RV8 plugs? and a couple of other q's...
Discussion
can anyone shed any light on this? im a little in the dark having never had this happen before! ive got a 3.5 RV8 out of an SD1 with carbs and it has a real issue with plug fouling. seriously, if i take a hot engine, bin the plugs, whack in a whole set of new ones and take it for a spin, the new plugs will be toast in about ten minutes. Im not sure why it happens but the plugs get fouled and then i get left with sparking back up the electrode and misfires unless i really rev it in which case all the cylinders will join in eventually. (i think) - sounds like it anyway but it misfires all the way up the rev range till it clears. any ideas? compression test shows 100 on all cyls except no 4 which had 120. bit wierd and not sure if its relevant. on a scope if its at tickover with new plugs you can literally see them dropping out one by one. can anyone shed any light? current best guess is to go for 'hotter' plugs but has anyone any experience or knowledge they could share?
The other little issue ive got is an oil leak out of the d/s bank right at the back. its getting on to my headers and making a smoke screen and i dont like the smell. im at a loss as to how its getting there unless my head gasket has got an external breach. does that happen? the rocker gasket seems ok and it cant be the sump gasket as my tubey manifolds are far above it. any ideas of what i might have missed? it doesnt seem to leak and smoke unless i actually drive it but then, when its in motion i cant see where the leak is! very annoying!!
erm, i think thats it for the time being, er, unless anyone knows where ive put my locking wheel nut key - its gone missing and i cant find it.....
as ever any ideas on any of the above gratefully recieved!
The other little issue ive got is an oil leak out of the d/s bank right at the back. its getting on to my headers and making a smoke screen and i dont like the smell. im at a loss as to how its getting there unless my head gasket has got an external breach. does that happen? the rocker gasket seems ok and it cant be the sump gasket as my tubey manifolds are far above it. any ideas of what i might have missed? it doesnt seem to leak and smoke unless i actually drive it but then, when its in motion i cant see where the leak is! very annoying!!
erm, i think thats it for the time being, er, unless anyone knows where ive put my locking wheel nut key - its gone missing and i cant find it.....
as ever any ideas on any of the above gratefully recieved!
That is well down on compression, which will exagerate any running problems. If the engine is worn it might also be burning oil internally which can foul the plugs if they are too cold. What plugs do you have in there, and what do they look like when they come out? I've had an engine that would foul one plug quite consistently on the second time it was started from cold, caused by a big oil leak on that cylinder. Maybe you're just burning too much oil and the plugs are being fouled before they are up to temperature. The info on the plug rating and what the dead plugs look like would help prove/disprove that theory.
Getting visible sparks round the outside of the plug is also very strange, is there anything unusual about your ignition system and HT leads? Perhaps when the plug is fouled the resistance across the points goes up and the HT leads can't handle the increased voltage? Pure theory, but you could make sure the HT components are all up to scratch.
Getting visible sparks round the outside of the plug is also very strange, is there anything unusual about your ignition system and HT leads? Perhaps when the plug is fouled the resistance across the points goes up and the HT leads can't handle the increased voltage? Pure theory, but you could make sure the HT components are all up to scratch.
like stevie says what plugs mixture are you running? but if your engine is only giving 100 psi the compression is so low i would expext it to foul plugs! did you check the compression with the throttle wide open? the oil leak is most likely to be the valeey seal leaking down and arournd the back of the head
thanks for the replies guys,
taking them in order, the compression is low admittedly but it is an l/c engine (suspected from an auto SD1) and they guy i had come tune it didnt bat an eyelid at the readings - so i thought that ok? i know some go as high as 180 odd so just thought mine was 'lazy'? can that be so? plugs ive got ATM are champion though i dont know what type -they were just the most available during tuning - i can pull one out and get the codes tomorrow.. i wont know what they look like till then either but i suspect they will be a bit 'sooty'. the arcing can clearly be seen on thier predecessors on the enamel. the whole of the plug is pretty black but with a white streak down the insulator - hence my belief that they arent firing right. Is there anything i should be looking for on the plugs? theres no visible oil on any of them and ive had a good gander at all 8. Ah yes, i do i confess use a ballast coil ATM having bought the wrong one from my local motor factors. ill be getting an elec ign one tomorrow but could that really be doing it? and if so, would the problem clear itself in time or are those plugs toast?
also, my HT leads are a mishmash of ford and rover - relevant? i think about 50/50 is the split. could that be doing it? i thought leads were leads?
its a DEH48 dizzy if memory serves, stiched into my capri ignition system. i dont think thats the issue as it works ok with new plugs but then as the plugs give up it dies. is there a way to check its ok?
Ill check the plugs tomorrow either way and let you know what they look like and what kind they are. hopefully that, or some of the other info will ring bells and get me going! its very disappointing having gone to such cost to 'V8' my car to find it misbehaving! id also add that its WAY down on power but then i suspect thats down to it being on about 4 cylinders at tickover and so lacking any torque to move the car at all. well, at least thats my 'fingers crossed' take on it!
thanks for all the replies so far, i really appreciate the input on this.
Paolow
taking them in order, the compression is low admittedly but it is an l/c engine (suspected from an auto SD1) and they guy i had come tune it didnt bat an eyelid at the readings - so i thought that ok? i know some go as high as 180 odd so just thought mine was 'lazy'? can that be so? plugs ive got ATM are champion though i dont know what type -they were just the most available during tuning - i can pull one out and get the codes tomorrow.. i wont know what they look like till then either but i suspect they will be a bit 'sooty'. the arcing can clearly be seen on thier predecessors on the enamel. the whole of the plug is pretty black but with a white streak down the insulator - hence my belief that they arent firing right. Is there anything i should be looking for on the plugs? theres no visible oil on any of them and ive had a good gander at all 8. Ah yes, i do i confess use a ballast coil ATM having bought the wrong one from my local motor factors. ill be getting an elec ign one tomorrow but could that really be doing it? and if so, would the problem clear itself in time or are those plugs toast?
also, my HT leads are a mishmash of ford and rover - relevant? i think about 50/50 is the split. could that be doing it? i thought leads were leads?
its a DEH48 dizzy if memory serves, stiched into my capri ignition system. i dont think thats the issue as it works ok with new plugs but then as the plugs give up it dies. is there a way to check its ok?
Ill check the plugs tomorrow either way and let you know what they look like and what kind they are. hopefully that, or some of the other info will ring bells and get me going! its very disappointing having gone to such cost to 'V8' my car to find it misbehaving! id also add that its WAY down on power but then i suspect thats down to it being on about 4 cylinders at tickover and so lacking any torque to move the car at all. well, at least thats my 'fingers crossed' take on it!
thanks for all the replies so far, i really appreciate the input on this.
Paolow
OK!
just fitted 8 X NGK plugs, new cap, new leads and the correct coil. The result? its better but it still lacks torque (and the exhaust is blowing like a bastard which probably doesnt help!) Wierd thing is though, when i pulled the other plugs out many were really really white which leads me to believe the carburation is off. the oil leak remains though and its overheating
- one step at a time though! i think ive effectively ruled out any ign issues as my problem - im now looking at my SU carbs - could they be underfuelling? the choke doesnt seem to make any difference no matter whats going on - though im sure it does work.my current best guess is to 'read' the plugs tomorrow and manually (by that i mean guess work) richen up the mix. any other ideas i can try?
just fitted 8 X NGK plugs, new cap, new leads and the correct coil. The result? its better but it still lacks torque (and the exhaust is blowing like a bastard which probably doesnt help!) Wierd thing is though, when i pulled the other plugs out many were really really white which leads me to believe the carburation is off. the oil leak remains though and its overheating
- one step at a time though! i think ive effectively ruled out any ign issues as my problem - im now looking at my SU carbs - could they be underfuelling? the choke doesnt seem to make any difference no matter whats going on - though im sure it does work.my current best guess is to 'read' the plugs tomorrow and manually (by that i mean guess work) richen up the mix. any other ideas i can try?
I think 8 is the number of plugs! I will back steve on that one at 100 psi cr a 5 at a maximum? before you start setting the mixture on the carbs, take the tops off them and set the jet level with the bridge, i have seen on many occasion one jet and one jet high ultimetly you get the correct co level at the exhaust but 4 cylinders are running rich and 4 weak, its easy to do unscrew the 3 screws holding the tops on, and if you lookdown where the needle runs you will see the jet, turn the adjusting screw clockwise to lower the jet and vice versa to raise the jet, but you do need these level as a reference point, put it all back together then uncrew the black caps on the top and fill with a 10/40 oil and then gently put the caps back on
thanks for the replies guys - ill start with peters post - sorry - my earlier post was a bit rushed and garbled! it currently misfires on at least 3 cylinders and possibly more - it wont tick over properly but it IS firing on all of them (at least some of the time) that much i do know. when it sits there misfiring i have to get the accelerator almost to the floor and then it misses all the way up to around 3k and then the other cylinders join in and itll rev cleanly again until i let it drop down to <1.5k at which point it will start missing again and the process will repeat itself. I havent had these plugs out again (because ive burnt myself enough times today) but i suspect theyd be showing signs of being lean. and help? oh yeah - i had it tuned yesterday by a guy who does know what theyre doing and he got it running cleanly but sadly its fallen out of tune in about 16 hours. (this could well be due to the engine being unused for about a year and so its just 'settling in'.
Lol - steve - it was 8 as in 8 plugs - the actual ones i bought were the ngks made reference to earlier in the thread
ignition should be spot on though - i saw the strobe dancing on the bottom pulley only yesterday - does that leave weakness being the culprit?
Ill check the carbs tomorrow Rob, sounds about the right lines though as it does cut about half the cyls when it gets grouchy. I may well run some carb cleaner through it too and see if theres some gunk in there thats holding things up.
Overall then it looks like mixture? oh yeah! i just remembered, it spits back through the carbs when i accelerate (until it gets to about 3k and then it scoots off cleanly) this is worst at partial throttle. Relevant? its a shame because it does fly when its behaving - just - when its this grouchy its really taking the shine off it!
thanks again for all the help - hopefully well get it fixed soon!
Lol - steve - it was 8 as in 8 plugs - the actual ones i bought were the ngks made reference to earlier in the thread
ignition should be spot on though - i saw the strobe dancing on the bottom pulley only yesterday - does that leave weakness being the culprit? Ill check the carbs tomorrow Rob, sounds about the right lines though as it does cut about half the cyls when it gets grouchy. I may well run some carb cleaner through it too and see if theres some gunk in there thats holding things up.
Overall then it looks like mixture? oh yeah! i just remembered, it spits back through the carbs when i accelerate (until it gets to about 3k and then it scoots off cleanly) this is worst at partial throttle. Relevant? its a shame because it does fly when its behaving - just - when its this grouchy its really taking the shine off it!
thanks again for all the help - hopefully well get it fixed soon!
stevieturbo said:
Am I missing something ? I still dont see mention of what heat range is being used ?
What is the part number of the plugs you are using ?
paolow said:
Lol - steve - it was 8 as in 8 plugs - the actual ones i bought were the ngks made reference to earlier in the thread
GreenV8S said:
I suggest you get a new set of leads, a new set of NGK B7ECS plugs, the right coil, and try again.
Hope that helps.
BTW What in the part number refers to the heat range?
Leo
***Update***
ive given up trying to figure it out and took the car to my local capri specialist on fri afternoon. He didnt seem happy about the low compression but he said hed give it a look over in the coming week. Ill post whatever he says in case its of help to anyone in the future. Thanks again for all the help.
ive given up trying to figure it out and took the car to my local capri specialist on fri afternoon. He didnt seem happy about the low compression but he said hed give it a look over in the coming week. Ill post whatever he says in case its of help to anyone in the future. Thanks again for all the help.
***Update***
ive given up trying to figure it out and took the car to my local capri specialist on fri afternoon. He didnt seem happy about the low compression but he said hed give it a look over in the coming week. Ill post whatever he says in case its of help to anyone in the future. Thanks again for all the help.
Oh yeah! are there any reasons i might have such low compression? theres not any appreciable blue smoke and there doesnt seem to be too much coming from the breather. Could it be the valves? as the engine had been sitting a while could it be that theyre not sealing properly? the wierd thing is that comp is the same across all cylinders - surely that would rule out anything serious with one of the cyls?
ive given up trying to figure it out and took the car to my local capri specialist on fri afternoon. He didnt seem happy about the low compression but he said hed give it a look over in the coming week. Ill post whatever he says in case its of help to anyone in the future. Thanks again for all the help.
Oh yeah! are there any reasons i might have such low compression? theres not any appreciable blue smoke and there doesnt seem to be too much coming from the breather. Could it be the valves? as the engine had been sitting a while could it be that theyre not sealing properly? the wierd thing is that comp is the same across all cylinders - surely that would rule out anything serious with one of the cyls?
you obviously have a low compression 8.13-1 engine anyway which lets face it isnt going to blow the spark plugs out! but if someone has put an aftermarket cam in ther too with a wider overlap that will murder the static cr, if you want my honest opinion i would throw it away and go and buy a 3.5/3.9 of ebay and start off again with a minimum of 9.35, the 8.13 only made around 135 bhp anyway??
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