7bolt head with 12mm bolts without bigger bore?

[snooopy365]

Hey guys,
just 1 simple question: Why is my engine still running?

I just realized today that the Oilfeed is using the bolt hole... and how can my engine work if the hole is 12mm at largest point, according to: [ame=http://www.youtube.com/watch?v=T97Ri0ouDeU]Cylinder Head 109 - Oil Port Mod - YouTube[/ame]

I use 12mm ARP bolts with a 6bolt block and a 7bolt head.
The head was stock, so the bolts did only fit very tight.

I'm running like this for about 10k miles and also feeding the Turbo from the head.
The engine is running fine, but that video scared the shit out of me.

Anybody have a clue how my engine can be running?? 12mm hole and 12mm bolt means there is 0.0Xmm clearance for the oilfeed?

Does anybody have an idea why it is working?
And what should I do? Just say: never touch a running system and just leave it like that?

 

[BogusSVO]

If you look in the head bolt hole that oil feeds through, it is larger than the rest of the bolt hole, to just under where the oil galley cast in the head, about an inch from the deck surface.

You will get oil flow, but not as much as if the bolt hole was reamed to .500

 

[snooopy365]

On 5:50 in the video you can see that the oil needs to pass the 11.95mm hole. In my case there should be a 12mm bolt blocking this passage.

the upper part doesn't scare me it is big enough

 

[BogusSVO]

http://www.dsmtuners.com/forums/newbie-forum/341028-4g63t-head-oil-port-mod.html

http://www.dsmtuners.com/forums/cylinder-head-short-block/341885-oil-port-mod-2-4g63t.html

You must be logged in to view this image or video.

The factory bolt hole is a loose 12mm, The arp stud is a tad under 12mm on the shank.

So you are getting oil to the head.

If the head was starved for oil, you would have bad lifter tic, or worse, the cam journals would have galled to the cam

 

[snooopy365]

So the numbers of the video aren't correct? He measured 11.95mm for the inner bore and 11.91mm for the bolt... so there is next to no place for the oil to go.

Should I just leave it like that because there is no lifter tick?
Or leave it like that and get the turbo oilfeed from the filter to be on the save side?
Or install 1 stock 6bolt screw because they are undercut and should supply more oil and leave everything else like it is?

 

[Miasma]

So the numbers of the video aren't correct? He measured 11.95mm for the inner bore and 11.91mm for the bolt... so there is next to no place for the oil to go.

Should I just leave it like that because there is no lifter tick?
Or leave it like that and get the turbo oilfeed from the filter to be on the save side?
Or install 1 stock 6bolt screw because they are undercut and should supply more oil and leave everything else like it is?

I've asked myself the same question, I've been worried about it as well but nothing has happened so far. But I didn't think that 6 bolt studs will bolt to a 7 bolt head? Don't quote me but they're 11mm right so how would they thread properly. I've been trying to figure out the most efficient solution to this.

 

[BogusSVO]

Mi, you have to use the bolts/studs for the block.

The only way to use 6 bolt head studs in a 7 bolt block, is to drill and tap the 7 bolt head bolt holes.

When installing a 2g head on a 6 bolt bottom end you should ream the head bolt hole in the head out to .500/13mm

Snoopy, you have 10k miles on the build, if you were going to have oil issues, They should have shown up before now.

 

[gorf]

Agree with Bogus.
I put a 2g head on a six bolt before the oil port mod became common practice. I ran it for about 25k with no head problems. However, if you have to take the head off for some other reason, by all means do the mod.
If you are nervous about it, just run 5w-30 oil.

 

[snooopy365]

Agree with Bogus.
I put a 2g head on a six bolt before the oil port mod became common practice. I ran it for about 25k with no head problems. However, if you have to take the head off for some other reason, by all means do the mod.
If you are nervous about it, just run 5w-30 oil.

Did you use ARP headstuts? Because with stock headscrews there still is about 1mm for the oil to flow around.

I did order a Oilfeedline of the filterhousing... that will defiantly give me a higher chance of not having a catastrophic failure.

I'm using 5w50 oil.

 

[gorf]

Yes that was with ARP head studs.
If phantom knock becomes an issue, you may have to pull the head, or just use 3g lifters.

 

[tkelly27]

The previous owners of my car used a 7 bolt head with studs on the 6 bolt engine. They ground down the studs to fit and forced it on. Pulling it off caused the studs to bite in and I had to use a shop crane to pull up on the head and jump on the radiator core support to get it off the studs. I decided to jump on the rad core support when the shop crane lifted the front tires off the ground.

 

[snooopy365]

They ground down the studs to fit and forced it on. Pulling it off caused the studs to bite in and I had to use a shop crane to pull up on the head and jump on the radiator core support to get it off the studs. I decided to jump on the rad core support when the shop crane lifted the front tires off the ground.

Did the head had an oil failure? And how long did you use to run the car like that?

I didn't ground down the studs, but if they are really handling the clampforce after being ground, that would mean I could just ground the one bolt and don't worry about braking that thing?

My head did fit tightly on the bolts but there was no brute force needed to get it on or off (yes I allready had that damn thing of last year but didn't know the problem).