Valve springs - Toyota Nation Forum : Toyota Car and Truck Forums

NZAE92 · 11-14-2010, 01:24 AM

Hey all,

im going to be getting a performance cam grind done one my corolla 4af, yes i know it's a 4af but i want to be different so don't diss

.

so, what i was wondering was what sort of poundage can the valve springs handle?
and should i just spend that extra bit and get all new valve springs that can handle the pressure that the new cam grind will be forcing onto it? also what will i need to do have this new cam grind work like will i need new shims for the head or should the new grind be fine just to bolt right back in with out any work to the shims or buckets?
I'm not going cheaply with this work.

Any replies back will be much appreciated.
Cheers Greg

Blof-fan · 11-14-2010, 05:24 AM

Well, the way I see it, you're not really in need of new valve springs.
The only reason why they replace the valvesprings on, say a tuned 4A-GE, is because in most cases, they really rev the pants of those engines.

With the original springs, they might get valve float because the springs just can't cope with this. And thus they install springs with a stiffer spring rate.
This has nothing to do with higher lifts or something like that. The spring will not be loaded all the way to it's max travel, even with higher lift. So the spring will always be able to handle the changes in cam profiles.

So if you plan to modify the engine extensivly and will rev more, than yes, change the springs, if you are not going to go past the rev limiter, there will be no need to change them.
Do keep in mind that uprating the springs can cause higher friction losses in the engines valvetrain.

As fot the shims...if new cams are fitted to the engine (even if they are of the same type and profile) always check the valve clearance and adjust if neccecary.
Do expect that you will have to re-shim most of the valves.

Are there going to be more mods to the engines besides the new cams?
Are you going to dyno it afterwards? Good luck with the cams, go for it and please let us know the results!

Donald · 11-14-2010, 05:40 PM

If you are grinding for more lift or duration, they will probably need to grind the circular section of the cam.
That will definitely require thicker shims in order to maintain valve clearances, since that is where they are measured.

I suggest before you do any cam grinding, talk to a Toyota perfomance specialist.

I have heard that grinding the Corolla cams is not recomended, but don't take my word for it.
I don't know enough to give an opinion, just sharing what I have heard.

Talk to a Toyota specialist.

NZAE92 · 11-14-2010, 07:56 PM

I'm wondering are the valve clearances adjustable? don't the shims do that? cause my mate works at Toyota and says that they aren't adjustable and that i have shims so they will need to be thicker or skimmed or something?.

So it would be recommended to just get the valve springs done aswel? since they will create less friction and it would be safer to be revving higher up the rev range.
I have since got into motorkhana and i maybe needing that extra power so the higher it can rev the better.

the cam will be fully ground from the lobes to the circular section.

Quote:

Are there going to be more mods to the engines besides the new cams?
Are you going to dyno it afterwards?

of course there will be more mods lol im hopefully going for twin sidedrafts a big downdraft or quad bike carbs.

unsure of what i will get since the bigger cam grind will allow for more fuel and air to get through but not sure if the standard carb will be efficient enough to put more air and fuel in, but that will be come into play when i get the cams done and get more info on what i will need to do.

Donald · 11-15-2010, 10:18 AM

Quote:

Originally Posted by NZAE92

I'm wondering are the valve clearances adjustable? don't the shims do that? cause my mate works at Toyota and says that they aren't adjustable and that i have shims so they will need to be thicker or skimmed or something?.

So it would be recommended to just get the valve springs done aswel? since they will create less friction and it would be safer to be revving higher up the rev range.
I have since got into motorkhana and i maybe needing that extra power so the higher it can rev the better.

the cam will be fully ground from the lobes to the circular section.

of course there will be more mods lol im hopefully going for twin sidedrafts a big downdraft or quad bike carbs.

unsure of what i will get since the bigger cam grind will allow for more fuel and air to get through but not sure if the standard carb will be efficient enough to put more air and fuel in, but that will be come into play when i get the cams done and get more info on what i will need to do.

The valve clearances are adjusted by swapping out shims to get the correct clearances.

How that is done is:
1 the cam is set to a predetermined position
2 a feeler gauge (thickness gauge) is used to find the clearance between the cam low section (circular section) and the shim
3 if the gap is incorrect, the bucket is depressed and the shim is pulled out
4 the shim is measured
5 calculate what thickness shim is required to get the correct gap (thicker or thinner)
6 a shim of the correct thickness is installed, and then the gap checked again

Shims here in the US cost about $8 each, and I believe that if you grind your cam, you will need to replace all 32, (32 x 8 = $256).

I understand that you want to be different, and any engine can be made to make more power, but you need to figure out if the gains of modifying of your 4AF is worth the expense (time, and or money).

What is your ultimate goal performance wise?
What kind of power gains do you expect from your intended mods?
Is this car a daily driver + motorkhana steed, or just for motorkhana?

Have you considered the other possibilities, 4A-GE swap, 7A-FE swap, turbocharging?

For motorkhana/autocross, I suggest you look at your suspension and tires before the engine, but make sure that your engine is in propper tune (valve adjustment, carb adjustment, timing, compression).

Flashmn · 11-15-2010, 10:43 AM

Quote:

replace all 32

32?! theres 1 per valve and the engine has 16 valves, so how does he need 32 shims? its not a V8 he's got in his rolla ;D

Blof-fan · 11-15-2010, 10:59 AM

Quote:

Originally Posted by NZAE92

I'm wondering are the valve clearances adjustable? don't the shims do that? cause my mate works at Toyota and says that they aren't adjustable and that i have shims so they will need to be thicker or skimmed or something?.

Well, they are adjustable in a way. But you have to adjust them with the shims

There are various sizes shims (thicker and thinner) and by replacing them with the right shim thickness, you can adjust the valve clearances until they are within spec.

Quote:

Originally Posted by NZAE92

So it would be recommended to just get the valve springs done aswel? since they will create less friction and it would be safer to be revving higher up the rev range.
I have since got into motorkhana and i maybe needing that extra power so the higher it can rev the better.

If you plan on really reving the engine, then yes...go with the uprated valve springs. But they will create more friction!

Donald · 11-15-2010, 11:07 AM

Quote:

Originally Posted by Flashmn

32?! theres 1 per valve and the engine has 16 valves, so how does he need 32 shims? its not a V8 he's got in his rolla ;D

Oops!!! LOL
So sorry. Thanks for the correction.

That's what I get for typing before I wake up.

***MR2Jedi*** · 11-15-2010, 11:45 AM

When upgrading cams and/or revving past redline, upgrading to stiffer springs is a must or you risk valve float(as stated above).

To calculate new shim thickness:

T..........Thickness of used shim
A..........Measured Valve Clearance
N..........Thickness of New Shim

N = T + (A - specified valve clearnce )

NZAE92 · 11-15-2010, 03:12 PM

ok.
I don't want valve float so i will want new valve springs but more friction isn't wanted either.
im just gonna go with it and just do the valve springs aswell it seems like the best way to go.
If i follow all your info it should be a simple modification.

now i need to know the specs on the valve grind etc and then find the right thickness shims for it. this is starting to get interesting lol.

Quote:

its not a V8 he's got in his rolla ;D

i wish then i wouldn't be doing all this work lol

canadianae92 · 11-15-2010, 03:33 PM

i would switch to a more efficient head(newer 4afe/7afe heads) before worry about internal work

***MR2Jedi*** · 11-15-2010, 05:53 PM

Quote:

Originally Posted by NZAE92

ok.
I don't want valve float so i will want new valve springs but more friction isn't wanted either.
im just gonna go with it and just do the valve springs aswell it seems like the best way to go.
If i follow all your info it should be a simple modification.

now i need to know the specs on the valve grind etc and then find the right thickness shims for it. this is starting to get interesting lol.

You'll need to install the cams 1st , so you can measure the clearance to determine the new shim thickness.

NZAE92 · 11-15-2010, 06:03 PM

Quote:

You'll need to install the cams 1st , so you can measure the clearance to determine the new shim thickness.

what your saying is i need to get the cams ground first, install them then i will need to go out and get some shims for it? where can i get them from is my main question.

cause new zealand doesn't have as much aftermarket stuff for the 4af etc as America does.

***MR2Jedi*** · 11-15-2010, 06:26 PM

Quote:

Originally Posted by NZAE92

what your saying is i need to get the cams ground first, install them then i will need to go out and get some shims for it? where can i get them from is my main question.

cause new zealand doesn't have as much aftermarket stuff for the 4af etc as America does.

Correct. After cams are installed, you will need to measure the gap (clearance) between the cam and old shim, then determine the size shim you need to attain the proper clearance.
The ONLY place you can get the shims are Toyota.
PM or call Gary, ToyotaPartsMan , he's a cool guy and will go the extra mile to find what you need. Tell him I sent you.
Gary Smith-Parts Manager
garys@toyotaofnewnan.com
www.ToyotaofNewnan.com
678-854-9601

These guys do alot of online business and have good prices too.-

Toyota Parts Outlet

NZAE92 · 11-16-2010, 04:29 AM

Quote:

The ONLY place you can get the shims are Toyota.

That's excellent, I work at Toyota now lol as an apprentice mechanic only got the job like 2 weeks ago signing the contract tomorrow and will be starting there on the 6th dec but that's another story.

ok so i will have to get the cams out and make a date to get all this done when i come into some money, lol will prolly be the first pay day.

it's gonna cost me around 450 for grind and valve springs, and dunno how much the shims will cost?
Donald said that they would be around 8 bucks each? i may get them cheaper hopefully

and i need 16. doe anyone know if they differ in price depending on how thick they are? and how easy is it changing the shims and valve springs?
I can't believe how exciting this is!!!!