|
|
Thread: <timing>
|
tobanybe
Revvin Up
Posts: 80
|
posted June 03, 2004 03:21 PM |
|
<timing>
hi there-just took my 74 auto for a drive and noticed a good backfire on the downrev .... first checked timing and is @ o*5* which should be 0*10* right? wouldn't time right by turning distibuter so i looked under cap @ the lines i guess you could say ... <2 small.1 big.4 small.one big.4 small.1 big. and 2 small. it is set on the first large line, and i noticed large scratch on plate right near the 2nd big line,and another scratch across the 2nd set of 4 small lines ...> is this the position it should be ... i assume by loosening the the screws on plate?does the timing off hurt the engine at all ...? let me know what you know , thanks
<i think im about to slap myself for the thought of parting my repu's by the way(long island talking i guess back then)>
i am also getting the confidence i need to jump into a new carb and header for my 75 even though it is 12a, but will definitly ask more when the time comes.
tobanybe*
|
|
brad
Rotorhead
Posts: 1672
|
posted June 04, 2004 07:46 AM |
|
zero and ten
is fine for timing. trailing should be 8-10 degrees behind leading.
yes, too much timing advance can toast a motor. once timing is set and carb is cleaned, motor tuned up if it still backfires make sure all the exhaust gaskets are good and tight. leaky exhaust causes backfires on decelleration.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
|
|
tobanybe
Revvin Up
Posts: 80
|
posted June 04, 2004 01:29 PM |
|
here i go ...
i will give it a shot to time it back to normal. and check the manifold gasket cause it is a bit louder than my 75, i figured the 12a would be alittle bit more quiet but i am not sure ...
tobanybe*
|
|
tobanybe
Revvin Up
Posts: 80
|
posted June 04, 2004 06:09 PM |
|
<damn battery>
well,
in the middle trying to time the battery went dead,and i mean door knob dead ... so i need to replace before further timing, which seemed to only get worse ...i know turning distibuter is main timing aspect but how do you define the trailing and leading ... i got it 0*0* and could not get the trail @ 10* .. kinda lost about it now ... anybody been here before?
tobanybe*
|
|
tobanybe
Revvin Up
Posts: 80
|
|
posted June 05, 2004 12:59 PM |
|
grrrrr....
well ... <again>
got the new battery in ... timed according to my haynes book ... picture of timing procedures which i don't understand fully ...<talked about 4 adjustment screws/ but only the 2 outer screws loose enables base plate to rotate> which got it to 0*6* i would say.fired right up and took it for a test run... ran great there, on the way back a big loss of power when accelerating only.cheked timing again and the front rotor was the same and rear was way off ...
would getting a new or newer cap/rotor be easier to work with?heard today they slowly loose they're prime position from wear and time.?i am pretty sure the exhaust gasket has a slight leak. maybe a good time for a header :)
please help me out ... :(
tobanybe*
____________
revin secret 7*
|
|
tobanybe
Revvin Up
Posts: 80
|
|
posted June 09, 2004 05:22 PM |
|
update --->
worked alittle on my timing today, and heres where i am at.
its not boggin down now at all which made me feel alot better.. is @ 0L and 5T ... the base set screws will not adjust any further which needs to adjust slightly more to be correct, would this call for an overhaul possibly?And i have heard that upgrading to breakerless system is way better, what kind kinda change over is needed?or is it a drop it in and adjust?
the main? i have would be when the base set screws are as far as they can go and need to go just a bit further what do you do from there?thanks*
|
|
Klaus43
Rotorhead
Posts: 1259
|
posted June 10, 2004 12:17 PM |
|
Sounds like you're talking about
...the old original points ignition/dizzy...? Check your advance mechanism for sticking/stuck/rusted in place. Check also to make 100% certain someone didn't stick one of the old 'three point' setup dizzy's in there... (in those, the third set was underneath the others...)
Does the advance mechanism 'snap back' fully and completely every time? If not, it could be a big part of your troubles.
While you're at it, you might want to examine all the other bits --but especially the shaft-- for excess play, and remember also to lube the dizzy cam slightly...
I take it you know about points/dwell adjustment, accuracy, and utter cleanliness for point life? (Swab the contacts with alcohol, or brake cleaner, etc., if there's even a chance there's any lube/oil on 'em!)
And, yes, there's no substitute for a nice, clean cap and rotor. (I wish they'd s__tcan those aluminum contacts, and make 'em outta copper or brass!) In a pinch, however, it can really help to carefully clean up those contacts by scraping with a pocketknife blade to remove the excess oxidation...
**Beware the occasional old original points-style rotor that shorts out internally, for no apparent reason! They 'were' all superseded long ago, 'but'... you never know what'll turn up out there...
Hope this helps! --K.
|
|
tobanybe
Revvin Up
Posts: 80
|
|
posted June 10, 2004 06:39 PM |
|
?huh?
what do you mean by 'snaping back'? ... and if i pull the whole dist. out how do i put it back in the right place? i am not sure if there is more underneath the plate.i know its all real touchy and sensitive so i haven't really dug into it deeply, just light adjusting up to now from what i have learned. what else should i know?
|
|
Klaus43
Rotorhead
Posts: 1259
|
posted June 13, 2004 11:01 AM |
|
The dizzy itself is relatively simple...
Without pulling or adjusting anything,(dizzy still installed, set-screw tight), take the cap off, and see if you can move the shaft (turn it) *a bit* back-and-forth by manually turning on the (still-installed) rotor... You're looking for smooth, yet limited, 'advance' movement, (influenced/actuated via vacuum at RPM), with a distinct, definite, and complete 'snapping back', or positive return action upon release.
If there is no movement possible, it's either broken/rusted/corroded in place, or it's been modified to eliminate any mechanical or vacuum advance. Time to discover what's going on and either fix it, or work around it, knowing for certain what's going on...
If the movement is there, but the return is 'iffy' --the mechanism 'hangs up'-- time to clean, repair, or replace.
If you're worried about messing things up by pulling the dizzy, start by manually turning over your motor (by the belt/pully, by hand...), until you can get the timing marks lined up (E-shaft pully/front cover indicator). Then, make a note of the existing dizzy position, perhaps by making a match-mark with a sharpie, both on the base/adjustment plate/set screw (and engine itself), as well as rotor location relative to dizzy body, if you really wanna get obvious.
Next, just make sure the motor doesn't get moved/ignition cranked while the dizzy's out... and you should easily be able to put 'er back to the way it was after you pull the dizzy out...
|
|
|
|
|
