Author Topic: Cracks in intake valve seats at sparkplug boss?  (Read 2165 times)

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Joe-JDC

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Cracks in intake valve seats at sparkplug boss?
« on: October 03, 2020, 10:00:47 PM »
Finally getting around to another project engine I bought several years ago from a supposed reputable builder that has name recognition and a huge business dealing with FE's.  I bought a numbers matching '69 428 CJ that was bored +.015", and supposed to be ready to dyno test.  Since I had some time on my hands, I decided to break down the heads and check to see if there was any work done in the bowl area, and guides, etc., thinking that I may go ahead and port the heads and intake manifold for this project vehicle.  What I found are three cracks in the intake valve seats in one head, no valve job on some of the exhaust seats, and no guide work, umbrella seals, and one port was so rotten from water damage that I am afraid the rust has eaten all the way through to the water passages.  This engine was supposedly ready to put oil in, and start up.  My question is can the intake seats be salvaged where the cracks are located, or will I need to have intake seats installed?  The exhaust seats are hardened, but no valve job.  I am reluctant to install both intake and exhaust valve seats in the same head with all the seats replaced.  Has anyone had good results with fixing this kind of a problem, and if so, what was the fix?  Joe-JDC
Joe-JDC '70GT-500

Barry_R

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #1 on: October 04, 2020, 06:16:41 PM »
Don't think we've ever dealt with a CJ with that issue.  But I have seen a few tunnel port heads with cracks in the seat to the spark plug opening.

I asked a couple folks that had a lot of history with these - and they said it was a fairly common issue with those castings.  Recommendation was to just do a valve job & run it.
Went against everything in my nature, but it looked like installing intake seats would be a real challenge and there would be no functional press fit because of the crack.  I did that and as far as I know they are all still running anfter successful dyno sessions.

turbohunter

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #2 on: October 04, 2020, 06:38:20 PM »
I got scared with my CJ heads by the lack of bedding material in the casting in certain spots. Yikes.
My machinist didn’t want to press in new seats it was so thin.
Marc
'61 F100 292Y
'66 Mustang Injected 428
'66 Q code Country Squire wagon


ntheogen

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #3 on: October 04, 2020, 06:52:42 PM »
I've seen lots of hi riser and TP heads with those cracks and guys who know way more than I ever will said the same, run em...

Joe-JDC

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #4 on: October 04, 2020, 08:34:51 PM »
Thanks for the replies.  I have heard the same response in the past, but this valve job is so unorthodox that I am a bit perplexed.  I am definitely going to get the head pressure tested before I attempt to install the valvetrain back in it.  One crack extends down about .300".  That one scares me.  Joe-JDC
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Tommy-T

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #5 on: October 05, 2020, 11:41:43 AM »
I ran some very used up Hi Riser heads on my Mustang in the early '80's. They were milled to hardly any thumbnail at all and had cracks  through the intake seats to the spark plug holes on 4 cylinders.
I ran them on the street for a few years on a 454 incher. Had no problems with them except for trying to get an unmilled Hi Riser intake to bolt down and play nice.

I also have a C0AE-D head with a crack across the intake seat.
« Last Edit: October 05, 2020, 11:44:28 AM by Tommy-T »

Joe-JDC

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #6 on: October 05, 2020, 12:53:11 PM »
Here are a couple of pictures of the performance valve job with new valves.   You can see the metal shavings still in the ports from the seat install.  One exhaust seat was missed completely for valve job.   Joe-JDC
« Last Edit: October 05, 2020, 12:55:37 PM by Joe-JDC »
Joe-JDC '70GT-500

GerryP

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #7 on: October 05, 2020, 01:13:23 PM »
Wow!  It looks like someone did the valve job with a rat tail file.  Someone did that who should have been supervised or better trained.

Joe-JDC

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #8 on: October 05, 2020, 01:55:35 PM »
These heads have been sitting wrapped in the original plastic bags from the builder's shop where I bought the engine.  The shortblock and manifold are still wrapped in their plastic wrap.  I guess I will be taking the shortblock apart now to see what it looks like.  It is sad to think this was supposed to be dyno ready, with me only adding my NOS CJ camshaft, lifters, rocker arms.  Joe-JDC
Joe-JDC '70GT-500

gdaddy01

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Re: Cracks in intake valve seats at sparkplug boss?
« Reply #9 on: October 05, 2020, 07:52:19 PM »
looks like some of the work I have had done . bought new valves and had the heads at the shop , wanted a 5 angle job done , got charged for it , later took the valves out of the heads , had not been touch other taking them out of the box and dropping them in the heads .
« Last Edit: October 05, 2020, 07:54:12 PM by gdaddy01 »