OK, I know you guys are probably tired of hearing from me but.
I have a built 350. I ran it for break in and several times afterwards just in the driveway. I replaced my Holley 750 with a new rebuilt 650 DP mech secondaries.
I installed the new carb and it started and ran great. I drove it up and down my long driveway.
I went back the next day to start it and set the timing, my garage smelled like gas and it wouldn't start, it just chugs and tries but won't run.
Everything is new including the MSD HEI. I set the carb according to the sheet, I used a manometer to be sure I had TDC, I installed a fuel pressure reg and set at 5lbs. I pulled and dried the plugs which were wet with gas and it still chugs and won't run. It fires and tries but won't run. I tweek the distributer 1/4 inch at a time but nothing.
I put the old 750 back on thinking this was the only change in the equation and there was no improvement.

ANY ideas? Could it be an interior intake (aluminum Air Gap) leak? Could someting have moved or broken in my new engine? Should I be using a thick carb gasket? It ran great - I shut it off and it hasn't run since.

All suggestions welcome and appreciated.
JZ

 

Do you have enough juice going to your distributor? If you have the old resistor wire to the ignition, you may want to replace it with a solid reliable wire.

 

I doubt something mechanical broke in your new engine.
lets go back to basics....
1. now do you know you are getting a spark to the spark plugs?

2. now do you know you are getting gas to the carburetor?

3. now do you know you are getting juice to MSD HEI?

have you tried spraying starter fluid down carb and turning it over? if it does not turn over with starter fluid you probably do not have a spark...

edit: and if it does start and then dies you are not getting gas...

 

I will be checking that in the morning with a volt meter.
One of my thoughts was that I hit a wire on the header, I checked visually but will do a close check

 

Plenty of gas, it does fire off and chug but just won't catch and run.
I'll get a can of starting fluid tmorrow also.
Thanks for the repliees.
JZ

 

I'm sure its something really obvious thats just hiding out of sight....just to test your flexibility

 

I may be completely wrong with my guess but let's give it a try:

My Vette would run fine for about 30 miles, then I had to change the spark plugs. They were wet and I could not figure out what was wrong. I bought approximately 5-6 sets of plugs until I finally broke down and changed the cam and the carburetor which solved the problem. The cam was too hot (edelbrock performer RPM) and the carb too big (750 Holley)....

You said your 350 is built, what cam ? Did you try new spark plugs after changing to the 650cfm carb ??

 

Once the plugs get wet they are very hard to make work again. I don't know why, but if you ever get them soaking wet, you better get new ones.

 

Sounds like the timing is off to me. You said you tweeked it 1/4 inch atta time, to no avail, then changed back to the 750. You also said this was the only change in the equation. Well, it wasn't, because your timing was changed, by your own hand. Go back to your original timing, it ran that way, try it again. Do you have a timing light?

You also said the plugs were wet, were they black and nasty looking too? Clean them with a wire brush if so.

 

I just checked the distributor supply and I have 12v there coming in.
I'm running the Comp Extreme cam .519/.523 lift 297/306 dur.
I built the entire engine from bare block up with all new parts so the only time it ran was during the break in and sevaral times after just in my driveway, but it ran great and started instantly. The plugs were new at that time.

Yes my plugs were black and nasty looking and very wet with gas. I wire brushed them and sprayed them with carb cleaner, checked the gaps and reinstalled.
I'm running out this morning and I'll pick up a new set of plugs and starter fluid.
I have a timing light, I never got a chance to get it properly timed but I did find and mark TDC and I tweeked from there.
My experiances have and still do tell me it's a spark issue, I'll try new plugs today.
Thanks a lot you guys, Please keep em coming.
JZ

 

 

sound like too much fuel maybe floats are stuck. crank it over with the plugs out and try to blow gas out of the clys. before you put in new plugs also look in carb. to see if it is dripping wet with fuel. you will need to hold carb. wide open when you crank it over. also keep in mind to take into account for the initall squirt of fuel from the accelator pump when you look back down carb. after cranking. you will be looking for large volume of fuel if it's there then figure out why. there probaly will be some but not a massive ammount if every thing is ok.

 

I cranked it with the float sight plug out and it is just comes over the bottom edge. I'm using Champion V59C plugs and none of the local parts stores carries them.
I ordered a new set and they will be here Monday. They were/are SOAKING wet with gas.
I'll post my results when I get the new plugs in.
Any other ideas are still greatly appreciated. Thanks Guys
JZ

 

You're useing racing spark plugs in a street car? Sounds to me like this engine has slowly loaded up due to extremely cold racing spark plugs. Get some regular street plugs of the proper heat range. Champion 2025 maybe.

Hope this helps.

BigBlockk

Later.....

 

Thanks BigBlockk
I'm running Comp Extreme 519/523 lift, 297/306 dur, Eagle 2.08 230cc heads, forged .200 domed pistons, 10:1 compression, Air Gap intake, .060 over at 361cid. I called Eagle tech line and asked what plugs to use and they said to use the Champion V59C.
With this setup do you think they are too cold?

 

It sounds like the induction system is designed to run at 6000 rpm. Is this a street car or a race car? The recommended plugs will run great at 6000 rpm but will load up on the street. There is not enough heat to keep them clean.

It looks to me like the whole combo is wrong. That camshaft would probably work real good with 12/1 compression and a single plane intake manifold and I think your finding out that NO street 350 needs 2.08" intake valves. There is no velocity through the intake unless the motor is turning some serious rpm. The fuel is falling out of the air stream and just running into the combustion chambers as liquid fuel. After the first few times you started it the fuel has accumulated so much that you can't get enough air into it to vaporize it all. Liquid fuel WILL NOT burn.

As far as fixing it goes. If you get it started, don't let it idle below, say, 2000 rpm. When cruiseing don't go any higher than second gear..... everywhere. Running down the highway in second gear at 5000 rpm is gunna get old real fast. But seriously..... If it were me I would get rid of those heads. I know you don't want to hear that but their just too big. For the compression ratio you have a cam with between 276 and 282 degrees duration should do ok. You should be able to get .480" to .500" lift with this duration. Something else for you to think about is that your present combo would be a little more streetable if the engine had 50 or 60 more cubic inches of displacement. You notice I say a LITTLE more streetable.

Engines with too much intake port and/or camshaft, while screaming at the race track, are real pains on the street.

Hope this helps.

BigBlockk

Later.....

 

Well First of all if you have compressed air available and a sand blaster, Spark Plugs do not wear out for a looong time, they become fouled between the ceramic induction sheild and the anode. You can clean them up. Secondly ...Did you install an electronic fuel pump when you rebuilt the engine? If so did you put a fuel pressure regulator between the pump and the carb? What is the pressure of the pump? I've allways said that when jetting a carb on a SBC, less is more, even with your gas guzzeling heads a 650 carb would run the set up better. Drowned sparkplugs after several good runs could be just too much fuel pressure. Also an inexpencive fix could be a carb spacer and a smaller pair of jets. Less fuel and a longer run to atomize the fuel. Hope that helps.........

 

I have to agree on the parts selection of that motor, 230cc heads on the 350ci is serious track stuff. You need at least 406ci and a milder cam for the street. Like stated above your not going to want to hear this but quite possibly the combination is so out of whack that the plugs just plain load up in a matter of minutes. If you can swing it build a 406ci short block with 11:1 CR if you are going to use that cam and put everything on that and sell the 350ci short. Even then that cam is going to be trouble on the street.

 

SUCCESS
Thanks for all your input it was all exrtemely valuable.
This is my first engine build and a learning process. I realize the heads are a bit too big and will maybe swap them out in the spring.
The 650 should help out a little. It is a street car but nothing I will be driving to work or grocery store. My intention was to build a radical weekend car for fun.

The Champion V59C plugs were the problem as you identified. I installed a set of 2025's and it fired off and the exhaust isn't rich any more either. As stated above I also added the fuel pressure regulator to the mechanical pump, the pressure before that was around 10psi, which stopped the flooding issue.
Now to get the timing light on it and set the timing. I have Lars' tech paper on that.
Thanks again to all of you.
JZ