• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

I need a lecture

Share this page

Morris

Morris

Yoda
Offline
For those of you who have been following my posts...

I have drilled out the two offending valve guides and pulled two good valves from another head.

Somebody, please give me a stern talking to before I do something stupid.
 
When you say you drilled out the guides, do you mean the ID of the guide or do you mean you actually drilled the guide out of the head?
 
In my mind you already did something stupid, sigh. Should have taken the head to an expert to do the work. They cheep, and fast. If it is labor intensive do it your self. If it takes special tools, experience, etc. farm it out.

Now you must fight new valve guides, fit them and the valves and seat the valves. Easy job with the right equipment, a real PITA by hand.
 
I say go for it, put those two good valves and guides in!

Worst case it doesn't work and you take it to a machine shop.

I respectfully differ with Jack, whenever something needs specialized tools, for me it's a good excuse to buy them! /ubbthreads/images/graemlins/wink.gif It won't be the last time you need 'em, so might as well learn to do it right. Also, I'm begining to think the so called experts aren't so smart afterall, having fixed numerous things I had previously left to a 'professional'.

Just my $0.02
 
Oh yea, but machine work takes some good stuff and I have no room. Hand tools are a different matter.
 
Jack, I took the head to a machine shop reccomended to me by a local British mechanic, and had ALL the guides replaced "professionally." They are the ones who screwed up my head in first place. There are suprisingly few machine shops in Austin. I did not luck out and find a good one like you did.

Hap, I drilled out the inner diameter of the guides. Mainly just as an expirement and excuse to play with my drill press. The replacement valves seem to fit nicely.

Rob, what tools would I need to replace the guides. If the price of tools is close to having the half-assed machine shop screw it up again, I may be open to that. Do brand new valves need to be seated?
 
Yes new valves need to be seated.

Well, with a drill press you are prob good to go.
 
Morris - I haven't done the job you're about to do so I can't tell you what you'll need. I know Nial has done it on a 1500 and it sounds like Jeff has rebuilt more than his fair share of engines, might want to PM them if they don't chime in?
 
I think I have found a machine shop I can trust.

I could probably get it done for free at the place that did

it orginally. But it's not worth a coupla bucks for all the lost sleep.

Also, Rob, you were supposed to give me a lecture on how I should do it right! Not encourage my insanity! Just kidding.

Thanks for the lecture Jack and Patrick.

To everyone else, sorry for this stupid thread.
 
Ahh, that pleases me. sanity at last.

Was the head leveled last time? If not do so or at least have it checked.
 
Funny story that. When I picked up the head the first time (this was after they sent it home with the wrong guy) there was a deep scratch on the mounting surface. Machine shop says, "Hyuk, I guess we'll have to level that of for ya."

I will have the new machine shop give it the once over.
 
Monday, rush job?
 
Morris,
stem to guide clearance is .0007-.0023 inlet, .0015-.003 exhaust.
be hard presssed to hold those tolerances on a drill press. letting the machine shop do that is advisable.

mark
 
[ QUOTE ]

Also, Rob, you were supposed to give me a lecture on how I should do it right! Not encourage my insanity! Just kidding.


[/ QUOTE ]

/ubbthreads/images/graemlins/jester.gif I guess I'm just one of those guys who'd rather spend twice the money and ten times the time to do it himself and still get it wrong! /ubbthreads/images/graemlins/hammer.gif LOL

Glad you found a shop you can trust with the job.
 
Hey Rob, I am one of those guys, too. But the other day my wife had a hard time remembering my name when she was yelling at me for spending all me free time under the car.
 
LOL.I just had a similar converation with my wife, though I think mine was a little more amicable about it. /ubbthreads/images/graemlins/wink.gif In our case, it's not that I'm working on a vehicle, it's that I'm working on one she doesn't particularly like. She'd rather have me working on a Jeep...
 
By the way, reamers are what you want to use to ream holes in your valve guides. Drills get you close but reamers get you there. They are a bit expensive at first but if you learn to use them correctly (slow speed and lots of cutting oil and a steady hand) they will last a long time and the Spridget doesn't use too many sizes of them.
Bill
 
Provided that the valve guides are correctly fitted, the guides need to be precision reamed for proper stem clearance, say .0025", the valve seats reground concentric & square with the guides, & the valve faces checked for perfect seating in the newly cut seats. Required stem clearance will depend on the specific valve guide material. Special guide liners are sometimes used to improve valve stem lubrication. Knurling the guide inner diameter is no substitute for good liners. The equipment required to do this correctly is quite expensive & I would expect any competent shop to have the equipment & know how to use it. Ask a few questions before selecting a shop.
D
 
Ok, Morris I'm with you now. As many of you know I do this for a living, what your machinist did has been done by a kazillion good machinist before him, is set the valve to guide clearence too tight and when the engine gets some heat in it seizes the valve to guide, normally an exahaust valve, A a-series valve stem diameter is .2793", with bronze maganese guides ( I assume that is what you are using) you need about .0015-.002" clearence to prevent this. I've got a fancy .281" special reamer, but you don't have to have this, you can use a 9/32" drill bit .280" and then a 7mm flex hone to finish, drill and hone them dry, bronze does not like lubricating oil when drilling, reaming or honing. You want the valves to just fall in. So many people have put them up too tight thinking it was the right thing to do but you have to allow for the bronze to expand. As for replacing guides, you can get a guide drift from Goodson Tools and knock them in and out yourself, not much to it. You don't have use guide liners for A-series engine just use the maganese bronze guides to begin with. I shorten them in the heads I do and do some lathe turning on them to make the portion that sticks down into the port less diameter to increase flow in the ports, more important on the intake side than the exhaust but I do both.
 
Back
Top