Hot Rods New one on me (SBC question)

I have a hi-mileage El Camino. Bought it from an estate- Previous owner N/A for Q&A

It's been easy to maintain- I've changed most of the stock parts for peace of mind and had it to a place where I could feel great about giving it to school commuting daughter. Last issue was carb related. The 2 BBL Stock Rochester became troublesome, so I swapped in a new Edelbrock Performer Intake/1406 carb. After realizing that the Mechanical Fuel pump was delivering too much fuel, I replaced it with an eight pounder and added a Fuel Pressure Regulator/Gauge to keep it happy at 5.5lbs.

No problems since that "upgrade" last summer. Recently the car began to shudder over 35 or so- un-driveable. Checked for vac leaks/fuel line crimps/fuel filters. Holding steady at 5.5lbs. Gas into a qt jar is plentiful. Battery is good. Vac pressure is 23Hg in Park. Air/Fuel seems very happy. New cap/rotor.

Now I can't get it to start at all. I had the Pertronix Ignitor and Flame thrower Coil in. Backfire no start- no matter how much advance I gave it. So all things (so far) checking out, I put fresh points in- preset to 0.19 Back fire- no start. I pulled the distributor out and dropped in a new one with fresh points- SAME DEAL. Cranks fine. Starter fluid no help. The coil gives a good spark- so does #1 plug through the distributor. The distributor is dropping in fine and aligning with the No 1 post in the cap dead on at TDC. It's getting light through new plug wires (suppression type) I know points are supposed to be run through COPPER CORE plug wires, but shouldn't I still be able to get this started with modern wires. After all, people that installed Pertronix all say they have their points in the glove box in case of their e-ignition dying, they never say they have the plug wires as well.

At this point the only thing coming to mind is bad timing chain. Help a brother out, if you have any ideas.

 

A lot of times if the coil is breaking down it will buck under load. Also, is it a backfire through the exhaust or popping back through the carb?

 

I'm with Roothawg- throw a different coil on it and replace the ballast resistor if you're using one just to be sure.

 

I echo the previous comments
Coils rarely go bad but they do. Some coils need to be mounted right side up. Also Condensers are the most common problem, dont even trust a new one.

 

after the coil, if that doesn't change. Take the cap off and pull the plugs, watch the rotor while cranking it one revolution over with a ratchet on the crank. after one revolution try turning the crank backwards and watch the rotor. This can help you see how sloppy the timing chain is. The rotor should move as soon and the the crank is turned. If it sits still for any of the reverse turning of the crank, that is due to slop in the timing chain. It could be ignition, realated. But it sure sounds like the chain may have jumped a tooth....

 

OK, I'll get anther coil on. The backfire this morning was from the carb. Just the once, after that I just had a crank, no start.

 

I'd be doing as Nailhead Jason first before trying a lot of other things. You may be fighting a sloppy timing chain or a plastic gear loosing it'teeth.

 

No extra or or ceramic Ballast Resistor, still have the resisted wire pairing the ignition wire from the key switch- it looks good. The perfronix was being fired from a 12v dedicated relay. (off line now)

 

Well I have a spare "known good" coil- but can I get away with leaving the condenser attached to the coil bracket disconnected while I try to get her started? (connected to the COIL NEG)

 

OK, I'm going out now and check the chain. Be right back.

 

Had a bad coil bite me a few years ago. The car would run fine on light throttle and shudder/miss if you tried to push it a little. I chased my tail because I had spark so I checked everything else multiple times. It finally died and wouldn't restart, had to tow it home. When I started checking it and again it had spark, but wouldn't start. However, once in a while it would start and run fine, but not restart after you shut it off. After exhaustive testing I finally tried a new coil; problem fixed. I have an old Sun coil tester so I tested both the new and old coils. The old coil put out about 10K volts while the new one pegged the 40K scale.

 

After a couple of full turns clockwise, I came to 0 degrees and then watched the rotor as I reversed the crank- I got a full 10 degrees before the rotor budged. Is it safe to say the problems is the timing chain?

Any way to start the engine in this condition- my brother has a big shop I can work in, but I have to get over there. If I advance or is it retard the timing by an additional 10 degrees, or add/subtract a tooth to the distributor drop? Something like that maybe?

 

Also any word on the COPPER CORE wires? Should replace these new resistor wires with copper ones with the points. I kinda hate to, as I am planning an HEI upgrade as soon as I figure out what to get. Also Once up and running- since the timing chain appears worn, I'd like to add a mild cam during the timing gear/chain replacement. Any pitfalls here? I never cammed up before- only went to OEM in past cam installs.

 

The wires are fine, don't sweat them. The move away from copper core wires was just because of electrostatic interference on electrical parts, points are mechanical so it never bothered them, but HEI's and radios get all stupid with it. The suppression stuff works fine with points.

Your timing chain is shot. If you pull the distributor and move it a tooth it may work for a min, but your cam timing is now off in relation to the crank shaft. If its jumps again, you could be hitting valves on pistons and causing even more issues. Your best bet is to get you a good quality timing chain, a Cloyes double roller is like 45 bucks, and start changing it out. The best part is, you'll probably be shocked at how much better it runs after you swap it out. While you there, put in a new front crank seal and one piece oil pan gasket, and a new water pump, it will be sealed up everywhere and no more worries for all that stuff for around a $100, plus an afternoon of work.

 

10 degrees sounds like the timing chain is all done, and if it stretched it may have jumped a tooth. I don't think I'd try to run it like that. If it jumped once, it could again, and then you're bending valves.

 

Automakers used radio suppression wires for years with points and condensers.

 

Ditto on the timing chain!








Bones

 

I had a sbc backfire and then would not start. A buddy suggested the timing chain, replaced it, problem solved.
By the way, it just happened to be a '70 El Camino!

 

I never did like the nylon aluminum cam gears that GM used.Pontiac was the worst offender for failures. Chevy and Buick were not too bad but still bad enough. Pontiacs were so hard on cam gears that the factory replacement was steel, P/N 483047, still remember that part number and the ones for the associated parts for a gear and chain replacement from the early 1970's. Think Chevy was 340235 but not sure of that one.I'm agreeing with other posters here about the cam sprocket and or chain failure. You might be dropping the oil pan to clear out the remains of the sprocket if it started to flake off.

 

ok, so I'm ordering the timing chain set C3023K + JV881 Cloyes/Mahle. I'll put on a new water pump since the ld one is off and probably 7 years old anyway. Any reason not to put a cam in as well. I wanted a mild street cam to go with the 4bbl Edelbrock carb/intake. It can wait, but since the teardown is this severe, I thought I'd consider it.

Any tips to seal up the oil pan since the timing cover has to come off?

 

Yes, spend the money on the one piece oil pan gasket with the little steel inserts. I put them on every sbc I build. Best money you will ever spend. They are reusable as well.

 

Milodon makes a nice one piece oil pan gasket that works great. About 30 bucks from Jegs. Clean the surface real good and put a bout a nickel size dab at the corners of the main cap and the timing cover. It has steel sleeves in the bolt holes so you can’t over tighten it.

 

Ha. Beat me to it!!

 

I wouldn’t put a cam in it without changing the valve springs. High mileage plus a cam with more lift and duration than it has had for a long time is a recipe for valve spring problems. Swap a mild cam in it with a set of Z28 valve springs and your good and should fit your heads and retainers you already have. And yes you can change springs without pulling the heads.

 

Next someone will tell you to do a compression/leakdown test and the next thing you know its....hey,I'm going to have the thing partially tore down to do the cam and timing chain I may as well do rings and bearings.
Mission creep

 

Check out the Melling MTC-1 camshaft. The advertise it as an “RV” cam, but it’s got the exact sam specs as the Edelbrock Performer cam. Great low cost upgrade, it really woke up my stock 350. The cam is around 70 bucks from The Rock. Don’t forget new lifters and new springs are a great idea. I would also install a new set of spark plugs.


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If the truck is late 60's with aluminum/plastic cam gear with over 30K on it , I guarantee it's shot and based on your description the next time you start it ; you could be bending some valves. Tear it down now and replace the timing gear and chain.

 

FelPro one piece oil pan gasket.

PN1881 1980-85 thick front seal RH dipstick; side rails trimmed for strokers
PN1880 1975-79 thick front seal LH dipstick; side rails trimmed for strokers
PN1885 1957-74 thin front seal LH dipstick
PN1882 Thick front seal straight side rails; side rails trimmed for strokers
PN1886 1986-97 thick front seal, one 1pc rear main seal GM bowtie short deck block


http://www.speedwaymotors.com/Tech/seals-thick-vs-thin-oil-pan-gasket.html



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It snowballs, if you aren't careful. Trust me, I am the king of project creep.

 

I suppose now would be as good a time as any to do the cam, if it's already on your to-do list. You'd just have to pull all these same parts off again to swap it out, and you've already got most of the front of the engine taken apart to do the timing chain. Not sure how much room you've got, but you'll probably need to pull the radiator, though you should have most of the coolant drained if you're doing the water pump. (Although, as soon as you think you have every last drop drained out and move the drain pan so you can get to work, another 17 gallons comes out all over the floor)

Follow the good advice above and replace the lifters (obviously) and springs when you do the cam. Check the pushrods too, while you're in there, make sure they're all straight and none of the ends are starting to mushroom.