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Calling crossflow experts! - Conclusion


John Ryan

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Finally finished my rebuild. However, the car was a b#'#er to start last night, and now today is not playing ball at all. It is 'catching' but not going on to start, and I am getting a lot of banging and spitting back through the carbs. When it did start the carb banging was almost continuous.

 

Salient points are

 

Engine, 1640 crossflow completly rebuilt, good oil pressure 4+

Ignition - Mictro dynamics system, very good spark

Petrol pump - New

Fuel - New in new tank. Fuel is getting through

Carbs - Serviced by Redline, returned to base settings

 

I think the problem may be timing, but I haven't a clue how to check or fix.

 

I am really fed up by the because I really want to drive the thing now... *mad* *mad* *mad*

 

Any ideas?

 

 

 

 

 

Edited by - John Ryan on 29 Jun 2006 19:24:38

 

Edited by - John Ryan on 7 Jul 2006 16:15:18

 

Edited by - John Ryan on 7 Jul 2006 16:15:52

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Firstly check your plug leads, don't forget the crossflow has an unusual firing order, however is this likely as you say you ran it yesterday *confused*.

 

If that doesn't fix it and you are certain about your timing, then I would be tempted to lift the valve cover and look at the tappet clearances. If one is very large then it could be bad news. Crossflows have a propensity for ripping off cam lobes after a rebuild or wrecking followers (usually the former). Several of us here have had that problem ☹️

 

Being more optimistic most of the time though this is usually down to plugleads or getting the dizzy one tooth out on the cam, so the timing isn't right

 

Edited by - Graham Perry on 28 Jun 2006 20:01:18

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Not unusual problems with a new built engine. There are so many things that could be out of adjustment etc.

Don't panic!!!

Starting is a bit of an art with twin 40s, if it's not been run for a while,you will need to pump the pedal about 10 to 15 times to fill the carbs. set the idle a little high, about 1200 rpm, then check the 4 idle mixture screws,( having previously screwed them fully in, then 3 turns back as a starting point) A synchrometer is handy here!

If you can't get it to run smoothly, you will need to go through the timing, valve clearance, fuel pressure settings etc.

You could do with an experienced helping hand, any more cross flow people near by?

Good luck

Cheers J&J

 

JFDI

(Just F*****g Do It)

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John - Many thanks. Tried the full in and 3 turns out, and the engine starts relaibly now. For some reason it had been set at 2 turns out. Ho hum

 

Still sounds rough, but at least now I can get it to a place for the timing etc to be set properly.

 

Graham - Thanks for the info, but my blood ran cold thinking I would have to take the engine out again!

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You should check the ignition timing with a timing light at whatever revs is set to max advance.

 

However a rough guide is to set tickover to about 600 and move distributor till you get highest revs (if revs rise above 600 then reduce tickover) when you've got max revs at tickover retard 50 rpm.

 

Then check it with a good timing light.

 

Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here

You and your seven to The French Blatting Company Limited

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I'd love to know how you can turn the dizzy while the engine's running without losing your hand at the wrist *confused* On my Xflow, the dizzy is under the front carb, so not accessible from the top (or back due to the rear carb). The thought of sticking my hand in from the front past moving belts -- *eek*
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Well, i used the above method (we've all got to die sometime, a fact that eludes the H&S experts), but the engine is still not running right, so I've called in a mobile mechanic, who can't come for another week.

 

I am so bloody fed up, having a complete car, some great weather, and not being able to drive!

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Hi John

 

No, the carbs were with the car, but I am using a different engine now. They have been serviced and have jets suitable to the engine. By settings I meant the 'full in, 3 turns out' on the mixture screws.

 

I still think it is the timing that's out.

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John

When you say three turns out is that three complete screw revolitions 360% or just three hand screws with the screw driver something about 180% rotation?

I have dabbed a spot of white paint on my ones to measure if x 3 complete or just x3 turns so need to know .

Would like to know please.

 

 

Ian Hoper

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Hi John

Thanks for that fitted the Brooklands and Techcraft silencer and did what you said and went for a blat . All seems much better now great .

Was only turning out x3 @180% each before,hunted a bit up to 30 mph then went well top end.Lately it goes well till warmed up then starts to hunt in town so may be jets? No probs over 30 MPH upwards .

Always bugged me how much to turn out the idle screws .

Best of blatting to you on in these lovely evenings.

 

Ian Hoper

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Just incase you have not checked this, are the carbs on to tight or have you got the correct amount of travel of 5 to 10mm up and down at the trumpets?

A mistake I made when I first had my car thinking they were loose.

 

X/FLOW 1700 DD 1990

ROAD USE ONLY..SO FAR

 

 

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John, sorry to have not thought of this before. You say you've just finished a rebuild. If this has taken some time then drain the fuel and put a gallon of fresh in the tank. Drian the fuel out of the carbs as well.

 

ed to ad apology.

Oh well, just read that you've done that. Sorry

 

 

Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here

You and your seven to The French Blatting Company Limited

 

Edited by - nverona on 4 Jul 2006 22:46:19

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OK - Final update on this.

 

Nice mobile mechanic came round, sorted it in 30 minutes. The timing was miles out, and the carbs needed balancing and tuning.

 

But, the main issue was the fact that despite them being numbered, lead 2 was on plug 3, and vice versa. Bu**er. I had checked 1 to 2 and 3 to 4, but not 2 to 3.

 

I do feel a bit stupid, but the bloody leads were numbered.....

 

Ho hum, you live and learn. Engine sounds great now!

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