Inliners International Forums General Discussion Engines Good News / Bad News

The good news is I got the motor in the car yesterday and shouldn't be long before we fire it up. The Bad new is.... #1 only has 30psi the rest range between 145-165. Oh well should be able to run and drive it with a low cylinder but its going to need some work before it sees a turbocharger.

Hey; "not to worry" you (most likely) set a valve to tight is all.

Re-adjust that cyl before you start it.

Good luck.

I will check them but we didnt touch the valves noone has since this engine came out of its original car. Who knows its worth a shot.

Well looks like its a case of the Old valves/seats being subjected to years of unleaded fuel. The #1 intake valve/seat is leaking horribly.

You might try this:

Turn entgine till that valve just starts to open. Then with a pair of 'channel locks' rotate that valve & spring retainer about 45 degrees and re-test compression.

If It's still @ 30# you'll have to pull the head & do a "valve job".

Good luck.

PS: Don't 'fall for' that steel seat BS as that's for aluminum heads.

From my understanding, you should put in steel seats.
Unless you are putting in some additive for a lead substitute.
The lead additive was used for cushioning the valves when it hit the seats.
Also to raise the octane.
Prevents the valves & seats from erroding eachother.

Yeah unless you plan on running a lead fual additive you really need hardened seats. They will work fine without but not as long.

Gentlemen;

In the 60s when those engines were designed/built the amount of lead (octane) in 'regular gas' was nill compared to todays fuels. :rolleyes:

It's true the seats last longer with the steel insert, but your "looking at" perhaps a 10% difference at best (maybe).

There primarly for aluminum heads is all.

The lead 'aditive' is for use in engines with the 'higher' (than stock) compression ratio(s) to avoid paying for 'premium' fuel.

"Hot Rod" (high reving) engines are always apart for valve work & they save time/labor in that application where compression, combustion tempature(s) and spring pressures are much-much higher.

For the basic (stock) Sixties or older engines don't waste your money; as the 'octane rating' of fuel then was LESS than 'unleaded' today.

"Think about it"; Will you ever put 100,000 miles on your engine rebuild, to gain the benifit??

Believe what you want !!! You should have seen the exhaust valves that came out of my 1970 350 v/8. Allthough it was used to pull a 22 ft. travel trailer all over the USA. Looked like someone tryed to be beat them out of the head the wrong way. The seats were beat flat and the valves junk.I didn't know if it was the seat or the valves that caused this (the old chicken or egg thing). I just replace both. The intake valves were just fine. Now the other side of the story...I drove my old 216 Chevy around 10,000 miles on unleaded gas with no ill effect.Like John said I think it,s the type of service you intend to use your motor for that will help you decide if you want to replace the seats...SCRAP

Scrapiron, your heads came apart due to hard use, just like they should have. Work them hard, they wear out. But for a every day, drive around car, you will never wear out a stock valve seat! The turbo engine might be hard on parts, but the amount of air coming past the valves will be enough to cool them and keep from burning the seats. As we all know its the heat that kills them, low rpm lugging heavy loads, the valves overheat and beat the red hot seats to death. Joe

i would say you need a valve job done.i have been doing heads for over 25years and done alot of testing on this issue of hard seats.one finding i have found is the guides wear out and then beat out the seats. some heads have softer guide then others. another is detonation that beats things up in a hurry.

now for this other b.s. about needing steel or hardened seats or additive. YOU DON'T. lead was added to gas to raise the octain rating that is all it was cheaper then other ways. even in the 50's and 60's there was ammaco which was unleaded and there was no problems then.lp. gas has no lead and it was and is used in fleet trucks with no valve problems. methenal has no lead and it is used in race motors with no valve problems.

a lot of valve problems come from not getting a good valve job to begin with. i have seen a lot of poor work from the local machine shop. you have to shop around. read about valve work then when you go to the shop ask questions.

i can tell you you will not get a good job unless you pay for it. and you will have to go to a shop that does hp work. not the nappa store on the corner where it is in by 9 out by 5.


scorpian your problem sounds like detonation. the wrog grade of gas or timing or over heating.but it was not the seat or valve fault.

Concerning valve guides and seals, what's the recommendation on rebuilding a 250 cylinder head with worn valve guides? The stock 250 does not have valve guide inserts, so is knurling of the cast ironguide bore then reaming acceptable or should bronze valve guides be installed? What about installing valve steam seals?

vlave guides are rebuilt with bronze walls. i use the walona system where the guides are taped and the a bronze insert is threded in then a expander ball is driven through to lock it in place then it is reamed to size. there is another sytem that is close to that it is called the nu-way.

now about knurling it was popular at one time but then people found out it lasts about as long as it takes to talk about it. think about it this way. you take an already over size hole run something through it that raises some high spots then you ream more metal out of that hole.

just putting seals on will last a little while till the valve rattleing around in the guide
wears them out too.

so the way it works is after takeing the head apart getting it clean the most important thing is the guides if they are not to size or rebuilt right then everything else is just throwing away good money

Ill have to see what the shops around here get for simple valve job. Just need to get this running right Ive got another engine I should be getting in a few months that is completely built, screw in's roller rockers, cam, ect....

Well said Bob & thank you.

For those interested; GM (& others) added the steel seats because the EPA forced the catalitic converter, which raised the head temp killing the valves & all related parts etc.

For a 'cheap valve job'; just go to a 'full service' Garage & fix the one in that cylinder. The other readings were okay for temp street use.

"Happy trails"

Yeah I think ill take it to the shop we have do all our service and have that one replaced.

As for the rest while the head was off I thought about just lapping the valves just to be on the safe side.

Sure, that's fine.

In the time you spend on that you could have it running tohough. Those valves were working fine.

The first rule of auto mechanics is: "If It's not broke, don't fix it".

Decided well just pull the head, have that one valve looked at and slap it back on with a new gasket.

Well we pulled the head and sure enough we have 4 exhaust seats that are sunk way into the head. So were having the entire head rebuilt. Even though it may be a temporary head id rather be safe then sorry. Especially if we plan on boosting this block.

RevOD,,,,
that is what happens when you do not have harden seats installed(w/no lead additive), it's not a fantasy, or a way of cyl. head shops getting money from you.

MBHD

I know.... and this engine only had 70,000 miles. Not out of the possibility of the mileage I put on my cars. My best friends 6 was the same way and hers only had 50,000 and they were both in Novas.

I have heard the argument before about not needing hardened exhaust seats but oh well...

Hey REVOD, you mentioned that four of the exhaust valves were sunk, was #3 and #4 the two that were still OK? Just curious.
Dan

nope #6 and #2 were in the best shape

and the myth goes on and on told over and over buy people that do not know what they are talking about. they see a problem and don't know what caused it so they lay the blame on something. and the guy that does the work knows nothing.

if you are beating the seats out you better find out what is causing it detination or preignition. and fix that.

I thought maybe the outer cylinders had run leaner/hotter, guess not though. Of the 5 Nova's I have owned the last three have been inline's and I have had no valve problems, I am not going to say that there is no advantage to hardened seats, (I currently run a non-integral smog head on my 250) but I have to agree with BOB308's advice because the same detonation/pre-ignition that sink's valves will "knock" loose hardened inserts too.

I have seen too many valves beat the crap out of seats because there is no lead.
GM later model heads, the seats are flame hardened (no harden seats installed)that is why the newer GM heads do not beat the seats in like the older GM castings.

Would it be possible to flame harden/temper older head valve seats instead of using inserts?? Just wondering for the sake of wondering.
Dan

I tend to believe the so called myth for one reason. We had the heads rebuilt on our old fullsize Dodge Van. The exhaust valve seats were beat up like mine were on the 6. That was at 85,000 miles. We had hardened seats put in it and drove it for another 200,000 miles, only had to replaced valve seals @ 190,000 and when it finally spun a bearing @ close to 300,000 miles, we pulled it apart the valve seats looked great... without them we would have had to do 2 more valve jobs.

yes you do flame harden them when you start them up and run them. another thing that beats out the seat is if the valve guides are worn that lets the valve rattle around and beat out the seats. on any head i have taken apart and the seat was bad the guide was shot too.

as far as beliveing tha myth go ahead it is not my pocket that $300 comes out of to pay for them.

Your still "missing the point" here.

Steel seats are good for commercial engines especially with the catalic converter. NO WAY was 300,000 miles put on a passenger car.

Most Hot Rods use them too.

But for a stock 250" engine, for use in a passenger car (W/O a 'CAT') save your money as you'll never get it back.

My original 327" Bell Air has 138,000 & never been apart and been using unleaded since it came out(60.000). Last tune up the compresson was close to perfect.

It's the usage or 'planned usage' that's the main factor.

Hey John I have to beg The differ here,My Mom had a 71 chevy Impala which Had over 300.000 Miles on it before She sold it to a friend And he put another 100.000 on it and it Only Had two timing chains replaced The first Chain had been replaced at 250.000. And at Normal oil changes The Motor was still pretty clean on the inside THAT was a surprize. I had a 87 sub. I had bought with 89.000
and I racked up 200.000 So when i sold it,It was Pushing the 300.000 mile mark.
So my 2cent point is It is possable TO rack
Up that kinda miles.

The old saying goes: "If you take care of something, it will last a long time".

Exactly 300,000 on a passenger car or in the case of our family van is not uncommon. Heck these even a Camaro around here that has 500,000+ on it.

As for $300 I would never pay that much to get a valve job on an inline 6 you'd have to be crazy. I'm paying $180 to get a complete head rebuilt and have hardened exhaust seats put in. The fact of the matter is they were going to have to be replaced anyways why not pay the few extra $$ for hardened seats....

Also john the exhaust seats on my 6 although beat into the head still showed fine compression on all those cylinders so even though you went 100,000 plus doesn't mean there isn't damage there.

This debate is not by any means specific to this site.
I googled -'hardened valve seats unleaded'- and there is no real consensus, Chevron claims all passenger cars and light trucks are safe from valve recession.
They even say that antique cars actually benefit from unleaded because of less exhaust corosion and oil contamination.
But we can't expect them to say "hey our fuel will ruin your ride".
And of course there are tons of articles that say exactly the opposite, I think it is safe to say that if you plan to operate under heavy loads or at high RPM's then hardened seats are a pretty good idea.

On the subject of leaded gas, check this timeline out. It will amaze you and even might make you mad.
http://www.thenation.com/doc/20000320/timeline
Back to valve seats, a little something from the EPA
http://yosemite.epa.gov/r10/AIRPAGE.NSF/0/adebd4b8879d36bc88256c0800760bf5?OpenDocument

Do I or don't I?

That is the question I've been kicking around.

My machinist says I shouldn't need them, as they are hardened from the factory. But then he goes on to say that as long as nobody did a valve job and ground through the hardening it should be fine.

So I'm still trying to figure out, do I or don't I?

I honestly think you have nothing to worry about.

if you don't need them to fix a bad seat don't put them in. look at it this way you are adding 12 more things that can go wrong. you ever seen a motor that a seat has poped out?

Not sure if you know this,,,,,,,, but you only typically need harden seats for the exhaust valves.
Only 6 are needed.

Put the seats in ,unless you are planning on not using the cylinder head that long.
Try & tell him to put the shallow seats in, so you will not get into the water jackets.

All the factory alum heads have seats in them, do you think they would be putting in seats if they would fall out?

If you install them correctly, w/enough interference fit ,you will not have any problems.
Goodluck!