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Thread: What sparkplugs to use?
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bliffle
Revvin Up
Posts: 95
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posted March 22, 2004 12:26 PM |
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Jeff20B,
thanks for the info. Sounds easy enough.
I checked the periphery of the main pulley, and, sure enough, there are more notches, including one an inch away which has faint traces of yellow (so I dabbed more yellow paint on it) and another painted brick red. Maybe there's another nick or two.
I re-timed to the (new) yellow mark, which restored the original timing it had when I got it, and it runs good. But trailing seems to time to the same mark as leading, which puzzles me since the RX7 has different timings. And I couldn't find a way to adjust the vac-advance base, as there is on the electronic RX7s.
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Jeff20B
Moderator
Posts: 661
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posted March 22, 2004 01:12 PM |
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It doesn't have three points, does it? My Cosmo stock dizzy did and it didn't seem to have mechanical advance (the upper shaft wouldn't turn a few degrees and then spring back like RX-7 ones do). I think advance was accomplished by several relays and the three points. I pulled it all out and replaced it with a GSL-SE dizzy and DLIDFIS with three FB coils. It ran enormously better. BR8EQ-14 plugs in all four holes. I could go with BUR7EQ (or BUR9EQ) in leading some day. No need to upgrade the trailing plugs since they're still running stock FB trailing ignition, and they don't wear nearly as fast as leading.
The rotary B2000 that I listed for sale last night has a really nice ignition setup. Go to the for sale section and check it out.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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bliffle
Revvin Up
Posts: 95
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posted March 23, 2004 02:02 PM |
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I bought the Chiltons manual, and it tells how to time both leading and trailing (by adjusting the base of the plate carrying the points), so I'll scan it and post it.
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bliffle
Revvin Up
Posts: 95
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posted March 24, 2004 09:02 AM |
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I don't know how to post a picture. Do I just put it in the gallery?
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Jeff20B
Moderator
Posts: 661
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posted March 24, 2004 09:28 AM |
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Yeah.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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bliffle
Revvin Up
Posts: 95
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posted March 25, 2004 06:45 AM |
 Edited By: bliffle on 25 Mar 2004 06:48 |
I uploaded the points timing instructions from Chiltons manual to the "REPU Gurus..." album: it's the 9th and last picture, named "TimeYerPoints".
I'm also assembling the info for converting to electronic ignition with coils and distributor from an RX7 12A.
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bliffle
Revvin Up
Posts: 95
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posted March 26, 2004 08:49 AM |
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The points came from Mazdatrix, so I'll set those up first. Nice thing about points: you can static time them, just set the timing spot then rotate points base until a bulb across the points comes on.
When I put the electronic distributor on, maybe I should setup the DLDIFDS system. All I hafta do is find the instructions.
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Jeff20B
Moderator
Posts: 661
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posted March 26, 2004 10:37 AM |
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Did you see the link on the big forum? I'm not sure why the first one didn't work, but the other one further down that thread does work.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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Uncle-Jim
Revvin Up
Posts: 64
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posted June 04, 2004 11:17 AM |
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Where to find these plugs?
I would like to try the BUR's or even the Autolites. I wonder if anyone has a good source at a good price. I understand the Bur's are expensive.
Thanks, Jim.
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Uncle Jim
72 Rx-2 Show Car; '77 REPU (250K & goin' strong) 2 - '76 Cosmo's
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Jeff20B
Moderator
Posts: 661
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posted June 04, 2004 11:27 AM |
Edited By: Jeff20B on 4 Jun 2004 11:40
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I think BUR7EQs are like 4 or 5 bucks at Shuck's (Checker/Kragen). Since I only need two per engine, it's very economical.
I would never put autolites in any of my engines. I don't care if they're like $0.99 or whatever per plug. It's stupid to let something like a couple bucks dictate whether you're going to get correct rotary plugs or some autolite junk that could possibly destroy apex seals. Then again, some people have had seemingly good results with autolites after a mod or two to the ground electrode. I'd honestly rather go with the plugs that have been proven to work great with direct fire and have ran for millions of miles in thousands of '86 and later rotaries. I also don't need to spend time modding them before installation. I guess the money vs time aurgument goes something like this: The time I'd have to spend modding the autolites is better spent on buying the correct plugs.
Of course that's just my opinion. Speaking of which, I just installed a rebuilt R5 13B into my REPU with BUR7EQs in the leading holes and BR8EQ-14s in the trailing holes. I've already test ran this engine with interesting results. I can't wait to see how it does in the truck.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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Uncle-Jim
Revvin Up
Posts: 64
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posted June 04, 2004 01:02 PM |
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I've been using the BR7-ET, with the triple electrode. However, I'm hearing that the quad electrode is proving to be the better set-up. I wonder if that seems to be the consensus?
I seem to recall my '81 Rx-7 running better with the BR7-EQ plugs.
Jim
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Uncle Jim
72 Rx-2 Show Car; '77 REPU (250K & goin' strong) 2 - '76 Cosmo's
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Uncle-Jim
Revvin Up
Posts: 64
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posted June 04, 2004 01:06 PM |
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3rd Gen plug problem?
Didn't I hear a few years back that Mazda had a surface gap plug in the 93's that had some problems, so they went back to an earlier design?
I thought those plugs were the BUR series.
Perhaps I misunderstood the problem
Thanks,
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Uncle Jim
72 Rx-2 Show Car; '77 REPU (250K & goin' strong) 2 - '76 Cosmo's
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Jeff20B
Moderator
Posts: 661
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posted June 04, 2004 09:39 PM |
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The '93s have BUR7EQP and BUR9EQP (platinum). The '93 ignition system isn't as good as '86-'92 stuff. Just ask anyone who's tried '93 stuff only to have to swap over to '86-'92 stuff on their 20B swaps. The '93 coils appearantly suck.
Never seen BR7-ET or BR7-EQ, but I have a set of BR7ET that were in my Cosmo. It ran a lot better when I put some BR8EQ-14s in it.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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Uncle-Jim
Revvin Up
Posts: 64
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posted June 07, 2004 08:45 AM |
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Thanks Jeff,
My nomeclature on the BR7ET plugs is not correct, but I'm sure those are the same plugs in your Cosmo. Hayes Rotary is recommending the Triple electrode plugs in all their pre-81 rebuilds, (like in my REPU and Rx-2 which both have carbureted 13-B's).
My Repu has the DLDIFDS, and the RX-2 has a Jacobs CD ign.
Of the two series, which do you like; the BUR or ...EQ?
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Uncle Jim
72 Rx-2 Show Car; '77 REPU (250K & goin' strong) 2 - '76 Cosmo's
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Klaus43
Rotorhead
Posts: 1259
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posted June 07, 2004 09:38 AM |
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2 more cents...:
I'm a dedicated NGK man, myself. Personal experience has led me to prefer their plugs over all others, for all applications: rotary, piston, 2 and 4-stroke motorcycles...
I'd say, experiment with whatever plug types you wish, until you find the combination that best suits your engine's level of build/porting, your driving style, and the desired results.
IMHO, however, the rotary's directional charge-flow and (at times) supersonic (!) flow rates (or so I've read), tend to benefit from the most powerful, and redundant, ignition opportunities... hence my preference for larger numbers of side-wires, or--better yet--zero side wire plug styles.
Yes, the position of the electrodes in the combustion zone does affect performance! And, different plugs do better at different RPM's...
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Jeff20B
Moderator
Posts: 661
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posted June 07, 2004 10:36 AM |
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13-B or 13B? There is no hyphen in the raised letters on the engine, so I won't use one on the internet. More nomenclature stuff. :)
Yep, Hayes told me to get a set of BR7ETs for my REPU way back in '97 when I asked them about plugs. Well, I stuck with BR8EQ-14s and I'm glad I did. Now I'm going to move everything over to BUR7EQs in leading on everything with DLIDFIS (which is everything by the way) the next time I do a 'tune up' (not really tuning the carb, so why is it still called that?).
I know why Hayes says that. It's because of the old style ignition systems of of all the pre '81 engines. They're not in business to tell you how to upgrade the ignition system of your older rotary. Again, my '76 13B ran much better after after upgrading to BR8EQ-14s with an '81-'85 distributor in my Cosmo. Then upgrading to DLIDFIS made it run way better. Infact, after sitting for several months with a bad fuel pump, after I changed it and went to crank the engine, it fired up in the first second of cranking! It was like RrMMMMMMM. I was more worried about oil pressure at that point since the engine fired up a little too quickly (before the oil pump had a chance to build a little oil pressure).
Of the two series, do I like BUR_EQ or BR8EQ-14 better? I'd say it's best to match the plug to the ignition system. That means if I'm running a direct fire ignition system on leading (all of my engines are currently running this way), I'd say to go with the plugs that Mazda's and NGK's engineers used = BUR7EQ. As for trailing, again, I'll go with the engineers' favorite choice = BR8EQ-14 because it matches that particular ignition system (through the cap). I've now done two engines like this (three if you count my 20B's leading only circuit) and see no reason to change.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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1repuwannabe
1st Gear
Posts: 26
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posted June 17, 2004 03:35 PM |
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bliffe where are you located?? i'm in spokane washington and when you mentioned pick and pull i thought thats in my area.
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