Webers wanted but.......

[Motorsport Mickey]

Hamish, 

Stuarts on the money, 40s sidedraughts are less sort after ( everybody fools themselves that 45s or 48s ( not getting at you Rod) will be better, but of course on the road never are, you just can’t use the extra flow beneficially. Also The 40s are much more flexible in mid range say up to 4500-5000 revs which is where you live when sprinting. 
Then to “gild the Lilly” a little more, if you choose 40s Dellortos, the Weber name carries more bragging rights ( many people who ask say “Weber’s “? Not knowing that people who do ,rate the Dellorto as the equal if not better. So the Dellortos 40s would be my choice for sprinting and road use.

PS: Just as Teriann says

"If you intend to keep the engine at or below 5000 RPM, the 40DCOE will provide you with your best all around power curve. This will handle fast street applications and 5000 max RPM auto crossing quite well and give you lots of low end flexibility. The 34 chokes will give you fast street and you can choke down for additional low end grunt or better fuel economy. As a comparison, the 2L Alfa Romeo engine was equipped with 40DCOEs and 32mm chokes from the factory for both power and economy. So this combination should provide adequate power and economy for a 2L ex-tractor engine. "

Substitute Dellortos for Webers and you get all this AND change in your pocket.

Mick Richards

 

Edited June 29, 2020 by Motorsport Mickey

[Motorsport Mickey]

33 minutes ago, Hamish said:

No not thought of bigger SU’s anyone done it ??

As you may expect yes, been there done that in 1987.
We had the best developed head and flowed inlet manifolds... and yet couldn’t get the 2” SU pistons to get to full lift, resolutely stopping at about 3/4 hole opening ( viewing on the rolling road with engine on full chat). Conversely the 1 3/4 SUs would fly up to full aperture as the revs passed 5000 and  gave great power.

Review the people who race and have won and see what they used, doubt if 2” SUs were part of it, and if it did They would have done even better  with other carbs.
The only time we got full piston lift on 2” SUs was with cables to lift them. Took off like Billy Whizz But you needed a right leg like Schwarzenegger to break the vacuum onto the piston from the bridge, no good for variable throttle openings and therefore racing.
Which is how we realised we needed a carb  with an air bleed to break the vacuum  to use, Hhmmmm if only we could find a 2” SU with an air bleed, Or even twin chokes.... just like a SU DU6 !  but they only made 85 x DU6 which is why we went and found some.... but that’s another story.

Mick Richards

Edited June 29, 2020 by Motorsport Mickey

[stuart]

1 hour ago, Motorsport Mickey said:

As you may expect yes, been there done that in 1987.
We had the best developed head and flowed inlet manifolds... and yet couldn’t get the 2” SU pistons to get to full lift, resolutely stopping at about 3/4 hole opening ( viewing on the rolling road with engine on full chat). Conversely the 1 3/4 SUs would fly up to full aperture as the revs passed 5000 and  gave great power.

Review the people who race and have won and see what they used, doubt if 2” SUs were part of it, and if it did They would have done even better  with other carbs.
The only time we got full piston lift on 2” SUs was with cables to lift them. Took off like Billy Whizz But you needed a right leg like Schwarzenegger to break the vacuum onto the piston from the bridge, no good for variable throttle openings and therefore racing.
Which is how we realised we needed a carb  with an air bleed to break the vacuum  to use, Hhmmmm if only we could find a 2” SU with an air bleed, Or even twin chokes.... just like a SU DU6 !  but they only made 85 x DU6 which is why we went and found some.... but that’s another story.

Mick Richards

FWIW 1 3/4" SU`s were also happy to run 3.8 Jaguar engines up to 220HP but they were red lined at 5500 though the best rev range was 3500 to 4000. They only went to 2" SU`s when they increased capacity to 4.2 with a red line at 5000.

Stuart.

[roy53]

Yes i have used 2" SUs following another very potent 3a advice.

Yes Mick i have had race wins with all 3 types 1 3/4   2"   and 48s , agree these may be a bit big for road use. All on the same engine set up by MASS

The 2" SUs were the type used on the D type Jags which took a bit of finding and plenty of cash when finally located on ebay.

will look at the model no when i go to the garage tomorrow , i seem to remember D in the model number

Roy

[stuart]

14 minutes ago, roy53 said:

The 2" SUs were the type used on the D type Jags which took a bit of finding and plenty of cash when finally located on ebay.

will look at the model no when i go to the garage tomorrow , i seem to remember D in the model number

Roy

Are you sure your not referring to DU6 Roy as referred to above by Mick.

 FWIW D types actually used Webers from the start.

Stuart.

Edited June 29, 2020 by stuart

[roy53]

[stuart]

1 hour ago, roy53 said:

Thats standard HD8 as fitted to E types.

Stuart.

[NigelH]

Jags and Healeys running 2" SU's were offered with 'red'(common on many SU carb sizes) and particularly 'black' springs too, only 4.5 oz, probably to improve the lift problem mentioned earlier?

Nigel H.

[ntc]

So basically back to the point, you can only get more power by the amount of air/ fuel you can get in as well as out, Weber's or types of do this better by serving each cylinder on there own.

[Hamish]

Thanks Neil. 
Cut to the chase as usual. 

[roy53]

yes HD8 rings a bell

[Bleednipple]

Very interesting thread. I've no experience with twin-chokes but have heard it said that Webers (and presumably Dellortos) are much more pernickety than SUs. But after they've been set up properly on a rolling road, do they need much ongoing fiddling with?

Sorry I'm sure that's been debated a lot on the forum before, but as we currently have some experts on here...

Nigel

[ntc]

2 minutes ago, Bleednipple said:

Very interesting thread. I've no experience with twin-chokes but have heard it said that Webers (and presumably Dellortos) are much more pernickety than SUs. But after they've been set up properly on a rolling road, do they need much ongoing fiddling with?

Sorry I'm sure that's been debated a lot on the forum before, but as we currently have some experts on here...

Nigel

Nigel

None that’s where a lot go wrong set up right and they are fit and forget just keep all fuel and air filters clean 

[Motorsport Mickey]

Nigel,

I'm with Neil,

I think that's a good example where supplying a product which is almost infinitely variable can cause more heartache than a product with more broadly set parameters.

The Webers and even more so the Dellortos can be tweaked many different ways, which is good,...but not if you choose the wrong way ! If set up with a good technically able operative (preferably on a rolling road) the different tweaks can refine the Twin chokes operation and once set they are very robust and will stay at the operating parameters.

The SUs these days suffer with not enough experience in many of the tuning shops unless specialist in more classic machinery. Especially because the tuning often reflects the operatives skill in defining how a carb with more restricted tuning opportunities reacts, part science, part art.
I was fortunate to find Peter Burgess without doubt one of the best SU tuners available these days.

 

Mick Richards

Edited June 30, 2020 by Motorsport Mickey

[andyhall]

Hi, I agree very interesting thread, Mickey, I've hear of the term "offsetting" before but what does it mean?

Andy

 

Edited June 30, 2020 by andyhall
mistake no font

[andyhall]

I agree, very interesting topic, Mickey< I've heard the term "offsetting" before but what does it actually mean?

Andy

[Motorsport Mickey]

Hi Andy,

Welcome to supertuning the TR engine.

The head on the 4 cylinder TRs is what is called a "bathtub" design, quite common in the era when the Standard Vanguard was designed (late 1940s but with pre war influences). The valves are pocketed (the bath tub) in position on the cylinder head, but because of space limitations (the head design and getting inlet and exhaust to exit the head in the correct position) the valves are pushed up tightly towards one side of the chamber as viewed in the attached diagram

The otherside of the chamber has a "squish" area where the incoming fuel charge is "squished" by the upcoming piston top helping it turbulate and mix correctly, the chamfers found on some of the heads help this fuel charge reach the extremes of the chamber easier. The normal modification for more power is to get more fuel mix into the chamber...bang ! more power, but the inlet valve position is not only squashed by the edge of the bathtub (where it says "sharp edge to remove after milling on the diagram) it is also hindered by the outside radius of the liner which the valve comes very close to. Fitting any larger valves than those commonly in use in performance TR engines only chokes up this flow. If you look on the second diagram you can see where the headgasket shape has been scribed (lightly) into some engineers blue wiped upon the area. The overhanging lip has been completely removed so as not to block the fuel charge from the inlet valve in that area, and this modified chamber shape will be transposed upon the top of the liner where it overlaps. (wipe the liner top in blue and then a merest smear of grease, fit the head and clamp lightly, remove head and where the grease has been cut into by the head scratch a light line into the blue). Clean off the grease leaving the marked blue on the top of the liner, the liners are then filed (that's what I do) with a fairly rough half round file into the wall of the liner thinning it up to the scratched line which marks where the head and it's gasket will be fitted. It's important that an angle be adopted upon the file when removing the metal so that the bottom of the chamfer (that's what it is) doesn't come any closer than about 1/8th from the top ring of the piston (do it by eye, thereabouts is fine) to avoid damage to the piston and ring.

All this is documented above and is pretty standard stuff, however the offsetting of the head is what REALLY releases the TR engine power. When we were developing the 1988 head we were trying to move the valves themselves more into the centre of the liner and give more freedom to the incoming charge that is restricted by the liner walls, more flow equals more power. Flow bench testing with Peter Burgess proved a large power increase could be achieved if only the valves and the bathtub chamber could be moved more centrally across the liner and away from it's walls. The engineering looked to be a problem, offset valve guides are not unheard of but have problems of their own, uneven heating upon the walls and transmission into the head, and developing a Z plate which has angled surfaces to match up the opposing surfaces whilst imparting an offset to the chamber would require two sealing surfaces and various other tricky and likely failure points.

So why not move the head in it's entirety ? Somewhat radical and as far as I know not practised by ANY other TR tuner, determined to give it it's best shot and worried about gaskets crossing sealing surfaces I decided moving the studs across would give the best chance of success. The sealing surfaces are not compromised. So cast iron studs (as close to the material of the block to minimise different expansion) were made to the appropriate cylinder head stud dimensions threaded one end and screwed into the block with Loctite 648 and then the studs cut off flush leaving a smooth deck surface with no stud holes. The head was fitted 3 mm across the block towards the exhaust side in exactly the same position as normal front to rear (premachined slip gauge slots), and set upon a Jig borer the head stud holes transposed onto the cylinder block deck surface and then the stud holes redrilled  into the block (including the deep studs,...no they don't break through anywhere.). This leaves a crescent shape of threaded and glued in new stud material in the Block alongside the stud holes. The new holes were threaded as per standard to take standard studs, and trial fittings transposed the cylinder head chamber sealing edges marked lightly onto the deck and liner surface to prove all was well. Where the cylinder head oil feed comes up from block to cylinder head I compared the new steel head gasket slipped over the newly fitted studs in position and marked the block surface for position for the oil feed to a 3mm different centre further across matching the offset head. Attacking it with my Black and Decker (this was winter 1988) I "chavelled" (technical term, part drilling part milling) freehand along the surface (no slipping) an oil way feed linking block to the now offset head position, the new steel head gasket when cut slightly removing surplus metal on the edge allowed the channel and holes to remain within the sealing ring. The steel headgaskets were also cut around the inlet valve area around each chamber and the remainder of the liner only using half of one of the gasket 2 pressed sealing rings to seal on...successfully. That car won the TR Register Championship in 1988 setting new track records, and again in 1989 after bearings and rings being refreshed driven by Chris Conoly as I was busy developing the TR7 V8 for future TR Register racing.

That's it, before offset head 132hp back wheels previous season on 1 3/4 SUs. The new head to take the bigger valves, more unrestricted flow and the more aggressive modding it allowed,  offset across the block using the same 1 3/4 carbs ...148hp back wheels. Same engine but on 45mm Webers 165hp back wheels, that's how an offset head works, now used almost universally, I don't know any 4 cyl racer now who doesn't do it...including in the US. That car and it’s engine are still racing today.

Oh and in Terriannns head review it's mentioned "that in the UK a popular mod is to move the head but it sometimes causes unreliability". I think she's been mislead (probably by racers trying to maximise their offset head advantage) I never had any problem with sealing or other problems on mine, but you have to build it carefully.

These days the offset heads are made using slotted cylinder head stud holes and pushing the head across, a lot easier, same difference and looks like I worried unnecessarily, they seem to seal fine also.
Oh...and to prevent other racers realising what had been done, when the offset head had been bolted onto the bare block we put all of it on a miller, and milled and removed the 3 mm step of the block edge sticking out below the head fitted and now exposed from the offset head on the distributor side (the manifolds and other junk hide the overhang on the drivers side ) and painted it black...tricky eh ?

Mick Richards   

 

Edited July 1, 2020 by Motorsport Mickey

[NigelH]

1 carb per cylinder..

[Motorsport Mickey]

Johnny,

PM sent but I think your account is full, let me know.

Mick Richards

[Hamish]

As an aside - follow on. 
 

yesterday I spoke to my rolling road guy, mike. He has looked after my carb tuning for a few years and did my head gasket replacement as soon as I got the car. He is used to classics of all sorts. He sets up a 250bhp Healey and had a classic formula ford on the RR yesterday.

i discussed with him carbs And my thought over webers. He thought the the H6 should be fine and capable of more power ( I have 116 at flywheel). Thus we talked cams. mine is unknown apart from a mid 1970’s revington fast road one!! and I know tech has moved on but in the old days the likes of SAH was producing power parts that worked. 
 

mike has suggested altering cam timing with vernier. But not sure we can undertake a process of vernier adjustments and rolling road each setting ?

i can easily remove the apron but does the rad have to be out to carry out multi vernier settings ? Which would critically hamper rolling road testing each time.

he wonders if anyone has modified the timing chain cover to allow this easy(er) access to vernier adjustment on insitu engine/rad etc 
 
oh and taking compression above 10:1 ( currently about 9.5:1) with head skimming. 
 

thoughts ?

[Motorsport Mickey]

Never seen this mod done but the timing covers are available cheaply especially if slightly damaged or worn by a timing chain tensioner (£10 ?).

I would be tempted to look at one to see if it could be split across with a hacksaw and the top half removed with an underlapping steel lip added to the bottom fixed half (welded to it say 10mm or so sticking out) and then a thin rubber seal added to the lip sticking out to help seal against oil seepage (there's minimal excess pressure pushing oil out) . Then when the adjustments have been made if the split timing cover is not completely oil sealed remove that cover and use the original one piece version to run and race on. There's a way to do it, experimentation will show whether it's a goer.

Mick Richards 

[Hamish]

1 hour ago, Motorsport Mickey said:

Never seen this mod done but the timing covers are available cheaply especially if slightly damaged or worn by a timing chain tensioner (£10 ?).

I would be tempted to look at one to see if it could be split across with a hacksaw and the top half removed with an underlapping steel lip added to the bottom fixed half (welded to it say 10mm or so sticking out) and then a thin rubber seal added to the lip sticking out to help seal against oil seepage (there's minimal excess pressure pushing oil out) . Then when the adjustments have been made if the split timing cover is not completely oil sealed remove that cover and use the original one piece version to run and race on. There's a way to do it, experimentation will show whether it's a goer.

Mick Richards 

Found this pic of a tr6 modified cam cover here

https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1972-triumph-tr6-looking-for-a-purpose/90123/page8/

but I don’t know if it’s enough to use the vernier sprocket On a 4 pot 

https://www.trgb.co.uk/products/vernier-cam-gear-tr2-4a

but I understand that the standard sprocket has 4 positions that are 1/4 of a tooth each.

[ntc]

2 hours ago, Hamish said:

As an aside - follow on. 
 

yesterday I spoke to my rolling road guy, mike. He has looked after my carb tuning for a few years and did my head gasket replacement as soon as I got the car. He is used to classics of all sorts. He sets up a 250bhp Healey and had a classic formula ford on the RR yesterday.

i discussed with him carbs And my thought over webers. He thought the the H6 should be fine and capable of more power ( I have 116 at flywheel). Thus we talked cams. mine is unknown apart from a mid 1970’s revington fast road one!! and I know tech has moved on but in the old days the likes of SAH was producing power parts that worked. 
 

mike has suggested altering cam timing with vernier. But not sure we can undertake a process of vernier adjustments and rolling road each setting ?

i can easily remove the apron but does the rad have to be out to carry out multi vernier settings ? Which would critically hamper rolling road testing each time.

he wonders if anyone has modified the timing chain cover to allow this easy(er) access to vernier adjustment on insitu engine/rad etc 
 
oh and taking compression above 10:1 ( currently about 9.5:1) with head skimming. 
 

thoughts ?

Hamish

With respect I thing he is wrong, with a mild cam you will achieve very little gain for the work involved. Time for you to decide for fast road car with the odd bit of racing or change to race spec, you seem to enjoy what you are doing now yes I know there will be a compromise but that sums it up to me.  

[Hamish]

9 minutes ago, ntc said:

Hamish

With respect I thing he is wrong, with a mild cam you will achieve very little gain for the work involved. Time for you to decide for fast road car with the odd bit of racing or change to race spec, you seem to enjoy what you are doing now yes I know there will be a compromise but that sums it up to me.  

You very well could be right.

i have too much time ( not enough money) on my hands during this furlough - and lack a life away from tinkering in the garage. 
 

What I really need to do is try out my rear axle and Front suspension mods at a little sprint track. 
 

but “looking into mods” is 80% of the fun !!

what else would you all be doing  if not guiding me !!

it is appreciated you know. 

[ntc]

1 hour ago, Hamish said:

You very well could be right.

i have too much time ( not enough money) on my hands during this furlough - and lack a life away from tinkering in the garage. 
 

What I really need to do is try out my rear axle and Front suspension mods at a little sprint track. 
 

 

Now you are thinking on the right lines  its no good getting fast to the corners only to find out it don't go round it  as for testing that can be arranged