Prawns 1380 trackday Toy: on the rollers at Slark today
Turbo Mini Forums

That's really nice Mini!!! I like it.
Well done Prawn!!

Jani

1399cc, Eaton M45 supercharger, N2O system, compression ratio 9.23:1, boost pressure 0,8bar/11.6psi.

http://www.garaget.org/?car=176816

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Bar what you've already mentioned about the doors and brakes.

What about the seats, the Cobra Monaco`s are heavy sods! magnum i remember did good value reasonable quality shell seats.

oh the seats are fairly heavy yea. I really fancy some cloth seats now too for a bit more restraint. THe vinyl ones were very cool when I was 17, but 6 years on they're not exactly what I want anymore.

I'd like some nice composite framed side mounted seats, but I really don't know what's out there, having not really looked into it all that much.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

This just arrived this morning, l;ooks' absolutely mint!





Can anyone tell me if there's a radiused arm missing from the throttle arm?

Also, how is the choke cable meant to be mounted? there's a tab sticking out that looks like it's in the right position to take a choke cable, but it's not got a hole drilled in it.

Does anyone have either an inlet manifold or an abutment plate (i think that's what it's called- the plate that holds the throttle cable and stuff) they fancy selling me?

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

on the NA version there is a plate that goes between the carb and the inlet manifold which has the connections for the cables.

I just put a small pilot hole in the tab for the cable then drilled it out a little to take a bike brake cable end to give the choke cable something to sit in.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I made my own Plate at my n/a mini:

http://www.minifreunde.at

cheers guys,

The plate is different on the turbo carb isn't it? as the throttle and choke are on opposite sides....

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

You can just see how the turbo one sits in this pic:

OK, so I've been having random running issues with the car for a while now. it's suffered from a top end misfire above about 6k on and off for months now. I was certain this was an ignition issue, with the electronic module missing fires at high revs.

Last weekend, I changed the electronic module for a points and condensor setup, and it's a lot better, but the problem still exists.

Pulling the leads off 1 by 1 on idle, removing leads 1 and 4 makes sodd all difference, yet removing leads 2 and 3 it nearly dies.

So, I did a compression test tonight, with interesting results

Results done cold:

1. 150psi
2. 132psi
3. 170psi
4. 140psi

Not overly happy with what I've found tbh, it used to make a good 180psi across all 4 cylinders.

I'm thinking the valve seats have been burnt, during my extended hot running to, at, and back from the ring (running at 100 degrees with all fans/heater on)

Meh. going to try it again hot tomorow, and with a drop of oil in the bores to rule out rings. then if it's still low I'll pull the head and regrind all the valves in this weekend.

Any thoughts?

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

do the test again and drop a bit of oil in the bores if the results are the same it will rule out the rings

that's the plan for tomorow evening Wolfie. I'm also tempted to order some valve springs from minispares tomorow along with the new head gasket. From a very unscientific test of pressing on each rocker as hard as I can, the inlet valve on number 1 is MUCH easier to press down than the others, so I'm wondering if it's gone weak.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Hi Prawn.

Nice car mate.

I'd check you've got good rocker to valve clearances before doing anything further. Try 0.016 Exhaust and 0.014 Inlet to set a cold baseline. You can always re-adjust later. If these are ok then go for the comp test with a squirt of oil to rule out rings.

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Thanks for the advice Richard, they were all set at 16 thou cold, checked last week when it was hot and none were tighter than 14 thou at all. that's with minispares 1.5:1 roller rockers.

I'll test it with oil tonight, and if it's the same, I'll have to pull the head.

Looking on minispares, they do a set of double 200lb valve springs for £25 which they say they use on all their fast road heads. At that money it'd seem silly not to chuck new springs on it.


In other news, I've decided against this supercharged idea, having seen the light and realised that whilst it would be fairly original, it'll never be as good as a turbo.

I'm now keeping my 18cc accralites, which I'll throw into a fresh block, and I've agree'd to have a mega sorted near miglia spec bottom end from my old man, so I can build up the new motor without ripping mine apart.

I also picked up an MED roadcomp head yesterday for an absolute steal, with 20.5cc chambers which will give me 8.5:1 CR. I'm going to rebuild that with new springs/seals/guides ready for the new engine.

Just need to find a turbo and manifold now, and all the little bits like a downpipe, and oil drains and stuff :)

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Valve springs and a head set ordered :) it's got to be worth doing, even if it's not the root cause.


Has anyone ever tried lapping in valves using a drill on the stem? A few people have suggested I try it, but I'm not sure it's a great idea....

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

I've one of these in the past to good effect-

http://www.gunson.co.uk/item.aspx?item=1825&cat=666

Well. bugger.

Pulled the head this morning, only took 20 mins to get it off. whipped all the valves out, and found this:



and this one cracked:



Now I know that's unlikely to have been causing my misfire, but still, not great at all. Interestingly, these two guides are the ones which the valves picked up in last year (hit the pistons) I had the valves replaced, and all the guides reamed, but teh guy who did it for me didn't mention at teh time that the guides were smashed.

The two centre guides also sit about 5mm lower on the top side of the head too! Very odd.....

New guides to be ordered Monday, and found a place who'll press them in and ream them fo £25.

Another week off the road.....

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

thats a rather nice mini prawn, i took your advice and signed up, i keep meaning to ask, were were those pics taken, coz its an awesome location

Hi Prawn,
Great looking car!

If the head has been skimmed 2 or 3mm & the block planed 1 or 2mm you should either shorten the pushrods an equivalent amount or the rockershaft pedestals should be shimmed up to make up the 'lost' height so the rocker arm to valve stem & pushrod geometry is correct.

The best method is to shim up the pedestals.

The geometry problem could be excaccerbated by the 1.5 ratio rockers.

What happens is the valve stems are forced sideways which at best causes rapid valve & valve guide wear, at worst it causes the valves to pick-up on the guides causing them to move in the head & break-up, hope this helps sort out the fault. Laurence.

the pics came out ok in the end mate =]

Hi Laurence, thanks for your suggestion mate, what you say makes a lot of sense indeed....

However :(

I've already got rocker pedestal spacers fitted, from MED, so the correct geometry should be restored. Also, shouldn't the roller tip rockers minimise side loading on the valve stems?

I personally think that the guides have been broken for a year or more, as these are the two valves that picked up on me. for peace of mind I'm not going to risk rebuilding it with these dead guides.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Hi,
Perhaps the cam gives too much valve lift when combined with the 1.5 ratio rockers (giving side-thrust) so it may be an idea to use 1.3 ratio rockers, are the valve springs getting coil-bound having said that though, is the phase 3 cam an ideal choice for a forced induction engine?
I would use a mild cam, one without too much overlap, for a blown engine, use the 1.5 rockers if you like, but not with a high lift cam.
Maybe you should be using A.P.T. manganese aluminium/ silicone bronze valve guides along with new valves & valve springs (from Kent Cams)
Phospor bronze guides may only last 2,000mls in a high performance engine.
Don't put stem seals on the exhaust valves if you use silicone bronze guides.

Cheers again for your advice Laurence. the current engine isn't forced induction, and I'm not planning on charging this engine at all. I'm building up a whole new engine to turbo, using an avonbar p2 cam

the current cam has 8mm lift, the springs don't go coilbound on full lift, but I do have a feeling one of them had gone weak.

The head had previously been built with 8 stem seals, although I'll not be refitting them on the exhaust when I rebuild the head.

I've bought a set of Manganese bronze guides from minispares today, which will be pressed into the head on wednesday.

I'll take pics when I build it up to see if there's anything obviously a miss that I'm somehow not spotting!

Thanks for your help as always :)

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Bought a plenum for £30 on ebay, modified for a DV already, but not for an IC.

the poppet valve had already been blocked off when it arrived, although it looked a little odd.



On further inspection, it turned out a penny had been siliconed onto the inside the the chamber! What a bodge....



On further thoughts, i'll probably sell this and try and get one from Nic if he still makes them

Edited by Prawn on 25th Feb, 2010.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.