I just want to post this so that others don't follow in my footsteps. When I first had this head built, I had limited experience with machine shops. It is extremely important to find a shop well versed in performance mods if you're going that route.

I had Isky springs installed, but those springs require an Isky hole saw to bore the head slightly where the spring sits so one gets the required spring installed height. My machine guy did not do that. What saved me was the installation of sbc valves which were .095" longer than oem ford valves. With the sbc valves, however, my seat psi was about 150 psi. I did not catch it until a year later, after reading like crazy about these engines.

By the time I found it, and removed the inside Isky spring, giving me a seat psi of 120, the damage had already been done. I had to replace two of the screw in r. studs because the top 1/2" had sheared off. I replaced all the studs with ARP.

But so much stress for so long must of damaged the keepers or retainers, or the end of the valve. It is hard to tell before I pull the rocker. Today I sucked a valve, so I'm piecing together the cause in my mind before I pull the head. When you get into machine work, it is best to be as knowledgeable as possible, and to find a shop experienced with the type of mods or oem that you are planning.

Good luck. Shizer!

 

Holy Crap!!!! is that a crack in the head, or just flash from the camera? I think I would put the piston on tdc, put 60 lbs of air in through the spark plug hole, pull the valve up with your fingers, the air will make it stay there, use the tool to smash down the valve spring, and install 2 new retainers... for now, while you build another head. I have a spare efi head here if you need it

 

I don't see any cracks so it must of been flash in an oil line. I can't find one half of the keeper. It must of gone through the oil return hole. The valve seems good, although only the collar of the v.seal remains. The spring and retainer look undamaged. The bottom of the rocker is a bit scrapped up, and there is noticeable scratch or impression on the roller itself. It must of really whacked the valve.

I also notice that the valve seems snug in its guide until I lower it about 1", and then I can feel it wobble just slightly.

So, I'm thinking to replace the v.seal and keepers, change the rocker to one of my four spares, ck the compression in that cylinder, and if all is good, give it a whirl. If there is low or no compression, I'll pull the head. Is it possible there was no damage? What do you guys think?

 

the spring letting go would whack the r-arm, so not to worry there, like you said, you have a spare. The retainer is in the oil pan, and will eventually make it to your magnetic drain plug. I would put it back together like it sits. Valve may be bent, but you won't know that till you put it back together. Keep in the back of your mind, you really need to replace all of the keepers, as that one is the 1st to let go. There is a tool that you set on top of the valve spring to remove the keepers, and change them, I have used it to replace valve seals before. Do not raise the air pressure above 60 lbs though, you can blow things apart

 

Yeah, I've used the type that you bolt to r.stud, and just pull it down on the v. But #6 I need the screw/clamp type b/c of firewall.

So if the valve is bent, it will just run bad? Letting compression out?

At this point, knowing what stress those keepers have been under, and the v. where the keepers sit, do you think it would be wise to replace the valves too? Or is that over the top?

 

valves will be fine, look at them real well tho. The keepers usually always fail on being used a second tome, so you are probably lucky they lasted this long, remember, you not only have exerted maximum pressure, the valves are longer than usual too, so there is even more pressure that you figured.


If the valve is bent, it will miss, and you will have low/no compression. I doubt that it's bent, but with you and a - bronc's luck, who knows. I know I won't go to vegas with you guys............ hahahaha

 

the valves are longer than usual too, so there is even more pressure that you figured.

Unless I am grossly mistaken, because the valve is longer, the spring is NOT compressed as much to fit the valve. I am over recommended intalled height. If the valves had been shorter--and we're only talking .095" (less than 1/8")--the psi at the seat would have been greater, not less.

Yep, dusty, AB and I are unlucky at cars, but the women just throw themselves at us!! Back me up here, AB.
And, if there isn't damage to the valve or bore or piston, then I'm the luckiest dog around.

 

Wow. I hope you got lucky and didn't bend the valve. If the valve is bent, you know what bent it, right? Yup, the piston. That *can* be really bad..........

 

Yep, I know. I well remember how it died when I tried to start it after pulling over. It was the sound of zero compression. But I don't want to go there. I want to have a healthy piston and block. I'll know tomorrow when I try to pressurize the cylinder to hold the v. up while I change the keepers, and the v. seal.

RW, thanks for clarifying about the Edelbrock. I'll take care of that too. I can't stress enough what a tremendous diff. there was just by changing the spring. It makes me wonder if my secondaries were opening at all. I wonder if what I thought was the secondaries opening was just the needle moving to the power mode.

Cheers. K.

 

NP K, they can be a bit confusing to the newcomers, since the float bowls feed one side of the carb both primary and secondary, where the old autolite 4100 and holley carbs have a float bowl that feeds either the primaries or secondaries.
I bet what you thought was the secondaries "kicking in" was in fact the carb either leaning out enough, or richening up enough, for the engine to make good power.
When a 4bbl is properly tuned, you shouldn't notice any change as the secondaries start to come online. It should just be a smooth transition from idle to high RPM, with the power increasing at a fairly steady rate all the way.
My rotary is slightly different, due to the fact that the intake has primary and secondary runners, as well as the engine having primary/secondary ports that are timed differently. It's like it has a stock cam/valves for the primaries to run off, and a massively radical cam and huge valves for the secondaries. Of course, rotaries don't use cams or valves, they use port timing (like a 2 stroke) to perform the same function. That is why I can feel a major kick in the seat of the pants as the secondaries come online. The engine literally changed from a mild mannered "stock" engine, to a radical "race" engine, just because the carb opened the secondaries. No cam or valves are utilized though, so the carb handles the entire transition.

Anyways, here's hoping you suffered nothing more than valve keeper failure. BTW, I agree about changing all of the keepers. 1 pair failed, so the rest are just waiting for their chance to do the same. Next time, you may not be quite so lucky. The valve could fall completely into the cyl, and get shoved thru the head, block, or piston, or worse, a combination of any/all of them........

 

I need a bit of advice. Right now, assuming there is no damage to my bore or piston, I'm going to install new comp keepers. I'm wondering if I should pull all the valves and install the oem ford length ones.

My valves are .095" longer than oem. They are sbc valves. But the Isky springs I have require boring the v.spring seat with a hole saw to get the Isky installed height. My head was not bored. So even with longer valves, I am just slightly shorter installed height. No bind. I have 120 psi seat pressure.

I'm thinking it should be fine like that. Or should I get oem length and change the springs to ones that don't need to be drilled? What do you guys think?

 

I would just go with it like it is.If you decide to pull the head, then make the changes.

 

I did a compression test: thumb over hole and turned it over w. remote switch. Great compression. So I swapped out all the keepers with Comp Cams ones to fit. They were so inexpensive I was worried. $10 for a set. I also checked installed height, and it was very close to the 1.750" that Isky wants for the springs. Then I put back on my oem rockers. I just feel safer with the Ford 1.6 ratio. With my oversize valves I don't need that added lift. Hopefully I'll see a diff at the pump...if I can keep my foot out of it.

I'm a bit scared to get on it again.

It started on first crank. It sounds quiet and smooth, no smoke, no miss. I must be pretty lucky to suck a valve at freeway speed and not have damage. I'm very happy, and itching to stomp on it again!

 

Of course I think of this after it's all together: I should have closely examined the top edge of the groove the keeper sits in. I wonder if that has taken a beating and has worn, thus allowing the keeper to escape.

 

the valves very seldom wear, you will be fine. look at the keeper, and they are kind of designed that failure is in the future. Mopor hyper pack has 2 groves to avoid that problem.

I'm glad it worked out, you should be fine to continue to drive as you normally do