tjsea
Full Access Member
I wonder if valve float is what broke the rocker arm bolt before.
Valve train questions/issues
- Thread starter laserjock
- Start date
I suppose it's possible. It had done it twice right before that happened. Got the valve cover off. I'm going in as soon as I figure out how to put air in the cylinder. I've got the damper mark almost on zero so the # 1 valves should not drop in. Air is just insurance.
Pulled rockers on #1 and 3.
All 4 pushrods bent slightly.
Tried to pull valve spring but my spring compressor wouldn't fit well enough. I noticed I could see the edge of the spring just barely sticking out from the cap. Stuck the calipers in there. Both intake valves measured 1.8 give or take a few thou. Both exhaust valves were 1.89-1.87 depending on where I measured. Most were closer to 1.89.
Needless to say this is all exceedingly disappointing. Guess I'll call Promar Monday. I have a feeling this is going to end in pulling the motor. My gut says I probably have dents in pistons.
All 4 pushrods bent slightly.
Tried to pull valve spring but my spring compressor wouldn't fit well enough. I noticed I could see the edge of the spring just barely sticking out from the cap. Stuck the calipers in there. Both intake valves measured 1.8 give or take a few thou. Both exhaust valves were 1.89-1.87 depending on where I measured. Most were closer to 1.89.
Needless to say this is all exceedingly disappointing. Guess I'll call Promar Monday. I have a feeling this is going to end in pulling the motor. My gut says I probably have dents in pistons.
As an alternative to pulling the heads could you sneak one of these down the injector and precup bore?
https://www.amazon.com/gp/aw/d/B01I...ore+camera&dpPl=1&dpID=41FOzkgjA+L&ref=plSrch
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https://www.amazon.com/gp/aw/d/B01I...ore+camera&dpPl=1&dpID=41FOzkgjA+L&ref=plSrch
Sent from my SM-G930P using Tapatalk
There is little to no chance of working a scope down injector and then past precup.
Removing intake and going past a valve may be doable.
Again stacking tollerances and adding lift are a quick way to compound the issue of kissing valves and pistons.
These clearances need be full checked and documented prior to firing and running an engine.
These aint yer average SBC or SBF engine....these require extremely accurate reading and math.
Friggen sbc can throw a cat between piston n valve for most part...lmao
Remember pistons chasing valves at 2x valve speed...
Removing intake and going past a valve may be doable.
Again stacking tollerances and adding lift are a quick way to compound the issue of kissing valves and pistons.
These clearances need be full checked and documented prior to firing and running an engine.
These aint yer average SBC or SBF engine....these require extremely accurate reading and math.
Friggen sbc can throw a cat between piston n valve for most part...lmao
Remember pistons chasing valves at 2x valve speed...
I'm just really frustrated. This is one of the few things I paid someone else to worry about. If they weren't going to take the care to check everything with the non-standard parts, they should have turned down the job or charged me a little more to take the time. This is one of the few things I have done very little of and I wanted reliable so I left it to "professionals". I have a feeling I will be well versed in rebuilding these soon enough.
It does suck that your having this problem with a new motor. Winter is coming soon so I guess that would be the time to pull it. As always, interested to see what you find and how you make out.
bbjordan
Snow Monkey
A lot/few of the guys on this forum do their own work because they know the only way to know 100% that it is done right is to do it yourself. There are no excuses. No one else to blame.
It really sucks when you take it to the "professionals", and it turns out substandard. The pro's are doing it for money, and faster they can do it, the more money they can make.
The DIYer is doing it to make sure it is done right. Different metric. And to save a few bucks...but that doesn't usually include paying yourself for the time. I know with all the time I spend on my vehicles, my time works out to be about 5 cents/hr.
That's why I don't work on other peoples vehicles.
The time gets eaten up putting parts together, measuring/testing, pulling them apart, measuring again...repeat. That is why racing engines cost so much. You have to pay pro's for that time.
Oh, and the sense of accomplishment. It's hard to beat that feeling when the engine you've been labouring on sputters/roars to life for the first time. It does wonders for your self worth...or maybe it's just me.
My 6.9cents/hr.
It really sucks when you take it to the "professionals", and it turns out substandard. The pro's are doing it for money, and faster they can do it, the more money they can make.
The DIYer is doing it to make sure it is done right. Different metric. And to save a few bucks...but that doesn't usually include paying yourself for the time. I know with all the time I spend on my vehicles, my time works out to be about 5 cents/hr.
That's why I don't work on other peoples vehicles.The time gets eaten up putting parts together, measuring/testing, pulling them apart, measuring again...repeat. That is why racing engines cost so much. You have to pay pro's for that time.
Oh, and the sense of accomplishment. It's hard to beat that feeling when the engine you've been labouring on sputters/roars to life for the first time. It does wonders for your self worth...or maybe it's just me.
My 6.9cents/hr.
Shame it's turned out this way. You paid for it to be done the right way the first time.
bbjordan
Snow Monkey
Did Promar shim the 910 valve springs? I understand it's common to have them shimmed .030 to reach min. seat pressure.
Maybe in post #16 tjsea is right about the valve float.
It makes sense. The valve floats and there is 0 valve spring pressure on the lifter. The lifter does it's job and takes up the slack. Pretty soon the valve floats into the piston. More like the piston abruptly closes the valve. There is no slack in the system so something has to give...the weakest link. The pushrods. That there is brilliance in engineering. A cheap, easy to access and repair piece is the weakest link! That is one more reason I like this marvel of engineering.
I have a hard time accepting that valve float would happen at such a low speed, but we're not dealing with a stock cam here. Non stock valve springs either. What could go wrong? 
Maybe in post #16 tjsea is right about the valve float.
It makes sense. The valve floats and there is 0 valve spring pressure on the lifter. The lifter does it's job and takes up the slack. Pretty soon the valve floats into the piston. More like the piston abruptly closes the valve. There is no slack in the system so something has to give...the weakest link. The pushrods. That there is brilliance in engineering. A cheap, easy to access and repair piece is the weakest link! That is one more reason I like this marvel of engineering.
I have a hard time accepting that valve float would happen at such a low speed, but we're not dealing with a stock cam here. Non stock valve springs either. What could go wrong?
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bbjordan
Snow Monkey
That's only because it is the wrong metric.
You have put a lot of time into your truck, and your truck is much better for it.
You have had a lot of trials and tribulations with your truck, and you have a right to feel frustrated.
But I must say, I've enjoyed following your build. I was also very pleased that you made it to the Rally and back again. It was a ballsy move deciding to go, but it showed your confidence in your build. I admire and respect that. My hat's off to you sir!
It really sucks that about the only part you didn't do is causing you grief. It will get figured out, and your truck will be awesome & reliable.
Macrobb
Full Access Member
All I can say is that you aren't alone. I spent almost $3K to have a local (reputable) shop rebuild the IDI in my '88.
Even with a stock cam... It wasn't quite right. Found out that one head wasn't recessed enough(by .010 or so) and every valve hit every piston. The other head was recessed properly, and no marks at all.
I only found this out nearly a year later when it started making a chuffing/ticking noise that ended up being the #1 exhaust valve having like 1/8" of play in the guide from being bounced around...
And then, to add insult to injury, after swapping on old(but in spec) heads and getting it running well enough again, a few months later it threw a connecting rod through the block.
Next build I'm doing everything I can myself, and double-checking any work anyone else does(like valve specs).
I also have a Typ4 cam just sitting around, because I haven't been able to make it work yet. I'm pretty sure that it needs above-average recession specs to make it work, something I didn't know about when I tried and failed to get it to run on an older 7.3 that I'd had new valves put in the heads.
Even with a stock cam... It wasn't quite right. Found out that one head wasn't recessed enough(by .010 or so) and every valve hit every piston. The other head was recessed properly, and no marks at all.
I only found this out nearly a year later when it started making a chuffing/ticking noise that ended up being the #1 exhaust valve having like 1/8" of play in the guide from being bounced around...
And then, to add insult to injury, after swapping on old(but in spec) heads and getting it running well enough again, a few months later it threw a connecting rod through the block.
Next build I'm doing everything I can myself, and double-checking any work anyone else does(like valve specs).
I also have a Typ4 cam just sitting around, because I haven't been able to make it work yet. I'm pretty sure that it needs above-average recession specs to make it work, something I didn't know about when I tried and failed to get it to run on an older 7.3 that I'd had new valves put in the heads.
IDIBRONCO
IDIBRONCO
So since I'm going to have my heads done, new valves and guides, and I'd like to run my Typ4 cam in it, would it be a good idea to request more valve recession? If so, how much? I've got a feeling that since we've had a wetter than normal summer here, it will be a wetter than normal winter too. I doubt that the 4x2 1/2 ton with the 2.47 rear end gears will be able to haul around firewood or go through snow drifts like my 4x4 IDI will. I really want this to last.
Macrobb
Full Access Member
I'd talk to typ4 first about it, but I think .030" is what I'm going to be going for.
The seats have plenty of meat on them to recess, and I would make sure that the shop takes only the minimum required off the valves - you want as much meat on those valves as you can, for heat dissipation reasons.
