Thread: 70 chevy with 350 engine trouble

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I'm gonna try to keep this as short as possible. Had my 70 chevy with 350 with a Q Jet for 2 years. Never a minutes trouble. Then over night it wouldnt crank. Smelled and acted like it was flooded. Checked the plugs cylinders 2 and 8 were flooded. Changed all the plugs checked spark. Had intermittent spark, changed coil then had good spark. tried to crank truck. It took me a solid minute of turning it over to get it to fire. once it fired it ran for an hour with no trouble. killed the truck tried to crank and it did the same thing. plugs werent flooded as bad but still wet. I then took the Q jet off and put an edelbrock 600cfm on it. Still will not crank. Where should i go from here. I am in no way a mechanic or even really a gear head. I just dont like spending money on something that i can learn and do. Starting to reach my limit.

How's the rest of your ignition system, and especially the distributor cap & rotor? Have you ever changed the plug wires? Since a new coil made a positive change, I'd be looking at replacing the remainder of the ignition components to ensure that they're not causing spark degradation.

My knee - jerk impression is too much fuel pressure, overwhelming the float. I don't suppose you have a fuel guage you can put in line?

If It's running poorly because of excessive fuel, and changing carbs didn't help, then fuel pressure makes sense.

Did you change the plugs a second time??? Once they flood they tend to stay that way for sometime

Just thinking out loud here, but since you've shown that you had a weak spark I'd say chances are pretty good that you're dealing with an ignition problem. Unless you changed out something in your fuel supply system, like if you added an electric fuel pump that you have not mentioned, I would think that your operating fuel pressure is probably OK and you're not pushing fuel past the needle valve to flood the float bowls. Now it's entirely possible that your needle & seat have aged and might be leaking, but the fact that you changed the coil and got an hour of good running before it started going funky makes me question your ignition system. Charlie mentioned the possibility that you've fouled those plugs, and another question is what brand plugs did you buy? There have been too many cases where new out of the box plugs are bad since the manufacturing shifted to China, and it seems that AC plugs have been hit hard.

what do you have for an ignition??? is it points ???????big difference in plug gaps for points systems--------

Originally Posted by jerry clayton

what do you have for an ignition??? is it points ???????big difference in plug gaps for points systems--------

Good catch, Jerry! For a 1970 350cid Rock Auto shows a point style distributor as the OEM replacement.

Originally Posted by rush

I'm gonna try to keep this as short as possible. Had my 70 chevy with 350 with a Q Jet for 2 years. Never a minutes trouble. Then over night it wouldnt crank. Smelled and acted like it was flooded. Checked the plugs cylinders 2 and 8 were flooded. Changed all the plugs checked spark. Had intermittent spark, changed coil then had good spark. tried to crank truck. It took me a solid minute of turning it over to get it to fire. once it fired it ran for an hour with no trouble. killed the truck tried to crank and it did the same thing. plugs werent flooded as bad but still wet. I then took the Q jet off and put an edelbrock 600cfm on it. Still will not crank. Where should i go from here. I am in no way a mechanic or even really a gear head. I just dont like spending money on something that i can learn and do. Starting to reach my limit.

Welcome aboard Rush, good to see you here. Unfortunately you've asked a question in someone else's thread and the replies following I think apply to you and not the OP (original poster) we're a pretty tolerant bunch and I just want to bring it to your attention that this is considered "bad form" or improper etiquette, so you should apologize to the OP for imposing and begin your own thread.. or, you can just tell me to stick it and mind my own business!

It is his thread post------------------

Originally Posted by 34_40

Welcome aboard Rush, good to see you here. Unfortunately you've asked a question in someone else's thread and the replies following I think apply to you and not the OP (original poster) we're a pretty tolerant bunch and I just want to bring it to your attention that this is considered "bad form" or improper etiquette, so you should apologize to the OP for imposing and begin your own thread.. or, you can just tell me to stick it and mind my own business!

Mike, look back to the top and Post #1 of this thread is Rush's. This thread is similar to another one, but looks like it's all good.

If you have a points distrbutor & points gone bad, replace it.
Verify correct gap in points. I dont recall what is should be.
Rotor, cap, points may come as a package. Its been 20 years since Ive messed with thst set up.
Check spark by grounding a sparkplug against the engine block with the plug wire in the distributor. Have someone try to start the motor as you watch the spark nump from the plug to the block. It should be a brilliant blue. Yellow is a weak spark.

Originally Posted by rspears

Mike, look back to the top and Post #1 of this thread is Rush's. This thread is similar to another one, but looks like it's all good.

Thanks RSpears! Seems I goofed! My apologies to all! I guess I lost my place!LOL..

As an aside, if you're changing points, consider eliminating them with a Pertronix I kit. Easy to do, improves spark and never needs any adjustment. Cost like 28 bucks.

A colleague and myself were discussing a similar situation with his car: turned out to be the condenser.

Rush posted his question at 10:38pm, logged off at 10:45pm, and has not been back to check answers unless he did it without logging on. I suggest that we defer further thoughts and ideas until he comes back and answers some of the questions that we've posed back to him. Just my $0.02, and ya'll can do what you want.