1974 Unibody Triumph Spit6 (with some detours inbetween)

Valve clearances seem to check out. Near as damnit 0.5 exhaust 0.4 inlet which is slap bang in the middle of the haynes figure which seem to check out from a bit of googling.

Ordered a decent leakdown tester to will try that next.

Compression tests were done on a hot engine, working from 1 back to 4. I'm guessing the leakdown is also done on a hot engine?

And yeah, figured it would be similar to oil pumps where end-clearance is critical for flow and pressure. Will pull that apart and check as soon as there's a garage space available

Haha I thought that was an 'or what'

Didn't do it at W.O.T actually. Will check how much of a difference that makes (there's a haynes figure of 11 bar for a compression check).

TBH I'd always thought it breathed a lot through the catch tank so I'm not particularly hopeful...

Interesting. Will try that next and see if the 9.8 piston gets up to 11 or so. Or just wait until my leakdown tester arrives and test it properly with and without oil in the bores. Still holding out for it not being rings as they look like they're a little tricky to find! Might do a quick dummy check cranking with my hand on the dipstick hole and see if there's pressure.

In other news, I've got the MG F back on the road turns out the crack wasn't just in the upper area but along one of the horizontal mounting points as well.




I'd bought a strengthening kit from Mike Satur which mirrors the Cup cars' setup, but looking at it I'm not sure it'll fix my particular problem.



Judging by where mine had cracked, I reckon what happens is the forces fatigue the bit where the standard rear brace meets the bodyshell, and because it's not braced across the two it can do that relatively independently. Once that's gone, then it just works it's way more and more loose along the top and down at the base. The Mike Satur kit would prevent this by bracing the two together so they don't flex independently of one another. Unfortunately, because mine's already gone it's probably likely to just punch the now-stiffened bracing clean through the weaker bits I've repaired around it :S

What we need is something to spread the load out a bit. Something a bit like this:




That should do it ok Adds additional points where it's connected to the bodyshell that are outside the fatigued areas. It's also usefully lighter than the Mike Satur one (understandable, given the latter needs to be batch produced).




Oh, and there's nothing like swaged holes to make something look proper. It's like parsley. Take a regular tomato soup and it's just plain, but add a sprig of parsley to the top and suddenly you look like a bit of a chef. Same thing with swaged holes

Yeah I didn't think it would help!

Interesting about the rebound not being strong enough. Didn't think of that, but it certainly fits with how it's fatigued and where it sat at rest (bracket pulled inwards).

Not overly surprised it's failed really, given that the horizontal panel is simply one layer of stamped 1.6mm steel, and I expect the vertical is not much better. Hopefully spreading the load out a little, and a little closer to the joins between other planes and changes in plane will stop it cracking again.

Honestly, I'm quite enjoying getting back to fabricating. All this visualising load paths is fascinating

Going by that analogy, jonomisfit has just made a giant salad?

Haha 'colander' did make me chuckle pretty good descriptor too!

kevins Glad I'm on the right track reinforcing it. Well aware that I'm largely eyeballing my chassis reinforcements without any recourse or experience with CAD or element modelling. Only really 'headphysics modelling' to try and work out which way the forces should go.

Fiat update
So, not much further forward with the Fiat. Leakdown tester's arrived but not got round to using it yet (read a forum thread with someone with dodgy compression that turned out to be a cracked exhaust valve so still some hope yet!).

Spit update
After watching an episode of Project Binky where they made some very good points about not painting their car before they've done a full dry fit of components to avoid damaging a good paintjob I've decided they might have a point. Besides, I'm tired of sanding paintwork!

So, a bit of musical chairs and the Spitfire's back where she belongs.






First order of business is relocating the fuel tank. Before I'd read up on the IVA requirements I'd plumped for a GT6 fuel tank in the boot and used the space where the old tank was for better rollbar locations, space for the battery and space for the fuel pumps and swirl pot. Unfortunately, I doubt the IVA people will like the fuel tank being in a place with such little crash protection so it's got to move.

There are positives to this. I get my boot space back. Although the weight distribution will be shifted forwards, it'll help a lot with polar moment of inertia. Oh, and less chance of a fiery death of course (drove past a burnt out new MINI today which reminded me to take this stuff seriously!).

I thought about putting the battery and fuel pumps in the boot, but the crash protection and polar moment of inertia arguments came up again so they're going on the parcel shelf behind the seats.



My thinking is battery on the left to balance the weight of the driver, and making up a fibreglass box of some sort to isolate the electrics from the cabin. I seem to remember IVA liking a metal bulkhead of some sort between fuel setups and the cabin so would welcome some input for that. Would a fabricated and sealed metal box to go over the fuel pumps be enough, or does it need to be completely separate from the cabin? If it's the latter I might see if I can position them underneath the floor of the car itself (might work better that way anyway...).

While that thought's rattling around I figured I'd sort the battery. Fits quite snugly in its space already, but a decent tab on the front to hold it there...



...and a beefy bolt-on clamp at the back should keep it in place.



I've also added a spreader plate underneath the body so it doesn't just pull through the floor in the event of a crash. Will also add some verticals to the clamp itself to stop it bending upwards and letting the battery go as well.

Feels nice to be working on this thing again

Huh, interesting on the tank location. Remember reading in the guidance about crash protection for the tank, but I suppose there's a lot of interpretation as to what that means in practice. Either way, relocating it further away from a crash area would be a good idea.

Gotcha on the fuel stuff in the passenger compartment. I was thinking of making up a metal box that goes over it with an access panel somewhere, but if they can fit under the floor then that's much better. If not then maybe in the boot would be good as I've got some space to spare now.

I know about the batteries outgassing. It's something a lot of battery-in-boot installs don't do properly either. Not only can it let off hydrogen into the cabin, but they leach a little acid as well which can rust things out pretty quickly. That's usually the reason the battery boxes in the back of E36s are rotten through. There's an existing hole in the floor which I'll put vent tubes through, and it'll be sealed in its own battery box.

Hmmm, you're right about the battery. I'd copied the setup on my MGF which just has a little clamp on the plastic bits (my Alfa does too), but I suppose they're not in the cabin. I'll see what I can do about making a second clamp setup and probably a stouter box around it than I was planning previously so that if it does break free it's still contained away from the passengers.

Mocked up a CAD model of the sump, and have a question for people...







There's definitely not enough space to fit the lift pump down there too, but if I scallop the body I should be able to fit both the high pressure pump and filter down there. At ~1.4l it's also a little bigger than I thought which is nice.

My question is about whether the design is sound.

So, plan A is to run a fat fuel hose down from the tank to the highest point in the sump which feeds the HP pump. I'd then have the return from the fuel rail come back to the sump so the only demand from the feed hose is whatever fuel the engine consumes. Hopefully any overpressure from the pump return or air bubbles would bleed back up the feed hose so I'd only need 3 connections.

I think I've worked out that if I have a 15mm feed hose then at ~0.03 bar pressure from gravity I should have ~258l/hr of flow, which is a little over the ~240l/hr I can get from the 8mm high pressure fuel line at 3 bar for the rest of the system so even at the most extreme it hopefully shouldn't be able to empty the sump. At a very rough estimate (200bhp x 2.64l/hr) my engine should use about 75l/hr of fuel so it should definitely be able to keep up with that.

Considering all that, do you reckon I'd need still need a lift pump? Plan B would be to try and find somewhere between there and the fuel tank to place the low pressure pump. Only real issue is a redtop-style pump is a bit bulky to fit anywhere so if anyone knows of any more compact inline low pressure fuel pumps that would be great!

Main reasons I want to avoid a second pump are space, more complicated fuel lines and wiring, and redtops weigh about 700g so if I can cut that out then I'm a fair bit lighter

Nice idea I was planning on using either the standard Spitfire tank or more likely a steel tank of my own construction that fits roughly in the same place. The main reason I was keen for an external pump setup is I'll have to chop into the stock tank quite significantly to fit it around the roll bar backstays. It's only 33 litres from standard which isn't the biggest tank to begin with, and I'll probably cut a good 5 litres out of that so I'd like to keep as much capacity for fuel as I can!

I'll probably be able to gain some back by making my own tank as the stock tank has quite a big lip around the edge, and the sump being 1.4l helps too. I'd like something closer to 40l but we'll see!

Same goes for foam, although it is a neat solution.