Trev Vaa 1,185 Posted March 2, 2015 thought i would write up the issue's I've had in the last few weeks with a mates cleveland and how we went about solving it, it may be useful to someone else. i put the engine together for him about 12months ago (maybe a little less), fairly simple combo but with a fair bit of compression. in the last couple of months with the hot days he had noticed it had been knocking/pinging from time to time under load and had started to run on upon shut down. the basic engine combo was 351 cleveland bored 20 thou 650street hp holley with a spacer (i think its 1") RPM Airgap Intake 2v CC heads with a bit of port & chamber work done (not sure what they flowed) and 4v exhaust valves Lunati 62503 cam 11.2:1 compression 6" rods balanced bottom end pacemaker 4>1 headers, twin 2.5" exhaust with Xpipemallory ignition system toploader 9" 3.25:1 the car made 245rwkw on Lakeside Automotives Dyno we tried backing off the timing at first, it worked, but then the car wasn't performing as well, so we put the timing back to normal, and chucked octane booster in, that shut it up as a temp fix (btw car runs on BP Ultimate only) but we kept searching for things to try. put better leads on with less resistance, put a new coil on, new dizzy cap, then upped the jet size to try and cool the fuel down, which again worked, but then we had a slight stammer. next up was plugs, and i shit you not he's put at least half a dozen sets in in the last month to sort it out. different brands etc we dropped the heat range, again worked, but introduced fouling, changed brands, didn't work. i did a fair bit of research and called up NGK, got through to a tech who had a fair bit of experience working with older cars with cast iron heads. he recommended i look for another plug that had an unprojected tip, this removing a hot spot from the chamber. spent the next day at looking for plugs trying to find the right one, then ordered in a set of NGK B6FS plugs in, same heat range the car had before, which were the plugs lakeside put in. chucked them into his XC, and instantly the car ran perfect again. detonating was solved, no more run on. fixxed, simple. no fouling either which i thought might be an issue. i was tearing my hair out for about 3 weeks trying to sort this fuckin thing and all it needed was the right plug. on the flip side, it was nice to drive an XC again, even if it was someone elses. 4 XTREME KARTS XF, gerg, XPT and 1 other reacted to this Share this post Link to post Share on other sites
bear351c 10,260 Posted March 2, 2015 Cool stuff. Hate it when you chase your tail, for what seems so simple in the end. Always likes NGK plugs, good for LPG, too. Share this post Link to post Share on other sites
gerg 10,871 Posted March 2, 2015 Funny, I've run BP6FS and now run 5s, both projected tip, without drama at all. Got a solid 30,000 out of the 1st set, if a bit oil fouled (not their fault). Mine are closed chamber heads but mines a little 302 with std (9.4) compression. Running stock iron intake with exhaust jacket. Having thermo fans helps a lot with regulating temps i think, but i run E10 most of the time so if running on was going to be a drama it would definitely show up when using it. I guess what we can take away from all this is if you up the comp on iron heads and have run-on and pre-ignition issues, going to a non-projected tip plug may fix it. Must say though, 11.2 is a bit much for iron heads on a street car, regardless of cam. 1 XTREME KARTS XF reacted to this Share this post Link to post Share on other sites
PRO250 1,506 Posted March 2, 2015 My ute use to do that I just run 28 degrees of timing, I did not care if it lacked grunt is still had 100hp on most cars as it wasI decompressed that engine cause 11points on a street pump fuel engine is just to much, I was at 11.3 before I went alloys and it was just shit the fuel is just not good enough for that amount of comp unless its on some kind of booster or like me avgas mixed in the fuelRun on with cast heads and over 11 points is a way of life if you run pump fuel mine will still run on if its super hot I just deal with itIts funny the dyno guys never sorted that issue, when ron tuned my crossy he fixed that issue I just thort that's what a engine with 12 points of comp did, but a different engine and alloy head Share this post Link to post Share on other sites
slydog 7,873 Posted March 2, 2015 Vintage racing services uses 12.5 comp on iron headed Fords with them plugs in a 9-10 heat range.But mainly race with BP AvGas...And there a smaller plug over all,well they are for a xflow Share this post Link to post Share on other sites
Trev Vaa 1,185 Posted March 2, 2015 nah, i don't put any blame on lakeside, anth wanted the engine at its limit, so that's what they did. plus, it was far cooler when the car was tuned. to be honest i don't think they anticipated it been driven in all conditions and used to its full potential. the car has an adequate cooling system (3 core XA GT radiator, thermo etc etc), everything was set up properly, and this problem only reared its head when he drove it in 35 degree + conditions and he was giving it a hard time, but still it reared its head, that's kind of the issue with non fuel injected cars, no ecu to pull timing and add fuel, it's all mechanical. if the car was only driven every now and again, i would have just told him to put octane booster in it when it was hot. naths 4v motor runs 12:1 with an iron head, but the cam is way bigger and bleeds off way more compression than this does. i'm trying to convince anth to let me convert this one to E85, bump the comp up a bit more, make a bit more power. at the moment, the engine is on the limit of pump 98, switch to e85, it can go up to 12:1 and be comfortable. Share this post Link to post Share on other sites
Jacked 8 Posted March 3, 2015 Your xc still in storage xcsedan? I've had similar problems with run on, but I think mine is timing related. Share this post Link to post Share on other sites
NZXD 2,328 Posted March 3, 2015 Can you describe what the end of the plug looks like? Share this post Link to post Share on other sites
Trev Vaa 1,185 Posted March 4, 2015 nah its parked downstairs jacked nice to see it around, just need to wash the fuckin thing haha NZXD the first set of plugs had a clean burn but had some black spots on the porcelain, every set after that was different, most had fouling on them or detonated worse. when it was run on octane booster it was impossible to read the plugs, it makes them red. Share this post Link to post Share on other sites
gerg 10,871 Posted March 16, 2015 Deleted... Found a more appropriate thread Share this post Link to post Share on other sites