Greg Weld's 65 Mustang fastback track car

[Stuart Adams]

Green for cash!!

[GregWeld]

It hasn't been 100% determined yet - but it "appears" the Mustang motor has a valve train geometry issue. That would certainly explain why the valve train issues of tips coming off valves and two broken rocker arms.

Given the fact that it's been out of the car and back to the engine builder 3 times (now on it's fourth) for valve related issues/head issues... Needless to say it's not going back there this time.

[Sieg]

So possible contributing factors are?
Rocker arm ratio
Pushrod length
Valve stem length
Valve spring coil bind
Head being surfaced

???

[GregWeld]

Originally Posted by Sieg

So possible contributing factors are?
Rocker arm ratio
Pushrod length
Valve stem length
Valve spring coil bind
Head being surfaced

???

Any of those singly or a combination... it's going to an engine builder to determine the cause and get it corrected. Of course --- ANY really good engine builder is going to do a complete rebuild. And I wouldn't take it to somebody that wouldn't want to go thru it from top to bottom and check everything. That's where these stupid little "mistakes" get expensive. There's no reason for it other than being sloppy with the build.

The heads being surfaced -- and block decking - can create an issue where the manifold starts to not fit. All machining of these surfaces - and which type of rocker used - and the length of the valve - and the spring height - and the retainer choice... and on and on -- all affect the geometry. Its so friggin easy to check that a kindergartner could do it. It's easily corrected with the correct length of valve - or use of lash caps - or the right length push rod etc. But a guy has to check it to know.

[Vince@Meanstreets]

Originally Posted by GregWeld

Any of those singly or a combination... it's going to an engine builder to determine the cause and get it corrected. Of course --- ANY really good engine builder is going to do a complete rebuild. And I wouldn't take it to somebody that wouldn't want to go thru it from top to bottom and check everything. That's where these stupid little "mistakes" get expensive. There's no reason for it other than being sloppy with the build.

The heads being surfaced -- and block decking - can create an issue where the manifold starts to not fit. All machining of these surfaces - and which type of rocker used - and the length of the valve - and the spring height - and the retainer choice... and on and on -- all affect the geometry. Its so friggin easy to check that a kindergartner could do it. It's easily corrected with the correct length of valve - or use of lash caps - or the right length push rod etc. But a guy has to check it to know.

What? You mean that same kindergartener that eats glue, can barely poop in the toilet and cries when mommy drops them off?

You would be surprised what a lot of guys miss. Some hard heads I see always have that "what the F do you know? Ive been running this combo for 30 years". attitude. Attention to detail goes to the waste side when dead lines and stress comes into play.

My machinist is lke a surgeon. He digs and digs till he finds a problem, not say "oh, I don't know why must have been a fluke"
Im not saying he is the best but he works hard and it shows.

[GregWeld]

Originally Posted by Vince@MSperfab

What? You mean that same kindergartener that eats glue, can barely poop in the toilet and cries when mommy drops them off?

You would be surprised what a lot of guys miss. Some hard heads I see always have that "what the F do you know? Ive been running this combo for 30 years". attitude. Attention to detail goes to the waste side when dead lines and stress comes into play.

My machinist is lke a surgeon. He digs and digs till he finds a problem, not say "oh, I don't know why must have been a fluke"
Im not saying he is the best but he works hard and it shows.

Everybody's engine builder is the "BEST".....So far - in 40 years of doing this - I've only ever had one guy build me multiple motors that have never had a single issue. I've had motors built by Dale Green... That motor was a complete and utter disaster. I had a motor built by a famous racing stable out of Tacoma Washington... it lasted about 300 miles... first oil change there was so much metal in the pan it looked like I hit a gold mine.... They managed to forget to install spring seat retainers so the springs ate the shims.... I had a big inch small block built where the guy didn't fly cut the pistons so the much larger valves kissed the "factory" cuts... But NEVER have I had a motor back to a builder 3 times for a similar issue and have it summarily overlooked.

[Stuart Adams]

So green is for cash.

That's a pisser. Are you limited on motor choices, cubes , etc?

[GregWeld]

Originally Posted by Stuart Adams

So green is for cash.

That's a pisser. Are you limited on motor choices, cubes , etc?

No rules.


If this motor isn't hurt real bad - I'll just have it gone thru - straighten out the issue if any and stick it back in. Next time - it gets replaced.

[Track Junky]

Thought it was the fuel pressure regulator?

[GregWeld]

Originally Posted by Track Junky

Thought it was the fuel pressure regulator?

That went first.... and we were able -- should say Ron was able -- to adjust the float levels so I could run (mostly WOT) with the 14 psi of fuel the carb was getting. I'd just go on grid as the last car was leaving so I didn't have to idle... roll out and rip it. Ran fine as long as I was into the throttle.

I was on track when that POS let go.... and I thought maybe that I was low on fuel as that's what it acted like... but the diaphragm had just gone hard and it quit regulating. I'm running an electric pump - so the car needs a FP regulator.

They got the pan off and the intake -- and there's no blued journals or beat up rods... and no big chunks of metal - so at first glance - it appears it's just the valve train issue...