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Hamish

Curborough fig 8 sprint 14-4-19

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A couple of runs from Sunday’s sprint  

first comp of the season  

 

 it was soooo cold the track never warmed up  

Here are a few of my runs. 

Practice 1

a very cautious first run of the year on a very cold green track  

Run 1 

 

Run 2

and personal best time 75.09 despite misfire over the line  



 

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To be honest Nick I think it’s sound over substance. I have a remote microphone near the tail pipe. I was worried about scrutineering. But the environmental/noise scrutineer noted the sound as 88dB(A) which surprised me but in a good way. 

the exhaust system may have affected the top end, I may have lost some scavenging effect as the headers are quite a bit bigger than previous. As my rolling road bloke dryly said - louder isn’t always faster young’un !!

not in a position to buy multiple manifolds. When mine rusted through - it was fitted in 1976 and welded a few times ! I bought a second hand extractor. So I have to live with it now. 

But what I need to concentrate on is body roll and suspension as I feel I loose drive through the corners.

in the car it feels really good, especially as I still have the steering box. So I don’t want to ruin anything  but I may try the TR4a front set up to give me some camber and slightly stronger front springs it’s reversible spanner work !

what do you guys think ?

H

 

 

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12 hours ago, Hamish said:

and personal best time 75.09 despite misfire over the line  

unless something traceable ignition wise that misfire sounds like fuel to me, i know you have fitted an electric pump, but do you have a pressure regulator fitted, have you checked what pressure you have at the carbs, where have you taken power supply for pump from, sharing with coil? if you havent fitted the electronic ignition yet, when you do make sure it has a good and solid 12v supply (not something that drops to 9-10v when something else is running, they can really play up on low voltage.

3 hours ago, Hamish said:

But what I need to concentrate on is body roll and suspension as I feel I loose drive through the corners.

i

first left hander (and a couple of other places)you are going up into 3rd before the corner and then going through on trailing throttle rather than driving through hard in 2nd (car will be far more settled under power, also listening to engine the revs don't increase after change to 3rd so would have stayed at about the point they were in 2nd (and in fact you probably had a few more hundred revs you could have pulled and held  in second (if you hadn'tthought time to change up before the corner) for the few secs or so elapsed through the corner

alan

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Do you have a front anti-roll bar fitted?  Honestly can't remember if my TR2 has one or not, but it's still being slowly restored (by me... the fact that I can't remember this should give you some idea of how things are progressing :) )

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no TR prior to 4A came with a factory fit anti-roll bar, which makes for an interesting discusion for those wanting to run one in class 1 road going where the addition or alteration of roll bar size is not allowed

alan

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Thanks for the thoughts. 

The elec fuel pump is powered from the main fuse “box” there are just 2 fuses. 

Pump pressure is 2.2lbs which I think is also right for the twin SU’s

this time I was trying either 2nd through the twisty bits or 2nd od. 

2nd was far to rev by 6k ( red line at 5k)

2nd od felt better through the twisty bits and it is 3rd over the line. 

I have a feeling that the last ( fastest run) I just over revved it and should have taken 3rd od or 4th. 

All my previous runs I was 73mph over the line, the misfire held it back to 68mph, as it was still a faster time I think I was carrying more speed out of the last corner thus reached peak revs earlier. Lucky not to blow it I think. 

The track was really cold but rubbered in noticeably by the end which is where my time came from.

I haven’t fitted the electronic ignition yet. I want to understand where my timing is at the moment and get used to my new timing light before I start messing.

my car had a 9/16 anti roll bar when I bought it. A very in period mod as I understand. Mounted on the bumper irons. 

I have since upgraded to a spitfire 7/8th version. 

H

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On 4/17/2019 at 11:56 AM, oldtuckunder said:

that misfire sounds like fuel to me

I agree.   Is the fuel tank baffled/foam filled?   That can help, but also check the float depths on the carbs - I had this recently when my car ran brilliantly and pulled like a train - until it didn't - and was misfiring like that and, of course, I spent (wasted) ages checking the ignition/timing/plugs etc. but it turned out to be one of the floats on one of the carbs was mysteriously well out..  

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On 4/17/2019 at 3:10 PM, Hamish said:

Pump pressure is 2.2lbs which I think is also right for the twin SU’s

they will happily take 3.5, but the question is where are you measuring it actually at the carbs or somewhere else, the most critical thing will also be have you got enough flow at sufficient pressure at the critical points. are you relying on the pump to control the pressure or do you have a pressuure regulator fitted?

On 4/17/2019 at 3:10 PM, Hamish said:

I have a feeling that the last ( fastest run) I just over revved it and should have taken 3rd od or 4th. 

All my previous runs I was 73mph over the line, the misfire held it back to 68mph,

as you have the numbers, gear ratios tyre size etc should be a simple calc to work out what revs you were doing across the line in 3rd and if that was in a range where you would have expected to have no fueling problem or not, or were you heading into valve bounce territory?

alan

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29 minutes ago, Hamish said:

Last run it wasn’t fine but a faster run time

thats because you were going quicker elsewhere :D i'm still fuel suspicious or a plug breaking down from the noise

alan 

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