bulge (as the H6 are a tad longer than the HS6 that were the usual fitment for TR4As). It looks like the issue, as noted by others, is that your intake manifold is shorter and, probably, also angled a bit mote upwards than that if the TR4A. Maybe an easier and less costly alternative to changing the manifold could be to fit thermal insulators (combined with longer bolts), which would move your carburettors one or more cms towards the wing, so they fall just below the bonnet bulge

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  • 2 weeks later...

Hey Solaise,

John Morrison recently contacted me advising that he’d been in touch with you and hopefully he’s been able to help you out.  Just by way of introduction I’m the GL for Forth and Borders and also The Scottish Director of the TR Register and I currently live in Edinburgh.

just wanted to let you know that we’d love to have you join us and we actually have a couple of TR4/a experts in our group with completely restored award winning cars and also a couple of chaps in the process of restoring them, so plenty of good honest advice like you received from others here in the forum.  And, in normal times the ability to visit and poke around and measure stuff in members cars. We even have a member that just taken delivery of a car he won in a Facebook lucky draw, you will be able to read all about this in our excellent club magazine.   Also, as you know this year is the 60th anniversary of the TR4 and at our annual meeting in August at Malvern we will be having a focus on the TR4, hopefully you can attend ?

Anyway, please let me know if I can help you and hopefully you’ll make the decision to join us, just let me know if you’d like to join and I’ll personally assist you with your application.

 

Have a great Easter and don’t eat too many Easter eggs !

 

Stephen Hall,

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On 3/20/2021 at 3:44 PM, solaise said:

If I have read correctly is looks like "304164" ie Exhaust Manifold - High Port Head - 304164

Is this correct?

Tom

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Here's a thought

Vanguard Sportsman inlet manifold and carbs perhaps?.

We had a set years ago and the manifold is machined so the carbs fit at a steeper angle to a TR.  The odd ball bit is that Sportsman used HD6 carbs, so it is not a complete setup

Read this from years bygone

Peter W

 

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8 hours ago, Scotland Director said:

we’d love to have you join us

Stephen - I have just joined the club and I hope to meet you soon in Edinburgh.

I have been working on the car this evening, and have the new inlet manifold (thanks John!) in place albeit temporarily. Its definitely put the carbs more in the middle, and a first look shows there is now a gap between the pots and the bonnet which is good and the bonnet can now close without touching. Its not as low as I was expecting as the top of the damper plugs are still above the line across the wings, unlike the photos from Quicksilver, but then there would be no need for the bulge in the bonnet if the carbs were below the line of the wings!?

I still need to finish fitting, it has not been as straightforward as I hoped due to some very non standard studs being stuck in the engine block and definitely non standard clamps with multiple washers packing things out. Whats more my kids have used up all my blue tack which is actually a very good way to measure the clearance with the bonnet shut, but squinting through the front grill seems to show at least 10mm gap between the the bonnet and carb.

Hopefully this weekend I will get it all back in one piece and I will post some photos of the outcome with some more precise conclusions.

Tom

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On 4/1/2021 at 8:56 PM, solaise said:

Stephen - I have just joined the club and I hope to meet you soon in Edinburgh.

I have been working on the car this evening, and have the new inlet manifold (thanks John!) in place albeit temporarily. Its definitely put the carbs more in the middle, and a first look shows there is now a gap between the pots and the bonnet which is good and the bonnet can now close without touching. Its not as low as I was expecting as the top of the damper plugs are still above the line across the wings, unlike the photos from Quicksilver, but then there would be no need for the bulge in the bonnet if the carbs were below the line of the wings!?

I still need to finish fitting, it has not been as straightforward as I hoped due to some very non standard studs being stuck in the engine block and definitely non standard clamps with multiple washers packing things out. Whats more my kids have used up all my blue tack which is actually a very good way to measure the clearance with the bonnet shut, but squinting through the front grill seems to show at least 10mm gap between the the bonnet and carb.

Hopefully this weekend I will get it all back in one piece and I will post some photos of the outcome with some more precise conclusions.

Tom

Tom, I’m really pleased that you managed to get your problem solved, the Forum is brilliant for getting help and advice.  Also, now that you’ve become a member of the TR Register you will have full access to the forum.

Hopefully you managed to get your car out and about, “whilst staying local”, over the weekend as the weather was brilliant.

I’ll contact you direct in a couple of days to formally introduce myself and welcome you to the Register.

Hopefully we’ll be able to organise some runs over the summer, first Minister permitting of course.

Happy Easter and enjoy the remainder of your weekend.

Stephen

ScotlandDirector@tr-register.co.uk

 

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  • 3 weeks later...

So its been a while since addressing my bonnet and carburettor issues, and I thought I would give an update of where I am at having tried a few things....

(The delay in replying was due to the usual constraints of life and job combined with the rather rash idea to resurface the garage floor and re-wire the place to have some more light having recently moved house and garage. One ton of self levelling compound later....)

Thanks to John a replacement inlet manifold arrived and the results are thus:

+ve The carbs now fit in the middle of the bulge and dont hit the bonnet
-ve The carbs are not any lower so I am not sure when the engine revs if they could hit anyway

The technical blu-tack test shows that there is a 1.5 cm gap between front carb and bonnet (one photo before bonnet was shut and other after). Is that enough to allow for movement when the engine revs?

The other photos show the height relative to the wings which compared to the photos from a while ago, are about the same. Perhaps this is not surprising as the manifold is longer but the angles remain the same.

Could it be that this engine setup was supposed to have Stromberg (?) carbs in the first place?

Is this enough of a gap to allow for normal range of engine movement ?

Tom

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Edited by solaise
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The TR4 should have a torque restriction device bolted to the front engine plate, it has an adjustable rubber buffer on a thread which you can screw out to very near touch the chassis side to restrict excessive torque reaction of the engine as it flexes on it's mounts.  Items 58 -61 on the diagram.

1259753574_Torquereationarm.thumb.jpg.06563acda66c2d4685806586870d7dbf.jpg

 

Mick Richards

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Although I fitted the torque reaction device mentioned by Mick, I wasn't too impressed with its capabilities, so devised a cheap and simple restraint device, which I described in TR Action 130 (May 1996), now in Section G15-G19 of the Technicalities CD. 

It will work on TR4 and TR4A, but not on the sidescreen cars, which are narrower.

Ian Cornish

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12 hours ago, Motorsport Mickey said:

The TR4 should have a torque restriction device bolted to the front engine plate, it has an adjustable rubber buffer on a thread which you can screw out to very near touch the chassis side to restrict excessive torque reaction of the engine as it flexes on it's mounts.  Items 58 -61 on the diagram.

1259753574_Torquereationarm.thumb.jpg.06563acda66c2d4685806586870d7dbf.jpg

 

Mick Richards

Though deleted as being unnecessary on 4a possibly due to different chassis engine mounting alignment as it wont fit on a 4a, I know I tried to fit one to mine and it doesnt reach to anything worth while.

Stuart.

Edited by stuart
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I think that, with 1’5 cm, you should have sufficient clearance. Your setup looks similar to mine, except that, as you can see in my prior picture, I have the valve cover breather well above the oil cap, and nothing touches the bonnet even when the engine is cold and the tick over irregular, which is when you tend to get more movements in the engine. Just give it a proper test drive

 

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I have just come across an article in Practical Classics  June 2019, with the same problem on a GT6. It was then fitted with HS6 sprint short dashpots, and the manifold was cut and rewelded to be square with the head flange.

John

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On 4/27/2021 at 3:21 PM, david ferry said:

Isn’t that a TR4a inlet manifold with H6 carbs?

David

Yes, that's what I see too.  Given that the carbs angle upwards, this combination will both make the carbs higher than "planned" and further from the engine. Both if these are likely to make fouling the bonnet/hood more likely I would think. 

Tim

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As I said before, my setup is the same: the longer TR4A inlets manifold with the also longer H6. I do see my dash pot covers are well above the engine cover, but no issues with the bonnet, so he should be OK with 1,5 cm clearance, which should be close to what I have

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