Author Topic: 428 heat related issue  (Read 5255 times)

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67428GT500

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Re: 428 heat related issue
« Reply #15 on: July 22, 2019, 09:24:33 PM »
Pertronix ignitions are fine as long as you follow the DIRECTIONS.   I always see someone complaining about them failing.  They require 12V constant power source. If you're running it off the 6-9 volts that is supplied to the coil you're going to destroy them and they do weird things as mentioned with low volt resistance wired vehicles.  I have a  1967 Shelby and it has a factory tach which requires running power direct PRE-Tach.
Anyway, just food for thought.
                                                                                                 -Keith

drafterman

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Re: 428 heat related issue
« Reply #16 on: July 22, 2019, 10:25:05 PM »
Just an update from my previous post from earlier tonight:  I pulled the carb back off after things cooled to look over that Demon Idle-Eze circuit and I noticed a film of oil in the intake manifold.  This is the first time I noticed it and I have had the carb off half a dozen times in the last week. (I always glance down the manifold just to be sure I didn’t drop anything inside).  The oil is in both planes of the manifold.  Not sure if a bad PCV valve would cause this, because with all the idling lately the engine has been in a high vacuum state for extended periods or if it is drawing oil from elsewhere.  As I stated on Saturday the plugs are OK, definitely not oil fouled.  Perhaps my original thought of a vacuum leak is correct? 

GerryP

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Re: 428 heat related issue
« Reply #17 on: July 23, 2019, 07:34:10 AM »
You are probably at the point where you need to pull the intake manifold.  What intake gaskets did you use?  The Felpro Print-o-seals have a very poor reputation.  I went through two sets before I threw in the towel.


gdaddy01

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Re: 428 heat related issue
« Reply #18 on: July 23, 2019, 10:32:56 AM »
pull all the vacuum lines off and plug , PVC , brake booster , spark advance etc , run till it gets hot and see if it still shuts off . just a thought .

6667fan

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Re: 428 heat related issue
« Reply #19 on: July 23, 2019, 10:48:02 AM »
If there was a significant vacuum leak why would it take so long after warm up to manifest itself? Engine would run poorly in advance of warm up IMO or are you surmising a gap grows after heat expansion?
Don’t like to hear about the oil in the intake but you could try something easy and rule out some things. Temporarily disconnect your existing PCV system for some VC breathers. The idea being to get away from pulling any oil into the intake for the short term, ( should your PCV set up be suspect). This is not the cure for the stalling out, just an investigative approach  to the oil accumulation.

JB
JB


67 Fairlane 500
482 cid 636/619.
Tunnel Wedge, Survival EMC CNC heads, Lykins Custom Hydraulic Roller, Ram adjustable clutch, Jerico 4-spd, Strange third member with Detroit Locker, 35 spline axles, 4.86
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wayne

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Re: 428 heat related issue
« Reply #20 on: July 23, 2019, 11:37:42 AM »
I would pull the pertronix and try the points.

drafterman

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Re: 428 heat related issue
« Reply #21 on: July 23, 2019, 09:53:22 PM »
Update for tonight.  I was going to yank the manifold, but since some folks suggested to swap in the point distributor I thought that would be easier.  I had to do some overhaul because the old one had a lot of play in the shaft, but I got it good enough for a test, however, I had a lot of ignition miss that I couldn’t get leveled out.  So I yanked it back out.
I made the following two changes and nothing else:
1)While standing there staring at it, I almost forgot that the I have a rev limiter under the dash...Remember, I said that I built this car for the wife  ;D. I disconnected it.
2)Then after putting the Pertronix billet distributor back in, I decided to just turn the timing way up, so it is now at about 20 initial!

I adjusted the idle mixture a bit and let it run until about 190 deg or about 15 minutes..funny thing, it would never get hotter than this!  It did smoke some, but I figured that was the oil in the intake burning out.  So I took it down the driveway which is about a 1/4 mile long and turned around...still no signs of a heat issue.  I pulled back in the shop and let it run some more and it acted great with good throttle response.  I shut it off and let it heat soak for about 10 minutes, hit the key and it cracked right off.  I let it run some more and it never showed any signs of trouble.  Too late for an actual road test, but I am anxious to see what happens.  So, is the advanced timing what it needed or perhaps the rev limiter acting up?  Who knows, maybe my timing light has been dropped one too many times.  Time will tell.  Hopefully tomorrow will be the definitive answer...stay tuned.

wayne

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Re: 428 heat related issue
« Reply #22 on: July 24, 2019, 10:30:49 AM »
I bet you found it the rev limiter. Maybe you have two things to look at tdc may be off on the balancer sometimes they slip.

drafterman

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Re: 428 heat related issue
« Reply #23 on: July 24, 2019, 09:36:55 PM »
 ;D I think I found it guys.  Headed out for another road test, but it all looks and feels very promising.  Any last guesses on what is was?

338Raptor

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Re: 428 heat related issue
« Reply #24 on: July 24, 2019, 11:12:31 PM »
Rev limiter.
ERA 427SC Cobra: Iron ‘67 625hp 482” SOHC, TKX 5 speed, TrueTrac 3.31 IRS, Magnesium Halibrands, Avon CR6ZZ tires. 

1969 Shelby GT350, 4 speed.

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drafterman

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Re: 428 heat related issue
« Reply #25 on: July 25, 2019, 06:06:20 AM »
I think wayne nailed it...the harmonic balancer has slipped.  I found true TDC and it proved the timing marks were off by 6 degrees.  So, even though the timing light read 12 initial, it was actually 6.  At an idle (or slowing down) there was just not enough timing to keep it running, especially with a hot engine.  The slow timing obviously causes a lot of heat as well.  When it was cold it ran great because there was enough advance in the distributor to make it run well.   I am currently at 16 initial with 36 total and still have no pinging on 91 octane.  Also, I hooked the rev limiter back up and no issues.  I really appreciate you all talking me through this one. Any thoughts on a good aftermarket balancer?

gdaddy01

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Re: 428 heat related issue
« Reply #26 on: July 25, 2019, 04:25:44 PM »
glad you found the problem , can drive you crazy and then you don't get to drive .