17 replies to this topic

[danie garry]

hi guys, 

 

hitting bit of a wall with the car I'm working on at the moment, 1977 Swedish 998(recon head from jonspeed & stage 1 kit from minisport). it starts and idles ok with the timing at 6degrees before tdc(set @1000rpm), once revved it will start to bog down at 3000ish rpm. if i rotate(clockwise) the dizzy as i rev so that its at 30degrees at 4000rpm it leaves me with a terrible idle

its a lucas 45d without a vacuum advance unit

advance weights and springs worn or not suitable for the stage 1?

 

any advice greatly appreciated

https://imgur.com/a/WSLv4FL

 

 

 

 

thanks  

Edited by danie garry, 10 February 2021 - 02:25 PM.

[cal844]

Did you change the needle? I use 10° at 1000 rpm vacuum disconnected and blocked

[ACDodd]

You need the advance curve changed for sure. You will also likely need a custom needle to fuel it correctly.

Set the timing at 10 Deg BTDC at 800pm. Then measure the advance at 2000, 3000, 4000, 5000rpm etc and post back the results

Ac

Edited by ACDodd, 10 February 2021 - 06:53 PM.

[danie garry]

You need the advance curve changed for sure. You will also likely need a custom needle to fuel it correctly.

Set the timing at 10 Deg BTDC at 800pm. Then measure the advance at 2000, 3000, 4000, 5000rpm etc and post back the results

Ac

Took it all back to basics and got her running the best it has yet,
So with it set at 10deg @800 I got
10/11 @1500
12@ 2000
14@ 2700
15@ 3000
16@ 3600
18/19 @ 4000
20 @ 4300

Runs and revs quite well now but I can't tell how it drives(snowed in with a steep drive way)
Had a bit of backfiring through the carb at idle but cured that by making it a bit richer
As for the needle, it's got an ABX in at the moment(I do have an AAV and an ADD here too if they might be more suitable? Other than a custom profiled needle that is)

[danie garry]

Did you change the needle? I use 10° at 1000 rpm vacuum disconnected and blocked

Upped to 10deg @800 as per AC's comment, much better, its an ABX needle that came with the kit

[ACDodd]

Yes that advance curve is way too slow no wonder it runs badly!

You need a recurved dizzy to make that run better.

Ac

[cal844]

Great, you now need to get that dizzy recurved (preferably a thorough going over to check for play)

Edited by cal844, 14 February 2021 - 12:23 PM.

[danie garry]

Thanks guys,
what's the best way about getting the dizzy recurved? I'll do some research into companies here in Sweden that might help but is there any general way of altering to suit? 123 dizzy for 300quid?
I know it's all based on each engine individually and the mods but is there a cheaper way of getting it better than what I have at the moment?

Thanks

[cal844]

Ship it to AC Dodd, maybe even Turbo Phil both here in the UK and both produce great results

You'd get a better result doing this even if its more expensive than the 123 ignition. Some people have had issues getting the curve acceptable

Edited by cal844, 14 February 2021 - 09:58 PM.

[timmy850]

The advance is set by the advance plate in the distributor as well as the 2 springs. The parts themselves are pretty cheap, but you’ve got to:
Know what you want
Get the right parts
Assemble it and test it

[danie garry]

Ship it to AC Dodd, maybe even Turbo Phil both here in the UK and both produce great results

You'd get a better result doing this even if its more expensive than the 123 ignition. Some people have had issues getting the curve acceptable

 

 

The advance is set by the advance plate in the distributor as well as the 2 springs. The parts themselves are pretty cheap, but you’ve got to:
Know what you want
Get the right parts
Assemble it and test it

 

 

Yes that advance curve is way too slow no wonder it runs badly!

You need a recurved dizzy to make that run better.

Ac

 

shipping in an out of the UK is proving a bit of a pain at the moment(Covid/Brexit/wonderful Swedish customs holding my stickyfingers order for the last 6 weeks!)

waiting to hear back from a couple of places over here if they know of any companies that can help

 

what would be an ideal advance curve(and parts to sort it) for this car given that it's a pretty low mileage engine(50,000km) standard recon 998 head, stage 1 kit(LCB, 1.75" exhaust, ABX needle, cone filter)

I understand that a full tune by a mini friendly guru would be best but if I can get the car sorted as best I can it's all good until I can get parts and tuning done a bit more easily

 

thanks for the advice so far guys!

[ACDodd]

If it’s an engine with flat top high compression pistons, aim for 8 to 10 degrees static start advancing at about 1600rpm up to 20 degrees at 2350 ish rpm, rising to a full 30 degrees at 4500rpm.

Ac

[danie garry]

If it’s an engine with flat top high compression pistons, aim for 8 to 10 degrees static start advancing at about 1600rpm up to 20 degrees at 2350 ish rpm, rising to a full 30 degrees at 4500rpm.

Ac

 

would that apply to a dished piston too? M2093 B12 stamped into the top of the piston(engine no: 99H834AJH......)

[ACDodd]

No that’ would need a faster curve.

Ac

[danie garry]

Little update, replaced the springs and now have a curve that's a little better
10 @ 800
19 @ 1500
25 @ 2000
27 @ 2500
28 @ 3000

Again getting a backfire through the carb at idle thats cured with a richer mixture(getting a little too rich now) but it still won't pick up while driving, maxxing out around 40-50kph
Waiting on a full rebuild kit for the carb just to freshen it up

Any more advice as to where I should be looking(short of taking it to a pro! That will be happening soon too!)

Thanks

Edited by danie garry, 28 February 2021 - 09:33 AM.