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Crossflow won't start after rebuild!!!
prawnabie - 19/10/08 at 07:56 PM

Hi Guys

Trying to start my engine after it being rebuilt because of a broken ring!

I have had is backfiring through the carb and the exhaust and also detotaing too early and stopping the starter turning the engine over - but not running (or even close).

Specs are-
1700 crossflow
234 cam
twin 40's
bestek bosch electronic dizzy/coil/powerpack.

I have built the engine myself (apart from machining work.)

Cam was timed in according to kents spec and checked a million times!

I have checked for spark and compression, and webers were off the previous engine and are fuelling.

I have set the rockers according to the haynes manual and swapped the leads round numerous times but it sill will not start! I am aware of the 1-3-4-2 sequence but just cannot get it started!!

Any help will be much apprieciated!

Thanks

Shaun

[Edited on 19/10/08 by prawnabie]

austin man - 19/10/08 at 08:06 PM

I would agree sounds like your timings out or you have the leads mixed up, I think the Kent is a 1432 sequence. Need to check this then set the timing up statically using aq test bulb in line with the poins this will time it as close a perfect make sure the bulb just startd to light on opening points,

nitram38 - 19/10/08 at 08:06 PM

Sounds like you distributor is 180 degrees out. Firing on the wrong stroke.
You should ensure that you are at TDC on the compression stroke by taking out the plugs and turning the engine over by hand (spanner) and placing your thumb over the number 1 plug hole. Set your distributer to number 1 once the piston is at the top of it's travel. Set the rest of your plugs/leads from there.

[Edited on 19/10/2008 by nitram38]

tjoh84 - 19/10/08 at 08:07 PM

i had that it was 180 out

prawnabie - 19/10/08 at 08:09 PM

do you mean 180 degrees out on cam timing or ignition timing?

As stated i checked the cam timing numerous times - i really hope that is right!

To set the igntion timing, I got no.1 to tdc on the compression stroke, then put the dizzy into engine with rotor arm pointing to no.2 inlet - so it was pointing straight up when dizzy was in place. I then turned the dizzy body until no.1 lead was more or less inline with the rotor arm.

Cheers

Shaun

nitram38 - 19/10/08 at 08:12 PM

I should have added to check your timing marks because you could have it on the exhaust stroke, hence the 180 degree error.

scutter - 19/10/08 at 08:14 PM

Easy enough to get 180 deg. out, your method of installing the dizzy is correct.

You can weather your at the top of the compresson stroke and not the exhaust by removing the rocker cover and seeing if both valves are closed if so then your spot on.

ATB Dan.

mark chandler - 19/10/08 at 08:20 PM

Distributor and cam turn once to 1 engine revolution. 180 degrees out is half a turn on the distrbutor.

To prove swap the leads around, ie advance them by two posts on the cap.

If the leads are stretched or awkward like this pop ou the distributor and twiddle the rotor arm 18o degress and pop it back in, no need to move the leads this way.

Regards Mark

prawnabie - 19/10/08 at 08:26 PM

Thanks for the replys!

I will whip the cover off now and report back!

Thanks again

Paul (Notts) - 19/10/08 at 08:35 PM

I had my Rover V8 180deg out the first time I started it. The flames were spectacular...Never again

Paul

02GF74 - 19/10/08 at 08:37 PM

quote:
Originally posted by prawnabie

I am aware of the 1-3-4-2 sequence but just cannot get it started!!


What exactly do you mean by that?

Crossflow firing order is 1-2-4-3.

Looking at distributor cap from above, the rotor arm turns anti-clockwise

It does sound very much like timing 180 degree out or you don't have the leads in the above order.

[Edited on 19/10/08 by 02GF74]

prawnabie - 19/10/08 at 08:43 PM

Been out and had a look - both valves are deff closed on no.1 cylinder so i know its on compression stroke.

rotor arm is pointing straight up. I cannot use the test light though as it is an electronic setup. it is pretty foolproof as all the wires are pre - connected so it just needs a live and an earth (but I am getting a spark anyway).

Is there any foolproof way of setting the static igniton timing on an electronic setup?

Thanks

Shaun

DavidM - 19/10/08 at 08:50 PM

If it is close it'll start. I agree with O2GF74, firing order of a crossflow is 1243. Sounds like your leads are on wrong.

David

02GF74 - 19/10/08 at 08:51 PM

just been downstairs to look at the fest manual; says there is punch mark on distributor body so it is aligned with the dsitributor mounting flange. a new dizzy is fitted so it is midway in the slots then timing lamp is used. doesnlt sound promising ....

... but not sure that applies to your enigne since ^^^ for fest.

if you put plug on end of lead from the coil and place the plug the block, if you rotate the distributor, can you get the plug to spark?

NB keep hands away from the plug!

prawnabie - 19/10/08 at 09:14 PM

Hi

Yes if i do the above, I get a blue sparkt hat will jump about 2cm from the plug to a head bolt.

02GF74 - 19/10/08 at 09:20 PM

quote:
Originally posted by prawnabie
Hi

Yes if i do the above, I get a blue sparkt hat will jump about 2cm from the plug to a head bolt.




okey dokey. now turn the engine so that the mark on the pulley lines up with 10 degree BTDC as cast on the timing chain cover - cylinder 1 is on compression stroke - both valves closed (50/50 change if you are guessing this!)

do the twisty distributor bit as you have done until you get the spark.

clamp distributor down in this postion..

as you go to fit the cap - it has a tab so can only be fitted one way - look to which lead the rotor is pointing to. that lead then goes to cylinder 1.

then going anti-clockwise fit the leads 2-4 and 3.

it should nun.

prawnabie - 19/10/08 at 10:14 PM

cheers mate, will get onto this first thing!

daviep - 20/10/08 at 07:10 AM

quote:
Originally posted by mark chandler
Distributor and cam turn once to 1 engine revolution. 180 degrees out is half a turn on the distrbutor.

Regards Mark


Only on the very rare 2 stroke crossflows !!! on all the rest the the cam and distributor run at 1/2 engine speed same as every other 4 strokes

Cheers
Davie

prawnabie - 21/10/08 at 01:30 PM

Hi guys

Thanks for help, got it to start briefly and then battery died.

One thing I noticed is that the starter turned the engine over very slowly, even on a new battery. Once i got the timing right ish it seemed to turn over a bit faster. Is this normal - I am going to fit a bigger battery to see if that was the problem.

Thanks

Shaun

nitram38 - 21/10/08 at 01:55 PM

If you have rebuilt the bottom end (rings/crank etc) then it will be tight and slow to turn over.
We used to 24v them with 2 batteries (risky) or tow start them.
It will take about 500 miles to run in and loosen up. After 500, change the oil.

prawnabie - 21/10/08 at 06:39 PM

Hi

Had another attempt today.

I have had the whole engine rebuilt.

So far i have used two 063 batteries and a 027 battery. (All New)

Turnes over pretty quick for about 4-5 secs on a new battery then really sluggish. I have tried 2 new starters so i know its not that. Also used a booster pack and still sluggish to turn over!

Really getting on my nerves now as i have no chance of starting it by cranking it this slow!

Any more tips?

Cheers

Shaun

rusty nuts - 21/10/08 at 06:46 PM

Check and clean all of the battery and earth connections .

prawnabie - 21/10/08 at 06:55 PM

Hi guys

Sorry to keep this thread open but am really at a loss here.

I have taken all the plugs out and turned it over on the starter and it turns over a treat. If i put the plugs back in it really struggles to turn over - (almost like a flat battery)to a point where the starter is stalling and starting to get hot.

Intially I thought this was the battery going flat, but the fact that it turns over without the plugs in dismisses this i think!

Im thinking its the compression that is causing this. Im 100% the cam timing is right at 103 degrees and i used a vernier pulley kit to achieve this. It was checked 6 times and i got 103 degrees everytime.

The valve clearances were reset and triple checked too!

Really stuck here, as i cannot get the engine to spin over fast enough to fire it up!

Thanks in advance

Shaun



[Edited on 21/10/08 by prawnabie]

flibble - 22/10/08 at 11:15 AM

Hiya, just thought I'd chime in and say I'm running a 1700 Crossflow and it too really struggles to turn over (it has no vac advance on the dizzy which doesnt help), it however eventually still starts more often than not.

In emergency "I need it started now!" situations I can turn the dizzy timing back a couple of degrees and it'll spring into life on the button. Have you tried turning the dizzy anti-clockwise a smidge just to see if it helps? (you wont do any harm), and triple checked your 1243 firing order (1 being the crank pulley end)?
Kev

Marcus - 22/10/08 at 11:36 AM

Does sound like you are a little over advanced. This can happen if you have no vac advance on the dizzy. As above turn dizzy a few degrees (less advance) and try. Basically you're getting a spark whilst the piston is still going up, which slows things down.

prawnabie - 22/10/08 at 11:51 AM

Hi mate

Just tried it without the plug leads on - still the same.

I am using 1300 powermax pistons which will increase the compression ratio (I know you all know this lol).

I found a thread on here with a guy with the same problem, which was cured by using a gear reduction starter from lynx ae for about £140+ vat.

I think this may be the way to go forward as there seems to be a theory that the crossflow starter cannot turn over an engine with high compression very well.

Shaun

flibble - 22/10/08 at 03:36 PM

If it was me (a shameless bodger) I'd take a plug or two out aiding in turnover speed and see if it starts up on two/three cylinders - (leave the removed plugs grounded though) just to see if it starts.
I know mine will start on 2 quite happily.
Probably best to ignore me though

rusty nuts - 22/10/08 at 06:14 PM

I have in the past started engines with one or more plugs removed as a last resort, in one case on a motorway slip road . If the engine starts you may be able to refit the plugs with the engine running if you are careful , then use a pair of plug lead pliers to refit the leads. I have the same engine mods but have never had any cranking problems although my car has a pre engaged starter which is more efficient than an inertia starter . If you do fit a pre engaged be aware the ring gear has a different number of teeth.

rusty nuts - 22/10/08 at 06:21 PM

flibble ,you have u2u.

ande - 2/8/16 at 08:51 PM

Hi guys, i know this is a very old thread, sorry to dig it up, but i have the exact same problem with my 1360 xflow and this was top of the google results when searching for a similar problem, turns over really fast without the plugs in but really slow, to the point of stopping and the starter getting really hot, only difference is i have had it running, seems to me there is a very fine line where it will start, if we turn the dizzy very slowly clockwise it will fire up, but once it's cut out, it needs to be turned back clockwise to speed up the starting.

rusty nuts - 3/8/16 at 06:52 PM

Have you ever checked the ignition timing using a timing light? Somewhere around 8 to 10 degrees BTDC would be a fair starting point. Also what distributor are you using? I've known Bosche to sieze the auto advance flyweights causing problems and the old Motorcraft were never very good . A bespoke distributor to suit the modified engine would perhaps help?

ande - 3/8/16 at 09:27 PM

i am using an accuspark dizzy, but i took it out anyway to see if it would turn over, anyway i just went out again, turned the key and it turned slowly, so i kept the key turned and it got a bit faster then faster and faster until it was whizzing over at full speed, then it kept doing it then each time, it was gradually slowing down i think due to the battery draining, but if i waited a few seconds it would whizz round again. i know this is a daft question but the alternator belt couldnt be too tight could it???

Murdoc - 4/8/16 at 01:05 AM

I don't know the crossflow engine but check if the wires, connections, fuses, ground points etc are getting warm/hot during cranking also check the connections are clean. If the wire is getting hot the resistance will be significant, the impedance of the motor will be tiny and the voltage across it will drop significantly if the wires heat up. Put a multimeter across it if you have one.

[Edited on 4/8/16 by Murdoc]