Compression test looks good, it has to be bad wire(s), bad plug(s) or wrong firing order. The way you have the wires tied together can be making one or more of them short out intermittingly? Best to keep wires separated just for that reason. Get new plugs, those look fouled. Looks like carb is running rich, do you have the right power valve in it? And like mentioned watching it run in the dark you sometimes can see if spark is shorting out by a light show. Would be hard to hear with open headers though. And yes check header tube temps. Derek
What do you guys think of the plugs? They're champion C59YC Speedway lists the c59yc and the 792 as the same plug. Blueprint says to use the Champion Racing Spark Plugs 792 Here's the links on summit. I don't see any difference do you? https://m.summitracing.com/parts/cpn-792 https://m.summitracing.com/parts/rhs-82215-1 Here Speedway lists them as a joint part number http://www.speedwaymotors.com/Champ...ug-750-Reach-5-8-Hex-59-Range-Cold,34306.html Derek posted while I was writing this one. I cleaned the plugs and they look new again was just about to put them back in when I thought I'd check the post. Guess plug brand preference is like car brands, but my racing buddy said to ditch the Champions and go NGK or just Delco's. Trying to be safe I went with the builders recommendation . Sure be nice if just the wrong plugs or wire/cap issue. Makes me wonder about that minor cap Crack now. Tough to not have wires together, whole reason they come with and sell fancy separators
If you have a multimeter, you could check the resistance across the plug wires. I'm not sure how one could detect faulty plugs, other than watching for spark while someone cranks the engine...
The carb is right out of the box minus idle mix tuning. Only #3 really looked bad, rest seemed relatively fine. 3 is pic above that's black. Changing anything on a carb other then idle mix or curb idle adjustment is COMPLETELY out of my skill set. Went with the carb the builder recommended and tuned it the best I could I tested each wire with a inline plug tester/light and all looked good but I didn't meter any of them.
With a continuity tester, a multimeter would have that as a setting. I heard Champion plugs are good, but not until they are continuity tested. I heard years ago that one out of 2 Champions are junk, not sure how good they are nowadays though. I always use AC/Delco or Bosch plugs, have heard nothing but good things about NGK plugs too. If you have a multimeter check plugs before you put them back in. What type of carb do you have? If Holley style carb then you need a power valve that is rated at half of your idle vacuum in gear. You'll need to get that vacuum more steady first. The cab paperwork should have the spec of what the carb came with as far as power valve, jetting front and rear and so on. If plugs are back in already do the temp test. Derek
It's a Holley 4160 750 cfm Plugs aren't back in yet and I'm wondering of I should just change them to get them out of the equation if they're prone to failure. Don't want to waste money but this is getting g ridiculous and I just want to drive the car
I was under the impression that just having continuity in the electrode is not enough, that insulation might be faulty and the spark may jump across the porcelain in some cases
I guess the free and easy thing to do would be to hold the suspect plugs while someone cranks the engine and watch for spark. It won't assure 100% that those components are working properly, but it should make complete failures very easy to catch before you spend any money.
Not sure, I don't buy Champion plugs so I never had to learn how to check them, I was guessing on how to do it. I would guess the porcelain would be a visual check for cracks? Anyone know the proper technique to check a Champion plug? o No: Derek
In order to check a plug, you would need to ground it. I've never had a bad plug that didn't have a visual cue. either the porcelain is cracked from over tightening, or there is a clearly seen carbon track. Not much else can go wrong with a plug.
Holy smokes, just put some new plugs in already. You'll never test a spark plug reliably unless you have a spark plug tester. Put some new plugs in, double check the firing order, warm engine up, pull one wire off at a time at the distributor and listen for an rpm drop. No rpm drop = problem cylinder.
I'd hardly call everything I've gone through to check things monkey farting around o No:. Everything here closes at 5 Sundays and we don't have parts Stores on every corner like you guys. Be trying to find some this morning
And I'm not. That's just one of Bob's terms from another thread a while back:grin: I was making a joke, maybe not a good one. I know you must be frustrated, you put in a brand new engine, and you don't expect these kind of problems. It has to be something very basic. Compression is good. You'll figure it out, and it will be worth it when you can drive the car.:TU:
One of the plugs listed on the that cross reference chart I linked is the NGK BP9ES. NGK plugs use higher numbers for colder plugs. In this case, 9 would be the heat range. That seems like a very cold plug compared to what I run in my engine. I use the NGK FR-5, which is considerably hotter (5 heat range). My roller cam is very similar to yours, 230/238, 112 LSA, .544/.577 lift. I have 10.5:1 compression with aluminum heads. http://shop.advanceautoparts.com/p/ngk-nickel-spark-plug-bp9es-7526/19650431-P#fragment-2
Perfect thanks, fighting traffic and 4 parts stores across the city since 6 am this morning to find someone who can have them within an hour. Reason why I get everything from Summit. The kid at the Parts store I borrowed the compression tester from had no idea what it even was..... same store I was told I couldn't buy a transmission filter from because transmissions don't have filters.ou: New plugs in by lunch and see if it clears anything and if not check header Temps to see for any dead cylinders. Least the compression numbers were bang on. It all really seems like an ignition problem.... change the plugs and all that's left is the wires and Cap really which are all also new but that doesn't seem to mean much these days
