1842 replies to this topic

[Petrol]

@petrol

 

Sorry to hear about the problems you’re experiencing. Especially since I feel the troubles are caused by more than just a carb problem. No matter how much retrominis’ carb mods have or have not upset behaviour under transition, when the piston is fully up under wide-open-throttle allowing the carb to flow the maximum amount of air accordingly (as checked by the RR operator) and AFR is good (as you state) THIS IS IT as far as max power is concerned. 
 

Driveability aside, I gues 40 Bhp @ wheels isn’t exactly what you were hoping to achieve. Sure there are carbs that are able to flow more air than your current one, I just don’t miraculously see them adding the 25 odd HP your ‘screamer’ seems to be missing. Things like fuel droplet size and atomization do have a minute effect on power but are unlikely to be noticed on anything else but a full blown engine dyno....basically when AFR’s are correct you’re good to go. There’s no such thing as ‘good mixture ratios that an engine is unable to burn due to carb problems’.....there simply isn’t.

Yep I get that but I can't understand why it was Kangarooing at low revs
There are 2 engine issues here
- Kangarooing at part throttle under about 3K revs
- Lack of power

Some thoughts.
SU carbs are not fixed choke, is it possible the piston is oscillating causing the kangaroo effect due to the modifications? The oil in the dashpot was genuine SU oil by the way.

The cam is a VP3, which I was advised would be best. Is it possible that this scatter cam is too hot for a 998? It's pretty wild but if it's ultimately reducing gas flow, it would reduce power. I didn't use a vernier cam pulley. I used an offset woodruff key

I'm trying to get to the bottom of the crunching gearbox too, oval baulk rings sound plausible.

The guy from the RR told me he had profiled the needle so the mixture is OK. I've bought a stock HIF38 carb, I'll fit the needle into that.

Just to add, the inlet manifold was modded. I'm going to buy a replacement, bolt the lot on and see how it drives.

Can't believe this is so complicated!

Pete

[Midas Mk1]

to be honest amongst people I know who’ve been to re in bury aren’t the place to go for tuning. Know of a few unhappy experiences.

Before throwing it in i’d get a different carb and go to someone who knows what their doing fully. Rob Waddington at Minisport used to be ace before he retired. If you ever went efi, efi parts in runcorn is the man.
Kangooring at low revs is what my base map had, sounds like a setup issue to me.

Edited by Midas Mk1, 22 April 2021 - 11:02 PM.

[Petrol]

to be honest amongst people I know who’ve been to re in bury aren’t the place to go for tuning. Know of a few unhappy experiences.

Before throwing it in i’d get a different carb and go to someone who knows what their doing fully. Rob Waddington at Minisport used to be ace before he retired. If you ever went efi, efi parts in runcorn is the man.
Kangooring at low revs is what my base map had, sounds like a setup issue to me.

Thanks, I spoke to Rob Waddington about 18 months ago as he lives in my neck of the woods. He is no longer able to work on cars unfortunately. I even offered to hire a RR for the day and pay him to advise me what to do, but unfortunately he couldn't do it.
I'm taking things slowly at the moment. I've built 99.9% of this car but there are few things I don't trust. I've bought a good condition, stock, replacement carb so I'll see what happens when that's fitted along with a new inlet manifold.
Thanks for the feedback, I'm listening to all advice and I'll keep you updated how it's going.
Pete
 

[GT Jimmy]

Did you have any joy with the running issues? Aidie at AB garage in Chester sorted r kids Cooper, it would run like crap if started up when the engine was warm. Got 71 bhp on the rollers

01244 537701

[johnR]

 

 

 

 

I'm in a similar situation - less than 100miles on a newly built engine and the big ends and crank journals (and crank)are scrap but no sign as to why. At least I still had the old 998 to put back in which has a new lease of life with an RC40 and the lighter flywheel from the 'new' engine. As you say there's very little to go wrong with this basic tech - it does feel personal! I also had an issue with the newly built gearbox (new bearings and baulk rings etc)- in my case it didn't want to go into first without initially being in second. I'm currently stripping it back down to try to see what the issue is there. 

It's gutting when that happens. First thoughs are oil pressure. Do you have a gauge? Gearbox is a different kettle of fish though. That sounds like a synchro problem like I have. When the baulk ring wears it hits the gear preventing spin up and ultimately crunching. On mine there was loads of gap which is why I'm thinking the tapers don't match. Good luck and please keep me posted

 

 

 

Like you I used new baulk rings - I wasn't getting crunching (just had that on my Focus and sorted by replacing the baulk rings) there was just a resistance, no noise. As you say yours may be a poorly manufactured baulk ring not matching the taper.  

[Petrol]

It's been parked up in the garage for almost 12 months. I've decided to sort everyhing out. First thing is to fix the hesitation at low revs. Once that's sorted I'll pull the engine, gearbox and fit new baulk rings.
I've fitted a stock HS4 along with the profiled needle that was made whilst it was on the rollers. Just need to find some fuel I'll report back what happens.
I've had plenty of time to think about it and have come to the conclusion it can only be a carb or distributer problem. We will see.

Pete

[Mini Waco]

watching intently as I will be rebuilding my engine so I'm keen to learn the do's and don'ts..  

[Hexxeh]

Thanks guys. The S13 is being stripped and restored but that's another thread for another forum.

 

Thanks GraemeC for pointing out the problem with the rear brake shoes.

 

I used this pic to sort it and thought it might be worth posting

 

 

I know this is a mega old post, but just for anyone who happens to see this and copy it like I did (because this thread is an absolute bible for doing things the right way generally!): I think this shows the handbrake levers the wrong way around. I fitted them this way with brand new everything and genuine Superfin drums and found the drum wouldn't fit on at all. Swapped the levers so the long section is to the top and it slid on straight away.

 

Excerpt of the old Haynes manual validates this configuration:

 

 

Glad to see this build finally getting the last niggles sorted out, can't wait to get a ride out in it again once it's done!

[Petrol]

It's been a long time since I've updated this thread but the engine was kangarooing between about 2 and 3k revs when it left the rolling Road. The operator, who profiled the needle, suggested I try replacing the carb to resolve the problem.

I have fitted a stock carb along with the needle that was profiled and the car drives exactly the same.

I've come to the conclusion that it's running far too rich at these revs and it's hunting. You get the same result pulling the choke out with a hot engine.

 

I could try other needles but the reality of it is, there isn't anyone within a reasonable distance that can properly profile an SU needle.

The other thing is, the cam is way too wild for a road car. Its only a 998 and has very little torque off cam.

I'm thinking of pulling the engine and box out, fitting top spec baulk rings to the gearbox and fitting a mild road cam along with a stock 998 distributor. That way I should be able to run a stock 998 needle. I can set the mixture up myself by feel / trial and error / plug colour.

 

There's also other problems like 2x insane oil leaks that I've got to to the bottom of and the exhaust is wrong for the manifold. I'll get to those when I pull the engine out.

Pete.

[MiniCarJack]

It's been a long time since I've updated this thread but the engine was kangarooing between about 2 and 3k revs when it left the rolling Road. The operator, who profiled the needle, suggested I try replacing the carb to resolve the problem.

I have fitted a stock carb along with the needle that was profiled and the car drives exactly the same.

I've come to the conclusion that it's running far too rich at these revs and it's hunting. You get the same result pulling the choke out with a hot engine.

 

I could try other needles but the reality of it is, there isn't anyone within a reasonable distance that can properly profile an SU needle.

The other thing is, the cam is way too wild for a road car. Its only a 998 and has very little torque off cam.

I'm thinking of pulling the engine and box out, fitting top spec baulk rings to the gearbox and fitting a mild road cam along with a stock 998 distributor. That way I should be able to run a stock 998 needle. I can set the mixture up myself by feel / trial and error / plug colour.

 

There's also other problems like 2x insane oil leaks that I've got to to the bottom of and the exhaust is wrong for the manifold. I'll get to those when I pull the engine out.

Pete.

 

Glad to get an update on your project! I would very highly recommend AC Dodd for A-series engine tuning & needle profiling - he often travels up and down the country tuning people's Minis so he would probably come to you.

[CMC]

If you're going to try tuning the carb/choosing the needle yourself, I'd suggest fitting an AFR gauge. That will help immensely and shows your changes in mixture immediately. I have set up three of my Minis nearly perfect that way.

[sonscar]

I am a redneck tuner but I would think kangarooing is a result of too lean and/or too much advance.When the mixture is set it has to be the number the engine needs and not the number the tuner thinks it should be.I am casting no assertions on what has already been done.
My MGB has EFI,with AFR of 13.8 it kangaroos at approx 1 to 2.5 k.Set at 13.3 it is smooth.Just a few thoughts from a truly diy "tuner" Steve..

[Petrol]

Thanks for the feedback guys. I've taken your comments on board.

Time to sort this mess out

 

 

First problem.
Oil leak and loss of oil pressure

Minisport!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!   supplied me with 2 inner CV's or pot joints
They are made with a hole through them and bunged with a core plug to stop engine oil getting into the joint and CV grease getting into the oil

You can see the core plug in the middle here

 

It pushed out with my finger

 

This is the hole the core plug is suppost to bung

 

What's happened is both the core plugs were leaking. This meant that the engine oil leaked into the boots. The boots swelled up with heat and then forced the CV grease into the engine oil. The molybdenum in the cv grease then blocked the oil filter causing lack of oil pressure.
The boots then split causing an insane oil leak


This is another heads up about buying cheap crap from Minisport. BOTH CV's had the same problem. I need to strip the engine to see if theres any damage from lack of oil pressure and boy, the mess all that grease has made is crazy.


Pete

 

[Mini Manannán]

Minsport. Say no more. I was bitten by them years ago, never again.
I hope the stripdown doesn't reveal too many horrors.

[evansisgreat]

Christ, that's genuinely insane! I can't believe I'm still hearing so many minisport horror stories. I also have my fingers crossed for you, I regularly refer to this build when looking at how I'm going to tackle things on my own and really hope the engine is healthy.