![]() |
Hotrodders Bulletin Board
Home · Bulletin Board · Project Journals · Tech Article Wiki · Knowledge Base · Photo Gallery · Classifieds · Company Reviews · Calendar · T-Shirts |
|
|||||||
|
|||||
![]() |
|
|
Thread Tools | Search this Thread |
|
#1
|
||||
|
||||
|
Hello,
Just thought that I'd continue my saga for everyone to enjoy. I'm the guy that left the blue shop rag in his manifold, bolted the card on and then started the engine. Now I have 2 exhaust pipes that glow red hot after the car has been running for 3-5 minutes. (The 2 pipes are the back 2 on the passenger side only, all other exhaust pipes seems fine). I'm also the guy that had his 289 rebuilt last summer by a mouth piece that would say one thing one day and then something completely different the next. Anyways.....I took the passenger side head off and everything looks fine. Starting with the engine rebuild, the pistons look good, they are flat top with the valve notches cut into them and the piston comes all the way up to the top of the cylinder. The pistons say 030 on them so I will assume that's what the new bore is. Also, the heads are 1969 302 heads at 58'cc's. The Ford book says that with this combo I should have 9.5:1 compression. Fine....sounds good to me. 302 valves and good solid compression. I'm happy with that. So, I now know what the rebuild shop did and I have my engine documented and the bottom end looks good. Peace of mind. But....that's my problem.......everything looks good. I was expecting to see chunks of blue shop rag in my valves or maybe even a backwards head gasket, but no....everything looks real good. I don't see any problems anywhere. The valves seem to seat nicely and I have examinded them closely and I don't see blue shop rag chunks anywhere. So what do I do now, could it be carburation on timing? I did crack the back 2 throttle plates open on my Holley to feed the bigger cam the guy put in, would that do anything? Wouldn't they be glowing red on both sides of the engine? I have to take my time now and figure out my next move. Maybe the rag is a "red herring" and the exhaust pipes have been glowing since the rebuild....or maybe not. I need to figure out what to look for next....any ideas? Update:........I just talked to Holley Tech Support about my problem and I told them about opening the secondaries to get more RPM and better vacuum at idle. They assured me that too much gas isn't the issue. In fact they said that an engine that runs rich will run cooler. They are saying that it sounds like a timing issue, that the engine is getting too much timing at idle. I have no problem considering that, but then why just 2 cylinders glowing red and not all of them? I will close the secondary plates and put the carb back to the way it was, and I will definately have to look at the timing but the rebuilders put a bigger cam in and had the timing set at 16 initial. I don't know the spec'e on the cam but I can tell you that my vacuum was 18 before the rebuild and now it's 14 and I have to open everything up to get a good idle out of it, so I assume it's a bigger cam and can take more initial timing. Right now I have the timing set at about 14, I guess I can drop it down to 8, but I need to know that timing is the issue before I put everything back together again. |
|
#2
|
||||
|
||||
|
can you check the valves better than just a visual? also, have you bent any pushrods? roll them across a table
|
|
#3
|
||||
|
||||
|
Invert the head and fill with the chambers with gasoline, time how long it takes to leak out. If it takes only a few minutes to drain out you have found your leak. A good valve seal will not leak raw fuel.
|
|
#4
|
||||
|
||||
|
I would do a double check of the valves as suggested, but is there any possibility that the intake manifold wasn't sealing on those cylinders? Examine the gaskets and see if they have a good imprint from the 2 surfaces. The fact that they are right next to each other makes me ask.
|
|
#5
|
||||
|
||||
|
i would check the header tubes to see if the rag didn't get stuck at the end it could of gone past the valves and wedged in the header some where holding the heat in and making it glow. or put a 6-71 blower on it and blow the crap out the tail pipe. that is if you dont have a bent pushrod or loose rocker <img src="graemlins/evil.gif" border="0" alt="[evil]" />
|
|
#6
|
||||
|
||||
|
Coupe, I will throw in some off the wall BS that may or may not help. I my researching Fuel Injection, vice Carbed motors, I ran across several interesting points and one may help you. At wide open throttle, at best in a V8, you will have three cylinders at the correct richness, three cylinders too rich and 2 cylinders too lean and no amount of carb tuning can change this. At idle, you can have the same conditions, so if you are not properly tuned at idle, then you could have the conditions of 3 cylinders too lean, 3 cylinders about right and 2 cylinders dangerously lean ie two glowing header pipes. I have followed this thread and assumed the missing rag was a contributor as you and others have. It seems as though you have just eliminated that problem and may need to look hard into your idle circuity/plumbing of your carb as well as your timing, which has been mentioned. The two plugs in the glowing tube cylinders should show signs of extreme leanness and you should not have any signs of richness on any of the other plugs under glowing conditions). One other thing you can try if you are not making any headway is changing the heat range of the plugs in the cylinders in question. I would try two ranges hotter first and then two colder.
Trees |
|
#7
|
||||
|
||||
|
I feel your pain <grin>...
One question; You've had two exhaust headers glowing red-hot for the last two months or better. You pulled the heads and your valves all still seem to be OK... Tell you what. I think your motor is due for an honest-to-goodness "Exorsizzzzm" It's posessed.. <img src="graemlins/sweat.gif" border="0" alt="[sweat]" /> |
|
#8
|
||||
|
||||
|
Are the two cylinders on the same vacuum run? If so I would double check that there is no vacuum leak. Sure sounds like it.
|
|
#9
|
|||
|
|||
|
red hot rag
how was this car running with these glowing red pipes?
Was it missing? Did it idle smooth? Take the valves out of the head and have them faced on a valve grinder. Blacken the valve face with a sharpy pen, then grind it gradualy, if the ink grinds off evenly its not bent, if it grinds it off part of the valve and not the other, its bent. If they're not bent, check to see if the rag is still in the intake. |
|
#10
|
||||
|
||||
|
re: 2 Exhaust Pipes Glowing Red Hot (Part 3- The Head is Off !)
This is an old thread, did it ever get resolved? I couldn't help but wonder when I re-read it if the valves on those two cylinders weren't adjusted properly. Those are positive stop studs and if the lifters weren't collapsed to check valve clearance they may have been tight allowing a lean condition from valves not fully closing. Coupe's post count is still low after the 2 years that this thread has been around, is he still on the board?
|
|
#11
|
||||
|
||||
|
re: 2 Exhaust Pipes Glowing Red Hot (Part 3- The Head is Off !)
The manifolds on the 383 in my 65 Fury get REALLY hot REALLY fast too... Almost to the point of glowing, I haven't checked it at night though...
Can timing do this? My timing jumps a bit when I have the light connected, but I still need a cap, rotor, wires, and coil. So that may be it. It ran pretty damn good on an 80 mile round trip though, even with this condition. Seemed a bit sluggish, but had plenty of power once you got your foot into it. Just thought I'd add my two cents to a thread that was already up. |
|
#12
|
||||
|
||||
|
re: 2 Exhaust Pipes Glowing Red Hot (Part 3- The Head is Off !)
Retarded timing can cause that. It would affect all cylinders though, not just 2 like Coupe had.
|
|
#13
|
||||
|
||||
|
re: 2 Exhaust Pipes Glowing Red Hot (Part 3- The Head is Off !)
Quote:
|
|
#14
|
|||
|
|||
|
re: 2 Exhaust Pipes Glowing Red Hot (Part 3- The Head is Off !)
Quote:
If the timing is too retarded, then the combustion may not be complete when the exhaust valve opens, causing exhaust temperatures to rise, could also make it sluggish. Check the timing, try advancing it 2 degrees and see if it changes. Listen for pinging or slow cranking starter motor because this means too much advance. |
|
#15
|
|||
|
|||
|
re: 2 Exhaust Pipes Glowing Red Hot (Part 3- The Head is Off !)
Wow, the tech support sucks at Holley. That is a terrible advice.
A rich mixture along with retarded timing will make a manifold glow red. Not lean or advanced. Holley must get their tech employees from Quick Lube's rejects. A bigger cam needs a richer idle and more timing. What are your cam specs? 14 in hg would need about 16 to 18 degree at initial timing. Adjust the idle mixture screws until the highest vacuum in obtained. Don't crack open the secondaries for more air at idle. Pull the carb and drill a 0.100" hole in the center of each FRONT throttle blade. This is described in "how to tune a Holley". I can't believe the Holley tech guy wouldn't know this. Maybe air flow through the secondaries is causing a rich mixture in the rear of the engine. And if you have a dual plane intake, the last two cylinder are feed by the opposite sides of the carb. |