GT40 Engine Build Mirage Chassis

[Doc Watson]

Peter,

My filters fitted very well.... sounds like the problem is the foam sandwitch between the hexagonal grid.

Im now looking for some stainless steel fine mesh which can replace the foam. If all else fails I will get a flour sieve and cut that up. Let you know what I do.

Pete,

Nothing could detract from the looks of your car........ did they really last 200K or 20K? either way it would take me a few years to get up to that sort of milage...... been a fan of your build site for a while now.... as for the good lady.... I told her when we met that the car thing is happening so no real surprises there....

Andy

 

[Bill Hara]

Doc

I think Pete is talking "Queensland speak" again and actually means 200 Kilometers, not 200 thousand kilometers...

Whatever you decide, I think you're doing a super job!

Bill

 

[Doc Watson]

I've found a few suppliers of stainless steel wire mesh which can be used instead of the 'foam' insert in the stack screen filters the question is what size wire mesh to use? any ideas?

I was thinking of this.......

Plain weave
Mesh Count =40 x 40 (wires per inch)
Wire Dia mm=0.180
Wire Dia inch=0.0071
Aperture mm=0.46
Aperture inch=0.0179
Open Area %=51
Micron Rating=455

The open area is 51% with all particles greater than 0.46mm filtered, another possibility is this....

Plain weave
Mesh Count =80 x 80 (wires per inch)
Wire Dia mm=0.140
Wire Dia inch=0.0055
Aperture mm=0.18
Aperture inch=0.0070
Open Area %=31
Micron Rating=177

A much finer mesh but only 31% open area and 0.18mm aperture, perhaps restricting flow to much? (BTW im only showing 2 from a selection of about 50 types of mesh of varying sizes).

The stuff is sold in sheets 1m wide minimum length 1m so there will be loads spare for you guys if you want some. Im also concerned that the edges will fall off when the mesh is cut into a circular shape but will talk to the supplier about this.... laser cutting service is possible.

Any comments? suggestions?

Andy

 

[John W]

Doc,
Imo any mesh that has holes big enough to let enough air through will also let debris through...

get on the blower to K&N.
They sell a thing called a 'pre-charger', designed to keep dust out of their filters.
Buy one of those (pick a suitable one) and then cut discs out of it to replace the foam in the ones you have above.

At least that way you get good airflow, and manage to keep out most of the debris that would otherwise damage your engine.

Just a thought...

K&N PreCharger Filter Wraps, DryCharger Filter Wraps, and Airforce Pre-Cleaners

 

[Danimal W]

Doc,....

As I am somewhat new to engines/designs.... I think you are on the right track with the SS mesh. I agree that (when I can finally get a '40) I would use some sort of filter. I do not like the look of the K&N or Pete's red socks (Sorry Pete), but then again, they look better than a wrecked engine!

The "tea strainers" from what I've read here are better than nothing, but they can have problems. I think the first size of mesh would improve them in a few ways: 1. Better than nothing
2. No foam to deteriate
3. Would keep out sticks, stones, chevy parts
4. Would probably offer the least amount of restriction
while being the most visually appealing

Now I have not done any research on feasabilty on making these,....but I would it be possible to have them shaped (like the lower right hand corner of Doc's picture)??? I though I've seen pictures of vintage race cars with filters like that. If so, it would increase the surface area of the filter so the restriction would be minimized and still provide some sort of protection.

Just my .02.

 

[Jim Pearson]

Hi Andy,

Given that the surface area of a hemisphere is exactly twice that of its base circle, wouldn't the tea strainer shape shown in your photo would give you [roughly] unrestricted flow if you used the 455mic material?

Lotus had the same idea .....

http://www.atspeedimages.com/donington_collection/lotus_49b/1968_lotus_49b_cosworth_dfv.jpg


Regards,

Jim

 

[Doc Watson]

John,
I will look into that but will the material still degrade if there is a few coughs and spits of flame?

Danimal,
Yes my thinking on the subject exactly..... although a new method of attaching them to the stacks would be required if they were hemispherical....unless they were formed with a flat lip.

Jim,
Given twice the area wouldnt it increase the unrestricted flow to 75%? still much better than 50%.

I've talked to the supplier and they can plasma cut the mesh which 'welds' the edges of the wire together to prevent them falling apart.

Forming the mesh into a 'dome' shape wouldnt be a problem would just make a 'mould' (male and female parts) and the wire should form into shape easily.

Im still not to happy about the rubber seals which hold the screen filter, but will get some mesh and have a play with it to see what works and what dosent. Im also thinking about producing a split collar which could hold the mesh in place but will initially use flat wire mesh (the first one I quoted).

Then try using the rubber holders with a domed mesh, and if all else fails devise a split collar to hold a domed mesh.

Andy

 

[Jim Pearson]

Hi Andy,

I just figured 50% of 2 being the same as 100% of 1 would mean no restriction - based on your 51% open area mesh.

Are you in position to give details of the supplier? I'd certainly be interested in 'tea strainers' for 48IDA's.

Cheers,

Jim

 

[Doc Watson]

Jim, your right I think I just had a blond moment........

No secret about the supplier..

Locker Wire Weavers - Home Page

They will plasma cut as I said but I have no quote as yet... I will sort that out next week.

Andy

 

[John W]

Doc,

I don't think the material will melt or degrade.
infact, I have heard it acts quite well as a flame a barrier.

The best bet is to put the question to K&N.

I've had major blow-backs through the 40s on my Caterham, and never had them catch light yet

 

[Jim Pearson]

Hi Andy,

I live about 45mins from Lockers in Warrington so, if you need any leg-work, just let me know.

Jim

 

[Doc Watson]

Thanks Jim.... will let you know.....

Andy

 

[Doc Watson]

I have ordered some wire mesh (uncut) and will see what its like to cut and form, should arrive next week some time. Also Post #9 shows the gaskets that came with the phenolic spacers, they are about 1/8 thick about 2 mm oversize around the edges. I've ordered some 0.8mm gasket paper and might replace them with the paper.

Still awaiting news on the small block - last reports are that internals have been balanced and assembly was about to take place. Its a 1966 289 block which has been rebored 30 thou. Original crank (took 1/10 thou off the mains to clean them up), forged h beam rods and forged pistons.

Also got the original cast iron heads which have had bronze inserts for the lifters (roller lifters will be used) and stainless steel inserts for the exhaust valves.

Not to much progress this week as I've had to cover for a sick work collegue.... damn work always getting in the way....... hoping to cut the final holes in the cold air box plate this weekend though.

Andy

 

[Danimal W]

Doc,

Any updates on your filters???


Another though I had.....I know it's dangerous..

Two layers of the SS mesh,.... Bottom layer of smaller mesh size, top layer, large mesh with a layer of the K&N material between????

The upper mesh would keep large debris out, and the lower mesh would support the K&N filter (and provide some protection should the K&N deteriorate...

 

[Bill D]

I would love to see a picture of the chassis

 

[Eric]

I was just fooling around with this same idea the other day...

I drew up a model of a trumpet and the beginnings of an idea for a filter.

In this model, there are 2 rings that sandwich a pre-formed filter foam. The sandwich rings are bolted together with M2 fine bolts. The assembly uses a double adhesive backed epdm rubber ring to bond to the top of the trumpet (not the best I know-still working on it)

There could also be a minimal wire dome form to keep the filter foam from sucking into the trumpet and tearing. There are some new very strong foam types available now from companies like ITG that resist tearing and flame very well.

I would probably redesign it to be a complete assembly where the trumpet itself forms the lower sandwich.

I am going to run it past Fran at RCR to see if he wants to take on building something along these lines.

Cheers
Eric

 

[JimmyMac]

Doc,
How about this ?
Not quite my own taste however.

 

[JohnC]

I was just fooling around with this same idea the other day...

I drew up a model of a trumpet and the beginnings of an idea for a filter.

In this model, there are 2 rings that sandwich a pre-formed filter foam. The sandwich rings are bolted together with M2 fine bolts. The assembly uses a double adhesive backed epdm rubber ring to bond to the top of the trumpet (not the best I know-still working on it)

There could also be a minimal wire dome form to keep the filter foam from sucking into the trumpet and tearing. There are some new very strong foam types available now from companies like ITG that resist tearing and flame very well.

I would probably redesign it to be a complete assembly where the trumpet itself forms the lower sandwich.

I am going to run it past Fran at RCR to see if he wants to take on building something along these lines.

Cheers
Eric

Sintered stainless mesh might be interesting for the filter element. This stuff is used for hydraulic filters, it's available from 2 to 200 microns, and should be pretty durable, but it probably needs some framework under & above to keep it formed.

Sintered wire mesh data,prices, helpful information#

 

[Doc Watson]

Jim, not my taste either.... bottom half (im assured) will be with me in May... will post pics when I get it.

Eric, my idea was to use a ring as support however I dont want to drill the trumpets and was a little stuck for ideas on how to attach them. I then thought about wiring them and this seems the best option. I also want to braze the mesh onto a stainless support ring which has a lip that goes over the trumpet and wire attaches it to the trumpet. I dont see a problem with the brazing.... have you seen the brazing on the mesh used on 48 IDA's?

Glacial progress on the engine untill I get my short block, although I think I've found a 1965 Autolite distributor.......

Andy

 

[Doc Watson]

Got a 1968 distributor which has a Petronix system retro fitted,and has vacuum advance. It also had a small amount of 'Ford Blue' on it when someone in the past had not taken it off to spray the engine. Paint stripper a toothbrush and some WD40 later it looks in good condition. Rotor shaft spins freely with no side wear and the end play of the shaft is 0.032" (0.035" is about the limit). I took off the vacuum advance and the petronix unit and top plate to look at the weights and the centrifugal advance is in the 13 degrees slot, giving a total of 26 degrees centrifugal advance. I have read that engines with a compression ratio of between 9.5:1 - 10.5:1 run best with 35-38 degrees total advance.

If I start with 10 degrees initial advance with the 13 degree slot I will get 36 degrees total advance.

I might need to change the weight springs to lighter ones to get the total advance in at 2500RPM. As at the moment there is one light and one heavy spring on the weights which bring in the total advance at around 4500.

Im also buying a new dual point plate and condenser, and have got a new black distributor cap with brass contacts.

Does 36 degrees sound right for a 289 on 48IDA's? 10 degrees initial? and full advance at 2500? this stuff is new to me and I realise that the best tuner is the dyno but would this be a good starting point?

Andy