Sooooo...... I just fired up my roadster for the first time and needless to say I'm pretty stoked about that. I have an old 350 in it until I get the funds to build my 327 the way I want it. The engine is pretty much stock, RV cam, intake, mallory dual point with Mechanical advance only and a new Edelbrock carb. I have the initial timing set to 12* advance and havent had it running long or well enough to set the total timing yet. At first I really had a hard time getting it to run. I've gotten it much closer by readjusting the rockers a couple times, re timing it, making sure plug wires are in order and checking for vacuum leaks. It definitely will stay running but bogs hard when trying to give it some gas. The accelerator pump is working fine. I pulled the vacuum caps off of the carb for ****s and giggles and it runs much much better which leads me to believe that I have a rich condition. How do I adjust the mixture aside from the idle circuits on these carbs? Does anyone have any other insight on a situation besides running rich? thanks
I'm not sure. The carb is new so I never checked it. Is this a common occurrence? Posted from the TJJ App for iPhone & iPad
Give it some timing, go counterclock wise with the distr just a touch and it should perk right up. If not then you have something physically wrong and you'll need to back thru ign etc.
Are you sure the engine is good ? You really need to pull a few plugs and read whether they are rich or lean... Typical idle mixture adj is in till they seat, then out 1 1/2 turns.... Both sides equal.... Turn out 1/8 turn at a time till max RPM is achieved, then back in 1/8 to 1/4 turn.... I have gotten a few bad edlebrocks out of the box.... Your kind describing the issue I had. It was the carb.... 1 on a 289 and 1 on the 350... If you have a buddy with a good carb, swappum and see.... Is the exhaust Black, Blue or clear? how does it smell? If your unclear on the engine, While plugs are out do a compression check...
What other reasons could cause the engine to run well after removing the vacuum plugs? Posted from the TJJ App for iPhone & iPad
What I know about the engine is that is was very clean inside with very little sludge etc. i pulled the heads to check the bore and give it fresh head gaskets and ther wasn't a crazy amount of carbon deposits. The cylinder bores could stand to be re honed and there is a small ridge at the top. Oil pressure seems to be good. It's an older engine, my plan is to use this engine while working out the bugs in the car, then save to build a nice 327. The exhaust seems ok but has a rich smell to it. I pulled the plugs after barely running it and nothing really stood out as being abnormal. I will pull the plugs this evening and take a reading again. Thanks Posted from the TJJ App for iPhone & iPad
Flooding. Stuck needle and seat. High float level. Excessive fuel pressure. Sunk float. Stuck power pistons. Damaged metering rod tips. Low manifold vacuum. Choke not fully opening. How much manifold vacuum do you have at idle?
New carb, so I haven't opened it. Fuel pressure is regulated to 6 psi and I have a gauge to verify this. Don't know manifold vacuum. I need to get a gauge. Posted from the TJJ App for iPhone & iPad
Obviously you are giving it air and if it is rich then it will clean up. And 6lbs is a tad high for the edelbrock, i keep them 5 1/2ish - the edelbrock isn't dramatic as a holley when needle & seat are overwhelmed, easiest way is to look into the secondaries and see if fuel is laying in the wells on either side of the venturii, the wells are what the gate for the secondiaries pivot into. There shouldn't be any fuel inthere. If timing is overly retarded it will bog when applying throttle because it is firing right on top of the piston and can't make power. It too will love some more air when you pull the vacuum caps. I bench set edelbrocks at 3/4turn out from seat (idle screw), there are times when it wants more fuel and that will have a lot to do with cam and valve timing. But 3/4 turn will always work and will not be rich. If you have it at 3/4 turn and the motor idles rougher than it should with the cam that is in it then you give it more fuel to see if it likes it. best not to give it too much fuel at first, let the engine tell you what it wants. Another biggie is the type of spark plug, it is very easy to make a mistake and put the wrong plug in there. What is your plug and do you have cast iron or aluminum head?
Good advice.. I'm on my way to a BBQ so I can't make these changes. I don't know the exact spark plugs but they are new ac delcos. The local parts store recommended them to me. What plugs work well on these?The heads are stock low compression cast iron heads. Posted from the TJJ App for iPhone & iPad
I had BBQ earier, NorthCarolina pulledpork with hotsuace and coleslaw! man, thats eatin. The plug might be a problem, depending on the year the plug could be either gasket or taper seat. Others on here mght be able to narrow the break better than i but i think the plug is tapered seat from around '71 on up and the earlier are gasket. For som ereason i was thinking gasket were even earlier but not sure.
Going to another HAMBer's for brisket so it can't be bad! Definitely taper seat plugs. Posted from the TJJ App for iPhone & iPad
What measurements should I shoot for with a vac gauge? Thanks Posted from the TJJ App for iPhone & iPad
Shoot for the highest reading on the gage using the idle mixture screws.... Then reset the idle R.P.M. to factory settings.... Anywhere from 650 to 750 rpm's... Then recheck the vacuum readings... I've gotten 23 inches inches of vacuum off a 302 Ford and I was able to dial down the rpm's to 350 and the motor still ran...
Plug readings probably aren't real accurate or critical right now as it sounds like it's obviously running rich. You've proven that by unplugging vacuum ports and seeing the idle improve. As mentioned, manifold vacuum at idle, in neutral, at running temps, should be around 20 inches, with a "stockish" cam. An RV cam might pick you up another 1 or 2 inches. More initial timing will also increase vacuum, up to a point. Do you have another distributor with a working vacuum advance that you could swap in? Street motors love vacuum advance, especially full manifold vacuum. Make sure you're not connecting the distributor, or a vacuum gauge, up to "ported" or "off-idle" vacuum. Once you get your fuel pressure and tune-up sorted a bit drive it a while and then do your plug readings.
The advice to use a vacuum gauge is one of the most useful Tips I've ever been given. Basically, I got the motor running, but it was pig rich and would die after a few minutes. I plugged the vacuum gauge in and only managed to get 13" vacuum at idle. I rechecked initial timing, regapped plugs to .035" and loosened the rockers 1/4 turn as the vacuum readings indicated that the valves could be too tight. All of these changes made relatively little improvement. I opened the carb up and found a little bit of sediment in the bowls. I cleaned the carb and blew compressed air through it. The floats were slightly too high as well. I swapped jets and metering rods which helped with the richness and improved the vacuum to 15". Even with these adjustments the engine would still bog and eventually die. After exhausting all logical possibilities I was convinced that I must have a vacuum leak in the intake manifold. Before I pulled the intake, I decided to swap in a crusty old stock vacuum advance dizzy in place of the new Mallory dual point (mechanical advance only). Lo and behold the engine ran like a champ!!! I wound up settling on 0.092" main jets (edelbrock #1425) and the 0.073"x0.047" metering rods (edelbrock #1446). Vacuum now reads 23" at idle. It might be a tad too lean but it's a night and day difference. How could a brand new distributor run worse than an old one? Even at idle I could tell a huge difference. The new dizzy is ugly and the cap looks too modern so I will look for a more period replacement, but I'm very happy none the less. I hope this info is useful to someone who encounters the same problem I did.
First, thanks for reporting the solution that you found to your problem. A vacuum gauge is one of the most important diagnostic tools. The new distributor might have worked but you would have to advance the timing quite a bit more at idle which is what the vacuum advance does but then it might have too much advance at higher rpms. Distributors without a vacuum advance are for race applications where you aren't worried about power at idle. When you buy a new carburetor, it often needs changes to make it work on the engine you install it on.
TESTIFY, BROTHER DEVIN!!! For thine eyes have been opened and thou art being BLINDED by the LIGHT OF TRUTH! Can I get an AMEN!!?? Like I said, street engines love initial timing and manifold vacuum advance is a great way to get it. Now mount the vacuum gauge to your steering column with a hose clamp where you can see it while driving and get ready for a real education. Check the vacuum at idle in neutral. Watch what happens when you drop it in gear. Watch what it does when you accelerate, decelerate, advance or retard your initial timing, go uphill or downhill, or drive into a headwind or with a tailwind behind you. Then figure out how much vacuum it takes to raise or lower the power pistons in your carb. If the power pistons start to raise at 15" of vacuum and you're idling in gear at 12" or 13" the carb is trying to richen things up like your were accelerating down the road when you're actually just sitting idling in your driveway. This is where it pays to tune for maximum steady vacuum at idle. And if you can't get the vacuum up sufficiently (big lumpy camshaft, etc.) then you look at putting lighter springs under the power pistons. Don't worry about how the distributor looks as much as how it works. Anyways, thanks for sticking with it and following thru and posting your results here. Several member here, including myself, will go on and on about using a vacuum gauge to sort out these kind of problems. But I don't think one person in twenty ever bothers to actually try it and learns just what the engine's manifold vacuum is trying to tell them. Stick with it. You're just getting started.
In an earlier post you thought the plug is an r45, that is the old style gasketed plug and it'll screw into the tapered seat but the motor'll run ****py.
So if I wanted to put the dual point back in what would be a good initial timing? I had it at 12* before. Posted from the TJJ App for iPhone & iPad
Well you could check the initial timing you have now with the "ugly" distributor with the vacuum advance connected. Then you could drop in the "purty" distributor with no vacuum advance and set the same initial timing. BUT I HAVE TO URGE YOU NOT TO DO THAT! You could end up with too much TOTAL timing and end up with spark knock. You could end up with an engine that doesn't want to start hot or bucks against the starter when cranking. Street cars like vacuum advance for much better driveability and better mileage. If you have to, find a more period correct looking distributor with vacuum advance, polish it up or whatever and run it. Or contact GMC Bubba here on the HAMB and see what he can fix you up with.
Cheap way out,dual point with vacuum:http://www.ebay.com/itm/ACCEL-DUAL-...Parts_Accessories&hash=item5af2c45008&vxp=mtr
The distributor I installed is truly UGLY lol! It has peeling chrome, rust, dust and spray bomb overspray. Not trying to sound superficial. I'd like to replace it with a more period looking unit. I'm just curious about initial timing settings with the mech advance for knowledge's sake.
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