thrustnut Posted March 20, 2009 Share Posted March 20, 2009 The build is a stock 1977 Z block, flat top pistons, P90 head with stock cam, Arizona Z intake, Carter AFB 625 CFM carb and headers (fresh rebuild). The ignition is a Crane Cams Hi-6R. The problem is it WILL NOT start if you don’t pump the gas like three or four times to get it to fire. I know this is normal with a carb. car, but when it fires it revs up to like 4-5K RPM, hangs for a second or two, then dies. You can catch it (sometimes) by pumping the throttle. It will not idle at all, I adjusted the idle stop in a couple turns to try to get it up high enough and it had no effect. I turned the mixture screws in then out 1.5 turns, but adjusting them out just seems to make it run worse. I took the top off the carb yesterday and the floats where pretty screwed up (bought the carb used) so I adjusted the upper limit to 7/16, and the dropped to 15/16 (carter specs) and disassembled and cleaned the carb with solvent and compressed air. I know the carb is big for my app, but i was intending to use it on a 350, and figured it would be good enough to at least do my engine break in and get it over to my new house. I have checked and re-checked the timing, when 1 is at TDC I read 0 on my timing plate, the notch is aligned with the slot on the cam, its in #1 hole, that’s where it was when i took it off and the cam #1 lobes are "bunny eared". The dizzy shaft is at 11:25 position with the rotor pointing at #1 wire. Every once in a while it will blow a little fuel out of the carb, usually when it comes down from its 5K burst, and it seems to run sort of ok when your pump the throttle to keep it going. It is also non responsive, like you can crack the throttle, even a little and it takes a full second (at least) to respond, then revs up what i think is not matching the little bit of throttle movement. Im running out of ideas on what it could be, I have a strip kit for the carb, so I can try different stuff but it should idle the way it is. I should also mention, the intake looks to be fully seated on the head, the carb gasket is new, I have disconnected and plugged both the vacuum port for the brake booster and the line going to the carb, with no change. I have plugged all the vacuum ports on the carb, with no change. I would like input because my next step is a NEW Holly 390 carb, and they aren’t giving them away, so I will be pretty upset if I get one and it still wont run. Any input is helpfull, I know there’s a bunch of older guys who have been running these for years out there who have to know something. Thanks, Chris Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 21, 2009 Share Posted March 21, 2009 I'll be honest and say I don't know a thing about Carter carbs so your specs and adjustments mean nothing to me! What I will say to you is that during the break in period is not when you want to be fiddling around with your carb to any great extent other than to adjust simple stuff like idle speed. A sloppy rich or dangerously lean carb will shorten engine life in different ways, but it will shorten engine life! Can I say that if the effort has gone into rebuilding your engine, give it half a chance to run right by making sure that things like your distributor and carburetor are in half decent running order, and a new Holley may solve your problem, at least it may have a calibration that's somewhat close to what you need. Even if it isn't the carb fouling things up, you know your carb, at least, shouldn't be the culprit! Once you've managed to sort out the basic running ie proper idle, you can then move onto tuning the rest of the carb to your needs. The whole exercise sounds like you have a massive air leak somewhere, so triple check everything on the induction side of your engine, even to the point where you strip it all down and reassemble it. A single carb setup is straightforward to remove and reassemble, I know! Good luck! As far as starting your engine, when warm, you should be able to simply turn the key and the engine should fire up without blipping the throttle. When cold, one press to the floor with the throttle should activate your electric choke (if you have one) and dump enough raw fuel into the manifold via the accel. pump to again fire the engine right up. If it starts and dies, then its a mixture issue, either lean or rich but mostly lean and with a rev to your rpm's, sounds like it's lean due to an air leak somewhere. All of this applies to stock or mild cams, big cams are more 'cranky' when they're cold and harder to set up with a smooth hot and cold idle due to their lopeyness. Not impossible, just harder. I hope this helps a little. Cheers. Quote Link to comment Share on other sites More sharing options...
steveosupremeo Posted March 21, 2009 Share Posted March 21, 2009 sounds like a big vacuum leak. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 21, 2009 Author Share Posted March 21, 2009 I pulled off the intake and exhaust today, exhaust first to make sure the intake wasn’t sitting on the exhaust somewhere preventing it from sitting flat on the head, no problem there though the hardware was all a little loose (thermal expansion?). What I did find is that it appears one or two of the exhaust ports may be leaking into the intake manifold. I just see some staining from exhaust to intake. I was using a stock gasket, I am gonna order a MSA header gasket today. The imprint from the intake on the gasket makes it look like it was sitting much tighter on the top then the bottom, maybe adding to the transfer from intake to exhaust? It also appears i am running rich as I had fuel puddeling in the intake. I pulled the carb off and noticed that the on the Arizona intake two of the stud holes are drilled into the intake passages. The studs where tight, but is there any reason to seal the threads? Just wanted to see if this may be a step in the right direction, if anyone else has had this problem, or if I’m crazy. Thanks Quote Link to comment Share on other sites More sharing options...
jt1 Posted March 21, 2009 Share Posted March 21, 2009 Just checking- do you have the big nipple on the bottom of the carb capped or hooked to the brake booster? jt Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 21, 2009 Author Share Posted March 21, 2009 There are two big nipples, on the primary (front) of the carb and another on the secondary (back) of the carb. The secondary side is plugged, the primary side I had attached to the intake, which also has two ports. The second port in the intake was attached to the brake booster. I have tried with all the ports hooked up, and blocked off with no change in the running. Just another side note... i also noticed that the back three cylinders appear wet (including plugs) and the front three are dry. This obviously is an issue with fuel in the primary towers, gonna take the carb back apart and check it out. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 22, 2009 Share Posted March 22, 2009 If ever in doubt...do it again. If you're not sure, then chances are 'things' are not right and they must be corrected before proceeding any further. A new gasket is a good place to start. A loose manifold is common and can be corrected by using a little locktite on the threads or do as I did and replace all of the studs with long high tensile allen head bolts. Much easier to tighten up with a 6 inch long allen head bar stock on the end of a 1/2 inch socket. You can actually torque all the bolts to spec that way. Not essential but handy and a 5 minute job to check, even when hot! Fuel puddling... get that carby off and get it sorted. It sounds like it needs some serious lovin or binnin. Get a carby on there that works! The intake manifold. Studs holding the carb onto the manifold can be wrapped with some plumbers tape before you install them. That eliminates the chance of leakage in this area. I would do it for piece of mind. Cheers. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 22, 2009 Author Share Posted March 22, 2009 Thanks OZ, the gasket is on order and im gonna take the next couple days untill it gets here to go through the carb again and get it sorted. I think this may be a combination of little things adding up to one big problem. I will post again when i get it back together and give an update. Quote Link to comment Share on other sites More sharing options...
kolonelklink87 Posted March 22, 2009 Share Posted March 22, 2009 Probably an irrelevant question but I'll forget to ask later if I dont ask now... How do you set up your crankcase ventilation on those arizona manifolds? Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 23, 2009 Author Share Posted March 23, 2009 Im just running a breather on the tube to the block and there’s a Carquest hose P/N called out for the valve cover to air filter. Check Arizona Z's site for pretty detailed install instructions. I think i found the vacuum leak i was looking for. I feel pretty stupid, but I brought the intake and exhaust into work tonight and laid them flange side down agenst each other as installed and found that a couple of my primary tubes are actually hitting the intake causing it to sit off the bench about .032" on the bottom. When i put it all together I noticed they where close, but it appeared the intake and exhaust where sitting pretty flush (it's hard to tell .032" when installed) and i also noticed that the intake flange was sitting pretty proud from the exhaust, but i chalked this up to a nice flange on the intake, and a shitty one on the exhaust. With them both sitting on the bench, it looks like they are pretty even. So, im gonna go ahead an "clearance" the exhaust and reinstall both with the MSA header gasket. Im also gonna rebuild my friends Holley tomorrow and install it as a test before i shell out the 350.00 for a new 390. Any one else had fittment issues with the Arizona intakes? Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 23, 2009 Share Posted March 23, 2009 Probably an irrelevant question but I'll forget to ask later if I dont ask now... How do you set up your crankcase ventilation on those arizona manifolds? Not hard really, there are two vacuum access ports on each bank of runners. These are threaded so I bought some brass fittings and adapted a brass tee block which also had the same thread as the PCV valve. Have a look at the picture and you'll see how I did it. Note the allen bolts and the phenolic spacer which eliminates any interferance between carb and manifold. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 23, 2009 Author Share Posted March 23, 2009 Who is your intake made by Oz? Mine only has one port per bank of runners and the back one is running my brakes. The front was going to the primary side of my carb, but i think that may be incorrect, so im gonna plug that port on the carb. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 23, 2009 Share Posted March 23, 2009 Thrustnut, I just found that my setup from the PO is wrong as well. I have the Arizona Z intake and Holley 390 carb. Here is how mine is rigged, having just looked at the Arizona Z website I will be changing mine this week. Daniel Quote Link to comment Share on other sites More sharing options...
jasper Posted March 23, 2009 Share Posted March 23, 2009 Where is your PCV VALVE located??? You can't install vents/ breathers without one. Could be a MAJOR vacuum leak without the CORRECT valve, installed correctly. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 24, 2009 Author Share Posted March 24, 2009 Hey Citjet, if your talking about your forward vent on the intake going to crank, thats kinda like Oz's set up. Mine is diffrent, but not wrong i dont think. Your upper vent you may want to have going to your air filter (mine vents to atmosphere for now). Your set up is kinda unfinshed looking, i spent alot of time on mine and it came out pretty good. Im getting a new camera in the next couple days and will post pics. I got it running right, i think it was just the interference between the intake and exhaust. I also found a chart for my carb online and set it up per spec. I started it up and it sounds BADAZZ, timing is set at 10 deg. idle aout 850, need to put the O2 sensor in and get some readings. My only problem now is my oil pressure, verry low, but i think its an indication problem. It is ok when up around 1500 rpm, when you let it idle it drops just above 0, then drops all the way to the low stop (off the chart). Im gonna look this up in other posts and bring home a mechanical guage to check it. It dosent sound bad, no weird rattles, valves not any noiser then normal and it ran for about 20 min. like that, so i would think it would have seized up if it was that low on pressure. Well, thats it for now, will post finshed pics soon. Thanks all. Oh, BTW my vacuum readings are 17 inHG, Arizona did not have a reading for base set ups on the intake, maby this will help someone. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 24, 2009 Share Posted March 24, 2009 My crankcase vent system has its origins from two points, one is from the front 3 runners and the other is from the rear three. The picture below shows the pickup from the rear three. The other vacuum line travels to my brake booster. Why choose two origins? I wanted a good vacuum draw onto the PCV valve. I also looked at the size of the rubber hose that connects to the PCV valve. I figured two smaller lines would approximately equal the larger hoses cross sectional area. Also, if there was to be some oil vapor or mist sucked into the cylinders, it would be shared amoungst all six cylinders, not just three of them. The hose that connects to the top of the rocker cover also plumbs back into my air filter assembly and any vapours that come from there are sucked back into the engine via the carburetor. No more fumes into the cabin that way. A properly sealed setup the mimics the factory setup as closely as possible. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 24, 2009 Share Posted March 24, 2009 Hey Citjet, if your talking about your forward vent on the intake going to crank, thats kinda like Oz's set up. Mine is diffrent, but not wrong i dont think. Your upper vent you may want to have going to your air filter (mine vents to atmosphere for now). Your set up is kinda unfinshed looking, i spent alot of time on mine and it came out pretty good. Im getting a new camera in the next couple days and will post pics. I got it running right, i think it was just the interference between the intake and exhaust. I also found a chart for my carb online and set it up per spec. I started it up and it sounds BADAZZ, timing is set at 10 deg. idle aout 850, need to put the O2 sensor in and get some readings. My only problem now is my oil pressure, verry low, but i think its an indication problem. It is ok when up around 1500 rpm, when you let it idle it drops just above 0, then drops all the way to the low stop (off the chart). Im gonna look this up in other posts and bring home a mechanical guage to check it. It dosent sound bad, no weird rattles, valves not any noiser then normal and it ran for about 20 min. like that, so i would think it would have seized up if it was that low on pressure. Well, thats it for now, will post finshed pics soon. Thanks all. Oh, BTW my vacuum readings are 17 inHG, Arizona did not have a reading for base set ups on the intake, maby this will help someone. This was how it looked when I bought it, it has been cleaned up considerably and I will try to get some more pics here soon. The main setup difference that I see is that the front line front the manifold is running to the lower crankcase vent which has a tap going off to the vapor control valve, there is a vacuum line running from the lower port on the carb to the vapor control valve. The upper port on the carb is run to the vacuum advance on my distributor. The rear port is run solely to my brake booster. The rear I am fine with, it is the upper port on my carb going to my vacuum advance that I believe is wrong. On the picture from the Arizona site they show a vacuum line going off of the lower carb port to what I believe should be the vapor control valve. The front manifold port is going just to vacuum advance for the distributor and the carbon canister (need to see where this will go for me as my 240 is before this setup). And they just have a filtered breather cover on the crankcase vent. I like the brake line fuel delivery as it cleans things up, but what do you do with the return line to the tank? Plug it? I am going to give Dave a call today and see what advise he may have as well, I'll post back his reply. OZ, your setup looks great! It looks like you used both sides of the fuel rail for delivery, what did you do with your return line? Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 24, 2009 Author Share Posted March 24, 2009 Hey Oz, thats a pretty nice looking set up. Whats up with the three guages on the right fender well? Also what size carb are you running? Looks like a double pumper? Just kinda wondering because mine is a 625 tuned pretty lean, it sounds good idling and raps up pretty good, no hesitation or anything. Im gonna change the oil and filter today, then it should be ready for a test drive. Citjet, i went ahead and plugged off all the ports to my carb and im gonna plumb my va. advance like AZ to the front bank of the intake. The vacuum for the vapor can was tee'd into my vacuum advance, for now i have nothing going to the canister. My fuel return line i just capped off, im running a low pressure fuel pump, so no need to return. I feel kinda bad, i diddent mean anything bad about your set up, just looks like the PO was not to concerned with looks. I just kinda figure if im gonna shovel cash under the hood, it might as well look like I did. My new camera should be here today, so i will post pics of the engine in the next couple days. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 24, 2009 Share Posted March 24, 2009 I feel kinda bad, i diddent mean anything bad about your set up, just looks like the PO was not to concerned with looks. I just kinda figure if im gonna shovel cash under the hood, it might as well look like I did. Don't feel bad...I've seen tackle boxes that looked better than my engine compartment! I have a lot of work to do and some I've been putting off until I get my L28 finished for the engine swap. I talked with Dave at Arizona Z and he had similar things to say that show up in the pictures. He is running no vacuum lines to carb at all, brake booster to the rear intake port and vacuum advance to the front intake port, that's all. He put a filter on the PCV port and routed the valve cover vent into the air filter on the carb, he said he has no problem with fumes and vacuum leaks with this setup. I'm going to try this setup and reset my timing and see how it works out for awhile BTW he sets timing as on the site as well advancing until pinging or rough starts and going back a couple of degrees. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 25, 2009 Author Share Posted March 25, 2009 I installed a Crane Cams Hi-6R with the timing retard commander. I have yet to install the controler, i wanted to make sure it would start and run good before i installed it. Im gonna play with the timing a little bit after the carb is tunned correctly, but i figured the book says 10 deg. so it would be a good place to start. Gonna take it out for a drive around the block tommarow and see how it runs. Its been five years, almost forgot how to drive it. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.