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How can I tell if I have a stock head or non jet valve head.


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#1 Hightops76

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Posted 25 August 2019 - 06:19 PM

I just pulled my head off because it started sputtering and missing. I noticed I ran a straightedge and a feeler gauge in between cylinders 2 and 3 and there was a 0.004 space in between there is that bad. I didn't notice the head gasket blown out anywheres. But I'm glad I pulled the head anyway to get that fixed or replaced not sure if it can be fixed. I also did a compression test on it before I pulled it and it was 110 on the outer plugs and 95 on the center to.





#2 Hightops76

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Posted 25 August 2019 - 06:27 PM

I was inspecting the exhaust manifold and notice the stud on the bottom by the firewall the stud hole was broke right off the corner of the head still attached to the stud was leaking exhaust gas. Can that be repaired

#3 croquest87

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Posted 25 August 2019 - 06:38 PM

OEM head has jet valves .If you look inside head chamber  you will see 2 valves a sparkplug and  jet valve protruding out by the intake valve.  Non jet doesn't have that obviously. There is a jet valve elimination kit that you can buy but new  non jet head is best way to go.
Known to crack cyl head right across the e seat  due to metal bushing/sleave pressed in to close to  valve area (gets hot).  I wouldn't waste my time w it if that's what it is.  Just buy new head from Engine Machine Service in Niles OH.Inspect all your parts from old head and swap it over w fresh valve job.

Edited by croquest87, 05 September 2019 - 01:19 PM.


#4 Hightops76

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Posted 25 August 2019 - 08:33 PM

Ok thx I see the jet valve now. Will junk the head. Next question I have is swapping my old parts onto new head. Wouldn't tbey be woreout and tired. Spings valves cam etc. just need to make sure.  Thx

#5 Hightops76

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Posted 25 August 2019 - 08:43 PM

Ive been looking around at heads. I see hydraulic lifters and mechanical. Is one better then the other.  What is in our cars.

#6 87redcat

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Posted 25 August 2019 - 09:15 PM

If your not too mechanically inclined then hydraulic lifters is a your best bet.
If your not sure about the parts, Engine Machine Service can build the head for you. Randy, goes by "Dad" on here is the one to talk to. Great guy and will take care of you.
I got blisters on my fingers!!!

#7 tux

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Posted 26 August 2019 - 10:02 AM

i wouldn't junk the head.

#8 TroyStarion

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Posted 04 September 2019 - 07:57 PM

Are there actually jet valves or have they been eliminated yet? If you look at the intake rocker arms you should see a protrusion with a hole, that's where the jet valves go. You should clearly see if they're there or not. If they are, just get an elimination kit. If they aren't, go through the basics, ign. system, fuel pump, etc.
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#9 mikec

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Posted 05 September 2019 - 12:35 PM

Early model StarQuests came with "mechanical" heads - these had screw & jam nut style valve lash adjustment mechanisms that needed attention periodically.  Later years came with the auto-lash adjuster "pill" shaped inserts in the ends of the rocker arms.  These use oil pressure to expand them until there is no lash.

Both work.  The mechanical setup needs periodic adjustments/attention.  Some folks feel they are better for sustained high-RPM operation as the auto-lash pills can have the oil squeezed out by the valve springs if there isn't sufficient time for the oil pressure in the rocker arm to re-fill the adjusters.  For normal street driving (even with a heavy right foot) the auto-lash setup is more than sufficient.  I did a couple hours at Willow Springs many years ago and had no issues with my 88's auto-lash setup.

Jet valves: remnants from when the 2.6 engine had a carburetor.  Many ChryCo cars and Mitsus used the 2.6 engine this way, they generally had "MCA-Jet" stickers on the car or on the top of the engine.  MCA-Jet was the jet valves.  They are small valves next to the intake valves and opened by the same rocker arm as the intake valve (there is a round "ear" sticking sideways from the rocker end to do this).  Inside the cyl head, where you'd expect to see valve head itself, you'd instead find a steel cylinder-shaped plug.  The jet valve feeds this plug that has a 90 degree passage in it; that 90 turn shoots the jet valve air along the edge of the cylinder to promote additional "swirl."  Swirl helps air+fuel stay mixed for a cleaner and better burn, especially in the carb days since carbs often didn't mix the air and fuel perfectly.  Swirl also helps get the air+fuel mix more evenly distributed inside the cylinder... again for a cleaner and better (i.e. more powerful) burn.  Throttle body fuel injection mixes better than carbs so the jet valves are not as essential on StarQuests.  Modern port fuel injection is better yet - spraying the fuel directly at the intake valve - so it goes right into the cylinder and doesn't have a chance to "un-mix" while traveling through the intake manifold.

Since you have the head off the car, look at the side where the intake manifold attaches.  You'll see a narrow channel running around the intake openings... that is the air channel feeding the jet valves.

As for the busted exhaust manifold stud: any decent machine shop can repair that.  The cause: look at the exhaust manifold - notice how the 4 runners end in one beefy plate that bolts to the head?  As the exhaust manifold heats up, thermal expansion makes the metal want to move.  Some runners are longer than others though so they'll expand even more.  That beefy plate limits them however forcing the whole manifold to bend; that bending in the beefy plate is what rips apart the stud.  Limiting the movement means something else "has to give" because the metal IS going to expand... typical result is cracks in the #1 and especially #4 exhaust manifold tubes.  If your manifold doesn't have any cracks - great - you are lucky.  To fix the issue: cut the "webbing" between the 4 ports in that beefy plate.  Make about a 1//8th gap between the ports.  That allows the ends of the tubes to move left/right with thermal expansion.  You'll see the bolt holes are bigger than the studs - there is already allowance for some motion.  Once the webbing is cut it is likely the face of the manifold (where it attaches to the head) will move a bit and will no longer be consistent across the 4 openings.  A machine shop will have to re-machine this area flat.  No big deal.  Just be careful when making the cuts as the manifold probably has a lot of internal stress in it right now - when you are 99% through a cut don't be surprised if the metal moves and grabs your cutting blade!

mike c.

#10 Hightops76

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Posted 05 September 2019 - 08:13 PM

Thx alot. this is a great place to learn all about these awsome cars.

#11 Hightops76

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Posted 12 September 2019 - 09:10 PM

have a question, I got a new head, gaskets, and ready to install it, but when I removed the old head I took the cam spocket off the chain, didnt think it would come off and go past the head and set chain on the ledge. now I see I shouldnt have taken it off, because I dont have enough slack in chain to put cam back  on it.. I hope there is a easy solution here.

#12 croquest87

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Posted 12 September 2019 - 09:29 PM

I am sure it can be done. Dont drop anything in that timing cover or it has to come off. Personally if l was that far into it. I would put in new timing kit.Timing guides if original are most likely disintegrated and worn out from age. Balance shafts would also be removed and BSEK installed to simplify things.But that's just me.

#13 Hightops76

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Posted 13 September 2019 - 05:02 AM

there r no slack adjusters rt. car is in grt shape, so I hope I dont have to take anything more off. really need to put back together before I forget things. old age and memory loss, lol.

#14 croquest87

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Posted 13 September 2019 - 06:31 AM

https://www.google.c...568460642289170

Here is some good info for you also complete schematic couple of posts down so you can get better picture .Notice that timing chain tension is from oil pump plunger w  small guide pushes against the chain during operation. There is a mechanical adjuster for balance shaft chain(completely separate).

Edited by croquest87, 13 September 2019 - 06:45 AM.


#15 Hightops76

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Posted 13 September 2019 - 09:58 AM

So no way to get the cam gear back on chain without removing the timing cover.

#16 croquest87

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Posted 13 September 2019 - 12:48 PM

View PostHightops76, on 13 September 2019 - 09:58 AM, said:

So no way to get the cam gear back on chain without removing the timing cover.
That would be my guess  It can be a big pain to push that plunger pack in w chain alone w cover on and all. Perhaps one of the other members on here could give you some input on how to do it without removing anything? Knowing myself that cover is coming off.

Edited by croquest87, 13 September 2019 - 12:50 PM.


#17 Hightops76

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Posted 22 September 2019 - 07:57 AM

almost back together now. doing the timing, is there a grove or notch in the bottom pully? havnt seen one. anyone have a pic of it.

#18 croquest87

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Posted 22 September 2019 - 10:52 AM

Yes  there is . Clean it up real good  so you can see it while setting your timing w timing light. Also clean your cover good so you can see your timing there also.

Edited by croquest87, 22 September 2019 - 10:53 AM.


#19 Hightops76

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Posted 22 September 2019 - 03:23 PM

I saw a nick on inside pully but nothing that jumps out at me

#20 Hightops76

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Posted 22 September 2019 - 08:08 PM

No grove on pully that I can see.  anyone have a picture of it.  Maybe that will ease my mind.




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