Webers

[Tr77]

Hi I'm gearing up to get my tr7 I just bought on the road and was wondering about putting Webers on it any advice?
Cheers George

[Hasbeen]

Hi 77. There is a great deal of difference from Weber to Weber, so how about a bit more detail.

Where you are located probably has an effect on what is available, & the fuel available to feed the things, so where are you.

Our experience with Webers is that they set you up for more power, if you do enough to the thing to exploit them. Just bolting them on has very little advantage, but will increase fuel consumption, for little gain.

In some places knowledgeable tuners are available for Webers, where no one will even look as an SU or Zenith carb. This could be the decisive factor.

Hasbeen

[Tr77]

Located in New Zealand and after I put the beast back on the road looking for the most power I can get out of the engine!

[Tr77]

Are zenith carbs as good as Webbers or a lot worse?

[Cobber]

As Hasbeen says, If your going all out for power and have the engine in a high state of tune then a pair of DCOE Webers ( not the DCNs that our friends in the US tend to use) will get the best out of that set up for carbs but proper fuel injection using multiple throttle bodies and a programable engine management system such as Emerald or similar will be better still.
I think that SUs will probably be best for mild to fast road tune, these have a huge range of jets & needles available to allow them to be tuned to get the best out of any tuning improvements you might have made.
The Zeniths don't have such tuning possibilities.

You would be spending a lot of $$$ getting the 8 valve engine into a state of tune to need Webers, I would suggest starting with the 16 valve Sprint engine and going to town on that.

[FI Spyder]

Or for the same or less money and way more power go for the Buick rear drive V-6 (or your equivalent down under, if you have them there.) In N/A the Sprint engine was never imported so everything has to be imported from UK, Rover V-8 are around but not that common and of course any 60's Buick V-8 is going to be in some collectors garage. With headers/low restriction filters/compression/porting/carb tuning you can get some horsepower increase but there are easier/cheaper ways to get hp that is meaningful. Or you can not chase the hp dragon and just drive it for what it is and not pursue the Japanese boy racers.

[Tr77]

Cheers for that. May try get my hands on a sprint engine or head! I may have to check out the 16v page haha

[John_C]

The 16 valve engine gives you little above what you can get out of the 8 valve engine unless you really want to go to extremes with tuning it. Remember the capacity of the 16 valve and 8 valve engines are the same so you'll be spending an awful lot for not very much.

For Weber carbs though you will need a new inlet manifold, thermostat housing and all manner of other paraphernalia associated with the conversion. Others will correct me if I'm wrong but with a change to SUs you'll only need the carbs themselves. Richer needles than standard are required if you go down the recommended route of an extractor manifold with through-flow exhaust and a fast road profile camshaft with uprated valve springs (tappets will need re-shimming and at this stage make sure none of the buckets are warped which is a common problem) and you'll have a fairly quick car. Brakes will need to be in tip-top shape as will the suspension but this can all be repaired or improved later on if required. Knowing what I know now I'd do all that first though.

And get rid of that giant fan housing off the engine which will significantly improve the revving ability of the Triumph slant 4. Any electric fan will do but I use a Kenlowe and have for 30 years now.

[Tr77]

Thanks John! It is my first project car and the first car I have bought myself would a rover v8 conversion be well out of my capabilities? I know a decent amount and do a bit on my current car a Morris minor.
Cheers George

[sonscar]

Who knows?Depending on your tenacity/desire/boredom threshold/cash it could be easier or harder,longer or shorter time to do.I cannot speak from TR7 conversions but lessons learned when I converted my MGB roadster,which on the face of it,seems to be a "bolt in conversion" it was not difficult as there already existed lots of others so all the groundwork is out there.However it was very time consuming and I soon stopped costing it in as it appeared to be spiralling.Was it worth it?At the risk of offending people;yes and no,it is powerful and quick and has lots of torque but to use it anywhere near it's capabilities needs more then normal roads.Saying that I am a fan of smaller harder working engines and love to rev.The V8 loves to rev too but the speeds seen become dangerously high,so it does not suit me.You and others may like it.Wish I had found one to try before doing it.Good luck and enjoy whatever you do.Steve..

[John_C]

If the cylinder head comes off then it's all rather easy except perhaps for getting the correct shims in the buckets to set the tappet clearances. When I first did mine 30 years ago the larger shims required were available (mainly from Saab dealers as I have the highest lift cam possible) but nowadays it may not be so easy. My head was off 8 years ago for checking and the shims required were worked out and made for me by an engine reconditioning house so that proved to be even easier than when I first carried out all the work.

A Rover V8 is a conversion a lot of people have done so you may find that even easier. This assumes you have a five speed car already of course. If you've got a four speeder, forget it!

[Tr77]

Thank you everyone for the advice I'll be carrying out the work over the summer so I have the time! Money may be a restriction though. I'll give it a crack anyway!

[Hasbeen]

TR77 if you have Zenith carbs you probably have a US spec car. US spec car with a detuned low compression engine to meet their emission requirements. This means 90 BHP when new, less of course those that have died of old age, or escaped. Just fitting UK spec pistons would give a big jump in power.

You can make a 30% increase in power very easily. A 7 with 125 to 130 BHP, if you have not gone silly with the cam, is a very useful car, with lots of mid range torque.

A set of SUs is a good investment. The ones from a Triumph 2500 or 2500S saloon particularly, are most suitable, & you can pick up the whole car for less than a set of Webers.

Our tuning guru reckons he can get 170 BHP with either SUs or Zenith, but that is the limit of the bottom end, & requires very high compression, & is not suitable for road use.

As Cobber says SUs have a greater range of bits to make for easy tuning, & the required needles & jets are reliably available locally.

I would suggest you make sure you have a good cam, with valve clearances to suit it, not worn, & not a bad regrind, good compression, a set of extractors & suitable tailpipe, suitable main jet needles, & easy flow air filters. I would look for SUs to do this.

This should give you about 125 BHP, with really strong mid range 2500 to 4000 torque. This is how my 7 is set up, & I easily keep up with higher tuned 7 on club runs. Below 100 Km/H it's top gear performance is stronger than my Honda S2000.

Hasbeen

[jeffremj]

170 bhp is the max you can get from 2 HS6 SUs, as per this diagram from an SU tuning book:



Note that the power would probably be at very high revs - 8000rpm?

My TR7 16V only got 140bhp with twin SUs and this was with a DIY ECU called megajolt lite jnr.:



My TR7 16V power run:

https://www.youtube.com/watch?v=ncpEtvBk9CM