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By lrs30 - 14 Years Ago
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1964 292 Y block in my F-100 I am at my wits end, I rebuilt the carb, installed new intake gaskets, and this thing still idles crazy, up, down, stalls when I come to a stop, it is acting like it has a big vacume leak. Or am I missing something,. I also am curious if these came with a factory PCV valve, for some reason this one has one screwed in to the manifold just under the front of the carb with a big rubber line going to a small canister on the back of the engine just behind the lifter valley pan. I'm not sure that these even had a PCV it seems to me that this is to early for one, and that it vents thru the oil breather. I know that early SBC had a draft tube (not comparing this to a SBC  ) and thats why I am thinking that this PCV screwed into the manifold is cause vacume leak symptoms, Or am I way over thinking thing All PCV i have ever seen are pushed into the Valve cover and then routed to the aircleaner plus the earliest car I have had that had one was an early 70's Impala..I am all ears and would buy you a beer or 24 if your ever in the area of Cincinnati..
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By GREENBIRD56 - 14 Years Ago
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The "screws into the ('64 truck) intake manifold" design sounds correct to me.......plug that line and see what happens with your vacuum leak. That should make some things clearer to you anyway. Different sizes of PCV's have different amounts of "flow" - so they bypass smaller amounts of air at idle. The other systems you are thinking of had their "check valve" - PCV valve on the other end of the suction line but they work the same. The PCV valve acts as a "check-valve" so that if the enigne backfires - it won't be pressurizing the crankcase. A small portion of the engine intake air is being siphoned out of the engine (the Y-block uses the valley space over the lifters to gather the "smoke") and "new air" is sucked in through the vented cap on its front stand pipe. In the later sixties, the stand pipe caps (Y-block was out of production by then) had a stand pipe cap with a hose that hooked back up to the air cleaner. That insured that even at full throttle - where an engine with blowby might be building a bit of crankcase pressure - all of the smoke was ingested by the motor....cough, cough.
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By lrs30 - 14 Years Ago
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I removed it from the canister tube on the rear of the engine, and it was tube attached to the PCV valve was sucking hard ( VACUME) but the engine still seemed to be idling rough. I removed the whole deal and capped it off and still idleing rough (DAMNIT) I checked the cap,button and points and they seemed to be ok but I think I am gonna replace them and the plugs and wires, and go backt thru the whole timing process and see what happens, the wires are older . I guess my hopes of it being the PCV valve idea may be dashed as it did'nt seem to make a difference. Still idling rough, and stalling when stopping...ANY IDEAS?
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By GREENBIRD56 - 14 Years Ago
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How are your valve cover gaskets? new or baked? - pull the covers and make sure you still have a full set of pushrods. The "new" gas we have tends to make for sticky valves and eats pushrods...... can make things run rough in a big hurry. Bad plug wires are a good guess too....especially if they've gotten pretty cooked over the years. You might pull one at a time and see if one of them makes "no change". Don't do this bare handed OK? The carb rebuild you mentioned - have you done one before?
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By aussiebill - 14 Years Ago
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lrs30 (10/24/2010)
I removed it from the canister tube on the rear of the engine, and it was tube attached to the PCV valve was sucking hard ( VACUME) but the engine still seemed to be idling rough. I removed the whole deal and capped it off and still idleing rough (DAMNIT) I checked the cap,button and points and they seemed to be ok but I think I am gonna replace them and the plugs and wires, and go backt thru the whole timing process and see what happens, the wires are older . I guess my hopes of it being the PCV valve idea may be dashed as it did'nt seem to make a difference. Still idling rough, and stalling when stopping...ANY IDEAS?Just shopping for ideas, if you cup your hand just above carb top, without a/cleaner on and lower hand slowly over carb opening, usually if vac leak, the engine will start to increase in revs as it pulls air from leak. This is assuming carb rebuild is not a problem. We await progress. 
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By PWH42 - 14 Years Ago
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The PCV setup you have is the correct one for 63 and 64 trucks.PCV was mandated by Uncle Sam on cars and light trucks starting in 63.
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By PWH42 - 14 Years Ago
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I'd better correct a mis-statement I made about your setup being original.It is except that you said it had a rubber hose on it.It would originally have had a steel line from the valve to the fitting at the rear of the valley cover.
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By PF Arcand - 14 Years Ago
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Irs: Did this problem exist before you took the carb apart? If yes, continue looking, if not that's likely the problem...
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By Hoosier Hurricane - 14 Years Ago
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Have you checked the basics, compression check for valve problems, or broken valve spring(s)?
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By lrs30 - 14 Years Ago
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Yes it was doing this before the carb rebuild. I've rebuilt several carbs before with suuccess, I made sure I took my time with it.. Yes it will increase in idle if I cup my hand over it. I have search high and low for a vacume leak, with everything from brake clean, carb cleaner, starting fluid, hell even used my propane torch, and found no evidence of any leak anywhere. I used fel-pro gaskets on the intake, when I took the intake off I thought I found the problem as all the mating surfaces where painted, so I cleaned them off with a roloc gasket remover pad, and re-installed, still running rough, removed the PCV valve and capped it off with a plug and still running ruff. I am gonna do a tune up (plugs cap and such)this week and see if I can make some progress.. I got my timing set at 20 degrees, btdc. I will post an update as soon as I get back out there, thanks guys for trying to help, I really wanna get this thing right The more I drive it the more I love it, just need to fine tune. it.... Ryan
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By stuey - 14 Years Ago
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hi there i'm still learning "Y speak" but this is a wonderful place to learn 20* btdc should that be nearer to 10*?? the other guys will better advise best of luck stuey
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By Hoosier Hurricane - 14 Years Ago
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Try backing the timing off to about 10 degrees. Too much timing will cause erratic idle. Cupping you hand over the carb will also act as a choke and richen the mixture slightly. Maybe it's too lean at idle.
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By charliemccraney - 14 Years Ago
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I think he's including vacuum advance with the initial timing.
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By Timbo from Mempho - 14 Years Ago
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Power brakes?? A bad booster drove me crazy one time.
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By shakey pete - 14 Years Ago
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is this a stock motor what carb do you have I put a 4 barrel on my 312 y 600cfm holley and it did the same thing I rebuilt lot of carbs turned out it was to much carb for that application change to a smaller 4 barrel holley 350 to 400 and it ran like a top maybe you have to much carb for your engine just a thought shakey
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By Pete 55Tbird - 14 Years Ago
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Sorry to be so blunt but WHY should we have to guess your problem " 1964 292 Y block in my F-100 I am at my wits end, I rebuilt the carb, installed new intake gaskets, and this thing still idles crazy, up, down, stalls when I come to a stop, it is acting like it has a big vacume leak." YOU TELL US. What is the manifold vacuum? It should be simple.
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By lrs30 - 14 Years Ago
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Pete 55Tbird (10/26/2010)
Sorry to be so blunt but WHY should we have to guess your problem " 1964 292 Y block in my F-100 I am at my wits end, I rebuilt the carb, installed new intake gaskets, and this thing still idles crazy, up, down, stalls when I come to a stop, it is acting like it has a big vacume leak." YOU TELL US. What is the manifold vacuum? It should be simple.All I was doing was asking for ideas on what to look for, if it bothers you that I asked for information, then skip to another topic and don't bother to offer an opinion,insite,or suggestions. Sorry for being BLUNT! But I am not a mechanic, and do not have a Vacume GAuge but thanks for the tip I will get one and check it out, I would ask you what it should be but why would you tell me since you don't wanna GUESS whats wrong, or help!
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By lrs30 - 14 Years Ago
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charliemccraney (10/26/2010)
I think he's including vacuum advance with the initial timing. I am including the vacume advance with the inital base line timing, sorry I was'nt clear on this, It was at 30, So I backed it to 20 and 10, it seemed happier between 10 and 20, so I left it around 15..
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By lrs30 - 14 Years Ago
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shakey pete (10/26/2010)
is this a stock motor what carb do you have I put a 4 barrel on my 312 y 600cfm holley and it did the same thing I rebuilt lot of carbs turned out it was to much carb for that application change to a smaller 4 barrel holley 350 to 400 and it ran like a top maybe you have to much carb for your engine just a thought shakey It is the stock 2 barrel
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By GREENBIRD56 - 14 Years Ago
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I think you will find - as youi build up your know-how with the Y-motor - that setting the initial advance with the vacuum line off the distributor and plugged (to avoid a vacuum leak) - will net you much more consistent tuning results. Spark advance increases made at low rev's - increase the engine vacuum - which (if you leave the vac pot hooked up) then causes the engine to increase the vacuum still more. Not the best idea for achieving a repeatable adjustment. I don't know if this link is still live .....but it had some interesting live graphics... http://www.users.bigpond.com/ergoff/vac1.htm turned out to be dead - try this one...... http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm
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By junkyardjeff - 14 Years Ago
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I dont think there is supposed to be vacumn at the distributor at ilde.
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By junkyardjeff - 14 Years Ago
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If I was not busy getting my 55 ready to drive to Daytona and the late model beater developing a coolant leak I could come down and look at it,if you dont get it fixed by after thanksgiving I could bring down my holley 500 2 bbl and see if its the carb thats the problem. I might be able to get away next sunday,saturday me and Doug are going to get some parts from the local old junkyard since they have started advertising the cars on craigslist and we need to get some parts before someone needs the parts we want.
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By lrs30 - 14 Years Ago
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Jeff thanks, If your ever down this way for sure stop by, either to lend a hand or just BS... PM me for a phone number.. I am gonna do a compression check here soon, either tonight or atleast by this weekend.... Ryan
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By shakey pete - 14 Years Ago
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just wondering the carb kits that are sold give you the wrong power valve if it,s simular to a model 8ba 94 carb the shoulder for the seal is in the wrong place if it,s leaking it will do the same or very simular thing Shakey
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By lrs30 - 14 Years Ago
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Mine is an AUTOLITE Everything in the kit matched all parts perfectly. But that does'nt mean that they where the original parts from the get go, maybe the carb was rebuilt in the past (I"M PRETTY SURE IT WAS BY the TOP SCREWS :w00t meaning thet the powervalve could have been wrong before me rebuilding it and thats way it still does the same damn thing...I still have not done a compression check on it I am so busy with work I just have not found the time yet...
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By lrs30 - 14 Years Ago
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timed,compression range from 128 to 130 on all cylinders, valves all adjusted to .019, removed and re-cleaned carb and still have this damn idle problem, and stalling on stopping...I am taking it to my good friend who is an ace with anything 64 and earlier on Sunday, I hope I am just a dumb-ass and overlooking something simple.....
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By junkyardjeff - 14 Years Ago
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Enough fuel pressure?
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By lrs30 - 14 Years Ago
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I'm not sure about the fuel pressure, It is style running the OEM mechanical fuel pump. I have an small generic electric fuel pump I could try and see if that makes a difference. I have never heard of a mechanical fuel pump not keeping up pressure. I figure the either work or don't..lol Guess its worth a shot....
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By junkyardjeff - 14 Years Ago
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I have seen them go bad gradually,the motor runs fine when the choke is on but after the motor warms up will run like crap. I have a gauge set I can hook up and check the pressure when running and a bad pump is then noticable.
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By lrs30 - 14 Years Ago
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put a junkyard Carb on it fixed everything I just have to figure out how to run the choke, mine was manual, this one is automatic, guess it ran off a heat riser, any suggestions?
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By junkyardjeff - 14 Years Ago
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You can switch the parts on the two carbs to make the one you want a manual.
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By lrs30 - 14 Years Ago
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Right! I may do that in the future, but its running so good now I am just gonne enjoy it.
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By estout81 - 14 Years Ago
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If you still got the carburetor that was giving you trouble just take out the idle mixture screws and give each hole a good blast of air. This will fix it most likely. It has always worked for me.
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