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Mike Fowke · 01-03-2018, 02:21 PM

#1 is 130. All others are 160-170, I found it chasing a bad, inconsistent idle, Could this be my idle problem? Before I yank the head is there anything else I can do?

Backstory: These are Kauffman 300 cfm heads I bought complete about a year ago. Each head has already lost compression in one cylinder and been back to Kauffman, #6 had a "funky" intake valve. Then I lost compression on #3. They weren't sure why, but retouched all of the seats.

Pistons are .014 out of the hole. .051 Cometic head gasket. ARP bolts at 95 lbs.

steve25 · 01-03-2018, 02:43 PM

If one of your valves in 1 is leaking compression then yes it can make for your idle issue especially if it's a Intake valve!

It seem like your not the only one to have issues like this with those brand heads!

694.1 · 01-03-2018, 02:52 PM

Wouldn't be those crappy seat inserts??

steve25 · 01-03-2018, 04:46 PM

Could be, it can also be that the seats that are being used do no have enough wall thickness left once a valve job is applied to hold there shape due to heat and the pounding they take from the valves .

Mike Fowke · 01-03-2018, 05:06 PM

I guess I'll pull the heads, again. I know a local machine shop that should be able to figure out what is wrong. Does Kauffman have a history of seat problems, or am I just unlucky?

STEELCITYFIREBIRD · 01-03-2018, 06:48 PM

I'd check valve adjustment and rocker arms for any problem before pulling heads. (PRW arms if I remember correctly)
Myself I would air check and/or leakdown test the cylinder to verify a valve sealing problem before removing heads. Also a wet compression test firstly.
Compression tests can be misleading, depending on the amount of lifter bleed down, if hydraulic lifter equipped.

Repeat failure would seem to indicate the cause was not remedied in previous repair.

Schurkey · 01-04-2018, 02:43 AM

Quote:

Originally Posted by STEELCITYFIREBIRD

I would air check and/or leakdown test the cylinder

Winner.

Might as well know WHICH valve (or both...) are leaking--or--know that it's a ring-seal problem. (If there's no air in the coolant, and no air out the valves...it's ring seal)

694.1 · 01-04-2018, 11:06 AM

"Does Kauffman have a history of seat problems, or am I just unlucky? "
My guess is that the seats are sintered or "powdered metal". I saw a pair with multiple fractures in the seats, at least the seats that remained and had not gone out the tail pipe. Now of course this can happen in a race engine.
After the fresh heads came back with new seats from Kauffman, upon inspection, at least one was cracked.
In my experience, the answer to your question would appear to be "both".

Blued and Painted · 01-04-2018, 11:25 AM

Add a table spoon of oil to cylinder and recheck compression to rule out a stuck or broken ring.
Make every effort to diagnose before tare down.

Re torque all the head bolts checking for any inconsistency.

Normaly a cylinder will continue to fire down to about 85 psi in a stock near application.
Being the highest to lowest cylinder difference is just over 10%, the drivability complaint can still be ignition or induction. JMO?

Mike Fowke · 01-04-2018, 01:47 PM

Thanks for the advice. I got up early this morning and pulled the head before I checked back in here. So, I'm off to the machine shop. Given the history of these heads, I just felt like they are the problem. A leak down test would have been a good idea, but this is the third different cylinder to go out or down. The last time I did a compression test, this one was fine.

I've never heard of a wet compression test. I'll research that one.

I've been through the induction system and feel like it's good to go. I've had two q-jets on this thing with very similar calibrations, and the idle was bad on both.

Thanks again. I'll report back when I know (or don't know) something.

track73 · 01-04-2018, 02:33 PM

"I've never heard of a wet compression test. I'll research that one."

Another reason to put vocational/industrial education back into to general education.

Mike Fowke · 01-04-2018, 03:54 PM

Just back from the machine shop. While I was there the machinist pulled a vacuum on both tracks. The intake is leaking.

gtospieg · 01-04-2018, 04:19 PM

Mike...a "wet" compression test simply helps to seal the rings helping to pinpoint whether it is a ring/cylinder issue or a valve/seat/head issue...if the # comes up it's probably the rings....sounds like you found your problem.

gtofreek · 01-05-2018, 01:48 AM

I agree those heads have powdered metal seats in them. Those seats are hard to cut concentric without carbide pilots which most shops do not have. I always pull the exhaust seats out of those heads and install a larger seat so it interlocks with the intake seats. This eliminates the thin sliver of aluminum left between the seats that eventually burns out, leaving a gap. I use a seat with a 1.812" O.D. x 1.437" I.D. x .375 deep, then cut the seat pocket just until the bottom cleans up[which is about .330" deep or so], then I install the seat, and trim it down until flush with the chamber floor. IIRC, the SBI J-Loy seat number is SB1812-17. By using this seat, you can also open the exhaust up to 1.77" if you ever decide to. The seat that comes installed in those heads is 1.75" O.D.

steve25 · 01-05-2018, 07:13 AM

To those of you who want to avoid this in a easy way and are shopping for head just by the Edelbrocks!!!!!

PAUL K · 01-05-2018, 08:43 AM

Quote:

Originally Posted by steve25

To those of you who want to avoid this in a easy way and are shopping for head just by the Edelbrocks!!!!!

Great advice!

STEELCITYFIREBIRD · 01-05-2018, 06:17 PM

Great info Paul,
This is the kind of info and professional opinion that only the guys out in the trenches, daily, can,...and fortunately you do, provide and share.
Thanks!

gtofreek · 01-06-2018, 12:52 AM

Quote:

Originally Posted by STEELCITYFIREBIRD

Great info Paul,
This is the kind of info and professional opinion that only the guys out in the trenches, daily, can,...and fortunately you do, provide and share.
Thanks!

Mike Fowke · 01-06-2018, 11:05 AM

"Mike...a "wet" compression test simply helps to seal the rings helping to pinpoint whether it is a ring/cylinder issue or a valve/seat/head issue...if the # comes up it's probably the rings....sounds like you found your problem."

Thanks. That makes sense.

"Great info Paul,
This is the kind of info and professional opinion that only the guys out in the trenches, daily, can,...and fortunately you do, provide and share.
Thanks!"

Ditto. I'll share this with the machine shop.

Ben M. · 01-06-2018, 11:11 AM

Quote:

Originally Posted by STEELCITYFIREBIRD

This is the kind of info and professional opinion that only the guys out in the trenches, daily, can,...and fortunately you do, provide and share.

I'd also add that any company I buy a product from that tells me "we don't know why" on a failure is cause for skepticism and frustration. Good to hear someone actually with experience speaking out on the real reason!

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