[panhead59]

I ve got a rebuilt 455 that won t start. Got fuel and spark. Lifters adjusted with intake off, so valves should be right. Installed dizzy with engine on comp. Stroke. Put balancer on zero. Rotor pointing towards #1 plug wire on cap. Firing order confirmed. Counterclockwise.. it doesn t even cough or spit !. What have i missed ? One ? Where should vac advance be pointing since that affects rotor to base orientation. Tks

[Scott65]

Not being critical, you need to back up and reevaluate. If you have fuel and spark, and the valves are right, you'll get a bang. Maybe at the wrong time (distributor off), but you'll get something. One of the things you've crossed off the list isn't right yet.

[george kujanski]

Agree with that. Getting fuel into the cylinder? Perhaps it needs a richer mix to start?

George

[dmac]

Compression test with all plugs out?

[mgarblik]

Originally Posted by dmac

Compression test with all plugs out?

It would be a good idea to check this. Most of the new no-starts I run into are an issue with valves not closing all the way. You didn't mention if you have an adjustable valvetrain or the stock-non-adjustable stuff the engine came with. During a typical rebuild, reusing the old valves, cutting and grinding the seats, gets the stem height all messed-up. You end up with valves with a too long effective length. Tightening the rockers up to the 20 ft. lb. stock setting for the bottle neck studs results with some or all the valves held open just a little bit. No-start is the result. Try to evaluate and fix the situation, whatever it is as quickly as possible. It's very bad for the rings, and hard on the camshaft to crank a long time without starting that first time for break-in. Good luck with it.

[STEELCITYFIREBIRD]

Originally Posted by Scott65

Not being critical, you need to back up and reevaluate. If you have fuel and spark, and the valves are right, you'll get a bang. Maybe at the wrong time (distributor off), but you'll get something. One of the things you've crossed off the list isn't right yet.

Agree

...Verify Fuel,and Spark to the plug, not coil wire (if equipped)
I’d work on #1 cylinder, verify everything, including dizzy install. Vacuum advance can location will change where #1 is on the cap relative to diagrams, but #1 is where the rotor points, just past TDC ...on compression stroke.

[Scott65]

Just verifying you're on the compression stroke for the distributor drop in by the finger over the hole method may help provide clues... No blow, start over on the valve train adjustment.

[sdbob]

35 yrs ago I had no start,timing on no. 1 Exhaust valve. I learned.

[Matt Meaney]

your timing is way retarded. confirm with a timing light, or just start moving the dist. clockwise.

[panhead59]

Adjustable valve train by the way. I think u guys are on to something with valve adjustment issue. It s the only thing i haven't dbl ckecked. Mainly cuzz i adjusted them with intake off, looking right at the cam lobes for low spot. I still could've got it wrong i guess. I'LL READJUST and let you know. I'd bet ya'll r correct though, because it doesn't really sound right when it's spinning over , now that i think about it. Tks.

[Jim Moshier]

Are you sure it’s number 1 and not number 2. Just saying .....asking for a friend?

[Schurkey]

Originally Posted by panhead59

Where should vac advance be pointing since that affects rotor to base orientation. Tks

This tells me you didn't static-time the engine.

WHAT DISTRIBUTOR DO YOU HAVE?

There may be more wrong than just this.

[panhead59]

No points. Pertronix III modual in stock style dist. I have fire at plug

[Schurkey]

Originally Posted by panhead59

No points. Pertronix III modual in stock style dist. I have fire at plug

Can't help you with static-timing a Pertronix. Never dicked with one that actually worked.

Point being, you'd want to put the damper at something like 10 degrees BTDC COMPRESSION STROKE for #1 cylinder. Get the rotor in the general direction of #1 spark plug terminal on the distributor cap. Then rotate the distributor body to the point where the module would trigger a spark. Easy with HEI or with points, but I don't know Pertronix.

[Cliff R]

Petronix is having some issues currently so don't rule out something going on in that area.

Visually observe #1 intake valve open then continue to rotate the engine in the normal direction till just before TDC. Wire up the distributor in the correct firing order from that point based on where you set the rotor orientation. Get the pickup as closely aligned as possible to when it would be triggering a spark. It should roar to life instantly if you are close.......

[steve25]

You have confirmed the 3 things the motor needs to start , but there's a 4th as mentioned, that being compression.
Do this, pull some plugs and if they do,not look wet then fill up the small center section of a spray paint can cap with fuel ( yes fill it up with fuel! ) then dump in into the Carb while holding both the choke and the primary throttle plate open some.

Next have someone Crank the motor over while you slowly spin the distributor clock wise to advance the timing.
In doing this if you have compression then the motor should become very hard to Crank over which is good and means you have compression , if not and the motor does not back fire then you have some valves set too tight.

The rotor in Pontiac distributors spins counter clockwise, so advancing will be made by spinning the dizzy clockwise.

[68lemans462]

Are the plugs NEW?

[tooski]

I replaced a points dist with HEI in my 68. Had spark, but still wouldn't start. Turns out I had 9 v or less to the HEI. Not enough spark for fire. Another one I thought I had everything line up but no start. Turns out timing was retarded instead of advanced.

[Lee]

Originally Posted by steve25

You have confirmed the 3 things the motor needs to start , but there's a 4th as mentioned, that being compression.
.

Yep, I got bit by this one about 25 years ago.

A buddy had his heads (350sbc) reworked, installed a new cam, and could not get it to start - so called me to come over.

Distributor was throwing a nice spark. Carb appeared to be working fine. I pulled a valve cover to confirm #1 on compression, spark plug out of the hole to confirm piston at TDC.

Turned out the machine shop did a REALLY sh!tty job on the valve guides. Valves moved around so much that no compression could be built, and it would not fire.

We put a new set of heads on a few weeks later, and it fired right up.

[STEELCITYFIREBIRD]

Originally Posted by STEELCITYFIREBIRD

Agree

...Verify Fuel,and Spark to the plug, not coil wire (if equipped)
I’d work on #1 cylinder, verify everything, including dizzy install. Vacuum advance can location will change where #1 is on the cap relative to diagrams, but #1 is where the rotor points, just BEFORE TDC ...on compression stroke.

Whoops


Also when working only on #1 cylinder, if all is well in your checks, but low compression...your cam timing could be off.