My 1995 GTR project thread.

[cortexx]

oil system will be a tomei oil pan baffle kit , tomei pump and an Accusump 3 quart pressurized resevoir.

Not this Winter but maybe another winter will see the tranny get an OS gilken gear set .

[PurpleStreak]

Any reason for not using the Tomei head restrictor? Will you still be using the RIPS catch can?

Sent from my MB860 using Tapatalk 2

[cortexx]

I am using a head restrictor , got a Tomei one with my gasket BUT the block i have already has one installed

And yes i'll continue to use the RIPS catch can , in fact when i go single turbo the catch can will drain back in to the front turbo oil return as the single turbo will use the rear drain.

So last night work began on further assembling the head . This is what i started the evening with :-



All parts being reused were blasted with brake cleaner and wiped down with lint free shop towels , basically they are surgically clean after this . Cleanliness is paramount . The wooden bench you see was wiped down with a couple of Tac cloths after being rinsed off with a damp sponge earlier on . The helps reduce the chance of debris contamination . Not exactly an engine building room but it's pretty clean here

Parts that are being reused :-



All of the followers were checked with my trusty digital calliper and found to be all the exact size and exactly middle of the road according to the tolerances started in the Nissan bible . A few had some very slight marks that i could feel with my finger nail when removed from the head so these were removed at the machine shop .

The Head is being upgraded with a set of Tomei Cam Cap studs. The head comes from the factory using bolts to keep the caps on , but using more aggressive cams in combination with raising the Rev limit of the engine puts a tremendous strain on the original design , so we replace with a set of precision studs that use 100% of the thread in the head to increase the overall strength of the cam cap fitting and ensure they stay in place.



After a bit of research online it was apparent that the small end of the stud was designed to bottom out in the head . When installed and torqued to the right spec (7nm) the thread in the head is in perfect contact with the thread on the stud. 2 Nuts are used to achieve this ...



It's also recommended to use a good thread lock. I used blue lock by Loctite which is not permanent simply because I might want to remove these studs at some time. The head has been decked , valve seats cut to +1mm valves, so certain mods have made the head not particularly rebuildable in the unfortunate chance that it needs to be. I can just extract these and transfer them to another head if i have to.

Once the locktite has been applied you have about 10 minutes before it semi-cures , during that time the corresponding nut needs to be torqued down with exactly the same pressure as the stud was set into the block with (7nm) .





You have to wipe the excess thread lock from the base of the stud so that nothing stops the cam caps seating perfectly.

Eventually we have the studs all in place and ready for the cams to be installed ....



It's also worth noting here that prior to installing these into the head , the threads on the head were chased with a tap and die set then thoroughly blown out with compressed air to remove any debris or swarf that might have been lodged inside . Any time machining has been done this really should be done as a safeguard. Foreign objects in the stud hole can at best stop the stud seating all the way down , at worst chew up the aluminium thread when torquing them in.

May seam anal - but i have all winter to get this done so time is not an issue and being meticulous is definitely a virtue .

Cams in next then the install and torquing of the cap nuts . I'm using Tomei Poncam b's here known for their excellent idle ability and the extra 10 deg of duration on the exhaust side will really help turbo spool by increase gas pressure. This build is about a balanced compromise between response , usable power, durability and reliability for the street .

The cam lobes and journals have been lubed with a coat of Tomei assembly paste - this will prevent scuffing the surfaces while rotating cams to measure the clearances. The shims and buckets have been carefully installed dry so that the lube does not prevent an accurate reading of the shims. It will be disassembled and lubed , re shimmed again shortly once i have the correct shims to install..





The seat and open pressures from the Brian Crower springs make it incredibly hard to spin the cams by hand compared to other engines i've have worked on . Next came the laborious task of measuring the clearances to calculate what shims if any I need. The head came to me in pieces and the shims in a bag so I just picked them at random when installing . It is inevitable that adjustments will need to be made here.

[cortexx]

When working on anything like this it is a great advantage to keep accurate records of what clearances were and what has been assembled with what torques etc. . This is the scribble sheet I used to record the exhaust and intake clearances. It's not pretty but it will be kept in a binder with all my other notes and records in case I need to refer to it..




At this point of the evening it was time to wash up and grab a tea so i went into the house only to realise it was almost 3am ....

Next morning after taking a few advil to get rid of a hideous migraine probably caused by sniffing copious clouds of brake cleaner and staring transfixed at the faded markings on my feeler gauges - i decided to set-up a simple spread sheet to calculate the shims i need and also record movement of shims to their appropriate locations. This makes it so much easier to keep track of what goes where once i disassemble and complete the final assembly of the valvegear/cams.

This took about 1/2 hour, 4 advil and 2 cups of coffee




Ill explain what it means as it probably means nothing to anyone except me.

Top group is the intake section , bottom is the exhaust section. Nissan states that the clearances can be as per the grey box at the top. You'll notice that the 2 cells contain median measurements allowing for +/- 3mm smaller or larger to stay in spec. This makes utilization of the shims i already have a bit easier.

Current shim is the thickness of each shim currently installed into the head.

Measured gap is the current gap between the bucket and the cam lobe

Required shim is the thickness the shim needs to be so that the clearance is in spec.

Populate from existing valve means that there is an ideal shim elsewhere in the assembly that can be utilized ( moved to this valve), this cell will either have the valve location where one can be taken from OR NEED meaning one needs to be supplied.

Taken/Open is a reference to show which valves have been earmarked (taken) to be installed in another valve location.

If anyone thinks they can make use of this spread sheet they are welcome to it , you can delete my shim sizes and gaps , insert yours and it will automatically calculate the shims you'll need. Its done in open office specifically so that you don't need to have excel to use it.

[cortexx]

As you can see I need a fair few shims , alot of think ones.

Another word on cam installation , these cams are hollow to save weight as are alot of cams in high performance engines these days . It's good to lose alot of mass on moving parts in a high revving engine but they are alot easier to damage.

You'll notice when you look at the cams closely that the caps are located in between each pair of lobes for each cylinder. This spreads load very evenly across the length of the cam but you have to be very careful on install not to bend them.

No matter what position the cam is in , it never has more than 2 pairs of valves open at any one time. This means that to seat the cam easily and safely you can place it in position and gradually torque it down using just the caps that sit in between the lobes that are going to compress their valve springs. Once the cap is just about touching the head you can pop the other caps on , spin down the nuts by hand and then torqe everything down properly . This saves a monumental amount of time on installation and you dont bend anything in the process

more updates soon ..

[NismoS-tune]

Nice write up and pictures sir! Appears you know what you're doing. I sometimes wonder if I should have taken the challenge of building my own engine but didn't know where to learn the tricks and information I needed. Definitely book marked for my next build (#3).

I have a green horn question though, I'm trying to picture this. when you measure between the cam lobe and bucket, that's when the lobe is downward? So the bucket is sitting down there with no spring (since the bucket isn't touching it?). Sorry haha

[cortexx]

Correct , when you look at the lobe , the thickest part of it's profile will be facing away from the bucket (up in the air) leaving the thinnest part of the profile closest to the bucket . This is when you have the gap you measure for . When blueprinting the head the final check to make sure you have everything shimmed properly is to rotate the cam in turn to each position where it fully compresses the valve spring. You measure the face of the valve with a dial gauge to make sure you have the right lift (in this case 9.15 mm). I'll demonstrate this when i get to this stage and throw up some pictures.

Check out this pic - when I do it the lift point of the lobe is totally vertical (12 o'clock) unlike this picture where the lift part lobe is about 60 degrees before 12 o'clock. But at least you can see the principle of how to measure the clearance.




Time permitting each stage of the entire engine assembly will be posted here with pictures and explanations etc .

[cortexx]

stardate 14th sept 2012

Continuing with head work and getting the cams shimmed in properly this week , have been slow to upload the updates because of some stupidity on my behalf and also a mini disaster while assembling

So i get my shims made up based on the previous measurements taken that i put into the spreadhseet BUT unfortunately - getting the shims back the next day and installing them proved to make it painfully obvious when i rechecked the clearances that something had gone wrong. I had valve clearances ranging from .12 mm all the way up to 1.10 mm .

I pulled everything to pieces and checked everything from valve stem heights to bucket deck thickness and nothing seemed to point to an error of judgement until -- i took a look at the spreadsheet used to calculate the gaps. Seems that while formatting the moving things around in the spread sheet the calculation cells had been grabbing data from the wrong cells so had made errors of calculation.

After fixing the spreadsheet calcs i recorded all the new retarded clearences and recalculated the new shim vales .

Here is the CORRECT sheet ...




Somewhat angry with myself I didn't want to go all the way back to mississauga engines that made the shims for me so I called one of my local clients that has a machine shop and he agree'd to help me out. I took some of the shims that mississauga engines had cut for me so that he could grind them down to the right thickness and took them to his shop.

[cortexx]

My client looked at the shims made by mississauga engine and tested the material only to inform me that they had been probably made from a non annealed 302 stainless material and was no where near durable enough to be used for the intended purpose. So in essence my screw up brought to light a potential problem in the near future as the shims would have flattened out over time and would have binded on the keepers possibly causing them to let go of the valve stem and drop a valve.

3 hours later i had a complete set made from 440b steel took along time to grind these down to the right thickness's. Charged me $60 for 14 shims and I was all set



SO feeling uch more confident this time I started the laborious task of reinstalling the cams , here are all the parts layed out ..



Test fitting the cap caps to the head bought about 2 observations .

1: the caps were a much tighter and more precise fit on the tomei studs instead of the bolts .

2: This sucks because when you torque everything down uisnt he original bolts - the cap settles over the cam journal and seats accurately on the head . Using the studs made it painfully obvious that the lack of lateral movement made it impossible for the cam caps to centralize over the top of the cams so that the cam journals did not seat perfectly round . This meant i had to painstakingly increase the cap's stud holes by about 5 thou longitudinally so that they had enough movement on assembly to correctly align with the journal part in the head . Without doing this a cap cap torqued down without the cam installed meant you could run your finger nail around the inside of the journal and feel an edge/lip where the 2 castings butted together .

So 2 hours of frigging around with a Dremmel taking tiny amounts of metal out of the stud holes in the caps I had everything lining up perfectly. (WTF does drop in cams and stud kit mean Tomei ? , this isn't exactly drop-in ). Another observation was how close the cam lobes come to the casting of the head . I measured this gap and it was 22thou - scary stuff when its all spinning lol . It states in tomei's installation guide that poncams do not need any machining of the head . If i had known this earlier I would probably have machined it a bit for piece of mind .

Anyway , after fingering all the interference parts with Tomei assembly paste we installed the shims ( for the third time) ..



then the corresponding buckets with moar green Tomei goop --



Everything seems to be going slowly so in with the exhaust cam , tighten the nuts all down with the torque wrench in sequence and HOLY F&^K .... i swear to F&^K!$$ god - the last cam cap nut on cap #1 let go at about 7Nm of torque ( rest were all torqued to 7Nm ) ... FFS

I put a couple of nuts on the stud to carefully extract it thinking the threads in the head had let go but NO , the cap stud had snapped in the head , the head itself is fine . this is the result :-



the busted stud ...



I emailed Tomei yesterday and have not got a reply yet . I drilled a small hole in the broken off stud and ill extract it tomorrow , glad i didn't use red thread-lock .

Tomei says these studs are made of chrome molly and are harder and stronger than Nissan studs (even though Nissan used bolts). I'm not sure if i trust these studs from Tomei now but i'll wait to see what they say. I seem to remember someone else breaking one of these studs on these forums a while back .

Somewhat dejected at this event i continued on with the intake cam which thankfully all installed ok - i checked the clearances on the cams on all lobes except the ones around the cap that had the busted stud and this time all numbers looked great - everything is in spec at last.

Going to extract the stud tomorrow when it's not 1am in the morning .

[GTRADDICT]

Why is there so much horror stories with jdm parts. Crazy. The joys of mechanics I guess!

[cortexx]

Well anyway , problem has been fixed , the stud would not come out , tried 3 different stud extraction divices and no joy - so going back to basics i grabbed the head , put it on my drill press and bored it out creating a fresh clean hole in the process - cut a new thread for an M8 bolt, re-washed and assembled everything and ended up with a fresh start ...



of course this meant i had to machine out the cam cap to take a larger part but that didnt take too long ...



This fitting torqued down no problems to 8nm torque and all seems ok.

Still no response from Tomei , i'd like another set of studs from a new batch number to carry on using these parts , but we'll see what they say - I honesty don't trust any of the other studs now . I wish ARP made a set. If tomei don't take care of this i'll have a custom set made up i think .

All back in 1 piece ....



Next part of the project is the intake side of things, here is what it all looks like in the nude ...



As you can see the intake manifold , throttle bodies , balance tube etc are suffering from a severe case of corrosion and dirt .



moar



moar still ....

[cortexx]

mooooar



The more i took this all apart the more obvious it was becoming how terrible the crap buildup inside it all was , going to need to purchase some chemicals to help with the restoration .. This is the AAC valve that you're not supposed ot take apart and clean , it was full of tar ...



Barbacue cleaner spray and some denatured alcohol does a good job of cleaning up carbon deposits if you let it all cook for a while

[frankiman]

This fitting torqued down no problems to 8nm/ft and all seems ok.

what??

my spidey sens is tingling
newton-meters/feet ?

[Windstheory_bnr32]

More now!!!!!!!!!!!!!!! Great read in lovin' it!

[xcye]

I'd say you should have helicoiled it and used the original cap bolt. The fit between cap and cap bolt is very tight and probably less than 0.001inch so the cap centers correctly and does not move during operation. Furthermore, the torque spec will not be the same when you change the thread spec. I'd strongly suggest to have a good machine shop to take a look at it.

Well anyway , problem has been fixed , the stud would not come out , tried 3 different stud extraction divices and no joy - so going back to basics i grabbed the head , put it on my drill press and bored it out creating a fresh clean hole in the process - cut a new thread for an M8 bolt, re-washed and assembled everything and ended up with a fresh start ...



of course this meant i had to machine out the cam cap to take a larger part but that didnt take too long ...



This fitting torqued down no problems to 8nm/ft and all seems ok.