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Author
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Topic: vacuum advance
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05s197
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Member # 13235
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posted
 
 
I have a 302 longblock from O'reilly with the basic performer intake and a holley carb. I don't know which one. We played with the timing and it runs great at low rpms, but once you start adding rpms it sounds like the motors going to blow. tweaked the timing more and at higher rpms it ran great and at low rpms the motor sounded like it was going to blow. I believe that the timing is not advancing as the rpms go up. What do I do to fix this?
Posts: 54 | From: walnut creek/concord | Registered: Oct 2013
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4IDFOX
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Member # 9921
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posted
What dizzy is it?
What year Carr?
When you put it together did you confirm that tdc on the balancer was actually tdc ?
There are three different timing pointers and they need the correct balancer two go with it.
There are 10,11 and 2 o'clock pointers
I bought my ranchero with this problem.
Are you running vacuum advance? If so is it hooked to ported or manifold vacuum ?
[ 2014-03-04, 05:36 AM: Message edited by: 4IDFOX ]
Posts: 375 | From: Redding CA | Registered: Apr 2010
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05s197
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Member # 13235
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posted
It is a 66 mustang the motor was bought as a longblock never ran when we bought it. The people before us screwed it up pretty badly ad were fixing all of their mistakes. I dont know abput the vacuum.
Posts: 54 | From: walnut creek/concord | Registered: Oct 2013
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Tom Renzo
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Member # 13165
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First thing do a TRUE TDC TEST and confirm the pointer location as instructed above. then plot the DIZZY on a distributor machine for total advance and full RPM advance of said DIZZY. Once you have plotted the dizzy @ or around 12* with full advance all in @ 2500RPM'S ditch the vacuum unit and or do not hook it up. Run a fully mechanical dizzy and put the wheel @ 12 BTDC this will give you 36* TOTAL @2500 RPM and run it and see how it performs!!
[ 2014-03-05, 03:59 AM: Message edited by: Tom Renzo ]
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I spend money i don't have. Building cars i don't need. To impress people i don't know.
Posts: 557 | From: CT | Registered: Sep 2013
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Secnd2nun64
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Member # 1431
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posted
The link below should help you. When I had my 289, I had setup the distributor to 14 degrees initial, the breaker cam to 10L and installed some soft springs for the weights that I got at the auto parts store. That allowed 34 degrees total that would come in fully by 2400 RPM. I didn't run the vacuum advance. The changes made a night and day difference at all RPMs. Also if you have not done so already, get rid of the points ignition and get yourself a pertronix.
http://www.bob2000.com/dist.htm
Posts: 1460 | From: CA | Registered: Jun 2002
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05s197
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Member # 13235
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posted
it had a pertronix (or same thing by different company) on it when I bought the car but my grandpa who is helping me out a lot for this project couldn't figure it out. There was a lot of probems so to simplify it we took it off and put points back on. If I put the pertronix back on will that fix my problem?
Posts: 54 | From: walnut creek/concord | Registered: Oct 2013
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4IDFOX
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Member # 9921
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posted
No. If it is running now don't mes with Petronix for now. You need to confirm the timing marks on the balancer before you do anything else for now.
Ford used three different balancers.
Is the timing pointer on the drivers or passenger side of the engine ? If it is on the drivers side that is the 2 o'clock position. You say it is a crate motor Wichita means it is probably a 50 oz balance motor which means you will need a balancer that ford never made.
This is very important stuff that you need to confirm before you can make any progress.
[ 2014-03-06, 05:51 AM: Message edited by: 4IDFOX ]
Posts: 375 | From: Redding CA | Registered: Apr 2010
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Secnd2nun64
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Member # 1431
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quote:
Originally posted by 05s197:
it had a pertronix (or same thing by different company) on it when I bought the car but my grandpa who is helping me out a lot for this project couldn't figure it out. There was a lot of probems so to simplify it we took it off and put points back on. If I put the pertronix back on will that fix my problem?
I would put the pertronix back on and while your in there setup the distributor like Tom and I mentioned above. While in there you may find an issue like stuck weights. Also keep in mind that ford put one soft spring and one hard spring on the mechanical advance. The setup won't advance fully until high rpm and get full advance in a normal rpm range. Doing the changes we've mentioned will improve the overall performance. The pertronix are really simple to setup. You just need a little gap between the unit and magnet. You can find the exact gap on a google search.
Posts: 1460 | From: CA | Registered: Jun 2002
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Tom Renzo
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Member # 13165
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posted
Years ago before we had a dizzy machine we used to take off the heavy spring and throw it away. And only use the one light spring. Also you can install a teflon sleeve ouer the advance stop to get whatever degreese of advance you want. Another words sleeving the 15* slot can get you like 12* or sleeving the 10* can get you 8* ETC. I have been building those dizzys for many many years and they are totally obsolete now, But every once in a wile the old mechanical vacuum DIZZYS show up in the shop. I used to like to set them up. Also make sure the center post of the cam mechenism is oiled with a good grade of light oil. They used to have a nasty habit of rusting from lack of lubrication and then not advance. Been quite a while since i have dun one of those old DIZZYS!! Or you can use a GM HEI converted to a ford shaft. Good luck!!
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I spend money i don't have. Building cars i don't need. To impress people i don't know.
Posts: 557 | From: CT | Registered: Sep 2013
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