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quartermilecamel
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Joined: April 16, 2008
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Location: ohio
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 Posted: Sun Jun 28, 2015 5:05 pm Post subject: I lost 2 cylinders, cannot figure out how they arent firing |
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1964 bus, had dellortos but took them off and threw on, the 30 pict 1 carb. Thought the dellortos were the issue. 3 and 4 do not fire at idle. They start to fire at higher rpms when noted plug wires are pulled. compression is 120 on 3 and 130 on 4. Replaced, cap, wires on 3 and 4, checked valves for tightness using finger feel. How can left bank cylinders have compression, and fuel but not fire until higher rpms. sprayed water on intake boot and at intake to head gasket(paper) no change but ......if they aren't firing......didn't tell me much anyway
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olliehank47
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Joined: May 04, 2011
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| Posted: Sun Jun 28, 2015 6:06 pm Post subject: Re: I lost 2 cylinders, cannot figure out how they arent fir |
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| quartermilecamel wrote: |
| 1964 bus, had dellortos but took them off and threw on, the 30 pict 1 carb. Thought the dellortos were the issue. 3 and 4 do not fire at idle. They start to fire at higher rpms when noted plug wires are pulled. compression is 120 on 3 and 130 on 4. Replaced, cap, wires on 3 and 4, checked valves for tightness using finger feel. How can left bank cylinders have compression, and fuel but not fire until higher rpms. sprayed water on intake boot and at intake to head gasket(paper) no change but ......if they aren't firing......didn't tell me much anyway |
You've eliminated spark, fuel, and compression, so I'd still suspect an air leak at the boot or the head gasket. You can rig up a vacuum cleaner to blow air and connect it to the intake, then spray soapy water around the boot and gasket, looking for bubbles to appear. |
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Stanagon
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quartermilecamel
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Location: ohio
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| Posted: Sun Jun 28, 2015 7:05 pm Post subject: |
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yes on feeler guage, checked 2nd time.......not tight using 006.
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quartermilecamel
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| Posted: Sun Jun 28, 2015 7:07 pm Post subject: |
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pertronix ignition on svda......vacuum not used. sounds like a vacuum leak to me also. did not have large end hose clamps for intake boots so used regular radiator style hose clamps(slightly wider than the narrow stock ones)
......possible cause of suggested leak.
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quartermilecamel
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| Posted: Sun Jun 28, 2015 10:08 pm Post subject: |
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gaskets must be old. tightened the end casting bolts. 4 cylinders now. also forgot to drill header crossover heat riser hole oh well at least it runs and I can send off the dells
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quartermilecamel
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| Posted: Mon Jun 29, 2015 12:39 am Post subject: |
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how does one get a torque spec on intake end casting nuts with no way to get a torque wrench on the nuts underneath the bend? I know your not supposed to german spec the nuts or you will warp the castings.
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catahoula lou
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Joined: August 30, 2008
Posts: 594
Location: south of Silver Springs, NV
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| Posted: Mon Jun 29, 2015 6:13 am Post subject: |
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Does your intake manifold have a nipple on the 3/4 side for a vacuum-advance distributor? I had a similar problem with my 1600DP/EMPI 38 EGAS carb, until I noticed that the cap that sealed off the nipple was gone, allowing a lot of air into the 3/4 side.
Replaced cap and all has been well since.
Best,
Thom
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1 1959 mango green Ragtop Bug (the "Mango")
1 1958 pantina red Lowlight Ghia (the "Chili Pepper")
Still looking for:
(1) My Dad's 1955 356 (he raced it amateur-class at Riverside and other courses during 1950s),
(2) My parent's black 1955 hardtop bug (CA license plate FWC 201 or FWG 201), and
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quartermilecamel
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| Posted: Mon Jun 29, 2015 12:54 pm Post subject: |
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hmm you mean like a small pound in cap? I didn't see anything like that but I have seen the brass vacuum port on some and I didn't see that.
Sometimes I wonder why I keep doing the same shit over and over, seems I done this before too. Tighten them, think they are tight and then nope.
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catahoula lou
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Location: south of Silver Springs, NV
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| Posted: Mon Jun 29, 2015 2:29 pm Post subject: |
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No. It's part of the end casting, between the head end and rubber intake boot to the central part, less than 1/2" long. Usually "closed" with a black rubber slip-on cap.
If you don't have one, then it can't be the cause.
According to a mechanic friend of mine, the intake boots can go bad within a few years, OR new one(s) could be "old" by sitting on the shelf for a long time, requiring replacement with new one(s).
Another problem I had with a different engine was that some heads have a small metal removable stud that fits through the small hole in the intake gasket. If your end casting does not have the reciprocal hole in its mating surface, the stud could be holding your casting up enough to let air enter. It this case, pull the stud from either/both heads and try again...
Best,
Thom
_________________
1 great wife
2 Catahoula Leopard Dogs (Mahogany Star and Spartan) - RIP Lucy, Braveheart, & Dusty!
1 1959 mango green Ragtop Bug (the "Mango")
1 1958 pantina red Lowlight Ghia (the "Chili Pepper")
Still looking for:
(1) My Dad's 1955 356 (he raced it amateur-class at Riverside and other courses during 1950s),
(2) My parent's black 1955 hardtop bug (CA license plate FWC 201 or FWG 201), and
(3) My parent's agave green 1957 ragtop bug (CA license plate LFK 734). |
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Stanagon
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Joined: July 11, 2003
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Location: Boston, MA
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quartermilecamel
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Joined: April 16, 2008
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Location: ohio
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| Posted: Tue Jun 30, 2015 12:36 am Post subject: |
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well sorta I guess but #3 runs 100 degrees cooler than #1 does. Yes Ive ruled out inaccurate measuring techniques too. Also yet again ruled out mouse/rat/landshark nest on top of clylinders/heads. Infared, lazers, cylinder head temp gauges, they alllllll say passenger side is hotter than drivers side. So Im wondering if I had an intake leak all this time. The methods suggested and one Id like to try will rule out any leaks. Id like to slightly pressurize the cylinders with the exhaust valves closed and backed off so all air stops at the cylinder then plug off carb. Use dawn soap and let the bubbles rip. Propane/map never did much and neither did water. Plus I was always nervous with a running engine and map or propane.
Yes, I remember the peg in the heads, my stock ones had this. Aftermarket Mexican heads now, no peg inbetween intake holes. Must go back and read the vacuum cleaner test again.
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Last edited by quartermilecamel on Tue Jun 30, 2015 12:47 am; edited 1 time in total |
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quartermilecamel
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Location: ohio
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| Posted: Tue Jun 30, 2015 12:44 am Post subject: Re: I lost 2 cylinders, cannot figure out how they arent fir |
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| olliehank47 wrote: |
| quartermilecamel wrote: |
| 1964 bus, had dellortos but took them off and threw on, the 30 pict 1 carb. Thought the dellortos were the issue. 3 and 4 do not fire at idle. They start to fire at higher rpms when noted plug wires are pulled. compression is 120 on 3 and 130 on 4. Replaced, cap, wires on 3 and 4, checked valves for tightness using finger feel. How can left bank cylinders have compression, and fuel but not fire until higher rpms. sprayed water on intake boot and at intake to head gasket(paper) no change but ......if they aren't firing......didn't tell me much anyway |
You've eliminated spark, fuel, and compression, so I'd still suspect an air leak at the boot or the head gasket. You can rig up a vacuum cleaner to blow air and connect it to the intake, then spray soapy water around the boot and gasket, looking for bubbles to appear. |
Ohhh I just figured out what you meant. Sorry my mind told me vacuum cleaners only suck air in lol. Mind read right over the blow part. I do have the rainbow vacuum cleaners and they have the discharge port.....perfect.
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Stanagon
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quartermilecamel
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| Posted: Wed Jul 01, 2015 12:23 am Post subject: |
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yeah we tried propane and it didn't change anything......weird. Just hate spraying flammable stuff near ignition wires. Next time I will test again will be Friday.......day off..until then bus hides in garage. Almost every day is rain here.
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quartermilecamel
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| Posted: Fri Jul 03, 2015 10:23 pm Post subject: |
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just tried the vacuum cleaner on carb, soaped up intake to head and boots. Nothing. cylinder 1 380 and upwards degrees on freeway, cylinder 3 under 300. Wait, #3 doesn't get over 260 degrees.
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