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Timing, fuel delivery vacuum leak??

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75Cj5 View Drop Down
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    Posted: Apr/25/2021 at 2:57pm
Originally posted by 75Cj5 75Cj5 wrote:

I am a new member and would like to first thank all of you for taking the time to read my post. I have had a challenging time getting my 304 up and running correctly. I am going to try to explain my issues without boring the life out of you.

1975 Cj5- AMC 304 - Stage 2 Cam - Edlebrock Performer intake - DUI Distributor - Long tube Hedman Headers - (Holley) Brawler Carburetor 600 cfm (vacuum advance) - everything else is stock.

Upon initial startup from complete rebuild I could never get the timing mark to line up in and consistent manner with a timing light.  I timed it by ear and by how the engine performed and it was almost perfect. Easy to start and good drivability. It did have some lag when accelerating, this is when it all went down hill. 

I tried to do a little carb tuning and when I put the vacuum gage on it held steady at "wrong valve timing" at idle but it I revved slightly it would be in the green. (I figured this was ok since the cam is slightly bigger and the carburetor might be a tad too big for this motor. 

Once I started making small adjustments with the mixture screws and the timing again things went south... I now have a popping in the carburetor and it will not go away, nor will it get even close to starting easily or idling nicely as before. (my spark plugs foul in a matter of minutes, even when I try to lean the carb out as far as possible)  

I had checked, rechecked and checked again that the motor was set at TDC correctly and every time I had myself convinced I screwed up and set it wrong... Each time it check out correct...

Yesterday I took the timing cover off to check yet again that TDC is correct. When I clock the cam gear at 3 o'clock I have 21 pins from the dot on the cam gear to the dot on the crank gear.  The manual says this is acceptable but is it really??

I did not complete a full inspection of all the push rods yet but felt of them and there does not seem to be any anomalies there yet. 

The only other thing I have yet to think of was my fuel delivery, I have a small Holley electric fuel pump that I tested and without the engine running it is pushing close to 7 psi.  I have the Holley Red fuel pump coming in today and plan to switch those out...

It really feels like a timing issue to me but from what I can tell everything is set in accordance with the manual... I'm at a loss.... 

Problem identified. I am pretty sure the valve is locked up. Lots of work to do now... 
 


1975 CJ5
AMC 304
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 75Cj5 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/13/2021 at 2:31pm
Well, it is looking like the cam has one or some lobes wiped...

I'm taking it down this weekend to confirm.



Edited by 75Cj5 - Apr/13/2021 at 2:41pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 75Cj5 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/10/2021 at 1:36pm
Originally posted by 6PakBee 6PakBee wrote:

Please stop with the green.  It makes it hard to read with these old eyeballs!!

Will do.
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Post Options Post Options   Thanks (2) Thanks(2)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Apr/10/2021 at 9:03am
Please stop with the green.  It makes it hard to read with these old eyeballs!!
Roger Gazur
1969 'B' Scheme SC/Rambler
1970 RWB 4-spd Machine
1970 Sonic Silver auto AMX

All project cars.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 75Cj5 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/10/2021 at 6:43am
Originally posted by iapexl8r iapexl8r wrote:

When your previously verified TDC did you verify it by running #1 piston up to TDC on the compression stroke verified by a piece of wire ran through the spark plug hole touching the top of the piston while turning the crank and watching the wire rise to TDC then fall as it passesTDC And back to the center of the rise and fall, then once the piston is verified  at TDC Look at the harmonic balancer mark, it should line up with the timing chain cover Mark. To find the compression stroke you can turn the engine with #1 spark plug removed and someone’s finger in the spark plug hole and when the compression pushes the finger off the hole that’s the compression stroke. Then after the balancer marks are verified, while at TDC verify the rotor is pointing to the electrode on the dist cap that is going to the #1 spark plug

Another thing to do is slap another carb on temporary to eliminate the carb being the issue, a carb is an easy one a lot of car guys have a spare carb maybe you can borrow one.

Also


If you have one of those infra laser temp guns you can check each exhaust manifold exit from the cyl for temp to verify no cold cylinders. In a pinch a bic pen with the cap on while the engine is running will slide from the heat and will not slide on cool cyl. 

The spits and pops in carb really sounds like timing.   we have all been there it can be frustrating, I hope my advice helps I try to over explain things I am not trying to be anything but helpful. The people on this forum have helped me many times.. yea you PHAT69AMX! Lol

-chris

I am beyond grateful for your advice, and yes this is sooo frustrating...  I did follow your procedure on finding TDC (I have also used a piston stop to ensure the timing mark on the balancer is in the correct position). I have second guessed myself everytime now but when I verify I did this the correct way I find that it is correct.

I am going to walk away for a couple days and look for another carb to try out I hate to think a brand new carb is already junk but it would not surprise me. 

I will be watching this thread and let you guys know if things change. Thanks again!!


Edited by 75Cj5 - Apr/12/2021 at 1:31pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iapexl8r Quote  Post ReplyReply Direct Link To This Post Posted: Apr/09/2021 at 9:15pm
When your previously verified TDC did you verify it by running #1 piston up to TDC on the compression stroke verified by a piece of wire ran through the spark plug hole touching the top of the piston while turning the crank and watching the wire rise to TDC then fall as it passesTDC And back to the center of the rise and fall, then once the piston is verified  at TDC Look at the harmonic balancer mark, it should line up with the timing chain cover Mark. To find the compression stroke you can turn the engine with #1 spark plug removed and someone’s finger in the spark plug hole and when the compression pushes the finger off the hole that’s the compression stroke. Then after the balancer marks are verified, while at TDC verify the rotor is pointing to the electrode on the dist cap that is going to the #1 spark plug

Another thing to do is slap another carb on temporary to eliminate the carb being the issue, a carb is an easy one a lot of car guys have a spare carb maybe you can borrow one.

Also


If you have one of those infra laser temp guns you can check each exhaust manifold exit from the cyl for temp to verify no cold cylinders. In a pinch a bic pen with the cap on while the engine is running will slide from the heat and will not slide on cool cyl. 

The spits and pops in carb really sounds like timing.   we have all been there it can be frustrating, I hope my advice helps I try to over explain things I am not trying to be anything but helpful. The people on this forum have helped me many times.. yea you PHAT69AMX! Lol

-chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 75Cj5 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/09/2021 at 5:53pm
I just started it and it runs like crap still... turned the mixture screws all the way in and it will still start.

I replaced the power valve and still have the exact same result. 

Spits and pops in carb and now back firing through exhaust... 


The exhaust backfire is the only thing new.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 75Cj5 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/09/2021 at 7:34am
For any of you that are following this, I have buttoned up the timing cover and re-installed the distributor.
I re-installed the plug wires and double checked the wires are all going to proper positions on motor and distributor cap.
I have the mixture screws on the carb 1-1/2 turns out from soft seated position.

I have changed the amount of initial timing from 5* to 10* BTDC (ATDC on the timing cover)... this is really the only change I have made thus far.

I am going to get the coolant back in this afternoon and give her another try... 

Any other suggestions before this evening are always welcome.


Thanks for all that have participated in this thread thus far, I really appreciate it.


Edited by 75Cj5 - Apr/12/2021 at 1:32pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 75Cj5 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/09/2021 at 7:21am
Originally posted by iapexl8r iapexl8r wrote:

The timing mark on the lower sprocket should be at 12:00 o’clock and the upper gear should be at 6 o’clock. So they line up . Your timing set should have instructions usually the o mark is zero and the little triangle  is advance and the square is retarded. You probably want the o mark .
Like this  https://static.summitracing.com/global/s/instructions/edl-7800series-perer-tim.pdf - https://static.summitracing.com/global/images/instructions/edl-7800series-performer-linktim.pdf

Yes Sir, I did that for installation. My manual says to check by rotating the crank until the cam gear dot is in the 3 o'clock position, then to count the pins from dot to dot. Manual specifically calls out 20 pins but also says 20 or 21 pins is acceptable. I'm just moving forward with the 21 pin count.

Thank you!


Edited by 75Cj5 - Apr/12/2021 at 1:32pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iapexl8r Quote  Post ReplyReply Direct Link To This Post Posted: Apr/08/2021 at 8:03pm
The timing mark on the lower sprocket should be at 12:00 o’clock and the upper gear should be at 6 o’clock. So they line up . Your timing set should have instructions usually the o mark is zero and the little triangle  is advance and the square is retarded. You probably want the o mark .

Edited by iapexl8r - Apr/08/2021 at 8:08pm
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