Weber Manifold Needed for pattern

atomman

atomman

Club Member
Morning

I posted an advert in the wanted section a while ago for a weber manifold to convert my 240 to tripple carbs but no luck yet,

But I did a favour for a pattern maker the other day and he said that he would make me a pattern so I could get some manifold's cast up in return,

It would be a lot easier if I had one to copy than to start from scratch,

So was wondering if any of you nice people in the club had a spare one lying around gathering dust in your shed/garage or workshop i could possibly borrow to get some decent measurements from,

I could then do a run of them for club memebers who need them at a good price as it would be better to make a few rather than just one for me,

If anyone could help it would be great :thumbs:

Gary
 
atomman

atomman

Club Member
Thanks Ben was nice to meet you on Saturday,

I went to the pattern makers this morning to disscuss the job and give him the manifold to make the pattern, He told me he would make a start this week :)

I planing on doing a run of 5 manifolds but will keep the pattern so could make more,

I have not worked out total costs yet as they need to be machined after casting and I need to modify the current linkage to work with the standard stock linkage on the bulkhead,

But im hoping to have a complete package with studs and linkage thats bolts on,

If anyone in the club wants one just let me know,

Gary
 
J.alexander

J.alexander

Forum User
Hi Gary,

I'm restoring a 240z and planning on putting it on motorbike injection. Just wondering if you would be prepared to sell me a set of raw castings un-machined as I will be able to do it myself and modify them to fit at the same time.

Cheers,

James
 
S

SKiddell

Well-Known Forum User
Respectfully
Will this give you as good a results as some of the high quality offerings around today? Such as Kameari, Mangoletsi etc, yes your route will fit (after some pain) but manifold design is much much more than just fit, with complex calculations for runner length/diameter and bend radius all required to yield good results.

Sorry don’t mean to appear a kill joy, It’s just that I know how hard and detailed this needs to be to get good results, only the other day we set up my pedal travel and quibbled about 1mm excess stoke meaning that the travel at the throttle bodies was an incorrect ratio meaning the geometry was out fractionally and butterfly opening was not linear. You couldn’t do that with the old prehistoric rod linkage system that plagues most setups, I have a fully CNC’d moving quadrant twin cable setup linked to a fully adjustable triple ITB setup which gives an almost infinitely adjustable throttle and which incidentally, is off the shelf, but doesnt come cheap quality never does.

Regarding motorbike throttle bodies and carbs, interesting as it gives you a short body length meaning an overall shorter runner length meaning that HP and peak rpm will be high (if everything else is built right) however it’s at the sacrifice of torque………. great for motorbikes, oh wait a minute.
 
Last edited by a moderator:
atomman

atomman

Club Member
J.alexander said:
Hi Gary,

I'm restoring a 240z and planning on putting it on motorbike injection. Just wondering if you would be prepared to sell me a set of raw castings un-machined as I will be able to do it myself and modify them to fit at the same time.

Cheers,

James
Click to expand...


yeah James no worries,

I Will be calling in the patterm makers next week to see how its going,
 
atomman

atomman

Club Member
Hello SKiddell,

I cant see why not ? The reason I borrowed the manifold was so I could make a pattern from it, So the calculations for runner length/diameter and bend radius have all been done, I could work them all out again but whats the point ?

I also will be using the same casting techniques as all the manufactures you have stated above to so I dont see a problem there either,

Machining wise should'nt be to much pain as I run a CNC machine shop

Have you got any photos of your linkage ? or a link ? would'nt mind a look as you said the old rod system always was a bit prehistoric


cheers

Gary
 
J.alexander

J.alexander

Forum User
Skiddell

I agree that motorbike engines give lots of power and little torque, mainly because they are not moving much weight they dont need the torque. However by altering the trumpet length, camshaft profile, valve timing, squish band, compression ratio, valve to piston clearance (bath plug effect), exhaust manifold primary and secondary sizes and length and of course the exact diameter of the throttle body. The peak power and torque figures can be put almost where ever you want them to be.

James
 
S

SKiddell

Well-Known Forum User
J.alexander

As someone who has spent £000's and hundreds of hours on dynos with various L series in various states of tune to say that you can move the peak HP and torque figures anywhere you want is not entirely correct.
You can only move them within the design and efficiency constraints (stroke, bore, BMEP etc) of the engine, some engines will have a bigger window of opportunity than others, a 2 valve single cam non cross-flow will never have the same power potential as a similar stoked and bored 4 valve twin cam.

With regards to altering trumpet length, on an S30 you are restricted with altering trumpet length to far due to body work restriction, but the principle is sound and works.
For example, I use adjustable trumpets to switch between a high torque or high HP setup depending on whether I want to drag race (high HP high rev short trumpet) or track-day setup (high torque medium rev lower HP)

At the shortest setting on the trumpets the engine produces 297 HP, 246 ft/lbs or torque and peak power is at around 7800 and will produce good power at 8500

At longest setting torque is up to 256 ft/lbs with HP down to 285 peaking at just over 7K and dropping off quickly at around 7500

So two very different scenarios for two very different applications.

From a cam perspective, ultimately the profile should be built around the flow characteristics of the head/port/valve/exhaust which mine was.
You can throw any old cam in and get something however its pot luck.
Currently I’m running a 585 thou lift, 310/307 duration with a lift on overlap of around 5mm

I have done back to back tests on exhaust manifolds and found huge variations depending on primary length, collector position and primary diameter.

You mentioned squish, yep it has an effect but it’s subject to a number of factors, mainly chamber design, weld up an N42 into a kidney shape, gaining a large squish area is great but if you don’t minimise the piston to head clearance (36 thou is about it as rod/pin/piston stretch at high rpm will clip the head) it’s a wasted opportunity.

In conclusion the engine (as you clearly know) is a cocktail of components and as with any cocktail, get on bit wrong and it’s a pile of ****.



 
atomman

atomman

Club Member
Called into the pattern makers on the way home to be greeted by this

null_zpsbb547e4c.jpg


bit more to do but should be ready by monday :)
 
Mr.G

Mr.G

Club Member
Gary, that's bloody brilliant! Very impressed indeed.

So what are the next steps in getting it cast, would be ace if you can potograph the process....
 
atomman

atomman

Club Member
still amazes me the skill of a real old school pattern maker :bow:cant be that many left these days,

The pattern splits down the middle, you can just see it on the photo, so that can it can be put into sand boxes to make each half and then the cores are put in to make the holes through the middle, then they pour in the molten alloy, Im sure ive forgotten few steps though,

I didnt get a picture of the core pattern but there is only one so all the internal bores are the same on each inlet, It's real piece of art how it all goes together,

Im hopefully seeing the casting guy tomorrow :)

I will try and get as many photos as I can of the proccess and put them up on this thread

Gary
 
richiep

richiep

Club Member
Looking very good indeed! As George says, the more photos the better as it would be really interesting to see this at each stage.
 
atomman

atomman

Club Member
here's a picture with the core box, 1 core box for all, so they are all the same,

null_zpsca46da42.jpg


Had a call yesterday from the casting man and the first one is all done :thumbs:

will be picking it up next week as im off to Tignes tomorrow for a long weekend snowboarding :)

will get some picture up next week

Gary
 
richiep

richiep

Club Member
Excellent Gary - like the "Atomman Speed Shop" branding!

Look forward to seeing the real deal in metal.
 
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