sunk valves, stem height problem

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col318

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Hi there,
first of all i am sorry for my english.
So here is the deal, i live in medellin colombia and im trying to rebuild a 318, the machine shops here are the worst you people can imagine( they will only use a micrometer if you force them to ) the dont use factory manuals to get measurements, clearances etc they build by guessing, you guys would not believe how bad the situation is. Blueprinting is something thas has never been done to no engine in this fking country...

So when ispecting the heads i found out exhaust valve guides needed to be replaced they had over 0.15 side play one bein as high as 0.21 so i send the heads to the """machine shop""" to have them replaced (not possible to get ovesise stem valves around here) as you guys may know after a guide is replaced the valve seat must be reground so they did a 3 angle "valve job"

When i got the heads back they indeed had new exhaust guides and refaced seats. The new guides where reamed out to get 0.15 side play :cheers: i payed for nothing O:)... most of the reground Seats didnt seal and the ones who did didnt have consistent widths and caused some of the springs to "stretch" to theyr limit specification 1.687..

So i went to a different shop and got the exhaust seats cut to a single 45 degree angle and now they seal perfect and have consistent widths within specifications the problem is now tje valves are sunk beyond specifications and the valve stem is now protuding 0.030 more than they should the manual says to measure them with tool C-3968 and mill the valve stems untill they fall within specs but i cant get the tool overe here

does someone knows what the valve stem instelled height should be for a 318 ? And how much can i mill the valve tip without going beyond the hardened surface?? I want to avoid bending a pushrod or burning a valve
 
Sounds pretty ugly. Depending on how crazy you're going - I'd just cut them. Shim the springs to get the pressure you need (assuming they're matched to the cam you're running).
 
Care must be taking here. The tips should be ground on a Serdi valve surfacer and no more than .015" taken off. After that a chamfer must be redone so as not to tear up the guide on assembly. Also too much removal will effect the fit of the valve locks and retainers. I believe the installed height of valve is 1.56" - 1.59" but I.m not sure. Engine builders call it 1.60" height but I don't know why.
 
I think you need to get the valves to the correct installed height and spring pressure you need for the cam you are running then if the tip of the valve is to high and the rocker arms don't touch the valve stem in the correct location you can shim the rocker shafts up to move the rocker arm to the center of the valve stem you shouldn't need to cut or grind .030 off the tip of the valve in order to make it work, but if the machine shop did there job you wouldn't be going through this stuff. It sounds like if someone opened a machine shop that did good work for a fair price they could make a very good living. Good Luck
 
Thanks for the help... I am reusing the stock cam with its worn lifters and pushrods, everything is stock (2 barrel tricycle carburetor) i just want a reliable engine for now, most of the books i have looked at call for a valve stem tip grinding limit of 0.010 0.015 ive read on some forum that 1 piece valves with welded tips can be grinded up to 0.060, 2 piece valves with hardenet tips only 0.010... Elgin industries says in their catalog that their pro stock valves ( what i am using) are maded either two piece and hardened tip or one piece and welded tip.... I called elgin industries today ( my first ever overseas call) fun. But the technical help guy wasnt there.

I am aware that i need shims for the springs i had to call an industrial machine shop to have a set of 8 4140 steel shims 0.040 thick custom milled because nobody uses or sells them in the entire city (or country) im afraid.
 
You may be able to improve the situation by juggling the valves around,, some valves may already be longer/shorter, by the way they were re-faced, so if you juggle it just right ,, you may be able to minimize differences,, then just trim the ones nec..
 
inertia said:
You may be able to improve the situation by juggling the valves around,, some valves may already be longer/shorter, by the way they were re-faced, so if you juggle it just right ,, you may be able to minimize differences,, then just trim the ones nec..
Click to expand...

x2. Given the machinist/equipment situation, and the fact you're running stock 2bbl cam, I'd say grind the to what you need, but after doing what inertia says. Chances are the seats are not consistent either so swapping around might fix a lot of this. Then number the chambers and valve so you know where they go, and just whack off what you need to. It's bot great, but it will run. I'm not certain the rocker tip will even be on the tip after you shim for a .030 varience.
 
tool C-3968 is a +/- dimension for valve installed height to run non adjustable stamped rockers and maintain + lifter preload with the same length pushrod on all valves.
In your case rather than grinding the valve tip, I would switch to 273 adjustable rockers with the proper length pushrods to maintain proper lifter preload.
 
Thanks for the help guys, i have to say all the valves are new and there isnt more than 0.003 difference in their height... I called elgin industries again, the tech guy didnt have any information about installed height or grinding the tips, i gess he has the same information i have (the online catalog) whatever the oem says he said...lame.

Grinding 0.030 off the tips without a book/manual/specification allowing me to do it is taking a big risk if i grind down the hardened surface the engine will die in no time.

I wish i could install adjustable pushrods or adjustable anything but i can barely get stock parts here and waiting a month for an aftermarket part to get here is just impossible right now so ill have to spend more money to get new valve seat inserts installed or get the heads detroyed in the process
 
Not to be difficult as I'm kind of ignorant of South American prices but why not just buy a stock set of running 318 heads from the US? Just a used set of 318 heads? That's what you're ending up with - and the local "machinists" have basically trashed them already anyway.
 
moper said:
Not to be difficult as I'm kind of ignorant of South American prices but why not just buy a stock set of running 318 heads from the US? Just a used set of 318 heads? That's what you're ending up with - and the local "machinists" have basically trashed them already anyway.
Click to expand...


Shipping would be a fortune....
 
IMO, without big spring pressure and a really high lift camshaft, you're probably ok grinding the valve tips. As long as everything is ok, they will get plenty of oil.

Unfortunately, grinding the valve tips is the dead wrong way to fix your problem though. I think used heads is a good idea, but surely you can find some locally.
 
RustyRatRod said:
IMO, without big spring pressure and a really high lift camshaft, you're probably ok grinding the valve tips. As long as everything is ok, they will get plenty of oil.

Unfortunately, grinding the valve tips is the dead wrong way to fix your problem though. I think used heads is a good idea, but surely you can find some locally.
Click to expand...

x2^ That was my line of thinking too. I know there are plenty of mass rebuilders that don't care about grinding through the hardening and they usually get 10-15K from them without major failure. Consideration has to be given to the local area he's in. It's not something I'd do normally - but if you have to - you have to.
 
..............I'd just shim the rocker shaft up the .030 or so to get the proper preload on the lifters and be happy........kim..........
 
Hi there again thanks for the comments so i finally got new exhaust valve inserts installed... i measured the springs installed height and they are ALL DIFFERENT but they are withins soecifications so good enough... Off course this wasnt for free the machinist thought i told him to replace ALL the seats so he cut out one intake seat ( i wasnt really surprised at this point) so i have 9 new seats... So now that i know the engine is not going to selfdestruct in five minutes I hope i can run this heads for 20k miles or so meanwhile ill look for an used pair in good condition.

When picked up my heads there was a pair of chevrolet 350 heads in The machine shop, It was the first time i saw a pair of those unassembled, I was very surprised by the obvious superior quality of the chevrolet cylinder heads here are a few things i noticed:

Bigger valves
Thinner stems
Bigger ports
Integral seats ( both intake and exhaust) vs integral int exh insert in the mopar
Nicer cast less flaws
Stud mounted rocker arms and all the otjer things everybody knows

Im not a fan of any car manufacturer i love all engines the whining hondas, the mazda rotary, the diesels etc. I am fascinated with all off them, i just preffer old V8's all that being said after taking a look at those chevy heads i was very dissapointed off my mopar cylinder heads i guess thats the reason why small.block chevrolets are so horribly popular in the performance world.
 
Chebbie undeniebly had a winner with its SB. Biggest thing over SBM is the angle of the valves in relation to the combustion chamber. I had a SBC running alkie with a blower injected making 1280 HP. Was in our mini rod tractor for tractors pulling contests. Mopar made some good SB heads as well. And not all SBC made a lot of HP.
 
Stock heads:

Bigger valves = NO - SBC = 1.74-2.02", 273/318 = 1.78” 340/360 = 1.88-2.02", Exh SBC = 1.5-1.6", 273/318 = 1.5”, 340/360 = 1.60"
Thinner stems - yes & no compared to 273-360 LA 3/8 yes, the 318/360 Magnum at 5/16" is thinner than SBC 11/32". LA valves are stepped down below valve guide.
Bigger ports - Not really I have a 350 in my boat (for now) with 461 double-hump heads, Intake ports visually appear about the same as 360J heads, exhaust at least appear bigger on J heads (maybe not be any better flowing though)
Integral seats ( both intake and exhaust) vs integral int exh insert in the mopar. Not always, Pre unleaded fuel both had integral seats, after unleaded was introduced insert are best for long life (not sure if/when Mopar introduced them in USA, In Australia integral seats went through to 1981, Same with Chev, not sure when/if they went to inserts on cast iron SBC heads).
Nicer cast less flaws - externally perhaps less casting flash present on the Chev – not really a flaw, just cosmetic.
Stud mounted rocker arms and all the otjer things everybody knows - Not an advantage, when Chev's want to try and rev high with any sort of reliably they mostly convert to shaft rockers. Also SBC pressed in studs are renowned for pulling out of head with heavy springs, Chryslers stock shaft rockers are far superior to stock chev stud mounted rockers.

SBM valve angle = 18 deg, Chev 23deg, Chev aftermarket heads often go to 18 or less deg to match Mopar's stock valve angle.


Comparing your probably stock valve size 318 heads to perhaps modified 350 heads is not a fair comparison. Compare them to stock 340 2.02' heads.

Cheers
Jamie
 
itsnoyfb said:
Stock heads:

Bigger valves = NO - SBC = 1.74-2.02", 273/318 = 1.78” 340/360 = 1.88-2.02", Exh SBC = 1.5-1.6", 273/318 = 1.5”, 340/360 = 1.60"
Thinner stems - yes & no compared to 273-360 LA 3/8 yes, the 318/360 Magnum at 5/15" is thinner than SBC 11/32". LA valves are stepped down below valve guide.
Bigger ports - Not really I have a 350 in my boat (for now) with 461 double-hump heads, Intake ports visually appear about the same as 360J heads, exhaust at least appear bigger on J heads (maybe not be any better flowing though)
Integral seats ( both intake and exhaust) vs integral int exh insert in the mopar. Not always, Pre unleaded fuel both had integral seats, after unleaded was introduced insert are best for long life (not sure if/when Mopar introduced them in USA, In Australia integral seats went through to 1981, Same with Chev, not sure when/if they went to inserts on cast iron SBC heads).
Nicer cast less flaws - externally perhaps less casting flash present on the Chev – not really a flaw, just cosmetic.
Stud mounted rocker arms and all the otjer things everybody knows - Not an advantage, when Chev's want to try and rev high with any sort of reliably they mostly convert to shaft rockers. Also SBC pressed in studs are renowned for pulling out of head with heavy springs, Chryslers stock shaft rockers are far superior to stock chev stud mounted rockers.

Comparing your probably stock valve size 318 heads to perhaps modified 350 heads is not a fair comparison. Compare them to stock 340 2.02' heads.

Cheers
Jamie
Click to expand...
Exactly. Mopars are always maligned
 
And SBM with casting number 302, heart shaped swirl heads are very good. As good as any factory SBC heads. IMO
 
Great info there itsnoyfb but i must say that i compared a set of stock 350 heads to a set of stock 318 brazilian cast heads, im aware that there migh be some great 360 340 or some special edition 318 heads but in my case my heads just looked like crap compared to the chevrolet's
 
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