I have had a little bit of progress.

I took the damaged plugs to the shop that serviced my head. He had a 3.9L head laying around and we put the spark plug into that and used a larger valve similar in size to mine to see what was going on (picture attached). it definitely is not the piston making contact, so it looks like it’s the exhaust valve making contact.

My measurements above for the spark plugs I listed were wrong.

I called NGK and got the total length from the end of the thread to the furthest most extruding point:

BP7ES = 6.4mm
BKR7EKC = 5.3mm
BR7ES = 4.3mm

BR7ES is the one that was recommended by NGK (and what I think the car may have been running originally). I’m confident this should work, if not then I may have to look into indexing washers.

I’m hoping to get the plugs today and try this after work tonight.

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it makes sense, as you would expect the valve to hit the piston before the plug would..

Ok so I got the BR7ES plugs and as you can tell by the below pick they are much shorter than the BKR7EKC’s.

I put them in the car and again drove around for a while, the first few times boost came on it was fine, but then the same s**t happened…

I am really stumped as to why its doing this….

The guy that serviced the head, changed the valve guides, and also machined the top of the exhaust valves as he said there were clearance issues. I also have Valve Lash caps on top of the exhaust valves (which were on it before I did any of this work) and he measured all clearances based on the lift of the cam and said its all ok.

So yeah I can space out the plug but I really don’t think the issue is from the plugs…. I has to do with the head…. I am at a point of not caring anymore as this has been very frustrating… I don’t mind taking the head off again but only if I know that by doing so it will solve these issues…

hmmmmmmmm

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and its only cylinder 3 doing this and none of the other cylinders? seems weird

interesting.....

maybe re post the issue in the 6 cyl forum or forced induction forum, there would be a few others that might be able to help that dont normally brouse the garage...

Well i havent pulled the latest plugs out yet but the last two times it was only cylinder 3, so im assuming this time its the same as the last two times...

it is really weird, maybe the valve is bent? i mean the valve guides were totally stuffed before he changed them... so i just dont get it

theres definatly something wrong with cylinder 3 that needs close inspection, are you on boosted falcon? maybe someone over there has had similar problems or have seen the problem before?

So still sorting out the issues with the plug closing on Cylinder 3, (thanks bry40l for the advice on posting on boosted). I went for a bit of drive with it yesterday as the weather was nice and cool for the car. Didnt let boost come on and it drove ok, wanted to enjoy it for a bit as its been a very long time since i have taken it for a longish drive...

Anyway the previous owner had decided to cut the standard springs in the back, with all the work done to the damn thing you would think he would be a bit wiser than that, anyway i had some super lows so i put them in, the car sat higher a few cm but i like the way it sits now with the stock wheels.

One problem i have though is that the gearbox sump is very deep and sits way too close to the ground with the super lows in the front. (it scrubs and its not a nice feeling knowing its the gearbox). So i will be putting the standard XR springs back in the front. (had to decide- car sit nice or fk up my power glide) decision wasnt that hard.

I also tried on the 10' widened stockies i have with MT slicks and it looked awesome!

I also took the RH sidce hi beam out and meshed up the hole for some CAI as the pod sits directly behind the light. Not really a fan of the look but the car breaths so much better like this so it made sense.

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Looks like i found the cause behind my plug issue!

I swapped injector 3 with injector 1, took it for a drive and gradually hit boost... I was SO surprised that it didn’t close any plugs, i gave it a few hits up to 10pounds and all good.

PROBLEM: Car is running super lean- if I keep driving it Spark plug one will have the same problem as spark plug 3 had. I have parked the car now and organising a tune for it ASAP.


need to get the car tuned ASAP.

Does anyone have any Standard height springs (not XR actual standard falcon) in Sydney somewhere?? i want to tow it to the tuner as he is a bit far but i want to raise it as much as possible before i do so...

thats interesting.. ive never seen that before..
if it is the injector? i would get them cleaned before you get it tuned, getting it tuned with one partially blocked injector wont help,,,

LOl yeah im throwing these injectors out, i have 65LB ones that i will get flow tested and put in pre tune.

Ok so i am getting my injectors cleaned today (not the ones that were on the car). They are 65 lb/hr Delphi Low-Z Injectors.

Should be picking up soon.

considering my car was detonating before, anything i should be watching out for now that i am putting these bigger injectors in? will be getting a tune in the new year.

A few other things i want to do this long weekend if time permits:

- Raise the front back to standard XR height (should i use the standard shocks or the yellow Ultima's i have in there now with the super lows? i will be using standard XR springs. both sets of shocks are in good condition). if the back is too low with the superlows then i will put lows in it too.

- If the weather gets better i need spray in my boot inner quarter panels, paint has flaked off in some areas.

- Might start playing around with a spare bonnet i have by hacking it up for some heat release/ cold air intake.

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those are the exact same injectors im using...lol

Nice car mate......

I am at a bit of a loss as to why one would need to put odd valves in when all that is usually needed is a decent porting job. At least the valve wasn't taking the end of the plug off....lol....

Haven't had any probs with my seimens injectors. Previously had bosch ones but they were too small...hehehe

Do you come out to Livo?? I'm bringing my turbo beasty out tonite.......

Cheers

Daz

good idea, ill be there.. i wouldt mind checking the ed out...