Street porting a 1.9 big valve head

[davegt27]

just looking at some of my notes

i used seat pressure of 118 @ 1.700 installed ht
275 open @ 1.200 coild bind @ 1.140

comp cams # 942 valve spring i guess i did not take good notes since this was a double spring setup

split a stock rocker in half at 9200 rpm ha ha (man did that car shake)

i also just found out i have to identical Cams
cam techniques grind F-306/290-6 solid lifter
lift is .459 at valve and .435 (EX)

so if anyone needs a HI-Po CAM

Davegt27

[RallyBob]

Isky Spring #4205 is 110 lbs @ 1.750 installed height and has a spring rate of 320 lbs/in. Outer spring is 1.240 O.D. and .925 I.D., Inner spring is .915 O.D. and .660 I.D.. Spring bind is at 1.020". So if I shoot for 1.765 installed height I should get about 105, then with approx. .490 lift I will have 262 open pressure. This leaves .255 before spring bind.

If you are using the cam I recommended, then true lift at the intake valve will be closer to .475" (you must deduct the valve lash from the static lift). Even still, you should have around 255 lbs or so spring pressure. Good enough for 8600-8800 rpms or so, which is way beyond your peak rpm power anyway. So you'd have a margin of safety. Sounds like it will work.

[Tru-Craft]

i have a flat top piston engine that i went to bigger valves about 5 years after engine was built.i also did not want to pull engine or dissasemble.
test drive--yee hah!big valves are a blast!
go to chiropractor!
this engine has been inuse since 93(after valve work)and still runs perfect.
Hope this helps!
when cars fly--i duck!

Thanks everyone for the quick response!
I should be able to check the valve/piston clearance now.
I will use a (cutter) slightly larger valve with notches ground in it, or the tool Travis mentioned to put piston relief cuts in. Machinist's can't use dremels, plus I don't want back problems!

I will keep the spring pressures low about 100-105 closed, 250 open.

Started hand porting a little tonight at the shop, looking good, but I'm slow! Will take a couple pictures to show progress.

David, sorry to hear about your car, glad your son is OK!
Thanks again
Lyle

[Tru-Craft]

Isky Spring #4205 is 110 lbs @ 1.750 installed height and has a spring rate of 320 lbs/in. Outer spring is 1.240 O.D. and .925 I.D., Inner spring is .915 O.D. and .660 I.D.. Spring bind is at 1.020". So if I shoot for 1.765 installed height I should get about 105, then with approx. .490 lift I will have 262 open pressure. This leaves .255 before spring bind.

Jeff, do we need a double valve spring setup?
With the lower spring pressures would a single spring be better?
Less moving mass!
Lyle

[markandson]

From what I understand the inner spring is there to act as a damper, which I assume is to avoid harmonics that may be set up at certain rpms. The original spring as posted by RallyBob was a Crower which is NLA as far as I know, but it too was a double. I just followed along when I chose the Isky. This is where Bob needs to jump in.........bye. P.S. Bob, you were right, I forgot about the lash.

[supertiga]

markandson
exactly right on the multiple valve springs.most material/structure has a frequency that it gives up at.saw a ww2 aircraft that looked to have 6-8or more springs for each valve.i think it was a rolls royce merlyn.long time ago.

the same formula for spring/damper selection for road springs should let you know what your springs quit working at
look in steve smith-advanced racecar suspension development
or
costin and phipps---racing and sports car chassis design(costin of cosworth)
or
len terry and baker--racing car design and development.

some where long ago i remember reading formula in an engine book--cant find now.

something i have done is to ask cam grinder what springs to use for cam/valve train weight/rpm/ect.i have always gotten an answer.

hope this helps

David.

[supertiga]

have looked in apile of books and online and havent found the math for valve springs.
waddel wilson calls it spring surge.(but no math)

lookin at formula for road spring/damper caculations--would probably take some one good with math(not me)to use it for valve springs.

did find this for chev small blocks (outer and inner spring)
110lb closed-1.7 installed hight
260lb open -1.25 hight(.45inch open)
max lift .485
GM p/n 3927142 paint code reddish brown
i think these fit the opel spring pocket

for up to 8000rpm
larger o.d. than above
135lb on seat
290lb at .5 open
GM p/n 330585--spring retainer p/n 330586

[markandson]

I checked original installed height of the valve springs in my 2.2 head. Rough measurement only with a machinists scale. Intake = 1 9/16" Exhaust =
1 13/16" with the rotator removed. Checking the length of the valves that I bought from SI against the original valve lengths yields the fact that the new valves are about 1/16" longer to the bottom surface of the retainer. Since I need approx 1.765 installed height to get the 105# of closed force it appears that the exhaust side is very workable with a shim. It also appears that I have to cut the intake spring seat about 1/8" deeper than it presently is. Here is the question----How much deeper can you cut the intake seat of a 2.2 head before the wall thickness to the intake port gets too thin?

[Tru-Craft]

Got my new double cut oval carbide burr this morning! From McMaster-Carr.
Wow, that baby can remove some metal!! One wrong move and you can do some major damage $$!!. I have smaller diameter burrs I am using when I get close to the valve seats, Yep I'm chicken!!!
Area's that have been tough are around the exhaust valve seat insert, the chamber upper edge and the valve guides.

I used the bronze valve guide as a gage to thin the cast area around it. Trying to maintain a .04-.05 wall, milling them to height has helped a lot.
They have a sharp milled edge now, I will be putting a radius around them as Bob show's, not sure how to do that yet.

Bob's pictures are a great guide to show how it should turn out! Doing it is another thing, this is not easy! I'm such a perfectionist this will take me awhile!
Will take pictures of the port and chamber area tomorrow.
Lyle

[tomking]

Jeff while the machinist was doing the deepening of the valve seat area for my 2.4 stroker he broke thru into the coolan chamber. It was massive core shift in the casting process. I would guess we were dropping the floor about 1/8 an inch. The next head machined OK.

[Tru-Craft]

Here is what I have so far. The valve guide casting and the bronze guides are ground concentric and milled to height to match valve undercuts. Will try to stream line them, but want to maintain valve stem support!
Take a look at the picture, any imput before I continue on?
Lyle

[Tru-Craft]

the guides look awfull long also(into port)hard to tell from angle of pic, I have cut to 1/2 stock height with no problems and a few times have removed 75%
i dont know at what point guide/stem wear starts to be problem
i bet rally bob does! David

David, I milled the valve guides lower by .100" since the last picture. I thought they were too long also! I milled about 5/16" total off the top of the guides. From the chamber to the top of the guide checks about 1.40" now.
Been busy, will try to port a little tomorrow at the shop.
I decided not to grind the cast guide away around the bronze insert, for wall strength. My thought is, if I ever have to replace the bronze guide this will keep the cast guide from cracking!? I know it will not flow as good as Bob's technique.
Will take a picture of it.
Any thoughts?
Lyle

[RallyBob]

I have searched the forum for a source for this size valves and its necessary ancillary parts and have even looked at web sites for companies listed in the replies and have not located part numbers for 1.72 or 1.5. My eyes are getting bloodshot!
Can anyone tell me Manufactures part numbers?
Many thanks

If you want dirt cheap then OEM type replacement 305 Chevy valves are all you need (not the HO models however).

If you want middle-of-the-road, then these work fine: http://www.sivalves.com/ocdomestic_valvesps_chevsb.html

If you want better quality then call Manley and order some cut-down valves (they start with a 1.94" blank). Takes about 7-10 days and adds $8 per valve to the cost. You have a ton of options for a starting point BTW, I usually just use the Raceflow 11/32" stems, stock length.

[davegt27]

i would scan this in but it takes time for approval

from the Manley 2003 catalog

stainless pro flow

int P.N. 10722-8 --- 1.940
stem diam .3415
installed ht: stock
OA length 4.911
tip length .250
underhead angle/radius: Pro flow-- 10deg x 3/8"
seat width .080
top of head 5 deg dish
wgt/grams 107

EXH P.N. 10721-8 --- 1.500
stem diam .3451
installed ht: stock
O/A length 4.911
tip length .250
underhead angle/radius: 12deg x 3/8"
margin .060
seat width .100
top of head 7deg dish
wgt/grams 89

2003 jobber price 10722-8 is $80.0
10722-1 is $10

10721-8 is (or was) $80
and again 10721-1 $10

HTHs
i can look up other number if you like
Davegt27

[azopelnut]

I found some Chevy valves that the seller states are 4.92 length.
Is the standard size length for opel big valve heads 4.88
Can this difference of .04 be machined off?

[Tru-Craft]

I found some Chevy valves that the seller states are 4.92 length. Is the standard size length for opel big valve heads 4.88
Can this difference of .04 be machined off?

4.88 to 4.91 is about the stock valve length. 4.92" that's the standard length of Chevy valves. They will work as is. The installed height will vary with how deep the seat is machined in the head.
Lyle

[Tru-Craft]

Working on the head again.
Have a couple valve spring questions.
If I use 1-1/4 Chevy springs, will I have to use cup type spacer to locate the base of the spring in the exhaust spring pocket??

Or should I just use a 1.440 spring (Pontiac 400) instead?
I would then just have to machine the intake spring pocket to 1.45 and proper depth, and be done!?
Lyle

[markandson]

Lyle,
I don't know the reason for using the 1.250 springs over any other, other than reducing the mass of the spring for higher rpm applications. You would need to make the spring cups you are referring to for the exhaust springs if you use the 1.250 springs. I, at this point, have only taken apart a 2.2 head, not a 1.9, so I am sure others out there will have better answers.

[RallyBob]

If I use 1-1/4 Chevy springs, will I have to use cup type spacer to locate the base of the spring in the exhaust spring pocket??

I always used double 1.25" springs, so the inner spring located on the valve guide.

My only exception to this statement was the roller cam setup which used a single spring with damper, and I had custom cups machined for the exhaust side that were quite thick, with off-the-shelf cups for the intake side. http://www.opelgt.com/forums/showpos...5&postcount=83

Bob

[neuropel]

Bob, I had a question regarding porting the heads. Another person on the list told me he was doing the porting BEFORE having any of the machine work done, which didn't make much sense to me. He is going with the 1.72" valves as in this thread. In your thread here you showed a funky little "lip" in behind the valve that you had to carefully blend in, and mentioned this is often why you go with a 1.84" or 1.85" valve. Is it possible or feasible to properly port a head before having the larger seats cut? I don't see how. It appears you have to work from the edge of the seat back, and I also noticed how you take away part of the guide (which in this case would be put in AFTER the porting). Ever hear of anyone doing it this way? He claimed that by doing the porting first, the "lip" area is already gone when you cut the seats.

Todd