engine popping
- Thread starter Francis Blake
- Start date
Mike
Well-Known Member
Ding, ding, ding, we have a winner!
It's the principle of Occam's razor. Why hit panic buttons until you have tried the most simple solutions? Sure, maybe it's been a while since Francis rotated the air in all four tires. Sure, it could be a stuck connuter valve actuating rod. But it could be as simple as some loose header bolts, too.
Ding, ding, ding, we have a winner!
It's the principle of Occam's razor. Why hit panic buttons until you have tried the most simple solutions? Sure, maybe it's been a while since Francis rotated the air in all four tires. Sure, it could be a stuck connuter valve actuating rod. But it could be as simple as some loose header bolts, too.
I am agreeing with you. With 20" of vac, all of the timing is great, and so is the cam, and no Vac leaks. A vac gauge is a great diagnostic tool. I found many a stopped up converter with a vac gauge, but that's another story.
Screaming Metal
Active Member
----I believe its something simple, or it would not start.---
Duke
Member
Just for grins I would pull the plugs and then spin the engine over some, letting it blow out Cylinders. Could be a piece of carbon in the Cylinder that gets hot. This cause's pre - ignition and cause,s a popping sound also backfires or even popping in the Carburetor. Is your vacuum gauge hold steady or bounce alot ? If it is bouncing bad it could be a valve sticking or carbon on the valve seat. If its steady the valve train is probably fine.
Francis Blake
Active Member
I finally got this thing going. I thought it had to be a bad intake gasket so I changed it, same old story, changed the gas same thing. So this morning I put in a new coil, put the air cleaner back on noticed there was some holes in the base (factory) so I closed them up. Started it up, runs line a tiger. This is one strange beast. Thanks a lot for your help guys I appreciate it very much.
Francis Blake
Active Member
Spoke to soon, about two blocks and right back to the same old thing.
Screaming Metal
Active Member
Francis, crank your car up, let it idle, grab the 12v. wire that hooks into your distr. cap top (the leads to your coil go in there), and just wiggle it while the motors running, and see if this might make a difference.
Wild Mango
Member
I would be suspicious of cross firing, now that so much else has been eliminated. Give the inside of the distributor cap a good clean with brake spray cleaner and check the inside under a good light. You are looking for voltage tracks on the plastic surface, or cracks in the plastic even. The surface inside the cap needs to be clean and mark free, especially between the terminal posts. Then do the same clean and inspect program on the outside of the cap and ignition leads, looking for damage, burns, cuts and loose plug ins on the HT leads. Include the spark plug boots and connectors in this, and finish up by giving the plug masts a good clean.
Screaming Metal
Active Member
That what I was thinking Mango, he said it ran fine after putting a new coil in it. He either tightened something or moved something. I know every once in a while the wire where it meets the plug (the pigtail that plugs into the distributor) will make intermediate contact sometimes....but I was also thinking of the cross firing. Unless he has a couple of wires that are cross-firing....
I know troubleshooting electrical will almost drive you batty if you have something like this.
Good thing though, is when you find the problem, it'll straighten all these things out.
Theres a spray that allows you to see cross-firing at the auto parts store. I've overlooked cracks in the cap before....they can be dam hard to find and pinpoint.
I know troubleshooting electrical will almost drive you batty if you have something like this.
Good thing though, is when you find the problem, it'll straighten all these things out.
Theres a spray that allows you to see cross-firing at the auto parts store. I've overlooked cracks in the cap before....they can be dam hard to find and pinpoint.
Screaming Metal
Active Member
Francis, any luck yet? Seems like the post where you installed a new coil is absent, along with the testdrive where 2 blocks later, the problem returned. Everything OK?
Francis Blake
Active Member
Hi guys, Thanks for all the ideas. I have replaced everything in the dist plus the cap tried three different carbs replaced the intake gaskets, am thinking the valve springs may be weak this engine is 21 yrs old and has spent a lot of time sitting. I had a mechanic friend that has built a lot of dirt track engines look it over and after checking the ign and cam timing thinks this is about all that is left. So I will change the springs and will let you know then
Screaming Metal
Active Member
Well, look at it like this, after its all said and done, it'll be ready for another 20 years of cruisin'....
Keeper
Active Member
Okay just to toss another theory out there, one that could be way out in left field.
Could it be a lifter going bad? When the engine is cold and the oil is thicker, its okay, but once it warms up and the oil thins out the lifter starts acting up?
Though I suppose you would hear that as a click/clatter.
I will go back to my corner now....lol
Could it be a lifter going bad? When the engine is cold and the oil is thicker, its okay, but once it warms up and the oil thins out the lifter starts acting up?
Though I suppose you would hear that as a click/clatter.
I will go back to my corner now....lol
Wild Mango
Member
If its been sitting a long while could be a valve stem rusted up and you got a sticky inlet valve. The spring on that valve may have sagged from long time compressed as well. You'll find out when you do the springs, I'd do the inlet springs first. If you do got a sticky valve, no quick fix unfortunately, it's an off with it's head scenario.
If its a streeter I like to use those bronze sleeves to recue a guide thats a sticker, easy enough and they seem to last OK.
If its a streeter I like to use those bronze sleeves to recue a guide thats a sticker, easy enough and they seem to last OK.
Screaming Metal
Active Member
What Mango said! Sticky valve or lifter either one could cause these things. Or a weak spring. I was hoping for a quick easy fix for our friend....
Screaming Metal
Active Member
He could try some Riselone, that would free up a sticky lifter or valve. Gotta be careful with that stuff though, will wash all the tarnish and sludge down into your oilpan and stop up the pickup.
I would only use the frees up sticky lifters and valve formula, the straight up Riselone is like a paint thinner, it WILL CLEAN YOUR MOTOR BIGTIME!
I use that stuff in all my motors, 1/2 qt. every other oil change, the inside of the motor is clean enough to eat off of.....or a 1/3 qt. ALL THE TIME! ITS STRONG!
As for the valvespring, theres a valvespring tester that works on the head, just pull your valve covers, put it on the rocker arm and use your torque wrench.
Sometimes you can pick these up at your autopartsstore if they are into speed equipment, or go online to Goodsons Engine Building Tools, they'll have what you need.
I would only use the frees up sticky lifters and valve formula, the straight up Riselone is like a paint thinner, it WILL CLEAN YOUR MOTOR BIGTIME!
I use that stuff in all my motors, 1/2 qt. every other oil change, the inside of the motor is clean enough to eat off of.....or a 1/3 qt. ALL THE TIME! ITS STRONG!
As for the valvespring, theres a valvespring tester that works on the head, just pull your valve covers, put it on the rocker arm and use your torque wrench.
Sometimes you can pick these up at your autopartsstore if they are into speed equipment, or go online to Goodsons Engine Building Tools, they'll have what you need.
"IF" he has 20" of steady vac he can not have a sticky valve. That vac gauge would be bouncing all over the place! Maybe we need to recheck that vac while the engine is doing its popping thing.
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