|11-12-2012 08:56 PM|
its advance and retard not before and after.
disconnect the vacuum advance and set the timing to 30deg advance using a timing light.
reset the carb idle speed to 900rpm and readjust the idle mix screws for best idle . what is the manifold vaccum at 900rpm>
do not drive the vehicle with the timing set so.. just tell the intake manfold vacuum.
|11-12-2012 08:53 PM|
Your best bet is to see what damper you have, 2 o'clock, 2:30 o'clock or noon and go from there. You can make a timing tape and transfer the marks onto the damper, then use a simple pointer to indicate zero. The timing will then be read from the damper instead of the tiny tabs that don't have enough range to show you total timing and vacuum advance.
If it's a 2:00 damper, that's what most all the aftermarket timing tabs are made for. Buy one and bolt it on. If it's a noon damper, the timing tabs are usually all tack welded to the timing cover. The 2:30 damper can be found w/either tacked or bolted on tabs IIRC.
|11-12-2012 08:43 PM|
|11-12-2012 07:23 PM|
here is a picture of my timing tab. can someone enlighten me on the marks?
F-BIRD'88-i checked it when the driver side was down. i spun the wheel and got the same result as when i spun the driveshaft...1.33:1
DoubleVision-i have the spacer plate that covers these holes
|11-12-2012 04:28 PM|
To figure out the gear ratio you can use several different procedures, more here.
BTW, I know sometimes getting a bunch of links can seem like I'm "mailing it in". Trust me when I say that it's about the only way I can cover a large amount of territory w/o taking up a huge amount of time and space on your thread. I trust you'll understand.
5 in/Hg is WAY low unless you have a way rad cam in there. I'm guessing you don't have and cannot get (or can you?) the original cam card that was shipped w/the cam.
Start out by verifying the timing marks are showing you true TDC. This is key. Then see what the timing really is if the lines were off.
Once that's done, set the initial timing (vacuum advance disconnected and line to engine plugged) to 24 degrees BTDC and see what the vacuum does. Now, you don't want to drive it like this because until the distributor is reworked, this will likely have the total timing too high. Timing too high causes detonation, and detonation kills engines. But as long as the engine isn't under a load- like when driven on the road- then you can over advance the timing w/o any damage to anything.
If it 'likes' 24 degrees, add some more just to see how the idle quality and vacuum reading responds. No need to go any higher than 36 degrees because that's all the timing you can run. This will give you a baseline to work from when it comes time to modify the distributor.
|11-12-2012 03:44 PM|
|DoubleVision||I would hope that you paid some attention to my post, I didn't post it for nothing. What I asked you to check is simple and if in fact the holes in the intake are left open it will cause all kinds of tuning headaches that you won't be able to cure no matter where you set the timing or the tune.|
|11-12-2012 03:39 PM|
|F-BIRD'88||with 32" tires you will want a 4.56:1 gear or more. 4.88+++|
|11-12-2012 03:34 PM|
32" tires will require a very high gear ratio.
ratio check Do it again but leave one wheel on the ground. This will result in the internal differential spinning
2:1 differential ( right /left wheel) This will half or double the ring pinion ratio.
You are getting a weird count cause the diff is spinning.
5" manifold vacuum at idle. either its got quite the cam in it or the timing is very retarded.
Find true TDC on the balancer timing tab, using a piston stop.
cammed motor will respond to a different timing curve with much more inital at idle (recurve the distributor)
this will improve the idle, manfifold vacuum at idle and the engine torque.
a low engine compression ratio will not work with a big cam, especially in a 283.
|11-12-2012 02:49 PM|
|vinniekq2||still not much information.what would you like when the project is finished? did you like the way it performed with the 305?|
|11-12-2012 02:42 PM|
|Jeepracer427||Well I went and checked some other things. My timing tab seems to be flipped in the sense that where most tabs would have a b or befor is where my a is. Same thing as where my b is. I don't know how much the lines on it are because it only has a zero. When I put my vacuum gauge on, at idle it reads 5in hg vacuum. Finally I checked my gear ratio...it is coming in at about 1.3/1 (one and one third driveshaft rotation to tire rotation). That doesn't seem right at all?? I forgot to mention the tire size is 32 inches.|
|11-11-2012 09:34 PM|
I'm sure you're familiar w/the term "lope" when talking about the idle quality of a cammed up engine. Does the engine have a lot of lope or does it idle relatively smoothly? You should use a vacuum gauge and see what the idle vacuum is- that will also give an idea of the size of the cam.
|11-11-2012 08:55 PM|
|vinniekq2||283 in a jeep,sounds like fun.try and find out your gear ratios and specs on camshaft..We had an old willeys jeep with a 283 and a standard in our shop years ago.It had 5.13s in the rear,in low range and first gear it barely moved.|
|11-11-2012 07:54 PM|
If you buy a "3000 stall" converter for your 283 you will come up short by about 500 rpm.
its cheaper to change the camshaft and lifters and get the right cam for the job.
|11-11-2012 07:41 PM|
Cammed up 283's ( and cammed up 305's for that matter) don't have a lot of low end torque.
So you need a stiff rear gear ratio and a higher stall converter to make em go.
A cammed up 283 needs a 3000++stall.... a typical "3500 stall" 10" converter will only realize about a 3000
stall when behind a 283CID motor.
A 283 with a big cam and a low compression ratio "stock" will be a dog.
A cammed 283 needs a 10:1cr a 3000++ stall (3500 stall rating 10" converter) and 4.10's or its not going to be even in the program. all the power is up higher in the rpm range.
305's are not much diffeerent. when you cam them up, they need compression, gears and a generous stall speed.
typical stall rating of typical converter will show about 500rpm less stall behind a 305.
So don;t be shy when selecting converter stall speed.
If you are not willing to do that, change the camshaft. very easy to over cam a 283 and a 305.
A cam like the comp 280H magnum (280 230@.050" .480" lift) needs 4.10+++ gears and a 3500-4000 ++ real stall 9" converter and 10:1cr in a 283-305 cid motor. The taller the tires and-or the heavier the vehicle, the more gear it will need.
If you're not gong to gear it up, don't use a big cam.
The stock HEI distributor advance curve will not work well on a 283 with a cam. It needs to be modified with a advance curve that suits the cam and purpose.
More detail if you ID the cam in the motor.
|11-11-2012 07:37 PM|
|DoubleVision||Remove the carb and study the intake. If it's the factory 4 barrel intake of that year, then it will have a hole on both sides of the intake, in front of the primary side. These 2 holes will be connected by a trough. These holes are connected to the heat riser passage of the heads. The job it has is to heat the carb for easier starting and to prevent butterfly icing in cold weather. If a standard carb gasket was used, these 2 holes are open and they push exhaust gas into the incoming fuel mixture, greatly diluting it and robbing power because exhaust gasses cannot be burned twice. These intakes require a special gasket which was paper gasket on the bottom, a thin aluminum plate, then another paper gasket. This seals off the holes so it just heats the carb, the exhaust gasses are blocked from entering the incoming air mixture. Check to see if your intake has this gasket, if it does not that's half it's problem. The picture I'm attaching isn't the intake you have, but the example is the same.|
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