GT mediated Awesomeness

[saintjamesy89]

Good luck with the new carb Jugostran! Fingers crossed it solves some issues! The GT was 105bhp at the crank from new

[Jugostran]

Good luck with the new carb Jugostran! Fingers crossed it solves some issues! The GT was 105bhp at the crank from new

Thank you! Also, thanks for that bit of info! It's quite surprising then how much the BX 16 TRS with 2 barrel carb (XU52C) makes. It's only 15 hp off with around 300 cubic cm less. I think we have the Solex 32/34 Z1 to thank for that
It's quite interesting how they used the same carburetor for the sporty GT and the architect-spec 16 TRS hah.
I am taking the kit and the car to a trusted mechanic to do the rebuild and adjustment. I can't wait for the results!

[Jugostran]

Hey there!
How's progress on your GT?
Anyway, I have but one question to ask. I'm looking into buying some GT wheel trims for my 16 TRS (because it apparently came with those from factory), but I am not sure how they mount to the wheel. I'd love to see some pictures of the front and back of the trim, and a bit of a close up of how it gets affixed to the wheel.
Thank you very much in advance, it'll be a huge help!

[saintjamesy89]

Happy new year everyone! We were up celebrating until nearly 4am this morning so I'm a little worse for wear

I'll see if I can get you some pics Jugostran, the trims clip into a plastic ring that is a push-fit in the steel wheel.

The GT has been busy, the OH was using it for two weeks whilst our Lexus was in for MOT and waiting on some suspension bushed, it has done 1000 miles in the last 6 weeks! This means the tired rear arm and wheel bearings are even more so, hence there are plans afoot. A pair of good rear arms have been sourced with new arm bearings already fitted, new wheel bearing hubs are ready to be fitted. Whilst the car is immobile I'll send the front calipers off to be refurbished, then when it's all back together I can replace the hydraflush with LHM, clean the reservoir and bleed everything. Several birds, one stone

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I'm not happy with the new carb still, performance is unreliable - sometimes it feels good but sometimes not at all, also when your holding a constant speed it's a bit fidgety and not smooth. Irritating. I'm not sure if the carb needs adjusting again or if the distributor vacuum advance is knacered, either way I'm looking into EFI conversions but I'm not sure how I feel about that yet, it is a GT after all - not a GTI.

[Jaba]

Nothing worse than a car that is not running smoothly for no obvious reason. BTW its easy to check the dizzy advance diaphragm and mechanism by sucking on the vacuum tube.

[saintjamesy89]

Nothing worse than a car that is not running smoothly for no obvious reason. BTW its easy to check the dizzy advance diaphragm and mechanism by sucking on the vacuum tube.

Ah, great - thanks John. I'll give that a go

[Jugostran]

Happy new year everyone! We were up celebrating until nearly 4am this morning so I'm a little worse for wear

I'll see if I can get you some pics Jugostran, the trims clip into a plastic ring that is a push-fit in the steel wheel.

The GT has been busy, the OH was using it for two weeks whilst our Lexus was in for MOT and waiting on some suspension bushed, it has done 1000 miles in the last 6 weeks! This means the tired rear arm and wheel bearings are even more so, hence there are plans afoot. A pair of good rear arms have been sourced with new arm bearings already fitted, new wheel bearing hubs are ready to be fitted. Whilst the car is immobile I'll send the front calipers off to be refurbished, then when it's all back together I can replace the hydraflush with LHM, clean the reservoir and bleed everything. Several birds, one stone



I'm not happy with the new carb still, performance is unreliable - sometimes it feels good but sometimes not at all, also when your holding a constant speed it's a bit fidgety and not smooth. Irritating. I'm not sure if the carb needs adjusting again or if the distributor vacuum advance is knacered, either way I'm looking into EFI conversions but I'm not sure how I feel about that yet, it is a GT after all - not a GTI.

I am sharing the pain in terms of carb issues. Mine now runs better and the fuel usage is better, however some things have gone wrong in the meantime. Namely, it now likes to stall from time to time. No reason, it'll just lower the idle so much that it stalls itself. I bet this is an issue with the autochoke. Also, performance can be spotty. Sometimes its excellent and it really does "go", but other times it just does nothing. There is no smoke present, so I am really not sure what the deal is. Anyway, good luck with the repairs on yours. I have given up on mine until I gather more information about how to go about sorting the carb.

[saintjamesy89]

That sounds a bit rubbish! If you think the autochoke is playing up this is likely the cause of your performance irregularities. If the autochoke is on, the 2nd venturi won't open - so you'll only be using the 32 bit at full throttle with the 34 disabled by the choke.
This is my understanding though, might not be wholly correct!

[Jugostran]

That's the ticket. I know this has been happening before, but it started again. However, I think it may have something to do with the cooling system. The autochoke operates based on temperature. There may be buildup in the system causing irregularities. The autochoke was cleaned out, but it may have become dirty again. I think the solution is to take it off (again) and then do a superflush of the cooling system. I'll drain it, put in distilled water and some sort of flushing liquid just to clean out all the crud.

[mat_fenwick]

The rolling road graph looks a bit spiky to me, and based on the one carb'd vehicle I've had tuned on a rolling road would expect it to be smoother - so that probably manifests itself in jerkiness. If the vacuum advance isn't working then this would not affect full throttle performance (its function is to advance the timing at low engine loads, for economy) so I wouldn't expect it to cause these issues.

[saintjamesy89]

The rolling road graph looks a bit spiky to me, and based on the one carb'd vehicle I've had tuned on a rolling road would expect it to be smoother - so that probably manifests itself in jerkiness. If the vacuum advance isn't working then this would not affect full throttle performance (its function is to advance the timing at low engine loads, for economy) so I wouldn't expect it to cause these issues.

I was a bit disappointed with the rolling road tbh, hopefully as far as jetting and AFR etc goes it all OK, but to only use 2500-5000 rpm and as you say Mat, it being less than smoith gives me less confidence.

The full throttle performance is either there or not, today it felt great, i even had a surprised smile on my face, but 10 minutes later it felt sluggish, it can vary at any time. The jerkiness is most obvious coming on/off the throttle and to a lesser extent at a constant speed around town and faster.

I haven't sucked on the pipe yet! The carb end has my greasy/oily fingerprints all over it so don't really fancy sucking on that Need to clean it first.

I do miss the induction roar of the original CISAC carb at WOT, this one is quite different. I'm still musing about an EFI conversion to remove the vagueness of carbs, but getting hung up on GT=carburetted and GTI =EFI. I'd be interested in the BX folks thoughts, not that I'm worried about being shunned for EFI converting a GT!

[jamescarruthers]

How is the fuel pump? Is it mechanically driven on a carburettor BX? I ask because a lot of engine driveability issues on my petrol Mk. 1 Master were cured by adding an online Malpassi combined pressure regulator (I think it had combined filter in it too).

[saintjamesy89]

How is the fuel pump? Is it mechanically driven on a carburettor BX? I ask because a lot of engine driveability issues on my petrol Mk. 1 Master were cured by adding an online Malpassi combined pressure regulator (I think it had combined filter in it too).

Ah, interesting It's the original camshaft driven mechanical pump that the car had when I bought it 10 years ago! So you kept the mechanical pump but just fitted a FPR? I guess it'd also work as a non-return valve which would help with starting.

[jamescarruthers]

How is the fuel pump? Is it mechanically driven on a carburettor BX? I ask because a lot of engine driveability issues on my petrol Mk. 1 Master were cured by adding an online Malpassi combined pressure regulator (I think it had combined filter in it too).

Ah, interesting It's the original camshaft driven mechanical pump that the car had when I bought it 10 years ago! So you kept the mechanical pump but just fitted a FPR? I guess it'd also work as a non-return valve which would help with starting.

I was advised to install as the lobes that drive the pump can wear a bit. Idle was smooth as silk, pickup better (it was mainly driven flat out with its engine size and vehicle size!). Not sure of the NRV properties but it woud make sense if it did that too.

[Jugostran]

The rolling road graph looks a bit spiky to me, and based on the one carb'd vehicle I've had tuned on a rolling road would expect it to be smoother - so that probably manifests itself in jerkiness. If the vacuum advance isn't working then this would not affect full throttle performance (its function is to advance the timing at low engine loads, for economy) so I wouldn't expect it to cause these issues.

I was a bit disappointed with the rolling road tbh, hopefully as far as jetting and AFR etc goes it all OK, but to only use 2500-5000 rpm and as you say Mat, it being less than smoith gives me less confidence.

The full throttle performance is either there or not, today it felt great, i even had a surprised smile on my face, but 10 minutes later it felt sluggish, it can vary at any time. The jerkiness is most obvious coming on/off the throttle and to a lesser extent at a constant speed around town and faster.

I haven't sucked on the pipe yet! The carb end has my greasy/oily fingerprints all over it so don't really fancy sucking on that Need to clean it first.

I do miss the induction roar of the original CISAC carb at WOT, this one is quite different. I'm still musing about an EFI conversion to remove the vagueness of carbs, but getting hung up on GT=carburetted and GTI =EFI. I'd be interested in the BX folks thoughts, not that I'm worried about being shunned for EFI converting a GT!

An EFI conversion would be quite painful. I considered doing it to mine, but it just isn't worth it. You'd need an ECU and wiring harness, a bunch of sensors, different intake and a different fuel pump. We really need to figure out whats wrong with our carbs. I have a new fuel pump installed. Cold starts always result in a stall before coming on second try. Top end power has the exact same issue. Sometimes there is power, sometimes there isn't. When there is, it feels so fucking good. But usually it's...blegh. It's either the vacuum advance (mine is leaking a bit of oil) or the autochoke mechanism.