Hey All, the snow finally melted away here in Seattle this weekend. I went to the garage where I'm storing my car this year to tinker on her a bit. One of my goals was to be sure the timing was set right and the carb adjusted properly. I know the guy I bought it from last year was messing around with it a little. Sure enough, it was about 12 degrees out, and he had cranked the idle and mixture screws around to compensate. It started hard, idled a bit high and hesitated and coughed when the secondary's oped up. Now it starts right up, idles nice and low and runs like a top when I drop the hammer down. Finally to my first question:
The distributor has been retrofitted to electronic. Stock Delco stuff. That wouldn't change any of the specs for tuning right?? It runs great, but just wanted to check.
Question 2:
It's cold out,..when the car is running, I've only got condensation (steam) coming out of the left pipe. I've had alot of 70-73 GM's, and none of those cars did that. I know it's not coolant being burned. I'm not really concerned, just curious. Anybody know the reason why??
Thanks

 

#1 you didn't mention what you set your timing to?

#2 yes there will be some condensate emmitted from the exhaust until is is warmed up. It will be in the form of white smoke and will probably spit some water out. Its a process of physics cold metal parts with a hot gas, creates vapor.

 

1) Stock delco electronics? You mean HEI? I wasn't aware there's a stock conversion that fits under the points cap. Plenty of aftermarket units.... Generally you'd aim for stock-like numbers if the unit still has points-style mechanical advance. One of the benefits of HEI is it can run higher initial and use less mechanical advance.

2) It's strange to *not* steam while warming up! There may just be a bend in that pipe that collects condensation when it's cooling.

 

I think the OP's question is why only the left & not both.

 

Theres a heat riser in the left. It slows the flow of exhaust to get mere heat to the engine and assist the choke.

 

Thanks for all the responses!
I just set the timing at 8 (b) like the book said, and yes...HEI. Sorry for not being clear on that. I haven't turned wrenches for a living in about 12 years and I'm losing some of my vocabulary and skill. So would there be a benefit to running the timing a bit higher?
As for the steam, Even after I drove the car it was still coming out of the left only.
It seems that if there was a fair amount of moisture trapped anywhere in there it wouldn't last that long. The heat riser theory makes sense. I do recall watching these running on youtube videos etc. when I got all giddy about buying one and seeing this effect. Maybe most people don't notice. I was just standing behind it listening to the sweet sound and thought it was odd.

 

Wouldn't hurt to check your plugs just to rule out any coolant issues.
(head gasket or worse) my guess is just condensation like oldcutlass said.

 

Yep, I pulled them out just to be sure and they're clean. I'm running a 50/50 of coolant, and I know what that smells like when it's coming out of the back, so I'm not worried about that anymore. Thanks for the tip though!

 

Yes, if it's HEI, then most folks run a higher initial - 15 to 20 degrees - with far less mechanical advance. If it came with this swap, you might want to double check the wiring to make sure the coil and HEI are getting 12V and don't use the resistor wire.

It can take quite a while for a car to finish steaming. I'm not as familiar with the big block exhaust, but I assume there's a 90degree bend on the driver's side right after the engine. Great place to catch water. If it's still doing it after a good drive, then it might be a little worrisome. The heat riser shouldn't have anything to do with it, as that doesn't actually impact the exhaust flow - it's just a manifold that fits over the exhaust manifold. When the thermo switch in the air cleaner is engaged, it'll pull air from around that area instead of from the end of the snorkel. So it's just pulling air *around* the exhaust manifold, which is hot, instead of cold air.

 

The mechanical curve with an HEI is different so the base timing needs to be bumped up the achieve the proper amount of total advance.

Start at 20° BTDC @ 1100 RPM and go from there IF the weights haven't been changed with an advance curve kit.

 

I'll get in there and find out exactly what's been changed before I do anything else. It makes sense now that it was set at 20, but it didn't run right. Thanks for the info fellas, I'll be back with more info and questions I'm sure...

 

That's not what they're talking about.

They're talking about the bimetallic spring-loaded butterfly valve where the exhaust or crossover pipe connects to the manifold on one side, which remains closed while cold (unless revving the engine), directing the hot exhaust through the exhaust crossover in the intake manifold, under the carburetor, to reduce warm-up time.

- Eric

 

Maybe one side of the exhaust runs cooler than the other (assuming stock style duals, no X-pipe). Do you have a meter with a temp probe? That might tell you something. 70-72 455's didn't use a heat riser valve.

 

I do have a temp meter. And no X pipe. Would this be normal?? What would make one side run hotter? I'll try to get over there this weekend and go down the list. I'll try to give it a good drive as well (weather permitting) to see if I can clear this up. Man, I can't wait to get that thing back in my own garage. I hate that it's out of reach. I just wanted to have some room to remodel my shop without having to worry about banging the car or parking it outside to do work, but this is anoying... thanks again for the ideas and info...

 

Like I said 2 posts above:
- Eric

 

Ha! So you did!!! You got to it before I did. I was sitting in a meeting, not thinking about the meeting but my Olds obviously, and realized that you had given an explanation for that already...thanks!

 

Well, that makes more sense then.
Those are high on my "throw away" list, so I completely forgot about them.

 

Anytime!

The same thing happens to me at work - inadequate internet access, so I use my phone, and when I get back to a message, sometimes I miss a few from just before, and end up catching them later when i get home .

- Eric