I was rereading Randys thread "SBC Temperature" and then C9s "GOT TIME? - A reprise on ignition timing for GM engines". Both are quite timely and relavent to me, as I've been experiencing similar SBC heat problems. Well, I took off the air cleaner so I could get a better view of my carb, and yes, my vacuum advance was hooked up to a port on the p***enger side of the carburator. So, I notice that there is an un used port low on the front end of the carb. I fire up the engine, stick my finger over that portm and ta da, much suction. So, I unhook the tube from the vacuum advance, hook it up to the unused port, fire up the engine, and it starts right up. Sounds a whole lot different. Idles faster, considerably so. So, here's where I get to the questions-Whats next? Am I needing to check or adjust the ignition timing? I've said it before-I'm a newbie-in most all automotive respects. I'm going to go back and read through the archives, but if anyone else would care to share their guidance on this thread, it'd be greatly appreciated. As always, Thanks in advance for the help! Oh, I had planned on actually giving her the road test, but my dumb*** roomate left the house, with his car parked right in front of the garage Maybe later tonight.............
the timing should be set eith the va***mport taken off thedist and blocked. it will bring the idle up some when reattached. just reset your idle speed. jerry
I've been tuned into those threads as well. This what I did and the sbc is purring. plug the port on the front of the carb with a plastic cap. Run your vacuum advance off of the manifold vacuum. I T'd into a port on the manifold where my ****** vac is attached. To dial in the timing be sure to disconnect the vacuum advance AND plug the vacuum line (golf tee works awesome). When your done setting the timing, fuel mixture, and idle; reconnect your vac advance and get back out on the road where that car belongs. Cheer, Tim
If you had your intial timing(at idle) already set and was just plugged into the wrong port, go ahead and change ports(plugging the old one) and nothing else. Now your getting the full benefit of the vacuum advance portion of the dist. I hate to admit that DrJ was right at ANYTHING, but he was on the vac*** ports on the carb. I sobered up and inspected my Holley and low-and-behold, there was the f---ing port low on the front right where it should be. I had been connected to the timed-port all along. Changed it, started up and turned down the idle, sounded a lot better, went for ride and engine prolly runs 15' cooler. It makes no difference at cruising RPMs, timing is 'all in' anyway and air is flowing thru the radiator. But off the freeway, its much cooler, running like a 'non-smog' engine should. Alright, DrJ and C9 can stay...
I've never quite understood how anybody can expect to get manifold vacuum from ABOVE the carb ****erflies Afterall, you are then just measuring a bit of **** through the carb, and if you stick on a restrictive aircleaner you will get more ****, so you are measuring how good your air filter is, not how much vacuum your engine is developing
[ QUOTE ] I've never quite understood how anybody can expect to get manifold vacuum from ABOVE the carb ****erflies [/ QUOTE ] I understand that some of the older Holleys have manifold vacuum at a small bib on the right side above the ****erflies. Makes sense I guess, specially with the Carter/Edelbrocks having ported vacuum down low (front right small bib) and manifold vacuum (front left small bib on the same plane). Any one of a number of simple tests will tell you what you have. Vacuum gauge, rpm change or not when vac advance hose is removed or replaced as well as a finger over the opening to test for vacuum at idle. I think the basis for this confusion is the Carter instruction sheet which calls for the distributors vac advance line to be connected to the right front bib - which is ported. They either ought to tell the whole story or leave the information off. The instruction sheet for my Carter 500's dating from 1985 make note of the right front bib for timing purposes. The approx 1999 Carter 750 says the same thing. And maybe we can't blame Carter for it. There seems to be a lot of confusion concerning where to source the vacuum. I see a lot of interesting arrangements at car shows and rod runs. Some of them more than interesting. My all-time favorite was a 55 Chevy - a nice one - with the vac advance line running from distributor to a small add-on bib on the oil filler cap on a rocker cover. Was a strange sight, especially when combined with the nice cast aluminum breathers on both rocker covers. Lotsa times I ask questions about interestng setups, but on this one I figured the owner either totally screwed up or he was so damn smart that I'd never understand why so I just walked away.
You did plug up the unused vac port on the carb right? It kinda sounds like you left one open? Which would defenatly make the motor run faster at idle.
Going to direct manifold vac increases timing at idle, bumping the speed up. Adjust to suit. This may lead to several rounds of minor tinkering, as the increased isle speed might have put you into centrifugal advance.
okay, I finally got to get the car on the road. Ran pretty good. Like I said, I swear it sounds quieter! Anyhow, temperature wise, started off pretty good. Got up to 180, and stayed there. Gradually started rising at the stop lights. Would get to 190-195. Then cool back to 180-185 on the road. Eventually, it'd get a bit hotter on the road, 190 or so. Maybe up to around 195-200 at the lights. Now, is 200 out of line, temperature wise? I'm just kind of fixated on keeping it around 180. Why? I don't know-just reading what some of the other guys are running at (180!) makes me jealous and envious So, I'm looking at a fan shroud as well-are those $20-something dollar universal shrouds worth while? I've seen some on ebay and other websites, my local Pep-boys and other shops don't carry them.....
Factory SBC's (New, emissions motors) run around 220 all the time!) Lower emissions, but also a little less power, but No, 200 is nowhere even close to "too hot".
Sweet! Glad to hear that 200 isn't that bad. I just had it in my head for some odd reason that with the 180* thermostat I should run around 180*. Any advice on fan shrouds?
The Jalopy Journal
