i have a little question concerning my 69 fastback with 302 engine:
engine is completely rebuilt, so is the tranny. i added a 280 H comp cam, holley 600 carb, pro products manifold, flowtech headers, new pistons, rings, and crank, pertronix ignition, 6 blade fan, 3 row radiator, and so on and so on.
so, start the engine, and it roars like a beast, very responsive, very powerfull it would seem... but, as soon as i put it in gear, DRIVE,R,2,1, the engine stalls. i checked all the vacuum hoses, all tight. if i set the ignition and idle to normal settings, and i drop it in gear, she stalls. if i keep it going in D and then i adjust everything to normal idle speed and ignition, and i take it out of gear, the rpm's go up to about 2500-2800...
i'm running out of ideas so i hope you guys can help me out with this... not too many people around here in belgium that know what they're talking about when it comes to mustangs and V8's.
any help would be greatly appreciated....
harald
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69 fastback 302, holley 600, typhoon intake, comp 280H cam and springs, flowtech headers,KB hypereutectic pistons and rings, pertronix ignitor, C4 transmission, ford 9" rear end, now 2.75 but 3.89:1 gears coming its way... http://www.gti-killers.be
if i do get it going it runs more or less okay, but not really powerfull, a bit lagging even. but it does not produce any black or blue smoke. this is something that has been this way since the 1st startup since the works have been done. problem is of course, that i did everything in one go, so that i don't know which modification is causing this problem.
the carb is a second hand job wich has been rebuilt with new gaskets and all that, but apart from that i don't know what application is was on before this . i know that when i got it it had 66 jets in, now i tried 70 jets to see if that made a difference but apart from it being more powerful in park, the problem stays the same.
with a vacuum gauge at about 1200 rpm's, i have more or less 0.6 bars of vacuum (sorry, no inches HG here...) but any lower than that and it stalls out again, even in PARK. so if i then adjust it all to keep going in DRIVE, i have only got about 0.2 bars of vacuum, wich is almost nothing really. and, when its in drive and idling to more or less the lowest possible speed, and i pull the throttle, it doesn't seem to want to rev up. almost as if its flooding with fuel. no blue smoke, however. maybe i should try a set of 64 jets and see what happens then.
but , i was trying it again a minute ago, it seems to backfire sometimes during cranking (and the ignition is correct) so that tells me too lean a mixture, or am i really mistaken now?
With the new info, I think 69 is on the right track. You have some sort of timing problem if it's popping back through the carb. Did a mechanic assemble the engine? Maybe the the cam/crank were not in time when the chain was put on. Double check the firing order and make sure the plug wires are where they should be and that the ignition timing is correct. Just keep in mind that even if the ignition timing is correct, the cam could still be out of time with the crank.
If the carb was running to rich, it would be belching out a lot of black smoke.
How did you hook up the new pertronix? I haven't got to that point on mine yet but have heard plenty of others having problems if they hooked it to the positive side oof the coil to power it and didn't have enough voltage. I think soaring said you need a minimum of 7.5 volts to fire it.
Just one more thought. I hate it when that happens!
Does anyone here know if the rockers on that year are adjustable or not? If it is, maybe one or more of the valves could be out of adjustment and/or too tight & prevent them from fully closing. That could also account for the popping & low vacuum.
Posts: 499
Joined: 5/25/2005 From: Waterford, MI Status: offline
70 should be fine for jetting on a Holley 600cfm carb... mine is set at 69 and I still have some room to go bigger before it starts to foul my plugs.
With the car running, look down the secondaries on the carb (the back two holes) and see if you can spot fuel trickling into the engine while idiling. (I had a problem that acted like yours, so while it seems off target... it's worth the 2 minutes to check out).
first off, the secondaries are not trickling, had that problem in the beginning but put renew kit in, that solved it. plus the fuel bowl level is correct too...
the rockers are indeed adjustable but i 'd hoped they were correct as once the engine is at operating temp it doesn't backfire anymore at low engine speeds when i give it some throttle.
next, afraid to say that i am a mechanic BUT i assembled the engine together with a another mechanic who rebuilds engines more or less daily so that should be okay, as goes for the firing order.
the timing, however. is set in PARK to 6° btdc at the lowest engine speed i can keep it running. like i said, i tried to set the timing to 6° btdc in DRIVE and see what happens, but when i do this it'll keep going, but when i put it back in drive it revs up to 2500 revs.
maybe indeed the valves are to tight, will check that tomorrow, getting late here now. the neighbours are this close to calling the cops on that weird guy with his american car haha. anyway guys i wanted to thank you again for the ideas and suggestions so far. i'll get it in the end, with your help...
another thought to go to bed with; someone mentioned converter lock up to me earlier today, but that was overhauled by a specialized company together with the tranny. anyone got experience with that?
Your vacuum is really low. 1 Bar (or atmosphere) is equal to aproximately 14 psi. A good vacuum reading should be around 18" Hg, or in metric terms aproximately -1.3 to -1.4 bar depending on the cam grind. I agree with the timing remark, and the vacuum leak. It would be easier to correct the timing after fixing the vacuum leak. The other possibility is your cam timing. Did you put a new cam in? Retarded cam timing will do the same thing.
If you have any carb clean or WD40 spray around the base of the carb and the vacuum nipples. Also pinch off the line to the power brake booster (if you have one). Spray around the intake manifold to make sure you don't have a gasket problem there.
Your base carb settings for a warm engine should be 1.5 to 2.5 turns CCW on the idle mixture screws, with the butterflies open aprox 2mm-3mm for an idle of 600-800 (again really depends on your cam and engine condition).
If your butterflies are open correctly but your idle mixture screws are way out, you've got a vacuum leak. If your idle mixture screws are close, but your butterflies are open further, you've probably got a timing issue (cam and/or ignition). If your butterflies are open and your idle mixtures screws are way out, you've got more than one issue (like ignition timing, vacuum leak, and possibly cam timing).
BTW: to convert CM Vacuum to "Hg, divide the CM of vacuum number by 2.54. (as an example a vacuum reading of 50CM would be equal to ~19.68" vacuum) and 1 bar (or atmosphere) is = to 13.7 PSI. To convert from Bar to "Hg multiply your reading in -Bar by 13.7 (example -0.6Bar times 13.7= 8.22"Hg).
Man, I almost forgot the most common cause of low vacuum. PCV valve malfunction!!!!
There is a hose that runs from the base just under the carb should be about 13mm in diameter. it goes to one of the Valve covers where there is a little valve. Pull the PCV valve from the valve cover and place your thumb over it. If it starts running better, replace it.
the holley carbs are a pain in da a s s unless ur familiar with them..i changed mine out with an edlebrock to fix the same problem u have..also check the back hose connected to the carb where the brake booster goes into,it slips of the holley carbs quite iften..
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1969 351w edelbrock carb & k&n filter msd hei dist., duel exhaust front disk.,new shocks
A quick search on the net and I see a lot of posts that show 1 Bar= roughly 14.7psi. Thanks for the correction. I'm stuck on 14.7 as the stoichiometric ratio and 13.7psi as the pressure at sea level. Need to pull out the books again.
I'm sure that 69Mach1377 is probably right. It just isn't clicking for me. I'll pull the books tomorrow just in case.
At that the vacuum of -0.6 Bar would be aproximately 8.8" Hg. which is still very low, and in the range of what a bad PCV valve would show.
69Mach1377, I hate the thought of giving out the wrong information, so thank you very much for jumping in on this. Greatly appreciated!!!!
i am starting to see some possible things here. 69, the tranny is a 68 C4. scott thx for the advice as well, did put a 280 H comp cam in, so that might be the problem but if so, how do i correct that problem? pcv valve might be a problem, hadn't even thought of that yet.
i did do the test with brake cleaner and it doesn't change the rpm when i spray the base or vacuum connections, so the carb should be tight, will check the manifold once again though.
for the carb settings; the mixture screws are where they oughta be, and in my opinion so are the butterflies, more or less (havent really measured that but will do later today when i get back from work.)
the only problem is, for these settings it revs a lot higher then 800 rpms i would say (don't have a rpm gauge), so that seems again like a lean mix to me, and then possibly due to vacuum leak
scott, before i forget to ask and do something really stupid, what if i disconnect the pcv hose and screw a bolt into the intake manifold? wouldn't that avoid having vacuum leaks at the pcv valve? or would this then affect the engine in another way? because i can see how it would suck air in through a faulty valve, but if i plug the hole in the manifold the valve would just ventilate to the open air, right?
i won't touch it till i heard from you, just to be on the safe side, hehe.
since you're all pretty much thinking about ignition, i tried the following: i hooked up the vacuum gauge and turned the distributor so that i got more vacuum (in this case, more advanced) just till it hit about 0.8 bars of vacuum, i can't turn the distributor any further because now the vacuum advance dashpot is almost against the intake manifold. and i threw it in gear. guess what....
IT'S RUNNING!!!!
hooked up the strobe light, and guess what now: its indicating somewhere around 30° btdc, ,kinda hard to tell on a stock pulley, wich only indicates to 20° btdc.
so, am i correct in assuming that yours truly put the distributor in one tooth off, or maybe even two?
it makes sense to me, in the way that for the same position of the cam and pulley, my distributor axle is now passed the point where it oughta be thus giving ignition way too late....
please confirm this way of thinking, or call me an idiot if i'm wrong but i think this could be it. just wouldn't like to take it out and start fumbling about with it if you guys think that this is not the problem...
gracias so far guys.
ps, got a call from my brother saying that he's on this forum too, asking the same questions obviously for the same car. so if you come across this problem somewhere else on this forum, that's him...
yo bro finally we get together on the forum, so from here you go alone and with results because the car is running and needs little adjustements. thanks in advance to all the guys who helpt until now. thanks and see you
Posts: 499
Joined: 5/25/2005 From: Waterford, MI Status: offline
Double check your TDC calibration on #1 piston with the marks on the balancer. 20 degrees is a lot of advance.
Easiest way is to pull #1 spark plug and manually turn the crank with a breaker bar (disconnect the battery!) check the position of #1 piston by carefully inserting a screwdriver in the plug hole.
The balancers are known to slip when the rubber insulator begins to rot out.
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69 fastback stalls in any gear... HELP - 
. the neighbours are this close to calling the cops on that weird guy with his american car haha. anyway guys i wanted to thank you again for the ideas and suggestions so far. i'll get it in the end, with your help... 
Vacuum really low - 
but i think this could be it. 
