MOHFpro90

iTrader: (11)

I was looking at my options on valves for my build this fall, and ran across something that looked interesting. On www.importperformanceparts.net they have two sets of VQ35 valves I am looking at. (intake only listed)

First set: 37.15mm x 5.96mm x 96.60mm (+1mm oversize, 0.7mm shorter length)

Second set: 38.15mm x 5.96mm x 99.10mm (+2mm oversize, 1.5mm longer length)

VQ30 Stock(from FSM): 36 - 36.3mm x 5.96mm x 97.3-97.8mm


So, to start off, what is the feasibility of 2mm oversizing? Im getting new valves, guides, etc and going to atleast 1mm oversize, so why not just do 2mm?

Also, Im not totally sure as to the effects of a shorter valve length, or longer for that matter. But the longer set could just be machined down. Input?

doublea

iTrader: (7)

Hey MOHFpro90, I'm dropping the heads at the machine shop on monday, I'll have a 1mm oversize job done on mine. I'll ask the tech about the increas to 2 mm oversize but as far as I know it might be pushing it, because with the 2 mm shaving you will have to remove some material in the bowl and that might be too much, piercing the water jacket would destroy the head. I'll let you know on monday when I get back for the shop.

Cheers

AA

MOHFpro90

iTrader: (11)

Do you really think there is that little material between the port and the water jacket? I would think that a 2mm oversize is possible, but definitely the max you could go.

doublea

iTrader: (7)

2mm is not that much but the way the bowl is shape around the valve seat doesn't allow for much shaving so you have to be very meticulous and carefull in that area. I cant say for sure but once I drop my head I'll let you know. I dont have finish yet, I though I would this week-end but I ended up missing some black emery compound and felt bob. Now I just need to finish the final polishing in the last exhaust port, I have about one last hour to go and then maybe another 2-3 hours to clean the deck and casting & I'll be done with the heads finally.

DrunkieTheBear

iTrader: (17)

I might try this if the valves are cheap enough.

Does anybody know how hard it is to modify the valve sleeves to accept the 1mm larger valves? If I can do all the work myself and not need a shop to assemble the heads for me I can the save money and use my money in other parts of the project.

DrunkieTheBear

iTrader: (17)

Its about $205 for the Intake valves.

doublea what do you plan to do about the exhaust valves?

KRRZ350

iTrader: (29)

Geuss who has an almost full set of vq35 valves Missing 2 exhaust ones though

accordingtou

iTrader: (41)

I have the 2 remaining exhaust valves.....

MOHFpro90

iTrader: (11)

Well, this is only one source. Im sure that you could find some cheaper sets, not made out of Iconel or special coating.

Doublea, I see what you mean. I am looking at my heads, and the exhaust valves have room to enlarge, but the intakes are probably no more than 1mm away from the edge of the bowl.

DrunkieTheBear

iTrader: (17)

the question is now, who has got the VQ35HR valve springs?

MOHFpro90

iTrader: (11)

You make really weird comments...


Anyone care to tell me what would happen if the valve length was increased?

Product_Of_Korea

iTrader: (8)

subscribed............
very intrested in doing some head work this summer since i have a spare engine just waiting for me to tinker with

i wish i could give some input but i dont know nothing about head work. so im learning as well

doublea

iTrader: (7)

To the best of my knowledge you cant modify the valve guide, you have to replace them.

I had custom valve guide made for my application by C.H.E Precision:
http://cheprecision.com/html/guides.html

One other thing is even if the valve is one or two mm wider the guide itself might be of the same diameter as the stock one. Replacing the stocker by manganese/bronze valve guide is the way to go, but you will have to give very precise informations to CHE in order for them to custom fabricate new valve guide. it would be a good idea to replace the valve seal as well. It is possible to replace the valve guide by yourself, but you will have to figure out a way to install the new one exactly where they should be, because we dont have any mark or indication as to how far we need to push the new valve guide in. The machine shop have the equipment to precisly install the new VG.

The machine shop will charge you 100$ to remove the old valve guide and put the new one in place precisely. In order for you to remove the valve guide by yourself you need to buy a long driver that goes on a Zip gun ( I bought mine from Goodson ) they costed about 40$ shipped out. The reason why I removed the guide myself is i needed to polish around the valve guide and once they are removed it's easier to polish that area.

The process is some how simple, you need to put the head in the oven for about an hour at 250 degree F. Also you need to put the valve guide in the freezer 24 hrs prior to the removal of the valve guide. It will take you just a few minutes to remove the valve guide, on the first head it took me like 5-10 minutes to remove the 12 valve guide.

I hope it helped.

AA

doublea

iTrader: (7)

The valve would hit the piston and that would make the engine blow, so you absolutely want to make sure the valve are of the right length. If you increase by only 1 mm you can still use the stocker valve, that is if they are in perfect condition, then the machine shop will only need to regrind the stocker to fit the new valve seat. If 2 mm oversize valve can be use make sure you buy brand new quality valve like Ferrea or other. An experienced technician in a reputable shop that does valve jobs knows all about that so you wanna make sure to double check with them.

doublea

iTrader: (7)

I'm having the stocker re-grind because they are in perfect condition. The tech at the machine shop told me that the VQ30 valve are made of very good quality and unless one is shooting for a 10 000 rpm engine that would push 800-1000 HP+, it would not really worth the investment.

In that case other aspect will have to be taken into consideration like replacing the stock valve seat by copper valve seat ( CHE precision can supply those ) but those are normally use in race engine that will be rebuild after every couple of race, so for a daily driven car it would not be a wise choice because we dont want to trade durability.

I mean if cash flow is not an issue then brand new valve would no hurd but if your stocker are in good condition here is a good opportunity to save yourself some cash and use it some where else.

A+

DandyMax

iTrader: (7)

I don't have all the valvetrain heights/dimensions in my head but likely you'd need to mill down the end of the valves such that the installed height underneath the buckets goes back to stock. Otherwise your spring install height is off, and the buckets will sit up higher (meaning screwing up all the lashes at the cam lobes, in fact probably consuming all clearance and causing interference).

MOHFpro90

iTrader: (11)

Well, I am going to email them and find out if we can get the 1mm oversize dish in a longer than stock length, that way it would be easy to machine the length down, assuming that there is enough material on the top of the stem to do so.

Or maybe they will just make some 1mm oversize VQ30 valves...

DandyMax

iTrader: (7)

It's not just the end of the valves, you also need to compare the groove for the retainer keepers, as that will change the spring height, and you don't want that getting longer (ie looser, less stiff).

doublea

iTrader: (7)

I mean if the top of the valve is shave let say 1 mm, then the groove where the retainer is locked, will be out of alignement unless the difference in the length of the valve is on top of the lock then you'll be able to shave a little bit and still be with in spec but otherwise shaving the valve would not help in any way.

I would suggest that you either stick with the stocker or buy after market valve like Ferrea with a 1 mm over size this way you'll have the exact same length.

My 2 cents.

MOHFpro90

iTrader: (11)

Doublea,

I didnt know Ferrea makes 1mm oversize for the VQ30?


To Dandy and Double,

I realized that right after I typed it. The distance from top of stem to bottom of dish isnt what is important, but from the keeper groover to the bottom of the dish. Hmmm....

KRRZ350

iTrader: (29)

Screw it, what we really need is some sideXside comparo shot's and measurements of a 3.0 VS 3.5 valve. Disregard what I said in that PM, before friday I WILL pull the heads off that 3.0 that is getting scrapped

DrunkieTheBear

iTrader: (17)

ah you suck I was gonna do it since you mentioned it....I might still have that nikon d70s kicking around when I go to do the campro pics

MOHFpro90

iTrader: (11)

Well Ive got my 3.0 valves, so all I need at some 3.5s. You bring up a good point kev. Ill have to find some 3.5s soon enough to really compare.

doublea

iTrader: (7)

I'm not sure at all if they have a stock 1 mm oversize for the VQ30 but I believe they can fabricate custom one but this has to be verified. There is other manufacturer that can fabricate custome 1 mm oversize valve for a decent price. I'm not building a race car so paying big buck for over size valve is not necessary and would not bring benefit over the stock re-grind valve.

doublea

iTrader: (7)

I've went back in the garage and took some measurement of one of the VQ30DEK stock exhaust valve below.

Head diameter 31.37 mm
Valve length 95.21 mm
Valve diameter 5.95 mm

Valve tips length:
From the tips of the valve to the upper part of the groove: 3.94 mm
From the tips of the valve to the middle part of the groove: 4.5 mm

Now here is the spec for a Ferrea 1 mm oversize valve for a
NISSAN 350 Z (VQ35) - 2003

F1565P - Type E-32.35mm - 5.96mm - 94mm - 3.5mm
22º Flo. Radial Gro. + 1mm o/size.Super Alloy Turbo Appl.

The Ferrea Competion Plus Valve are very close to the VQ30DEK spec, they are only 1.21 mm shorter than the stock VQ30 all other spec match pretty much.

This might be very good for very high boost application, a shorter valve stroke may prevent boost leake, but for us I think we would loose some power but that's just a theory.

MOHFpro90

iTrader: (11)

Andre, well would it really matter if the overall length is different? I guess what I am trying to say, is if the distance from the bottom of the dish to the middle of the keeper groove is all that is crucial, right? Because any extra length above the keeper groove can be machined down to stock specs.

doublea

iTrader: (7)

Here is what I came to think after all, is that the VQ30 DEK have longer valve by about half a mm or so depending from where in the groove we take the measurement. Using shorter valve might be good for boosted application since it may prevent boost leak thru the valve but to be honest I dont know if that theory can apply here. Boost leak true the valve are well known in high hp/tq motor used for race so I dont know if that can apply for let say a 400 HP engine like what we are shooting for.

One other thing I tough is if we raise the fuel pressure it can possibly compensate for the shorter stroke of the valve, since with VQ35 valve being shorter it wont open as much as the VQ30DEK valve so there might be less fuel getting in because of this, but this is hypothetic and I may just be plain wrong.

DrunkieTheBear

iTrader: (17)

Okay, I've been searching for days...

where the hell to get VQ35HR valve springs?

thats the only thing left on the list to get....unless I feel ambious and someone wants to donate a VQ35 crank as well (trust me I won't disappoint)

Shinjiduo

iTrader: (106)

Go to an online OEM parts seller like www.infinitipartsusa.com or http://www.nissanparts.org/.

pmohr

iTrader: (26)

FAST is showing the HR valve springs to be the same as the revups, just FYI.

PN 13203-JK21A. $4.90 ea @ Courtesy, probably cheaper from Dave B.

nismology

iTrader: (8)

The valve springs are different. It's the retainers that are the same.


http://forums.maxima.org/showpost.ph...62&postcount=1




(BTW, FAST 07 is giving me 13203-AC700 for the revup springs.)

pmohr

iTrader: (26)

That PN shows as 12/04-08/06 MT here...

Then again, since the 35th AE had a revup, that's seems right.

However 13203-JK21A shows as both HR and 08/06-11/06 VQ35DE, with the 6MT.

Odd. This is the A1 CD from 01/07.

aackshun

iTrader: (3)

Grave digging.... Anyone brought light to this yet?