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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 10:51 am Post subject: 1700 t4 will not run with valves "properly adusted" |
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Hi all, I have been struggling with a problem on my freshly built 1700 T4 in my 1974 bus. The engine is a CB code case
One head is stock rebuilt the other is AMC new replacement.
The pistons and cylinders are COFAP and the pistons are domed 10cc.
Lifters are solid, pushrods are stock, rockers stock
Dual solex 34 PiCT carburetors (not originals)
Pertronix flamethrower distributor.
Aftermarket camshaft from european motorworks "C" grind
Static compression 150-165psi
The issue Im having is that when I adjust the valves with #1 at TDC the engine will not run and i get suction back into the exhuast. If I adjust #1 lash with the rotor pointing at #3 and then continue lashing in the firing order the engine will run. If I swap all of the wires around to switch #3 and #1 after adjusting the valves this way the engine will not run. Any ideas would be appreciated |
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trailrunnerbus Samba Member
Joined: September 30, 2019 Posts: 26 Location: flyover state
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Posted: Wed Jan 20, 2021 10:54 am Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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Is the distributor installed 180* off?
Take a pic if you can, id like to see where the vacuum can is with your current location. |
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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 11:05 am Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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The distributor IS installed in the "wrong" orientation with the vacuum can pointing at the breather can ( or #2 cylinder) but I swapped the wires on the cap to compensate for that. [/img] |
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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 11:18 am Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50338
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Posted: Wed Jan 20, 2021 11:29 am Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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Look at what your valves are doing. When at TDC for #1 neither valve for the #1 cylinder should not move as you rock the engine back and forth 45° each side of center, while for #3 the valves will move. |
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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 11:50 am Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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I verified that the valves do not move on #1 when i rock the engine back and forth. I also pulled the #1 plug and made sure the piston is all the way up. The way it is running now (with the valves lashed 180 out) there is a ton of lash at TDC, but like i said, if I adjust them with #1 at tdc i get suction back through the exhuast. Im starting to wonder if my camshaft is clocked incorrectly as the new one came with the gear seperately and I installed it to match the stock camshaft gear orientation with the lobes and used the dots to mesh it to the crankshaft. |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Wed Jan 20, 2021 12:19 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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which direction is the fan rotating when you are getting suction on the exhaust, clockwise or counter-clockwise? _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 2:02 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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The fan is turning clockwise |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Wed Jan 20, 2021 4:39 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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how are you figuring out that the exhaust has suction? Are you putting your hand over the exhaust and cranking? Is it spitting fuel back up thru the carb etc. _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 5:05 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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I put my hand over the exhaust and felt it suck my hand in. It will start and run on cylinders 2&4 like this but 1&3 are totally unresponsive regardless of wire placement. Just to recap, i set #1 to tdc by lining the mark on the fan up with 0 on the scale, visually verified that the piston is at the top and rocked the fan back and forth to see that #3 valves both moved and #1 do not. Then i adjusted #1 then turned the fan 180 degrees cw then #4 then turned another 180 then #3 and then another 180 and then #2. My strobe light shows #1 firing 8btdc. |
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airschooled Air-Schooled
Joined: April 04, 2012 Posts: 12721 Location: on a bike ride somewhere
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Posted: Wed Jan 20, 2021 5:15 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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If you can physically feel suction up the exhaust, A) I applaud your physical devotion to your VW, and B) it sounds like you need to check your cam timing. Get the degree before/after TDC that the intake and exhaust valves open and close. We can compare that to stock and aftermarket cam profiles to make sure your gear is bolted on correctly and dots are dotted.
Extremely loose valve adjustment could delay valve actuation, which could help mask a cam timing issue.
Have you looked at all four spark plugs?
Robbie _________________ Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
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Jeff Geisen Samba Chaplain
Joined: December 21, 2004 Posts: 1881 Location: N.W. Georgia
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Posted: Wed Jan 20, 2021 5:42 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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Is your distributor drive gear oriented correctly? _________________ I Corinthians 4: 1 thru 5
‘63 ragtop - ‘68 single cab |
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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 6:06 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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No, the gear was not oriented properly because i was trying to clock the distributor so that the vacuum can had room to move. I was under the impression that as long as the rotor is pointing at the correct terminal on the cap at the right time then it will work regardless of drive gear orientation. I am pulling the drive gear back out to make the rotor point to the notch on the rim of the distributor with #1 at tdc. Also, my rotor turns clockwise, i hope this is right as i did change the brass drive gear on the crank as well. |
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bsairhead Samba Member
Joined: October 08, 2008 Posts: 3561 Location: viroqua wi.
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Posted: Wed Jan 20, 2021 6:14 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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74 Westy wrote: |
No, the gear was not oriented properly because i was trying to clock the distributor so that the vacuum can had room to move. I was under the impression that as long as the rotor is pointing at the correct terminal on the cap at the right time then it will work regardless of drive gear orientation. I am pulling the drive gear back out to make the rotor point to the notch on the rim of the distributor with #1 at tdc. Also, my rotor turns clockwise, i hope this is right as i did change the brass drive gear on the crank as well. |
Distributor drive makes no difference none. It is a factory setting for distributor mark and plug wire orientation. |
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Jeff Geisen Samba Chaplain
Joined: December 21, 2004 Posts: 1881 Location: N.W. Georgia
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Posted: Wed Jan 20, 2021 6:26 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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False info, the drive gear clocks the dizzy to the cam. Crank/cam/dizzy must all be aligned. _________________ I Corinthians 4: 1 thru 5
‘63 ragtop - ‘68 single cab |
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bsairhead Samba Member
Joined: October 08, 2008 Posts: 3561 Location: viroqua wi.
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Posted: Wed Jan 20, 2021 6:36 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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Jeff Geisen wrote: |
False info, the drive gear clocks the dizzy to the cam. Crank/cam/dizzy must all be aligned. |
The distributor drive gear drives the distributor off the crankshaft. The cam gear drives the cam off the crankshaft. Being that the distributor can rotate 360 degrees it's indexing is not critical. |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50338
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Posted: Wed Jan 20, 2021 6:54 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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bsairhead wrote: |
Jeff Geisen wrote: |
False info, the drive gear clocks the dizzy to the cam. Crank/cam/dizzy must all be aligned. |
The distributor drive gear drives the distributor off the crankshaft. The cam gear drives the cam off the crankshaft. Being that the distributor can rotate 360 degrees it's indexing is not critical. |
The clocking of the drive matters, especially if you are running a DVDA distributor. You can not correctly set the timing if the drive is installed too far off as the vacuum can limits how far you can turn the distributor body. There are multiple good reason for the book alignment spec. |
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bsairhead Samba Member
Joined: October 08, 2008 Posts: 3561 Location: viroqua wi.
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Posted: Wed Jan 20, 2021 7:07 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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Wildthings wrote: |
bsairhead wrote: |
Jeff Geisen wrote: |
False info, the drive gear clocks the dizzy to the cam. Crank/cam/dizzy must all be aligned. |
The distributor drive gear drives the distributor off the crankshaft. The cam gear drives the cam off the crankshaft. Being that the distributor can rotate 360 degrees it's indexing is not critical. |
The clocking of the drive matters, especially if you are running a DVDA distributor. You can not correctly set the timing if the drive is installed too far off as the vacuum can limits how far you can turn the distributor body. There are multiple good reason for the book alignment spec. |
I disagree. I have had 12 vw aircooled vehicles including type 3's and type 4's all you need is 44 degrees of movement to locate the distributor to the next or last plug hole. |
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Jeff Geisen Samba Chaplain
Joined: December 21, 2004 Posts: 1881 Location: N.W. Georgia
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Posted: Wed Jan 20, 2021 7:15 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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BS, airhead.
You’ve been misled. _________________ I Corinthians 4: 1 thru 5
‘63 ragtop - ‘68 single cab |
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74 Westy Samba Member
Joined: January 20, 2021 Posts: 18 Location: Pensacola, FL
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Posted: Wed Jan 20, 2021 7:23 pm Post subject: Re: 1700 t4 will not run with valves "properly adusted" |
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I reclocked the drive gear to the factory position and the rotor now points at the notch on the distributor lip. Still running on 2&4 and surprisingly well. I took note of what each vakve is doing with #1 at tdc.
#1 intake closed exhaust closed.
#2 intake closed exhaust opening
#3 intake opening exhaust closed
#4 intake closing exhaust closed |
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