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Discussion Starter #1
Hi Guys. I Just Rebuilt My Chevy 350 And I Am Trying To Start It For The First Time. The Problem Is It Wont Start. All Im Getting Is Spitting Smoke(backfiring) Up Through The Carb. I Checked My Wires To Make Sure Everything Is Correct. I Checked To Make Sure That My Rotor Is At The Number One Plug When The Number 1 Cylinder Is At Top Dead Center And It Is. What Could Be The Brob. I Built Two Other Engines Besides This One And Never Had A Prob. What Could I Be Doing Wrong. You Guys Have Helped Me A Lot In The Past And Im Sure You Can Now. Thanx
 

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Doc here,

The procedure is:

Compression, Top Dead center, Both intake and Exhaust valves closed, timing marks lined up. If you have this, you can rule out Mechanical problems, ( timing chain , gear mis~align)

Next pull the cap, Rotor should point to #1 plug tower, about 5 to 7 O'Clock. If not, reset the dizzy, and try again.

Firing Order: 1 8 4 3 6 5 7 2, be sure 5 and 7 are not reversed. (AT BOTH ENDS!)

If that is all good, I'd look for tight intake valves or a BIG Vaccum leak.

Doc :pimp:
 

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Do as Doc said... To make absolutely sure #1 is at TDC I like to pull the passenger side valve cover and look to see if #6 rockers are moving. If they are then #1 is TDC...otherwise roll it over again
 

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gilby246 said:
Do as Doc said... To make absolutely sure #1 is at TDC I like to pull the passenger side valve cover and look to see if #6 rockers are moving. If they are then #1 is TDC...otherwise roll it over again
Put finger over spark plug hole, hand crank..... blows air= compression

Stop hand cranking when air blows out, look at rotor, put #1 plug wire there, (or pull the dizzy and change it) be sure the firing order is going around the distributor cap in the correct direction.

Engine doesn't know where # 1 terminal is suppose to be, front or back.

EDITED= Hey, :D I use to install some deliberately with # 1 in a different position just to see if some genius noticed the difference. :thumbup:

From # 1======OOPs you already did that. If the timing is off by 15* it might not start. Have the dizzy loose enough that when somebody cranks it you can twist it to get it in time.

Like DOC said, tight valves?
 

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Discussion Starter #6
lifters

Well I Checked Everything And Everything Checked Out Fine. My Timing Mark On The Crank And Cam Are Dot To Dot When The #1 Cylinder Is At Top Dead Center On The Compression Stroke. Wires Are Correct. So Im Leaning Towards Tight Valves. What Is The Best Way To Adjust These. I Was Told When The Lifter Goes All The Way Down To Use A Feeler Gauge Between The Rocker And The Valve Then Give An Additional One Half Turn. Is This Correct? If So What Size Feeler Should I Use. Or Is There A Diffrent Way. Thanx
 

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bigtymer83180 said:
Well I Checked Everything And Everything Checked Out Fine. My Timing Mark On The Crank And Cam Are Dot To Dot When The #1 Cylinder Is At Top Dead Center On The Compression Stroke. Wires Are Correct. So Im Leaning Towards Tight Valves. What Is The Best Way To Adjust These. I Was Told When The Lifter Goes All The Way Down To Use A Feeler Gauge Between The Rocker And The Valve Then Give An Additional One Half Turn. Is This Correct? If So What Size Feeler Should I Use. Or Is There A Diffrent Way. Thanx

Not really..........

When the timing gears are dot to dot....... #6 is on compression.

I'd bet you are 180* out of time.
 

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Did you take the distributor cap off and see which way the rotor was pointing?
I know you say you checked everything, but you did explicitly mention it in the post.
 

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xntrik said:
Not really..........

When the timing gears are dot to dot....... #6 is on compression.

I'd bet you are 180* out of time.

Before you tear it all apart, just rearrange the wires on the cap 180* from where they are... If ya got them going the right rotation......

I bet it starts. :thumbup:
 

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Discussion Starter #11
My #1 Piston Is At The Top Of The Cylinder. I Put A Screwdriver In The Spark Plug Hole To Confirm. My Rotor Is Pointing At The #1 Spark Plug Wire. Should The #1 Piston Be At The Bottom Of The Cylinder When The Rotor Is At The Number 1 Plug Wire. Now That Im Writing And Thinking I Think I Am 180* Off. Could Someone Confirm This. If This Is So The Cam Mark Should Be At 12 O'clock Position And The Crank At 12 O'clock Position When The #1 Piston Is At The Bottom Of The Cylinder
 

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You dont understand....This is a 4 cycle engine. The piston goes up and down twice for every time the plug fires....you are on the wrong cycle. Take the distributer out and put it back with the rotor facing opposite what it is now.
 

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Discussion Starter #13
So What Youre Saying Is That When The Rotor Is At The Number One Spot My Piston Should Be At The Bottom Of Cylinder. Correct
 

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No......at the top on the other revolution of the crank.

The distributer runs off the cam. Every time the cam turns once, the distributer turns once. The crank, however turns twice every time the cam turns once....thats why the cam gear is much bigger than the crank gear....twice as big. The piston makes 2 revolutions every time the distributer turns once.
 

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No Piston goes up and down twice. You had your igntion set on the exhaust TDC. You need it on intake TDC. Get the piston TDC on #1 and take off the distributor cap. The rotor needs to be pointing at the Number 1 post. If its pointing at the passenger seat its 180 out. You need to lift the distributor out spin the rotor and put it back in.
 

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Incorrect. The piston is at the top twice. Once during the exhaust/intake overlap and once on the compression stroke. You are probably on the overlap. Hence the backfiring. One solution is to re-orient the distributor 180* (the rotor pointing to #6) OR to swap all the plug wires 180* on the cap. The second is easier, just to get it running. Do not do both, or you'll get the same result you're getting now.

Pat
 

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engine wont start

Im with xntrik and Poncho, on this . Especially when poppin back thru the Carb . <<, definate sign of timming issue . Is there a slash on. the rim under the cap, on distributor houseing indicateing Number 1 or a Does the notch, on capp Etc Indicate where Number 1 should be pointing . Quickly Pull a Valve cover Determine if , Both Valves are closed on Number 1 TDC , When At top of Compression stroke << as in Blowin Air Past your Thumb as you roll it up TDC << Both valves closed, on number 1 indicateing compression stroke and rotor pointed at number 1, While valves are closeing as in completely , Closed . indicateing TDC of the Compression stroke . Sean
 

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When you align the crankshaft sprocket dot @ 12:00 and the camshaft sprocket dot @ 6:00, you are on TDC firing cylinder #6. If you read a chevy engine manual, it will tell you to align the marks in this fashion then rotate the crankshaft 360 degrees to bring #1 cylinder to TDC firing. The marks are aligned this way so that there is less chance of being out of time, due to parallax error ( or the eyes ability to screw things up, lol!). What you have is cylinder 6 ready to fire and needing spark, and that spark is going to cylinder 1 which has just finished expelling waste gasses, and has both valves open for the beginning of the intake stroke. The unburned fuel vapors are still in the #1 cylinder, due to the spark timing being 180 degrees distributor degrees out of time. So when #1 fires, all that explosion is able to go through the open intake valve, and out through the carb. So, what you need to do is take a ruler (so you are sure of which wire on the dist. cap is 180 degrees from which) and remove one wire at a time and swap it with the one 180 degrees across the cap. when you do this, I can almost guarantee the engine will fire up.
 

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bigtymer83180 said:
If This Is So The Cam Mark Should Be At 12 O'clock Position And The Crank At 12 O'clock Position When The #1 Piston Is At The Bottom Of The Cylinder

Nope, cam dot at top, crank gear dot at top, #1 is all the way up on compression.

Cam turns once to crank turning twice. Everytime crank gear dot is UP, #1 and # 6 are at the top of stroke.
 

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Sean's said:
Im with xntrik and Poncho, on this .

. Quickly Pull a Valve cover Determine if , . Sean
WHY ??

Put finger in # 1 spark plug hole. Air = compression= valves closed
 
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