: Anyone using coils over plugs?
Sep 9th, 07, 06:25 AM
I have Accel DFI in my '68. It runs good and is strong, but I think it could be a tad smoother and stronger. I absolutely HATE the plug wires being close together, but there's no other way to route them. I see Accel is finally making a kit to allow coils over plugs, kinda like the LS1 setup, or virtually any new car.
New cars have pretty much all moved to seperate coils, which eliminates any chance of crossfire.
Has anyone switch their wires and coils to this setup? Any difference?
Hi Dave - I think you are stressing over crossfire needlessly. I'm not saying crossfire can't happen, just that with properly routed wires it won't happen. I've seen guys with all the wires tie-wrapped in a bundle and cringed but they never had a problem.
You got me interested in the Accel ignition and coil conversion but I couldn't find anything on their web site. I'm afraid it would be very costly, to run a coil per cyl. The entire ignition starting at the distributor would have to removed. Then there would need to be some type of timing trigger installed that would tell the coils when to fire. Would this be mechanical (like a distributor) or computer controled? Speaking of the distributor without it something will be needed to drive the oil pump.
Not impossible but a lot involved, if you have a link to some info could you provide it? Thanks,
Sep 9th, 07, 08:46 AM
Well, I used to feel like you about the crossfire. However, I've seen a few things which changed my mind. For instance, using your average lawn mower for this experiment; take two BRAND NEW plug wires and lay them side by side. Plug one wire onto the coil and the other wire onto the spark plug. The lawn mower will fire up and run perfectly.
I wasn't totally convinced about this crossfire issue though, until a couple of months ago when I was trying to help a buddy diagnose a boat engine problem. He installed two brand new GM V-6 engines (auto engines, basically) last year. This season (after moderate use last year) one engine would run fine up to 4,000 rpm, while the other engine would not get over 3,000 rpm. We checked fuel pressure and replaced fuel filters, still that one engine would not rev up. We swapped the carbs and distributors, no luck. Compression test on both engines showed good compression. New plugs and new wires, still no luck.
We were getting completely baffled. So we went out and ran the engines at WOT. We noticed the secondaries not opening all the way, so we carefully checked for vacuum leaks and again, we checked fuel supply. Still it would not rev.
Then we decided to disconnect one wire at a time (from the dist cap) while operating at WOT (easy to do in his boat, as we just left the engine hatch up). We figured as each good cylinder was disconnected, there would be a corresponding drop in rpm, thus we could locate the "bad" cylinder(s).
Well, imagine our complete and utter surprise when we disconnected one of the wires and the rpm's went UP!!!!!!!!!! How could this be, we muttered? The dist cap is brand new. The wires are brand new. We were amazed. But indeed, upon substituting a straight boot for the 90-degree boot, the problem was solved. The brand new wires were crossfiring at the dist cap. I used to be a auto mechanic and I never saw such a dramatic demonstration of crossfiring, LOL.
Anyway, sorry for the long story.
Here's the info on the new part -
Sep 10th, 07, 08:25 AM
Interesting stuff Dave - So with a dual sync dist there is some sort of crank trigger then as well as the cam trigger? If so to use the coil per plug would you leave the dist in place with the plug wires removed?
Sep 10th, 07, 11:03 AM
Yes, the dual sync acts as crank trigger.
Here's the kit they said I needed. Though I don't understand about timing adjustments console. I have all those adjustments on my laptop. I need to call them again.........
Sep 10th, 07, 11:09 AM
Man, this is looking like about a $1,500.00 project, which just seems like a lot of money for adding a few coils, damn.
Sep 10th, 07, 11:10 AM
You need 8 coils, plus these adapters:
Now, lemme ask a stupid question here, but if you have an Accel wiring harness, wouldn't you think it would plug directly into an Accel coil?????????????????
Sep 11th, 07, 11:31 AM
Well, I just got off the phone with Accel, and it looks like this would cost the better part of $2,000 - just to upgrade to coils-over-plugs...............
Like most older guys, I've got the money, but that's just too much moolah. Man, I can probably find a complete used LS1 (WITH coils-over-plugs) for about $2,000, LOLOL.
Sep 11th, 07, 11:47 AM
I figured costly but didn't think it would be a $2k deal... :eek: