I just bought a classic 1974 Revcon motorhome with a olds Toronado drive train. Bringing it home from the seller it started loosing power up a steep hill then started running rough. When I pulled over I noticed the engine temp running about 230. I was running the air conditioning like an idiot because Im used to my diesel which never overheats anytime. I shut the rig off and let it cool then when I started it back up it took a while and ran rough again than died and would not fire. Towed it home.


I ran a compression test and got 150 to 155 on all cylinders. I can see fuel squirt from the accelerator pump. I have spark but it looks kind of weak to me, maybe because its points? The plugs had good color but a few were kind of crusty. None smelled like fuel. The seller said the fluids were topped off but like an idiot I didn't check myself and the oil was 2 quarts low. I have fuel, compression and spark but no fire. Anyone have thoughts on this? Thanks.

 

Start with checking the points/dwell. Clean or replace the old plugs.

 

Old plugs are replaced. Would or could the points and dwell change that quickly? One minute its fine next its not. Also what do you think about going with a HEI or DUI distributer? Thanks for the reply!

 

Replacing the points and condenser is a whole lot cheaper than installing an HEI. Yes, if the condenser failed or there was no lube on the wear strip for the points or just a cheap set of points it won't take long. Timing issues will cause overheating.

 

Nice. Ill check it out. Thanks.

 

BTW cheaper is not an issue. reliability, efficiency and simplicity is more of a value to me. In that way do you think the HEI or DUI is better?

 

BTW cheaper is not an issue. reliability, efficiency and simplicity is more of a value to me. In that way do you think the HEI or DUI is better?

 

I edited your post and also sent you a pm.

As far as reliability, nothing is as reliable as points. HEI is a type of ignition system, DUI is a Vendor. HEI's are ok but its not as easy as it sounds. You have to run a full keyed 12v to it and then experiment with your timing and curve, possibly limit the vacuum advance. If you want to change possibly a points replacement setup like Pertronix.

 

One more question. If I am getting spark already how is a new points set going to fix this issue?

 

If you buy an hei from dui they will custom taylor th dist for no extra cost. I talked to them about ordering a distributor and they said they will curve them before they are shipped. You can find out toal mechanical timing on a bench pretty easy. since you have a heavy motor home depending on gearing you might need a slow curve. I disagree with oldcutlass and hei is pretty simple. there is some work involved but nothing scary.

 

Whats your dwell and timing? You can hook up a meter and light and get a figure by just cranking the engine.

 

Again I need a moderator edit? I also have not received a PM. I understand the HEI and DUI and don't have an issue with working the advance curve. Im much less used to points than I am a Ford Duraspark setup or fuel inj mapping for both diesel and gas. I used to overclock my computers to get the most out of them and now I find I just want reliability. Once you get the HEI or DUI setup it should be hands off for the rest of the time. That's why Im thinking in that direction. The wife is picking up a new points and condenser set in an hour so I will have that. What Im wondering is if the condenser or points are bad why am I still getting spark?

 

Again I need a moderator edit? I also have not received a PM. I understand the HEI and DUI and don't have an issue with working the advance curve. Im much less used to points than I am a Ford Duraspark setup or fuel inj mapping for both diesel and gas. I used to overclock my computers to get the most out of them and now I find I just want reliability. Once you get the HEI or DUI setup it should be hands off for the rest of the time. That's why Im thinking in that direction. The wife is picking up a new points and condenser set in an hour so I will have that. What Im wondering is if the condenser or points are bad why am I still getting spark?

I had planned on going HEI or DUI on my 460 engines I just haven't pulled the trigger yet. Is there a short way of explaining how to hook a meter up for dwell and timing? I can look it up but it might take a while. Im really not too familiar with points unfortunately. Let me know please. Thanks.

 

This might end up being a good learning experience for me.

 

Tell her to buy at a NAPA store and ask for quality points, or Standard ignition products parts. Don't buy a uniset. Gap them to .019. Your current set of points may be misfiring due to a bad condenser or burnt up, you can inspect the contacts. Make sure you lightly lube the cam in the distributor.

Timing should be somewhere between 8* and 12*. Dwell should be 30.

If the timing chain has never been changed it may have jumped a tooth also. Bring your engine to #1 tdc and see where the rotor is pointing with reference to the timing mark on the harmonic balancer. You can also turn the crank back and forth and measure how many degrees it takes each way for the rotor to start to turn.

I hate working on some RV's because of the room.

 

Napa is closed here. Oriellys is all I got for tonight. If this ends up fixing it I will definitely pull this distributor and put an electronic set in. Im missing out on big crabs in Bandon dealing with this crap. I just want it to run. I set it on the highest point on a lobe and adjust it there right?

 

Yes sir. I edited my post above.

 

Thought so. Thanks man. If that doesn't do it can you think of anything else?

 

I just realized Ive left my ignition on for over an hour. On my fords my coil would be smoking hot. This coil is cold. Is the Olds the same as the Ford as far as coils go?

 

Anyone?

 

If you can't verify fuel pressure I say start with mech fuel pump.

 

It depends on points position as to whether the coil has the small chance of overheating. In most cases no, it won't, the system is designed for the spark to fire once, however if the points for some reason keep arcing then yes.

 

Im getting 12 volts to the positive side of the coil but no spark when I put the coil wire to ground. Hopefully that's it. I just ordered a coil. It should be here soon.

 

The fuel pump was replaced the day I bought it.

 

New coil and still nothing from it. I have 12 volts to both the neg and pos side but nothing I can see coming from the dist wire from the coil when I put it to ground. Im stumped.

 

1974 was 41 yrs ago
When I dismantled some old 1968 era dist'rs a couple years back I found the upper bushing lube grease had become "cheese" and not grease at all. Some of the bushings were very worn- like 0.020". Guess that happens if the dist'r shaft [and points cam] moves 0.020" and your pts gap is 0.019" or so?

And, as the dwell changes so does the timing, which affects running, heating, etc.

You are doing all this coil checking with the coil's (-) terminal connected ONLY to your jumper to ground, and not at all to the dist'r wire, right?

 

The lube on the shaft looked good. Not bad in any way. I get quite a gap when I run it but no spark. The problem is I have almost zero access to the crank pulley bolt because of the rad shroud. I can't turn the bolt to get the dist cam to tdc. Ill have to get in there and do that but I thought with no spark from the coils fat wire to the dist on a ground then Im not getting voltage through the coil. That's why I bought a new one.

 

Unless you took the dist'r out
took the gear off
took the shaft out
pried out the plastic retainer and removed the felt washer...

you did not see the upper bushing lube grease/ cheese.

Sometimes you can move the shaft back n forth sideways and easily see the bushing wear, if it's bad enough. Or see the point gap vary, a lot. Depends on your vision and practice and whatnot.


I get quite a gap when I run it but no spark.
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Not sure what that means



The problem is I have almost zero access to the crank pulley bolt because of the rad shroud. I can't turn the bolt to get the dist cam to tdc.
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You can however turn the dist'r HOUSING such that the points open and close for testing purposes.



Ill have to get in there and do that but I thought with no spark from the coil's fat wire to the dist on a ground then Im not getting voltage through the coil. That's why I bought a new one
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This is also not clear to me. To prove out the coil:
take all wires off - terminal

place lead near ground, attach a plug, actual spark tester, whatever you have to show spark.

turn ign ON

Verify some voltage at coil +
like 12V probably, even thru a resistor, what with zero current at this time.

jumper the - terminal to your favorite ground point not too near the gasoline. Each time you ground and disconnect the coil it should make a spark.

An ohm meter could be used to ck the coil's low and high voltage coils for proper resistance- just guessing, around 5-10 low side and 10,000 high side.

 

I now have spark. I replaced the points and condenser as well as the plugs and coil. Its coughing when I try to run it. I have new wires to install.

 

Did you set dwell and timing?

 

Just want to throw this out, reading the beginning of the thread..he may have possibly damaged the quadrajet internally when overheating the fuel? It may not meter properly not to mention the accelerator pump is fragile specially if it's old.

 

I have spark now after replacing most of the ignition component's It still wont start and is coughing out of the carb.

 

Given the age of the engine and the failure mode of overheating, loss of power followed by no start and backfiring, i vote for a timing chain jump....plus i just tore down a very clean good condition 70 455 w original gear and chain that was about 1 revolution away from skipping teeth

history for the OP Olds used a a plastic material on its timing chain teeth. After 40 yrs or so the plastic is destoyed leaving a very loose chain that quickly wear the gear and jumps time....very common failure mode for these motors...many times a new t chain and gears along w a oil pump pickup cleanout will restore the engine to "like 40 year old" newness.

 

You also may inspect the cap carefully for hairline cracks or very worn or
crudded up electrodes. Make sure to run through the firing order again.

 

Are the plugs getting wet? If not try pouring a little fuel in the carb to see if it fires.

 

I poured some fuel into the carb and it coughed it out. Tru, I just replaced the cap, points and condenser, coil and plugs. Retro you may be on to something there. Thanks for that input. The engine has a legit 45,000 original miles but if the chains are like that I can totally see that being an issue. I just hope they are easier than replacing a chain on a 460.

 

Olds dist turns ccw, verify your firing order.

 

I had the plug wires backwards. It fires up now but still runs rough like it did right when this issue happened. Im wondering if its now a carb problem. Never worked on a Rochester which I think this is. Im pretty familiar with Edelbrock though and I think I have a 750 sitting in a box in my shop. What do you guys think? Running rough usually measn carb issues to me and this carb has been sitting for over a year. Should I swap the Edelbrock in there or just clean the Current one?

 

If the carb is questionable I'd put the Edelbrock.

 

The carb linkages are rusted all over the place. Im not familiar with this carb but Im very familiar with edelbrock carbs. Is there any advantage between the two? Thanks for the input.