4G63T Head oil port mod

[BogusSVO]

4G63T Head Oil Port Modification


This is a simple and effective mod done to the oil port from block to head.

I have found out a restriction can occur when excessive milling of the head has been done.
Resulting in low/poor oil flow through the cylinder head that can cause lifter tic, cam tower gaulding, and in some cases on turbo engines that feed the turbo oil from a port on the head, to cause the turbo to fail.

Appox mod time with head of engine is 2 mins.


Stock oil port….

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Take a die grinder with an aluminum burr and grind and chamfer the oil port, while staying inside the gasket-sealing ring. (I find a ¾ base tree burr works best)

So the end result looks like this.

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I prefer this to be done before the head is resurfaced.

I hope you find this useful.

 

[pneumo]

The compressed thickness of the stock Mitsu composite gasket is .038" IIRC
Cometic is .051"

 

[Jafro]

ok, so lets see if i'm thinking correctly here. so, the only oil feed for the head is threw the head stud and most people are increasing the size of their head studs restricting the supply flow. now if we put a tee in the turbo feed line off of the oil filter housing and ran the extra side of the tee in to the oil feed port on the head would this balance out the flow? just some random thoughts here, I'm not crazy about the idea of tearing my head down again.

I would say it's not necessary to consider this unless your head has been machined more than once. Shaving .013" shouldn't rob you of a substantial amount of oil, and neither will ARP bolts. The bolt hole tapers at the oil pickup in the head, so even enlarged studs wouldn't have significant issues. The 7-bolt head on a 6-bolt block guys might have problems after drilling out the head studs unless they countersink to the oil pickup on that stud... but I doubt you have anything to worry about unless you've decked it several times, or you've installed revised lifters and they still tick.

Feeding the head oil from the turbo won't work. All that will happen is the oil will drain both from the head and from the block back into the pan. Look at the size of the return line vs. the size of both feeds combined.

 

[sophat34]

in my case i was wondering if it would help lower my oil pressure, I have decked my head twice, once when it was built and again when the hg went. I was thinking that when i have the restricter placed at the turbo that the excess pressure would go threw the head. I might try just to see what happens

 

[Strm Trpr]

ok, so lets see if i'm thinking correctly here. so, the only oil feed for the head is threw the head stud and most people are increasing the size of their head studs restricting the supply flow. now if we put a tee in the turbo feed line off of the oil filter housing and ran the extra side of the tee in to the oil feed port on the head would this balance out the flow? just some random thoughts here, I'm not crazy about the idea of tearing my head down again.

The oil feed to the head is thru the head gasket around the head stud from the block.
I assume you are thinking the banjo bolt on the head near the T-Stat housing is oil supply to the head, where in fact that banjo bolt is 1g OEM Oil Supply to the turbo, i.e., OEM 14b Oil Supply.

If you tee'd the oil supply from the OFH to the turbo and ran a banjo bolt connection to the head, wouldn't cause a head on collision of oil at the banjo bolt?

I have read that the compressed thickness of the Mitsu MLS is .060'' and you are correct with the thickness of the felpo perma torque of .055''

I wouldnt worry about it. Guys have been running unmoded heads for years with no problem. Keep it simple.

Cool, thanks.
I've now heard, .060", .062" and .067", but .060 is close enough to those two numbers for me.

The compressed thickness of the stock Mitsu composite gasket is .038" IIRC
Cometic is .051"

Sweet, thanks pneumo, I couldn't find that info anywhere, part of the reason is it's a hard search...

Reason I ask is because Wiseco uses a gasket thickness of .042".
Perhaps that is the uncompressed thickness of an OEM gasket, which would make perfect sense.
.004" of crush is an RCH over the thickness of a sheet of printer paper.

Most piston manufacturer's use OEM gasket thickness when designing compression ratio.

When I use a MLS, I'm adding approximately .020" of thickness.
This is enough to lower static compression ratio to ~8.3:1.

Have a look.
Per Wiseco's Catalog with an OEM gasket thickness of .042" on the left.
Same piston using a Mitsu MLS on the right.
Notice the difference in compression ratio simply from .020" of gasket thickness.

 

[1qkfwd]

This mod makes perfect sense and with me installing a 2G head on my 6bolt I will be paying more attention to all of this.

One thing im surprised has not been brought up yet. If you know you have had your head milled or are in question about head studs blocking the oil passage could'nt you take two oil pressure readings? Take one at the head where the pressure should in theory be lower than the pressure at the lower end of the block. I guess thats one way of knowing if your heads getting enough oil.

 

[BogusSVO]

the reason I started this mod, is for a simple reason, I felt at this oiling point was getting restricted and not allowing enough volume of oil to reach the head and causing the lifter tic, due to the lifters not being able to fill with oil.

The kiggly HLA pressure reg is after this and will set the oil pressure to the hlas.

 

[eclipsh]

For what it is worth, this is not the first go-round for this mod. I've seen photos of it elsewhere with only a small channel ported out roughly the size of the stock oiling hole exiting the block rather than the whole area. Sorry but I'm not going to spend hours digging through the 'net to find the photos, you'll just have to take my word for it.

Still a nice idea and something I'll look at doing on my next build. I'd like to see some before/after numbers on oil pressure at the head too if someone can post them up.

 

[1995gsx20g]

somebody had to have done this mod by now.. any before and after oil pressure readings?

 

[BogusSVO]

I am sure there has been. but no one has taken the time to take readings and post

 

[jnf63]

I really don't think it's possible to put a 2g head on a 6-bolt block without enlarging the holes for the 12mm studs to pass thru.

I have a spare 2g virgin head that I'll take a look at and measure how deep the relief is
and I'll also check to see if that hole is actually larger than the other thru holes for the studs to pass thru.
Beveling the inner surf like the OP mentioned is an excellent mod, and I bet even the most experienced guys over looked this mod, and it was proven in a few posts.

if you are careful, with the porting and if everything else is fine with your head, I would not see a reason to have it resurfaced.

If you gan get your hands on an old HG, I would lay that over the head deck to protect it incase the burr skips out on you.

As far as new studs and/or HG, that is up to you, if you have ARP head bolts, and they been working well for you, stay with them, unless you have a mod in the future that will make them the weak point, the same for your HG, if it is a MLS style that is reuseable.

rEclipseGST... to what you have asked, I have one close friend who is big into DSMs, and the whole reason this mod came about, I can say it cured his lifter tic. But to start off the short block was a high mileage, and well wore. We did not take before and after oil pressure readings, and only oil port mod #1 was done. He has appox 10k miles on the rebuild and the oil pressure still looks good and no valve train noise.

This educational post by BogusSVO, as well as his many other tutorials, is exceptional.

Nevertheless, my novice experience creates uncertainty concerning several mentioned ideas within all the pages of the post. I have become confused among all the opinions compared to facts. I hope that BogusSVO, Jeff99GS, or rEclipserGST could explain to me the most beneficial methods to utilize.

Referring to Post #31
My plan is for a certain machinist to rebuild my motor as a 6-bolt block with a 7-bolt (2g) head. I have also been informed to use L19 ARP fasteners. The machinist mentioned the differently sized head fasteners (bolts [studs]?), and he explained that he would address the issue. My confusion lies in the necessity of further enlarging (more than the apparent different size of the 6-bolt fastener) the specific hole that has been discussed here to supply oil to the passage being ported. Is it safer (better) to further enlarge this specific hole, and if so to what measurement?

Referring to Post #63
Since I presently have a new (only 80 miles on it) Fel-Pro Perma Torque MLS head gasket installed, I would like to know if it truly can be reused. A post mentioned that a MLS should be reusable. In contrast, the machinist to be doing my rebuild stated that my Fel-Pro would absolutely be ruined and not able to be used again. Considering the piece was over $200, and it has only 80 miles (about 3 total hours) on it, I would be glad to use it again (my GSX had total crankshaft bearing failure while at a transmission shop, yet that is another horror story).

Referring to Posts #94, #96
I am also puzzled concerning the use of a thicker Fel-Pro MLS (0.055”) head gasket instead of the OEM (0.043”) head gasket. My 2g head had been previously purchased from SBR as a Stage 1 type, so I imagine it has been changed (resurfaced/milled) at that point. Now, I need a rebuilt 6-bolt block, meaning I imagine I need it changed (resurfaced/milled) to be worthy again. The machine shop (that alleges my Fel-Pro is not reusable) prefers to use an OEM (composite 0.043“) head gasket along with the L19 ARP fasteners. My concern deals with the clearance factors mentioned in this post. It has been mentioned that the “trough” should be 0.080” deep (factory), meaning that the likely changes done, and being done, to my motor could cause the need for compensation regarding the changes. Would it be beneficial to choose a thicker head gasket, or is the OEM gasket fine (considering that I‘ll have the two head oiling modifications requested). I apologize if I am so confused that I am over analyzing the gasket matter.

Consequently, I regret not being mechanically inclined enough to be one that posts before and after pressures in regard to using the two head oiling modifications. Moreover, I’ll also be mentioning the use of BogusSVO’s tutorial about porting the OFH (to the machinist) since I’m having a ‘90 OFH installed.
Thanks,
Jim

 

[BogusSVO]

This educational post by BogusSVO, as well as his many other tutorials, is exceptional.

Nevertheless, my novice experience creates uncertainty concerning several mentioned ideas within all the pages of the post. I have become confused among all the opinions compared to facts. I hope that BogusSVO, Jeff99GS, or rEclipserGST could explain to me the most beneficial methods to utilize.

Referring to Post #31
My plan is for a certain machinist to rebuild my motor as a 6-bolt block with a 7-bolt (2g) head. I have also been informed to use L19 ARP fasteners. The machinist mentioned the differently sized head fasteners (bolts [studs]?), and he explained that he would address the issue. My confusion lies in the necessity of further enlarging (more than the apparent different size of the 6-bolt fastener) the specific hole that has been discussed here to supply oil to the passage being ported. Is it safer (better) to further enlarge this specific hole, and if so to what measurement?

Referring to Post #63
Since I presently have a new (only 80 miles on it) Fel-Pro Perma Torque MLS head gasket installed, I would like to know if it truly can be reused. A post mentioned that a MLS should be reusable. In contrast, the machinist to be doing my rebuild stated that my Fel-Pro would absolutely be ruined and not able to be used again. Considering the piece was over $200, and it has only 80 miles (about 3 total hours) on it, I would be glad to use it again (my GSX had total crankshaft bearing failure while at a transmission shop, yet that is another horror story).

Referring to Posts #94, #96
I am also puzzled concerning the use of a thicker Fel-Pro MLS (0.055”) head gasket instead of the OEM (0.043”) head gasket. My 2g head had been previously purchased from SBR as a Stage 1 type, so I imagine it has been changed (resurfaced/milled) at that point. Now, I need a rebuilt 6-bolt block, meaning I imagine I need it changed (resurfaced/milled) to be worthy again. The machine shop (that alleges my Fel-Pro is not reusable) prefers to use an OEM (composite 0.043“) head gasket along with the L19 ARP fasteners. My concern deals with the clearance factors mentioned in this post. It has been mentioned that the “trough” should be 0.080” deep (factory), meaning that the likely changes done, and being done, to my motor could cause the need for compensation regarding the changes. Would it be beneficial to choose a thicker head gasket, or is the OEM gasket fine (considering that I‘ll have the two head oiling modifications requested). I apologize if I am so confused that I am over analyzing the gasket matter.

Consequently, I regret not being mechanically inclined enough to be one that posts before and after pressures in regard to using the two head oiling modifications. Moreover, I’ll also be mentioning the use of BogusSVO’s tutorial about porting the OFH (to the machinist) since I’m having a ‘90 OFH installed.
Thanks,
Jim

hey Jim, let me see if i can help you out here....

Re post #31 comment

yes to bolt a 2g 7 bolt head to a 1 g 6 bolt block, the head bolt holes need to be reemed to .500 both the 6 bolt and 7 bolts used a factoey necked down head bolt, where the studs are the same, if your machinist can/will just enlage the head bolt hole that has the oil port in it to 14mm (factory) or 9/16 to just above the oil port you should be fine...

Re post #63 comment

being that it is a MLS, it may be able to be resued, depending on how the bead rolls on the gaket is compressed and what shape the the coolent/oils imprinted bead sealer is in.
if you choose to re use it, the engine builder may not want to give any warrenty on the engine incase this "reused" part fails.

Re post #94 #96 comment

the head needs to measured for thickness, the mits manual states only a COMBINED total from head and block can be .008, AERA says .015 from the head... AREA says the "NEW" thickness of the head is 5.200, making the min thickness 5.185, If your head is at or past min thickness.. run the thicker headgasket to get you closer to the OE specs and compression along with having the cam to crank center line returend to spec.
as for having the head surfaced againthat should be left up to the machinist to decide, with factors such as warp, surface finsh to be concidered.

I hope this awnsers most your questions.

 

[jnf63]

BogusSVO,
Your response is very helpful for me. Using your straightforward explanation, I understand all the mathematical and quantitative values that you have provided. As for their application, I shall give this information to the machinist for its application (I lack the knowledge for the values' usage). Similarly, I shall have my Fel-Pro head gasket inspected prior to possibly using it again. Using your information, my choice of head gasket will be dependent on your values concerning the relationships of the minimum head thickness.

I expect my head to need little attention (shouldn't be warped) since it has only 2500 miles of daily driving on it. The head gasket has only 80 miles on it since I had recently upgraded my cams, valve springs, and retainers. My motor was still being "broken in" when a transmission shop took it on a "test drive" where all the crankshaft bearings were spun (yet, that is another horror story).

Since I'm a noob, I shall inform Brian (snowborder714, moderator) about your helpfulness in order for you to achieve more "reputation points" that are deserved.
Thanks,
Jim

 

[BogusSVO]

glad to help!

if you have anymore questions.. feel free to ask!

Thanks for the rep points!

 

[frankenstein406]

It seems my 6 bolt is suffering from lifter tick. Its never been resurfaced to my knowledge. I will be putting arp studs and new head gasket on soon. Will doing this mod sovle the tick or do I need the revised ones? Thanks

 

[BogusSVO]

I can not tell you with out measuring the head, but due to the age of the head, I would almost be certin that it has been mill at lest once in its life.

I would recomend that you do the mod any how.

 

[ziggo0]

Mounting my 2g head onto my 6 bolt, I haven't had much luck finding a 13mm drill bit...I'm surprised. So far I've only checked Sears. Going to ACE tomorrow...I found a 1/2" drill bit in my garage, this comes out to be 13.7mm...that may be to big? I read you said 0.500 in is about perfect. What would you suggest?

 

[whiteboyz]

BogusSVO, Can the mod be done on a 7bolt head ? the first oil port mod that is mentioned in this thread. as i deleted my BS and have 100+psi =[ and i dont like it.

 

[BogusSVO]

Ziggo0. a 1/2 is .500 which is appox 13mm

whiteboyz.. alot of guys that have done the BSE, have gained alot of oil pressure, this mod can be done on a 7 bolt head, but I doubt it will drop the oil pressure much.

 

[whiteboyz]

Ziggo0. a 1/2 is .500 which is appox 13mm

whiteboyz.. alot of guys that have done the BSE, have gained alot of oil pressure, this mod can be done on a 7 bolt head, but I doubt it will drop the oil pressure much.

Oh, eh but it still looks like a cool mod, mine aswell do it while i got the head off again dealing with my little problem. thanks SVO

 

[ziggo0]

Ziggo0. a 1/2 is .500 which is appox 13mm

whiteboyz.. alot of guys that have done the BSE, have gained alot of oil pressure, this mod can be done on a 7 bolt head, but I doubt it will drop the oil pressure much.

Just got a 15/32" drill bit which is about as close are your going to get to a 12mm drill bit, flipped the head over, applied cutting oil...just to find the drill bit goes into each hole without any resistance...grabbed a 1g head bolt and it goes right through each one without any resistance...is it possible that this head was already drilled for a 6 bolt?

 

[BogusSVO]

could be, most 1g heads I have measured the bolt hole at .503-.509

you do not want an excat 12mm hole, due to casting vareances, you need a little bit of wiggle room so the head slips down easy.

 

[ziggo0]

In that case I'll take my 1/2in drill bit through it just to open it up a pinch.

 

[ziggo0]

Another quick question, how will the dowel pins for alignment affect the 2g head?

 

[pneumo]

Another quick question, how will the dowel pins for alignment affect the 2g head?

It'll have no effect, the dowels are the same between 1G and 2G.

 

[joescool2008]

I've done this mod to my fresh rebuilt 6bolt and all i can hear is my injectors pulsing. I also have 3g lifters though. But it seems amazingly quiet and this mod only makes sense seeing as most of our heads have been milled 2-3 times and this lessens the amount that can flow because the chamber for the oil narrows. I have the stock oil pressure guage sadly and i have removed balance shafts and my pressure seems like that of stock car if not a little higher. I usually reach the middle oil pressure mark by 2500rpm.