No start and I am stumped

[germando]

Hey I need some ideas. 73 gmc c1500 with a 454 and th400.

It dropped compression on a cylinder so we ripped it apart and put in new rings, main bearings, rod bearings and cam bearings. Put it all back together and no joy.

It will crank for days, but will not start up.
We checked compression 120 across all cylinders. It is getting plenty of fuel. It has spark to all cylinders. It is running a retrofit roller setup with 1.7 roller rockers. The rockers were set the same way as last time, but I’m thinking the valve train has to be the problem.

We are at our wits end here, any ideas are extremely welcome. Please lol any and all suggestions.

Thanks
G

 

[Ricko1966]

Check vacuum. 120 compression is awfully low on a fresh engine. If you don't have enough vacuum it won't start,it won't draw enough air and fuel into the cylinders. I'm wondering if your cam timing is off.

 

[xm20k]

Timing chain dot to dot, distributor dropped in on number one?

 

[germando]

Cam was installed with both dots as 12. The distributed dropped in at number 1 and also rotated 180 and dropped just to eliminate it being off

While cranking the engine doesn’t even try to start, just keeps cranking


G

 

[germando]

We are going to restab the distro snd set the valves in the morning, then we can crank it and check the vacuum

G

 

[Camar068]

Cam was installed with both dots as 12. The distributed dropped in at number 1 and also rotated 180 and dropped just to eliminate it being off

While cranking the engine doesn’t even try to start, just keeps cranking


G

had one with a crappy spade connector going to the dizzy...fell off while driving. Just a thought.

 

[fast 99]

both dots at 12? Lower crank gear at 12 upper cam gear at 6.

 

[germando]

Spade connectors are good, verified all aspects of the ignition, coil, module, lower coil whatever the name of it is


Yes both dots at 12 and #1 was verified at tdc

G

 

[idahovette]

@germando ......Not what @fast 99 said........... Crank dot at 12.................. CAM DOT at 6.........BOTH dots at 12 is WRONG

 

[Radiohead]

Oopsie

 

[Radiohead]

@germando ......Not what @fast 99 said........... Crank dot at 12.................. CAM DOT at 6.........BOTH dots at 12 is WRONG

It's wrong, but wouldn't it be "right" after one revolution of the crank, making the distributor off 180°?

I might be talking out my butt, running on 4 hours sleep right now

 

[HotRodPC]

Hey I need some ideas. 73 gmc c1500 with a 454 and th400.

It dropped compression on a cylinder so we ripped it apart and put in new rings, main bearings, rod bearings and cam bearings. Put it all back together and no joy.

It will crank for days, but will not start up.
We checked compression 120 across all cylinders. It is getting plenty of fuel. It has spark to all cylinders. It is running a retrofit roller setup with 1.7 roller rockers. The rockers were set the same way as last time, but I’m thinking the valve train has to be the problem.

We are at our wits end here, any ideas are extremely welcome. Please lol any and all suggestions.

Thanks
G

Any backfires out the tailpipe, exhaust or both? This could mean 180 out on the timing chain. And how about on the Dizzy? You sure you were up on #1 compression stroke when you set #1 wire? could be the dizzy is out 180. If not backfiring out the intake or tailpipe, then I'd go to the dizzy first. You've mentioned fuel and comprssion, though I do agree, it seems low, but maybe the rings needs seated and that'll come up, but what about spark? Check for 12 volts to the dizzy cap. It's got to be something very simple that your missing.

 

[HotRodPC]

OK as I usually do, read the first 2 or 3 posts them start typing, so I see all this been suggested already. But yes, Dots not supposed to be at 12 and 12. The dots are supposed to be kissing each other or like fuggin unless it's doggy style, but it should be 10 toes up and 10 toes down face to face. Now you can get lucky and that still works cuz when you spin it 1 more time, then they should be dot to dot. BUT.....

So i've still not seen a thing you are getting spark. That's not been confirmed by pulling a plug and wire, grounding it out and seeing if you get spark??? I'm going to guess NO SPARK. Reason I say this is, you say it's doing nothing just cranking and cranking. So if you had spark and even if the cam timing was 180 out of the dizzy timing was 180 out, and you were getting fuel and spark, then it would burping and farting and backfiring out of the intake and exhaust BOTH cuz the fuel is hitting and the spark is hitting at the wrong TIME. If there's not backfiring, and it's not starting up and plenty of fuel is confirmed, then you don't have spark. Now if you have spark and it's burping and farting, now you know you're 180 out somewhere. I'll still stay with, it's something simple you're missing.

How about the wires on the starter??? Did they get on the correct pins on the solenoid? Should be an R and S on the solenoid. The little ignition wires, should be on the R side for Run if memory serves. Back in the day when we had points, you had 2 wires, one for Start on the S side that gave 12 volts to the dizzy to get it started. After it starts, the R side takes over and drops the voltage to 6 volts not to burn up the points. Now days with HEI, it's 12 volt all the way, for both Start and Run so I might be 2nd guessing myself now, and it's supposed be on the S side giving 12 volts full time. BTW, R and S do not mean Run and Start, that's just rule of thumb to help us remember which is which. Cuz I'm 2nd guessing myself now, point being, at least check the wires on the solenoid and make sure they're correct. We do know the activation starter wire does go on S that's what engages the starter with the key and you have that one correct if it's cranking over when you turn the key to start. Anyone else want to chime in and correct me if wrong here? but it's worth checking, cuz I have feeling there's NO SPARK.

 

[Rustisbest]

Cam spins 1/2 speed of crank, after 1 revolution of the crank it'll be dot to dot. Its easier to screw up and be off a tooth doing it that way though. Dot to dot is #1 TDC on exhaust stroke and #6 TDC on firing.
I've messed up plug wire routing 1 space all through the firing order before and they wont start. No backfiring or anything.

 

[germando]

Ok after a night of thinking on this

There is spark used a spark tester and using a plug next to grounded metal, also the sister is getting 12 volts to the battery terminal

Yesterday first thing it did try to start for a second, but never did again.

This made me think, it has hydrolic roller lifters. My thought is that the lifters drained down overnight which “loosened” them a little bit so it tried to fire since the valves were looser. Then while cranking they filled up with oil so the valves tightened up again leading to the no start all day from trying

I understand the worry about timing chain position. I have done it at 12 and 12 forever as long as the distributer is pointed at the right cylinder then either way works as long as you know which piston is at compression tdc


About to loosen all the rockers to just finger tight and crank to see what happens

G