bbjordan
Snow Monkey
Yes. I was lucky, it was still within spec.
6.9 Blowby...Rebuild or new rings?
- Thread starter Rusgo
- Start date
Yes. I was lucky, it was still within spec.
IDIBRONCO
IDIBRONCO
When I did the overhaul on my 7.3 last year, it had about 120,000-130,000 on a "rebuild" (machinist removed too much from my heads. I had to install some decomp pistons to keep the valves from hitting the pistons). I was going to install my Typ4 cam so I bought some Comp 910 valve springs and had the "machinist" install them. After I git the engine running, it had a bad miss on one cylinder. The intake valve wasn't opening on that cylinder so I had to put new lifters in it. Now it has no issues. I didn't put new lifters in at first since I assumed that they had been replaced before. I have no idea how many miles they actually had on them. My opinion now is that if you're going to be inside the engine, especially if you plan to install stiffer valve springs, then go ahead and replace the lifters. The springs inside them will eventually get weak as they are worked.
Got my heads back from the machine shop today. There were some minor surface irregularities pre machine work, so I told them to take the minimum amount off the surface. They ended up taking 10 thousandths off. Wasn't super happy about it.
I measured the deck to deck height and got 3.790". Spec is 3.795" to 3.805". Not bad. I might shave the pistons by .010" too. Especially with a typ4 cam. They did the valve job too, and that removed material from the valve and valve seat, bringing the valve up, so I thinks it's fine.
This shop has dealt with indirect injected diesel before, and they deal with precup by taking them out, and reeming out the same thickness of material as removed from the head surface. I like the approach, but it was not perfect. In spots the precup are sticking out by 3 to 4 thousandths. Spec is .0025 plus or minus. They also dont seem super even. Like on one side they flush or low, and on the other side they're high. It's very minor, but...
Not sure what to do. Take it back and tell them to fix the pre cups or take it to another shop?!
I've heard of a stone mill process that can mill both materials at one. Really want a good seal on this.
Sent from my SM-G975U using Tapatalk
I measured the deck to deck height and got 3.790". Spec is 3.795" to 3.805". Not bad. I might shave the pistons by .010" too. Especially with a typ4 cam. They did the valve job too, and that removed material from the valve and valve seat, bringing the valve up, so I thinks it's fine.
This shop has dealt with indirect injected diesel before, and they deal with precup by taking them out, and reeming out the same thickness of material as removed from the head surface. I like the approach, but it was not perfect. In spots the precup are sticking out by 3 to 4 thousandths. Spec is .0025 plus or minus. They also dont seem super even. Like on one side they flush or low, and on the other side they're high. It's very minor, but...
Not sure what to do. Take it back and tell them to fix the pre cups or take it to another shop?!
I've heard of a stone mill process that can mill both materials at one. Really want a good seal on this.
You must be registered for see images attach
You must be registered for see images attach
Sent from my SM-G975U using Tapatalk
Last edited:
IDIBRONCO
IDIBRONCO
I'd say, not good. You do realize that the heads are now .005" UNDER the minimum thickness? How's your valve recession? That has to be in spec too. This is why I had to install decomp pistons myself. The "machininst" that I took my heads to took .010" off of one and .012 off of the other head. The difference between the maximum and minimum heights is the .010" that was removed. I'd recommend the decomp pistons. Before you install a Typ4 cam, check the valve to piston clearances too. You may not have enough clearance to run Russ's cam. In fact, be sure to check the valve to piston clearance if you're installing a stock cam too. As for your question at the end, if you take the heads to another machinist, you'll have to pay for the work again. On the other hand, the machinist that worked on your heads and "has dealt with IDIs before" has already caused you headaches by not finishing your heads within the specs. Your call. Just a FYI, if you do check your valve to piston clearances (and you really should) Fel-Pro head gaskets are .010" thicker than Victor-Reinz head gaskets. This is both compressed and uncompressed. It may make a difference in final engine assembly.
Not too worried about deck to deck spec just because there are ways around it. Any resurface has the potential to put you out of spec, which is why international says dont do it. But people do it all the time. Any rebuilt IDI is probably out of spec there. Any rebuilt head is out of spec there.
But yeah, would rather it be perfect. Between a valve job, piston shaving, your thicker head gasket, there is more than enough wiggle room. Definitely going to check clearances as it goes together.
Dont think I have the gear to check valve recession. Figure it was an untouched head and it's had a valve job. Pretty standard stuff. Risk of being too recessed?
Sent from my SM-G975U using Tapatalk
But yeah, would rather it be perfect. Between a valve job, piston shaving, your thicker head gasket, there is more than enough wiggle room. Definitely going to check clearances as it goes together.
Dont think I have the gear to check valve recession. Figure it was an untouched head and it's had a valve job. Pretty standard stuff. Risk of being too recessed?
Sent from my SM-G975U using Tapatalk
DrCharles
Full Access Member
Too recessed won't cause pistons to hit valves. I recommend you not assume anything.
Check that valve-to-deck spec. You need a depth gauge or mic.
Check that valve-to-deck spec. You need a depth gauge or mic.
IDIBRONCO
IDIBRONCO
Or worse, not recessed enough.
I'm always surprised when machinists take bigger cuts than necessary. Its my experience that when folks have some mechanical/machining/measuring background they usually communicate what they want pretty clearly. Your pics show pretty clearly that you are looking/paying for quality machine work. Ten thousandths is more than I would call "minimum to clean up deck imprefections". I sympathize with your disappointment in their overzealous decking, and I would point out to the shop that did the work that in addition to taking off too much on the heads, the precups are not the right depth and questionable in flatness. If they didn't know the specs and agree to correct the precups, I'd ask them to make it right. If they gave me more than a sentence of why it doesn't matter, I'd take them someplace else. Machine work is generally expensive and you should always get what you pay for.
IDIBRONCO
IDIBRONCO
This is why I write "machinist" instead of machinist. One knows what he/she is doing while the other just thinks it.
Valve recession specs
Intake: .042-.054
Exhaust: .051-.063
My exhaust are all around .051- .054
My intake are all around .052 to .058
Unexpected that the intake specs are high after removing the surface material.
Seems the valve job did pull the valves up a good amount. Will remove some piston height to bring it back to stock compression at least.
Or have the shop recess the exhaust valves a bit more, use the thicker gasket, and call it a day.
Sent from my SM-G975U using Tapatalk
Intake: .042-.054
Exhaust: .051-.063
My exhaust are all around .051- .054
My intake are all around .052 to .058
Unexpected that the intake specs are high after removing the surface material.
Seems the valve job did pull the valves up a good amount. Will remove some piston height to bring it back to stock compression at least.
Or have the shop recess the exhaust valves a bit more, use the thicker gasket, and call it a day.
Sent from my SM-G975U using Tapatalk
Last edited:
I have a set of mahle gaskets laying around. Any info on those compared to the thickness of felpros?
They measure out at .090
Edit: reading from multiple places that that felpro's are around .075. Interesting...
Edit#2: These "Mahle" gaskets have "felpro" stamped into the part.
Sent from my SM-G975U using Tapatalk
Last edited:
Got the heads back today. No questions asked they took them back and refined things a bit. Turned out great.
Maybe a new guy was on them before!
New specs:
All precups are within .001 of the deck.
Intake valves are all recessed around .053
Exhaust valves are all recessed around .058
Pretty happy with that.
With the the thicker head gasket, typ4 cam will be no problem and compression will be at stock levels.
Unless there is a good reason to lower compression down a touch, gonna leave the pistons alone.
$500 for the rebuild and $100 to pull the cores from picknpull. Not bad for a new top end.
Sent from my SM-G975U using Tapatalk
Maybe a new guy was on them before!
New specs:
All precups are within .001 of the deck.
Intake valves are all recessed around .053
Exhaust valves are all recessed around .058
Pretty happy with that.
With the the thicker head gasket, typ4 cam will be no problem and compression will be at stock levels.
Unless there is a good reason to lower compression down a touch, gonna leave the pistons alone.
$500 for the rebuild and $100 to pull the cores from picknpull. Not bad for a new top end.
Sent from my SM-G975U using Tapatalk
Last edited:
Similar threads
