MGB Questions about timing and valve lash on a 74 MGB

[wkilleffer]

Hi everyone,

About a year ago, someone on the forum mentioned that you could simplify your adjustment of the valves by getting each valve into the proper position as directed by a manual, opening the lock nut, turning the screw until it was all the way tight, then back it off 1/2 a turn.

Does that sound familiar to anyone?

I've never been satisfied with my valve adjustments. They always seem too quiet and tight, or too loose and noisy. Anything that could make this easier and closer to foolproof would be great.

Also, I've installed a Flamethrower dizzy and coil into the car, which has an 18GK engine and HS4 carbs. The factory timing spec makes the car seem a bit sluggish. But I don't want to go too advanced and cause pinging or hot running. That I know of, it's not pinged. But it seems to run in the right half of the temp gauge if I have to drive at speeds exceeding 55 mph. The car lacks overdrive as well.

Any advice or suggestions would be appreciated.

Thank you,
-Bill

 

[Nunyas]

erm... I've never heard of the method for adjusting valve that you described. I reckon if you don't have any feeler gages that'll get you into the ball park. I believe the recommended feeler gages are the wire types. I personally use the flat type feelers (looks like a pocket knife with a billion blades), because that's what me old man used and what I learned to use.

When I first got my car I had the same problem as you. I'd either make them too tight or too loose. I've since rebuilt my rocker assy and have a much easier time setting the proper valve lash.

That's about all I can comment on... Hopefully, someone else can pipe in with better information than what I had and possibly help out with your other comments.

 

[wkilleffer]

Re: Questions about timing and valve lash on a 74

Ok, I found my original post from a long time ago, and the advice came from Barney Gaylord. Here it is:

I tried to do a valve clearance adjustment last night, and ended up getting the clearance too loose. Barney Gaylord of mgaguru.com responded to my question on how to do it properly with an interesting, and potentially time-saving idea.

He said that the clearance can be adjusted according to the rule of nine as long as one of the valves in the equation is partially open. Then, to adjust the closed one, loosen the jamb nut, rotate the pushrod and tighten the adjusting screw until the pushrod won't turn anymore, then back the adjusting screw off a quarter turn. He said this gives a very near .015 clearance, then tighten the jamb nut.

His website sounds like this is a rough but serviceable method, but the email he sent was of the tone that this would work very well for an MGB engine.

Has anyone tried this for themselves, and would it work if the engine is still warm? Any advice would be appreciated.
Thank you,

This brings up the question of where to find a wire feeler gauge. I just can't seem to get the knack of using a blade-type feeler gauge properly.

Thank you,
-Bill

 

[Hap Waldrop]

Re: Questions about timing and valve lash on a 74

I use feeler guages and set to the correct lash for a given cam, I din't know there was any other way to do it. Maybe if I was stuck on the side of the road with no feeler gauges I might try that method to get home until I could do it right.

 

[wkilleffer]

Re: Questions about timing and valve lash on a 74

I decided to have a go at making the adjustment with just a feeler gauge. No other fancy tools like the click adjust. The first thing I did was get started according to the rule of nines, then tried the adjustment method of tightening the screw all the way, then opening it up 1/4 turn. This seems to make the adjustment too tight. The Haynes manual says to adjust to .015 cold, and that won't fit. So, I went about it using the feeler gauge on each valve.

Now, they may not be exact, but the engine's much quieter now, sort of like a very quiet sewing machine. I started it with the valve cover off to do the go/no go test. .015 will go in all of them, with some feeling a little tighter than the others.

 

[Scott_Hower]

Re: Questions about timing and valve lash on a 74

This brings up the question of where to find a wire feeler gauge. I just can't seem to get the knack of using a blade-type feeler gauge properly.

Bill,

$30 from the Snap-On truck. I've had mine for years; it's BluePoint, so not technically mfgd by Snap-On, but good quality.

 

[jlaird]

Re: Questions about timing and valve lash on a 74

Now that's an nece looking feeler guage set.

Yep engine should sound like a sewing machine if valves are adjusted correctly.

 

[Ed Kaler]

Re: Questions about timing and valve lash on a 74

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif with Jack.

Another "rule" is if you CAN'T hear them, they are TOO tight. If "noisy", too loose!

Almost as old as our cars!! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif
/bcforum/images/%%GRAEMLIN_URL%%/cheers.gif
Ed

 

[wkilleffer]

Re: Questions about timing and valve lash on a 74

Trouble is that it still sounds like one or two of them might be too loose. This is going to drive me up the wall, but it needs to be right.

The extra noise was what prompted me to do this again. At least two of them were way too loose. Using a straight rather than angled feeler blade is alot easier than using an angled one.

Time to track down a 1 5/8" wrench to turn the crankshaft to make the job easier.

 

[DrEntropy]

Re: Questions about timing and valve lash on a 74

Stuff a 0.011" feeler (a sacrifice one) in the gap as it's running: If the "clatter" clears up you found the offending valve(s). Reset and press on!

 

[jlaird]

Re: Questions about timing and valve lash on a 74

Do not go above idle with the cover off or you'll be sorry, hehe.

 

[Tom_Fisher]

Re: Questions about timing and valve lash on a 74

Here's the way I use the rule of nine.

Put tranny in neutral and with your trusty 1 5/16th socket, turn the crank clockwise til the TDC mark is at the bottom.
Now, with the valve cover off, look at the valves. You will see one of four possibilities: 6 & 8 will be open (valve springs depressed), 2 & 5 will be open, 3 & 1 will be open, or 7 & 4 will be open. If it's 6 & 8, adjust 3 & 1 (see the rule of nine!), if it's 2 & 5, adjust 7 &4, if it's 3 & 1, adjust 6 & 8, and if it's 7 &4, adjust 2 &5. Then, get under the front and turn the crankshart 180°.
Now you'll see two more valves open. Do this two more times and you'll have adjusted your valves with two complete revolutions of the crank (or one stroke cycle).

Here's a simple little chart to use for reference:

6 - 8
2 - 5
3 - 1
7 - 4

In every other row, the numbers always add up to nine!

 

[Bruce74B]

Re: Questions about timing and valve lash on a 74

Mr. Fisher (or is it Professor?), that is the BEST concise explaination of the process I have ever seen...great job...love this forum!

Bruce

 

[Tom_Fisher]

Re: Questions about timing and valve lash on a 74

Mr. Fisher (or is it Professor?), that is the BEST concise explaination of the process I have ever seen...great job...love this forum!
Bruce

Hi, Bruce:

No - I'm not a professor. Just an office mgr. on the A/P staff at Purdue. Thanks for the kudos. However, the info I passed on was simply something I've picked up on some MG group, someplace.

You're right - these forums are the berries!