Thread: wont start!

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I am getting spark while cranking. Motor still doesn't run with dry plugs and the injectors off. I have tried initial timing everywhere from 8btdc to 4atdc. The most I get is a backfire or so. I was careful to make sure my timing marks were aligned while assembling the motor. I turned the motor over by hand and also clayed the chambers. If I had missed my timing this should have shown up then? I have this cam installed 4 degrees advanced, but it should still start. The duration is advertised at 280/290 and 214/224 (0.050). I am using the 2.02/1.60 valve combo. Could the combination of long duration and oversize valves be throwing me off or am I becoming nearsighted in frustration?

I've been watching the Nascar race


Have you checked for cranking vacume, compression? and are you absolutely sure that you aren't 180 out with the dist?

If you have properly timed spark, it should run on starting fluid

Jerry

You said that it was the same fuel and ignition setup---I asked if you had a key with the resistor for theft control--is this engine in the same vehicle and with the same wiring harness?
The earlier fi engines had an extra injector for cold starts, does yours?

Originally Posted by DennyW

Sounds like you need to regroup, and check all your settings. Leave the tbi un plugged. Make sure those plugs are burned clean. Crank over, and clear fuel from the cylinders. Let it air out some. And, even doing all that, remember, you will stil have some fuel in the intake, so don't hook up the tbi to soon. The temp is a big factor on how much fuel is being delivered. I have cleaned many plugs here in the North, simply because the customer always thinks they don't have to help it start at -10º. But, you do. That was a standard procedure here in the dead of winter to get people going. Pull the fuel supply, clean the plugs, change the oil, and then crank it until it started without the fuel hooked up. Let it run that fuel out until it died. Then, hook up the fuel supply and start it.

You may have picked a cam past the limits of what you can run. I haven't checked on what you have. Usually you can go i stage past your stock, and be within limits. The chip you bought, or installed should have instructions also on how far you can go. If your at say the 3rd step cam, you probably have went to far. Wide, or big duration will not work with that.

ps: I went back up and read what you have. That cam should work.

Denny thanks. I think I need to regroup as you said. I have the plugs out and will clean them. then I am going to sit down and eat something and not let this stinkin small block get the better of me. I think that I lost track of some basics and got ahead of myself. I was kind of iffy on the cam when I picked it with the fuel injection and I think I was just second guessing myself. I tried to do my homework and I am ready to see if it has paid off.

Denny--I don't know on the tbi but the tpi had them mid 80s.
And weren't most of the chev tbi only 305s?

I think chevy made 350 tbi for longer than maybe they should, for the truck market anyway since it had such a good torque amount down low.

This is a factory 350 TBI. It has 2 injectors and a dual plane manifold, one injector to each plenum. this is a rebuild of an engine that fragged on the interstate. I replaced the longblock but the manifold and intake stayed. There is just a standard steel stamped key. Theoretically the only thing that has changed is the cam affecting cylinder pressure and fuel charge in the cylinder. The distributor makes spark to the #1 lead on the compression stroke. I checked this by pulling both the spark plug and the valve cover and then turning the crank to where I wanted it. I disconnect the single wire connector called for. With a plug in the #1 wire I rotate the distributor to the point where it sparks. I have thus effectively checked my static timing.
I am leaning toward denny's suggestion of overfueling. I think I got it flooded early and have been fighting with it all day. I need to keep an eye out for fuel wash and go back to basics.

I checked some of his previous threads about the engine buildup and found reference to several conflicting items concerning cam timing, compression ratios, ignition bypasses

I think after he eats and rests some and rethinks his path about how he got to where he is, he'll hit on where he took a wrong turn. The temp guage thing was referred to before along with engine grounds

Got to go eat and see how the race is going

Jerry

Trying to fire and then backfiring, you've got spark going where it shouldn't be. Take a real close look at your firing order, dist. rotation direction, all the obvious things we all overlook now and again. Also make real sure all the little wires are actually going where they're supposed to. The temp gauge acting up would seem to be a wiring glitch.

Originally Posted by jerry clayton

I checked some of his previous threads about the engine buildup and found reference to several conflicting items concerning cam timing, compression ratios, ignition bypasses

I think after he eats and rests some and rethinks his path about how he got to where he is, he'll hit on where he took a wrong turn. The temp guage thing was referred to before along with engine grounds

Got to go eat and see how the race is going

Jerry

I ran into the thing with the temp gauge this morning and posted it as a separate post.
The engine build took a different turn about halfway through as I found an issue concerning my heads. they were assumed to be 76cc and were measured to be 64's. As far as the build goes.......

4.030 bore
3.48 stroke
5.7 rods
70cc chambers(cut for oversize valves and took extra material to achieve this target)
4.135 X .040 head gasket
.125" dome pistons that cc'd to -.3 cc's in the cylinder
0.025 piston deck height
57 abdc intake closing.

this gives me a SCR of 9.63 and DCR of 8.13
squish of .065 minimum clearances in chamber of 0.060 checked with clay.
I have done my homework on this one. It is a solid build.

I see we both posted at the same time--sorry

I believe that you are saying that you are setting the crank where you want it to fire and then moving the distributor to make a spark at the plug? Is that right?

I wish you had a name--threearmsinjune--well

Assuming that you have gotten the fuel pumped out of the chambers--
I would move the initial timing to 18 or 20 btc
Crank it and check with a timing light
add a spray of starting fluid
It should start if the cam is timed right, the firing order goes around the cap the correct way.

Now some things to check for ---is there spark when the ignition is in start?
use a remote starter switch so it doesn't go thru the ign switch assembly( they are a mess on those gm products)

If you are getting a constant spray out of your injectors you probably have a grounding issue

After looking at your prior posts, I see that you have listed three different intake closing points to control compression??????? 34, 65, and 57 have all been listed---why didn't you just set the cam where it was made for(105 intake cl) and did you use a dial indicator to check the valve lift for the settings?
Don't want to seem like am ass but I've found too many simple misconceptions over the years--you seem to have the bases covered, but it seems more than just being flooded.

Jerry

Jerry, my name is Chris Armstrong and of my family there are 3 born in june........
the cam came out of the box at 101 LCL not the 105. that was an option to bleed down the cranking pressure before I had the chamber volumes opened up. I chose to install it at 57ABDC and it should still fire as normal within a few degrees. I used a 24" degree wheel and a dial indicator to check the cam. I measured the piston dome and chamber volume using a 100mL burette. This is how I found the physical dimensions to be far from those advertised.
The reason I am leaning towards flooding is BECAUSE I HAVE EXCESS FUEL RUNNING OUT OF MY EXHAUST! The injectors are pulsing and not spraying constantly. The distributor firing order is 18436572 rotating clockwise and the rotor is matched to the "#1 cylinder at TDCC.
I am at a critical stage here with fuel rinsing down my cylinder walls. I am in for the night as nature is having her say with the weather, but tomorrow is a new day. I plan on double checking all of my connections. Going through the effort of checking my cam timing just for giggles and also the distributor as well. All the key ingredients are here but I believe it has to do with time.

The cam is from a local company called PBM performance. they have a website and their cams are from Erson. I have their pn# 140104K but I am not able to cross this over to Erson. I am wondering if it may somehow be a altered order style cam such as 18736542 or 18726543. This is what I intend to find out now that I am inside.

Originally Posted by DennyW

After you clean the plugs off, put a shot of oil in each cylinder. Disconnect the fuel supply. Rotate engine over a few times to get some oil around the rings. What is the outside temp ? The coolant sensor is what you start off of. That determines the amount of fuel you get for starting. Open plug gap to .040-.045.

If the sensor is faulty should it cuase this big of an issue? Or is it a periphery to keep in mind for future reference?

Chris

You could be correct on the flooding--it only takes a very wee bit of fuel to short out the high voltage ignition systems

I once fought the -20 degree weather for three days to get the plugs changed in an 86 tpi in a Iroc Camaro--the injector system just pissed away because of the temperature(or lack of warmth)

I'll check the thread tomorrow to see how your doing

Get a good rest

Jerry