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re vacuum hose diagram 73 455/rod knock?
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455farmer
New User
| Posts: 8
| Joined: 09/09
Posted: 09/04/09
07:33 AM
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Just had my 73 Y code 455 rebuilt and need a vacuum hose diagram for it. I have a knock and my builder says it is spark knock and my mechanic who installed the motor says it sounds like a rod. My carb needs rebuilt and between that and the timing is way off, we can not get this thing to run like it should. Rebuild was a mild cam and stock rest of the parts. My mechanic's book does not show a couple vacuum diagaram and there are some things that look differnt than pictures I have of other TAs. Any ideas? I have a cooler set of plugs and some octane boost to see if that helps, but have not put the hood on yet as might have to pull that motor again!!!! ouch
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Posted: 09/04/09
07:42 AM
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http://www.highperformancepontiac.com/tech/pon_0509_1973_emissions_control_systems/booklet.html
See if this may help you.
professional hi-performance engine builder
Horsepower sells engines and torque wins races
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455farmer
New User
| Posts: 8
| Joined: 09/09
Posted: 09/04/09
08:22 AM
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My original intake was cracked and we used one off a differnt motor, but transferred all the fittings over to the replacement, will that cause problems because of construction? I do not think this car was after the break in the numbers it has a 22000 series serial number.
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Posted: 09/04/09
10:34 AM
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my book is missing those diagrams also....
here is one that looks close...
http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/08/0f/c6/medium/0900c15280080fc6.gif
on the diagram... seems there is a vacuum hose coming off the front of the q jet to the passenger side near the fuel filter inlet... to a 2 port thermal vacuum switch... that goes to a tee in the line to the vacuum advance... another line runs to the tree vacuum connector off the back of the carb... but with a vacuum delay valve in that one..
does it have hei???or points??? timing spec is 10 with a manual trans... 12 btdc with automatic... set the dwell to 30 degrees first... then the timing... with the vacuum hose disconnected...
i would set the dwell.. then the timing... and rebuild that carb.. after you make sure that is the correct carb... proper jetting is important... if it gets lean... it will knock..
it will also knock if the EGR valve does not work properly... is there an exhaust back pressure valve??? between the egr valve and the other 2 port thermal vacuum switch.. and that plugs into the drivers side front of the q jet.. tee in a vacuum gauge... see if the egr opens properly... when the rpms come up and the engine is warm..
why would it ping when the egr is noto working... the egr flow dilutes the mixture.. reducing the amount of burnable air.. without this dilution.. the fuel mixture from the carb will be too lean...
the solution... might be installing a air fuel ratio gauge... along with an oxygen sensor in the exhaust... and rejetting the carb if the fuel mixture is off... do you have to smog the car ??????
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455farmer
New User
| Posts: 8
| Joined: 09/09
Posted: 09/04/09
11:26 AM
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It is a points car, has an EGR and we tested it and it works. I have another 73 automatic car that I looked at and it has a ton of lines on the driver's side with at least a couple tees. I will look at it closer this weekend as I plan on pulling the carb off for a rebuild. I am not so sure the dist may not be off a notch. I got it back with the dist pointing to #1 which was at TDC. Is that correct for a Pontiac? New set of points and I will check the dwell too. Dist is really tight and when it heats up, is hard to turn with one hand. I have to go away for most of the weekend, but will get some cooler plugs and octane boost in it to see if that helps. I have read many of the posts and appreciate your time in helping me. Have a great weekend.
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