RobBrown
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| posted on 3/9/07 at 08:43 PM |
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Inlet Manifold
I've decided to change to bike carbs on my pinto, but cannot justify the cost of a Boggs manifold, even though they look fantastic
I'm gonna have a go at fabricating my own using aluminium and Easy Weld.
1) has anyone else done this, is it as easy as it says on the tin?
2) what thickness does the base plate of the manifold need to be? is 5mm enough?
3) how many rods will I need, including a little bit of practicing
Any other advice appreciated
Cheers
Rob
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DavidM
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| posted on 3/9/07 at 08:49 PM |
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Use the same thickness plate as the existing manifold. I'd suggest you fabricate the parts and then take them along to a local fabricator and
ask one of their welders to do it in there lunch break for beer tokens.
David
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caber
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| posted on 3/9/07 at 09:00 PM |
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for the extra weight why not do it in steel? 5mm plate cut out to match carb manifold backplate, some bits of 2" pipe possibly from an exhaust
supplier if you want some curves and off you go! i am thinking about this for my Pinto.
caber
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RobBrown
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| posted on 3/9/07 at 09:02 PM |
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That is an option, but fancied having a go first.
I'm also concious of there being an element of trial fitting as I went along, which would require a a bit of tacking together, with the easy
weld stuff.
Maybe I could tack with easy weld then take to a local professional to weld up fully.
My current manifold is cast Ali, and looks a little overkill for the job, so just wondered whether experience elsewhere had a view as to 5 or 6mm
being OK
regards
Rob
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blakep82
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| posted on 3/9/07 at 09:05 PM |
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quote:
Originally posted by caber
for the extra weight why not do it in steel? 5mm plate cut out to match carb manifold backplate, some bits of 2" pipe possibly from an exhaust
supplier if you want some curves and off you go! i am thinking about this for my Pinto.
caber
i'm told that steel inlet manifolds are a bad idea. ali doesn't transfer heat as much as steel, hence why its used for inlet manifolds.
not sure id fancy a carb full of petrol heating up too much! (not sure it would catch fire, but still)
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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RobBrown
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| posted on 3/9/07 at 09:10 PM |
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caber,
is 2 inch not a little wide. I was thinking along the lines of 38mm.
Having said that, I haven't got the carbs yet, so not yet sure about spacing and choke diameter.
Also my welding isn't great, so thought I might have a better chance with the ali weld stuff.
also just seen blakeP82's post which hadn't even crossed my mind
Cheers
Rob
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coozer
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| posted on 3/9/07 at 09:12 PM |
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I made my own from some 4mm steel plate and bits of tube. Traced round the inlet gasket and cut it all out with a jigsaw!
It looks a little rough on the outside, but, I spent ages with a die grinder getting the inside matched and smooth.
Cost me next to nowt but it did take ages to build! Still, as I say cost me next to nowt!
[Edited on 3/9/07 by coozer]
1972 V8 Jago
1980 Z750
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BenB
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| posted on 3/9/07 at 09:17 PM |
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Easy weld / techno weld is strong stuff but because of the conducting ability of aliminium you need to be careful. When you're making one joint
all the other joints will melt and collapse and your beautiful workpiece will fall apart... so you need to use something like rivets to hold
everything in place, do all the "welding" then drill out the rivets and repair the holes with a product that doesn't require heat
(ie body filler!!)....
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will121
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| posted on 3/9/07 at 09:18 PM |
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i tried the easyweld route and failed!!!. i had a 8mm plate and 4mm thick tube and couldnt get enough heat into the ali for the easyweld to flow,
think even if i did the heat would have distorted the back plate to much. i ended up taking my back plate to an engineering firm to weld it up. in the
end the cost made a Bogg bros manifold look like very good value when you start paying £30/hr!!!
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RobBrown
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| posted on 3/9/07 at 09:30 PM |
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I've never been one to not have a go. It's the reason I built the car in the first place.
Not even I could blow weld holes in 4mm steel. Surely.....
I had read that every thing falls apart again as soon as the Ali gets back up to temperature. A bit of a disadvantage that.
However I take all the comments above, and will probably think about it a little longer. Maybe try and save a few pennies for the BB manifold. Or at
least wait until my carbs have arrived.
Thanks
Rob
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indykid
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| posted on 3/9/07 at 11:33 PM |
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jacko made a steel manifold and i'm pretty sure he's had no problems with his.
as for blakep82's comment about steel transferring more heat than ali..........ali's far more conductive than steel, and when it comes to
it, it can only transfer as much heat as is supplied from the head. the mixture doesn't explode as soon as it leaves the manifold, so
there's no reason it would in any material manifold.
if you're one to have a go, and can't weld ali, i'd definitely give steel a serious look.
tom
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blakep82
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| posted on 3/9/07 at 11:57 PM |
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^ maybe its that Ali dissipates heat quicker, but i honestly wouldn't use a steel inlet manifold. as for only being able to transfer as much
heat as the head gives it. think about frying pans. they have handles made of plastic, which are still given as much heat as the pan itself. would you
pick up a hot frying pan but the pan itself? different material, but ssame principal. I'll try to find the info i was given on steel mainfolds,
as i thought about this before too
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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PeterW
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| posted on 4/9/07 at 07:19 AM |
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Yep
Made my own, piccies are in my archive.
I used carbs from a 1200 Bandit, as the floats are level, and 5mm plate cut with a plasma and hole cutter for the runners.
Tube is 38mm IIRC 3mm wall stuff and it was all put together with the BrazeTech rods as they are more tolerant to oxidation.
Plate and tube came from Ringwood Engineering on eBay.
I made a wooden template of the carb spacings, and used this to hold the runners square. It does take some heat to make the joins but if you tin the
joints first its a lot quicker. All you need to do then is go round and fill the edges properly.
I know there are a couple of angled bends in it but I smoothed them with chemical metal !
All in all, a couple of nights work and about £30 of stuff
Cheers
Pete
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Mole
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| posted on 4/9/07 at 08:07 AM |
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The original manifold was plastic on my Zetec so surely the inlet side cannot get that hot?
[Edited on 4/9/07 by Mole]
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martyn_16v
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| posted on 4/9/07 at 08:39 AM |
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If heating the manifold is an issue then you could fit a phenolic spacer, basically a very thick insulating gasket between manifold and head.
They're made from a composite material, pretty sure you can buy it in raw lengths and machine it yourself fairly easily.
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DaveFJ
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| posted on 4/9/07 at 08:43 AM |
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I tried using lumiweld myself - absolutely hopeless!
therefore my money is going to FatboyDave
see this link
Or will be as soon as I have contacted him and let him know!!!
Dave
"In Support of Help the Heroes" - Always
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whitestu
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| posted on 4/9/07 at 08:47 AM |
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I was going to have a go at making my own and got as far as getting the 5mm ali plate and 40mm tube, but got half way through and decided Bogg Bross
looked like good value.
It would have taken me ages to get the tubes right for my carbs [ZX6R], and would have to have it welded up [I had a go at migging Ali and should have
listened to all the advice that it is nigh on impossible].
I'll be ordering min from Boggs in the next couple of weeks, and should have done so in the forst place.
Stu
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02GF74
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| posted on 4/9/07 at 09:19 AM |
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quote:
Originally posted by blakep82
i'm told that steel inlet manifolds are a bad idea. ali doesn't transfer heat as much as steel, hence why its used for inlet manifolds.
that is wrong. aluminium is a far better conductor of heat than mild steel and even more so that stainless.
it is probalby cost and ease of casting & machining why cars have aluminium alloy manifolds instead of steel.
You will have a hell of a job getting the lumiwled stuff to melt on a piece of aluminium that big plus the distrotion if heated locally.
You will problab use a lot of rods.
In short, I wouldn;t even attempt it.
someone on here is doing manifold for a cheaper price and better design the boggs.
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Peteff
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| posted on 4/9/07 at 10:41 AM |
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The bike carbs are insulated from the manifold by the rubber sections that hold them on so the heat will not transfer back to the carb. I can't
see any problems using steel other than it rusting.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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whitestu
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| posted on 4/9/07 at 12:01 PM |
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I had a Citroen GSA years ago and if I remember correctly that had a steel inlet manifold.
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indykid
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| posted on 4/9/07 at 04:20 PM |
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i thought the main problem with steel manifolds was icing?
not powdered sugar, but fuel vapour getting too cold.
sure it wouldn't be a problem on such a short run though, and hasn't proved to be in practice.
tom
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PaulBuz
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| posted on 4/9/07 at 04:46 PM |
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I made mine out of steel.
As has been mentioned you will never get enough heat into the manifold without a serious heat source, this in turn will warp the ally.
you could get around that by bolting it to the head to weld it, but that will shunt even more heat away.
Steel is a much easier way of doing it, for pennies. (assuming you have a mig welder of course!)
This is my heated manifold
[Edited on 4/9/07 by PaulBuz]
 
Rescued attachment inlet.jpg
ATB
Paul
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02GF74
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| posted on 10/9/07 at 02:14 PM |
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quote:
Originally posted by RobBrown
I'm gonna have a go at fabricating my own using aluminium and Easy Weld.
I'be been thinking about this, and as my previous reposnse and everyone elses, we all been thinking of making a chunky manifold like the cast
ones we can buy.
But here is another take.,
Make the tube from aluminium sheet, 1-2 mm max, then the flanfe for the engine = all of this could be lumiwelded easily.
Ofcourse it will be flimsy so here is the cunning part - make cupport brackets out of thcik steel that can be wleded ro bolted to hold the thin tubes
in place and support the weight of the carbs - clamping the ruber hose over the sheet metal tube may be trouble some.
It won#t look great but should function as long as the aluminium structure is air tight.
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