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1974 Datsun 710 can't advance timing enough
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Pontoyasun
Novice
Feb 27, 2009, 4:48 PM
Post #1 of 12
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1974 Datsun 710 can't advance timing enough
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Hey guys this is my first post, been searching the net for an answer, found you guys on google, read a few threads, figured i would start one. lol I'm just helping my son finish a rebuild on a 74 710 Wagon, the L18 4 cyl engine is all together. It starts and idles ok, but timing should 12 btdc and timing is varying btwn 5 and 9 and we have hit the adjustment limiter. We didn't replace the timing chain, it looked okay. Is that our problem u think?
Thanks,
Jeff
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Loren Champlain Sr
Veteran
/ Moderator
Feb 27, 2009, 4:55 PM
Post #2 of 12
(3240 views)
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Re: 1974 Datsun 710 can't advance timing enough
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First, check the points dwell. For every two degrees of dwell, the timing will change one degree. The dwell needs to be adjusted before timing is attempted. Is it possible that the distributor is in a tooth off? I can't remember if it is gear driven, or just a slot. If it's gear driven and you're still having a problem, hit back.
Loren
SW Washington
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Pontoyasun
Novice
Feb 27, 2009, 5:11 PM
Post #3 of 12
(3238 views)
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Re: 1974 Datsun 710 can't advance timing enough
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Thanks for the reply Loren. There is a helical gear on the crank that drives the oil pump and there is a slot on top of the oil pump that drives the rotor shaft. If the point dwell was off that much would it even idle?
Jeff
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Loren Champlain Sr
Veteran
/ Moderator
Feb 27, 2009, 5:17 PM
Post #4 of 12
(3234 views)
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Re: 1974 Datsun 710 can't advance timing enough
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Absolutely. The dwell should be 49-55 degrees.
Loren
SW Washington
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Pontoyasun
Novice
Feb 27, 2009, 5:51 PM
Post #5 of 12
(3231 views)
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Re: 1974 Datsun 710 can't advance timing enough
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Thanks again Loren, will check that tomorrow morning.
Jeff
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 28, 2009, 9:31 AM
Post #6 of 12
(3224 views)
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Re: 1974 Datsun 710 can't advance timing enough
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Nosing in again! Higher dwell or smaller point gap increases timing BTC #s. I suspect the timing chain is worn as might be normal but needs to be directly checked for alignment and freeplay. Even metal chains lenthen over time and use. They can be "covered up" by advancing timing till you reach the end of range.
IF nobody has pulled dist and it could be off a tooth on that then I do suspect the chain,
T
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Pontoyasun
Novice
Mar 3, 2009, 1:20 PM
Post #7 of 12
(3209 views)
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Re: 1974 Datsun 710 can't advance timing enough
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Thanks Tom, hey there Loren. We've been pretty busy. Finally got a chance to recheck the point gap (don't have a dwell meter). As I suspected the point gap is at .018, which is minimum, by the manual. Now we have no spark. There is power at the coil with the key on, there is a good ground at the dist, the points have juice (arced with a pick). Checked continuity of all the wires. Any ideas guys?
Thanks
Jeff
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 3, 2009, 2:41 PM
Post #8 of 12
(3203 views)
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Re: 1974 Datsun 710 can't advance timing enough
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If you now have spark - is it making along to the plugs? It may be weak spark?? Also, if not running and showing spark at the plug wire ends and you've been trying(cranking a lot) try drying out the plugs. Heated dry is much better than air dry. It's a PITA and don't mix up wires of course. Propane torch or I think I saw Loren suggest an oven once!
Warning! USE OF KITCHEN APPLIANCES FOR AUTOMOTIVE USES CAN BE HAZZARDOUS TO YOUR DOMESTIC RELATIONSHIP!
~Below more or a refresh on points~
When given a range for point aim for the larger end of the range as it will get smaller with use.
Some tricks or ideas: Slide a CLEAN but of stronger paper between contacts when on low spot and touching - try again testing for spark.
(BTW - a spark tester is nice to have. I have just one that goes in line of any plug wire and lights up that can be left on when engine is running. Dunno if they even make that type anymore?? I think it was K-D tools?)
Try to put point gap up to max of range. If you can see the contact with a light the two little round contacts should touch evenly - hard to see in car. Make sure nylon type bumper is truly on top of a cam high spot when checking.
The min extreme may still show spark but I swear you get a better spark at the wider gap allowed and can't really say why. Also - make certain your point feeler gauge (they make a mine feeler gauge for point adjustment) is right by adjusting such that it will just barely slide under it's own weight with the spring action of the points. I know - it can be like wristwatch repair! If you get it running properly do get a dwell meter that also shows connectivity*
*By that I mean they made them (I still have one predating the Nixon administration that works!) shows "good" - "fair" - "poor" or open. Love that sucker and still use it when needed.
~~~~~~~~~~~~~~~~~
Good luck - keep at it,
T
(This post was edited by Tom Greenleaf on Mar 3, 2009, 2:43 PM)
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Pontoyasun
Novice
Mar 9, 2009, 2:04 PM
Post #9 of 12
(3186 views)
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Re: 1974 Datsun 710 can't advance timing enough
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Hey Tom and Loren. Well we got her purring, at idle anyway, haven't tried a road test yet, we still have some electrical gremlins running around, and no insurance yet. LOL We restabbed the rotor shaft one tooth advanced and while Kevin ran the starter I adjusted the points until I got the best spark, put the rotor and cap back on and started her right up. But we do have a stretched timing chain I guess because now we have the dist fully retarded and still can't get 12 btdc, but we got 13. Good enough for now tho. Thanks again for your help. Our next project is dropping a chev 350 in a 1980 Firebird, I'm sure you'll be hearing from us again.
Jeff and Kevin
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Loren Champlain Sr
Veteran
/ Moderator
Mar 9, 2009, 4:53 PM
Post #10 of 12
(3182 views)
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Re: 1974 Datsun 710 can't advance timing enough
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Jeff; If you are that close on the timing, point dwell may bring it into specs. Dwell meters are very inexpensive. I'm sure you can find one under $20.00. They are also a tachometer combo. Which, is real handy on any rig, even if it doesn't have points. As long as it doesn't ping under acceleration, that's probably close enough. Really glad to hear you got Betsy running! Thanks so much for letting us know! Have a great week. Just thought of something else; Some of the older distributors had an 'octane' selector. A dial on the side of the distributor that you could 'micro adjust' in case of ping. Take a look.
Loren
SW Washington
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Hammer Time
Ultimate Carjunky
/ Moderator
May 25, 2011, 7:54 AM
Post #12 of 12
(3046 views)
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Re: 1974 Datsun 710 fuel system
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This thread is over 2 years old. If you need help with something, please start a new question of your own. This thread will be locked now.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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