starting troubles after engine mods
Thread Starter
Racer
Joined: Nov 2006
Posts: 495
Likes: 1
From: Lubbock TX
starting troubles after engine mods
i recently put in a new cam, lifters, rods, and edelbrock intake. its a 75 with a l-48. now everything is back together but i cant get it to start. i think its pretty close to being timed well enough to start.
the engine turns over fine but wont start, any ideas on what the problem could be. its not much info, but anything will help
thanks, sean
the engine turns over fine but wont start, any ideas on what the problem could be. its not much info, but anything will help
thanks, sean
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
that timing is the first thing to check. You do have a verified TDC, right? Make sure you're on TDC COMPRESSION #1 (remember, there are *two* TDCs in each power cycle - one compression, one exhaust) and the distributor rotor is pointing at #1. This is why people end up with their distributors 180 degrees out. Might as well make that scribe mark on the distributor body where #1 is now 
It's worth checking the spark plug wires for firing order again while you're doing this - it's bit people more than once My only adjustment is that it's not going to start at 0 degrees timing. Set static intial timing at 10-12 degrees BTDC and it'll fire right off if everything else is right.
I generally pre-prime the carb by pouring a bit of gas into the bowl through the bowl vent to ensure there's enough there to take up the slack if the line is a bit dry. IMHO the choke is not a factor and you can just leave it open/disconnected - you'll be running between 2000-3000 RPM during break-in.
Finally, you need to re-prime the engine for startup - this should be done RIGHT before start to ensure everything's wet.
Last edited by billla; Aug 8, 2007 at 11:05 AM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
If The Above Does Not Solve Your No Start Concern...Recheck And Make Sure That Your New Intake And/or Carb. Assembly Does Not Have Any Type....Of.... Air Leak. Such As Gaskets , Seals, Or Cracks... A Quick... Messy Way Is To Squirt A Thick Oil Along Any Component Mating Edge For Gasket Sealing.... As Well Around The Mounting Bolts For Possible Cracking Of The Manifold. The Oil Will Get Sucked In To A Leak And Form A Temprory Seal ...Do This In Sections/Stages, So That You Can Pinpoint The Source.
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Thread Starter
Racer
Joined: Nov 2006
Posts: 495
Likes: 1
From: Lubbock TX
ok, i checked the compression for the number 1 cylinder and i was getting around 80. im getting a spark also. when i turn the engine over it spins then hesitates a little like the timing is off. could some of the other valves be too tight/loose?
when first piston is at tdc the rotor is pointing towards the first point on the distributor.
any other ideas? maybe the cam is in the wrong position? i took the old one out with the dowel at 9 oclock and put the new one in the same.
when first piston is at tdc the rotor is pointing towards the first point on the distributor.
any other ideas? maybe the cam is in the wrong position? i took the old one out with the dowel at 9 oclock and put the new one in the same.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
ok, i checked the compression for the number 1 cylinder and i was getting around 80. im getting a spark also. when i turn the engine over it spins then hesitates a little like the timing is off. could some of the other valves be too tight/loose?
when first piston is at tdc the rotor is pointing towards the first point on the distributor.
any other ideas? maybe the cam is in the wrong position? i took the old one out with the dowel at 9 oclock and put the new one in the same.
when first piston is at tdc the rotor is pointing towards the first point on the distributor.
any other ideas? maybe the cam is in the wrong position? i took the old one out with the dowel at 9 oclock and put the new one in the same.
With the dots aligned on the timing gears, the pin should be at 3:00, not 9:00... assuming the engine is upright (crankshaft at the bottom). The crank key should be at about 2:00.
Last edited by billla; Aug 8, 2007 at 03:53 PM.
Thread Starter
Racer
Joined: Nov 2006
Posts: 495
Likes: 1
From: Lubbock TX
ok i had the distributor in backwards. i switched it and went back and retightened the valves. i tightened until there was no play in the rod then gave it a 1/4 of a turn.
it turns over good but wont start yet. gas shoots up out of the carb sometimes and i had a flame come out a couple times.
any ideas from here?
it turns over good but wont start yet. gas shoots up out of the carb sometimes and i had a flame come out a couple times.
any ideas from here?
Thread Starter
Racer
Joined: Nov 2006
Posts: 495
Likes: 1
From: Lubbock TX
most likely it was wrong but i tried to follow the book. i set the #1 cylinder at TDC, then loosened the nut. i twisted the rod with my fingers and slowly tightened until i couldnt twist with my fingers. then i gave it a 1/4 turn. i followed the firing order all the way around.
in the book it said to give half a turn, then in the picture above it, it shows 3/4 turn. on here ive seen people say 1/4 so thats what i went with
in the book it said to give half a turn, then in the picture above it, it shows 3/4 turn. on here ive seen people say 1/4 so thats what i went with
Burning Brakes
Joined: May 2007
Posts: 945
Likes: 0
From: Ventura California
This is a timing issue. On the cam gear and the crank gear there should be dots stamped into each. When installed, these dots should be pointing right at each other. Better yet, you should use a degree wheel. Sounds like you did the cam swap without the engine being TDC on #1. If thats the case, the cam timing and ignition timing are off. Let me know if you had #1 at TDC and where those points on the cam gear and crank gear were when you did the swap.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
most likely it was wrong but i tried to follow the book. i set the #1 cylinder at TDC, then loosened the nut. i twisted the rod with my fingers and slowly tightened until i couldnt twist with my fingers. then i gave it a 1/4 turn. i followed the firing order all the way around.
in the book it said to give half a turn, then in the picture above it, it shows 3/4 turn. on here ive seen people say 1/4 so thats what i went with
in the book it said to give half a turn, then in the picture above it, it shows 3/4 turn. on here ive seen people say 1/4 so thats what i went with
For valve adjustment, follow the recommendation from your manufacturer for the tightness. For the pushrod, it's not when you can't twist it with your finger...it's when you just feel drag on the pushrod - that's zero lash when there is no slack.
You recognize that you need to turn the engine; you can't just leave it on TDC #1. If you don't have the right adjusting process, I can mail you a .PDF (billla@warbird.org)
Basically its:
TDC Compression #1: adjust exahust of 1,3,4,8 and intake of 1,2,5,7
Rotate one full turn (TDC Compression #6): adjust exhaust 2,5,6,7 and intake of 3,4,6,8
Last edited by billla; Aug 8, 2007 at 07:09 PM.
Thread Starter
Racer
Joined: Nov 2006
Posts: 495
Likes: 1
From: Lubbock TX
here is before the swap. distributor is pointing towards number 1 cylinder.
and here is the timing chain without moving anything.
the marks werent lined up i guess. its close to starting, what do i need to do to fix this?
thanks for all the help
and here is the timing chain without moving anything.
the marks werent lined up i guess. its close to starting, what do i need to do to fix this?
thanks for all the help
Thread Starter
Racer
Joined: Nov 2006
Posts: 495
Likes: 1
From: Lubbock TX
You did catch my post above that the cam pin location indicates your cam may be in the wrong position?
For valve adjustment, follow the recommendation from your manufacturer for the tightness. For the pushrod, it's not when you can't twist it with your finger...it's when you just feel drag on the pushrod - that's zero lash when there is no slack.
You recognize that you need to turn the engine; you can't just leave it on TDC #1. If you don't have the right adjusting process, I can mail you a .PDF (billla@warbird.org)
Basically its:
TDC Compression #1: adjust exahust of 1,3,4,8 and intake of 1,2,5,7
Rotate one full turn (Compression #6): adjust exhaust 2,5,6,7 and intake of 3,4,6,8
For valve adjustment, follow the recommendation from your manufacturer for the tightness. For the pushrod, it's not when you can't twist it with your finger...it's when you just feel drag on the pushrod - that's zero lash when there is no slack.
You recognize that you need to turn the engine; you can't just leave it on TDC #1. If you don't have the right adjusting process, I can mail you a .PDF (billla@warbird.org)
Basically its:
TDC Compression #1: adjust exahust of 1,3,4,8 and intake of 1,2,5,7
Rotate one full turn (Compression #6): adjust exhaust 2,5,6,7 and intake of 3,4,6,8
i was turing the engine 90* at a time and tightened both valves for each cylinder, ill go back tonight and use your method. what do i need to do about the cam positioning and the timing?
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
[EDITS]
Everyone's done this at least once. :/ The one comment I'd make is you need to stop thinking of the distributor as a precision reference for TDC - it isn't. That's what the mark on the balancer and timing tab are for.
The good part is that it's an easy fix - and doable in the car if you really, REALLY don't want to remove it. Somebody check me on this, since there are a lot of steps here.
Am I missing anything, folks?
Here's a picture a buddy of mine took when I was building his 355. You can just see the timing marks, but you can definitely see the location of the crank key and the cam pin. This one fired off on the first crank
- just like yours will once we get this fixed.
.jpg)
Everyone's done this at least once. :/ The one comment I'd make is you need to stop thinking of the distributor as a precision reference for TDC - it isn't. That's what the mark on the balancer and timing tab are for.
The good part is that it's an easy fix - and doable in the car if you really, REALLY don't want to remove it. Somebody check me on this, since there are a lot of steps here.
- Turn the engine to TDC compression #1
- Remove the crank pully and harmonic balancer.
- Remove the water pump.
- Remove the timing cover; you'll have to drop the front of the pan to do this
- Loosen all of the rockers and turn them aside from the pushrods.
- Remove the cam bolts and timing chain.
- VERIFY that the engine is at TDC compression #1, and that the crank key is at about 2:00.
- WITHOUT the chain, attach the cam gear with 1 bolt.
- TURN the cam so that the mark on the cam gear is at 6:00 and aligns with the mark on the crank gear which should be at 12:00. IF THERE ARE MULTIPLE MARKINGS (a triangle, zero, square, etc.) then check your timing chain instructions. USUALLY the zero is standard timing.
- VERIFY that the cam pin is at 3:00.
- Remove the cam gear, reinstall the chain, reinstall all the cam bolts, making sure everything's still lined up.
- Reverse the disassembly process until it's all back together. Note that you'll have to goober the bottom of the timing cover/top of the pan with RTV to ensure you don't get a leak there.
- Reinstall the distributor, since you know you're at TDC compression #1.
- Adjust the valves - again Remember that it's just a very light drag on the pushrod...JUST when it isnt' rotating freely in your fingers. This is where a lot of folks go wrong.
Am I missing anything, folks?
Here's a picture a buddy of mine took when I was building his 355. You can just see the timing marks, but you can definitely see the location of the crank key and the cam pin. This one fired off on the first crank
- just like yours will once we get this fixed.
Last edited by billla; Aug 8, 2007 at 07:14 PM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
See my other post for the cam timing.
I hate to ask...but is there anyone around where you're at that's an engine guy that can just come and be a second set of eyes? Sometimes when you've been looking at this stuff for a long time it's easy to miss stuff - I've been there