dwell angle problem for 18r motor

**hassles** · 18-01-2011, 11:34 PM

thanks for previous replies... I still cant get 52 degrees (only approx 44 degrees)..the motor was working on 52 degrees b4 but i had to do some work on the dizzy which ended by removing it from motor etc..now although motor runs it still lacks power..I cranked motor to what i think is TDC timing ..marks on pulley were 2 lines 3mms apart is this TDC ?? or BTDC (BTDC is meant to be 7 degrees)..anyway the #1 piston was at the top but the rotor was facing NEARLY towards #1 lead (just a fraction past so i feel the points opened a bit too late!!..so to line it up I had to turn dizzy outwards clockwise but this ran the motors revs very low almost wants to cut out..and if you turn it towards motor anticlockwise it revs the motor and the rotor lines up the #1 lead but the timing marks are way past the pointer.. in the manuals it shows the dizzy with vacum advance facing slightly outwards!!..(i havnt touched carby at all it was overhauled a while ago)..I hope some of this makes sense...i cleaned the mechanical advance in dizzy but cant tell if its playing up..i recon it is working ok as it was prior to repairs including the orig dizzy which was taken out months back...cant see fuel being the problem but not sure how to tell.

**Willofan** · 19-01-2011, 09:45 AM

Forget setting the timing until you get the points gap correct using a feeler guage which should be about .018" (or a tight 0.5mm) as a starting point.
Then remove all plugs, check TDC by using a piston stop in the No1 plug hole by rotating it either side and set the marks to find the true TDC. This should be the mark on the left of the three marks in the balancer. If not, remark the balancer pulley edge to suit.
Plugs back in and use a test light across points wire on side of dizzy to earth to set static timing, turn ignition on, set 7 degree timing mark to pointer and rotate dizzy till test light just goes out then lock up dizzy lightly.
Start engine and check dwell first, this should be around 50 to 54 degrees, try to get 52 if you have new points. Check timing and set to 8 degrees which should be the middle mark, slighly advance if it an older motor.

If you cannot get 52 degrees dwell, recheck what you have done with the dizzy plate or cam lobes or maybe the points are not the right ones.

Goodluck

**hassles** · 19-01-2011, 10:12 PM

thankyou Willofan 4 your reply.. I set gap on points to .048 (the points had done about 3000kms) got #1 plug to TDC (that is if you face the motor front on then it was the 3rd mark on your left then about 2 mils away going right is another and then about 10 mils to the right of that appears to be another im assuming is 7 deg BTDC?)

set up test light and turned the pulley back to 7 deg BTDC timing mark?..(how do you measure 7 deg my timing light doesnt have a guage).. When I rotate dizzy til light comes on then to turn it back til light goes out you have to move the dizzy several degrees at least!!..there a discrepancy here?...i still get around 44 deg dwelland the rpm is about 250.. Then I set the test light using the TDC mark as 7 deg ..same result...I havent touch the lobes , the points were those stated as correct, they have been working fine for ages, the dizzy plate was taken out to clean but the mech cent/advance was just cleaned with petrol and some high temp grease applied sparingly it was not removed,the ....?earth wire was repaired and repositioned.I rechecked vacum hoses connections and although newish i did repair the one from dizzy vacum to carby.

This dizzy and the one orig from van were both working okay with in the last 18 months and I just replaced the vacum advance & set points done by a mobile mechanic..if you can think of anything else be appreciated..I took it for a ride and it struggled and wanted to choke a lot..(perhaps its is fuel??)

**oldcorollas** · 19-01-2011, 10:22 PM

i thought dwell was controlled by the points gap...
smaller gap = longer closed time = more dwell? (ie more coil charging time)

I used to run smallest gap (within specified range) to increase dwell, and check more often

**litldv8** · 20-01-2011, 11:17 PM

Originally Posted by hassles

thankyou Willofan 4 your reply.. I set gap on points to .048 (the points had done about 3000kms) got #1 plug to TDC (that is if you face the motor front on then it was the 3rd mark on your left then about 2 mils away going right is another and then about 10 mils to the right of that appears to be another im assuming is 7 deg BTDC?)

set up test light and turned the pulley back to 7 deg BTDC timing mark?..(how do you measure 7 deg my timing light doesnt have a guage).. When I rotate dizzy til light comes on then to turn it back til light goes out you have to move the dizzy several degrees at least!!..there a discrepancy here?...i still get around 44 deg dwelland the rpm is about 250.. Then I set the test light using the TDC mark as 7 deg ..same result...I havent touch the lobes , the points were those stated as correct, they have been working fine for ages, the dizzy plate was taken out to clean but the mech cent/advance was just cleaned with petrol and some high temp grease applied sparingly it was not removed,the ....?earth wire was repaired and repositioned.I rechecked vacum hoses connections and although newish i did repair the one from dizzy vacum to carby.

This dizzy and the one orig from van were both working okay with in the last 18 months and I just replaced the vacum advance & set points done by a mobile mechanic..if you can think of anything else be appreciated..I took it for a ride and it struggled and wanted to choke a lot..(perhaps its is fuel??)

.048 thou or mm? either way

.018 thou or .48 mm and put the tiniest amount af grease on the rubbing block
when you rotate it back turn it back past 7btdc then up to 7btdc to take up timing chain slack
old corollas is right smaller gap = bigger dwell
neil

**hassles** · 20-01-2011, 11:30 PM

oops, thanks for that (brain fade) it was 0.48mm..i have greased the rubbing block with the tiniest amount but i will look at the issue re timing chain slack..a good point...this 18r motor is in a toyota campervan..thanks

**litldv8** · 20-01-2011, 11:36 PM

try shutting the points down to .42mm to get the dwell up and give the point gap face a wipe with a clean rag
neil

**TRD-12A** · 21-01-2011, 06:48 AM

44 degrees is still sufficiant enough for it to function yes its not perfect but it will still work sounds as though dizzy may be out a tooth or something is defanetly not right inside of it are the points defanetly right??
Good old points soon as i bought my car i through the points away and threw in a electronic ignition into my dizzy best thing i ever did

**TRD-12A** · 21-01-2011, 06:49 AM

actually come to think of it isnt the dwell on a 4 cylinder more like 60

**hassles** · 22-01-2011, 07:39 PM

YAY!!! got the dwell to 52 deg...many thanks to ltldv8, willofan and neil..also TRD-12a... It runs okay but still chokes/splutter and struggles uphill will keep on looking at it until the mechanic returns from his (well deserved) fishing trip..keith.

**Dazza** · 23-01-2011, 10:42 AM

Sound like a carby problem to me. Check the little valve thing on the left side of the carby that is under the rectangle shaped plate held on by three screws. i had one fall apart on a hilux i owned and it lost power under load but was ok if i kept the revs up or cruised along with no load on the motor.