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283 Performance upgrade

  
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283 Performance upgrade

 
65chevysub 65chevysub
New User | Posts: 6 | Joined: 10/13
Posted: 10/11/13
08:25 AM

OK. I can't afford a new 350 for my Suburban, so I need some honest info on what would make my tired old 283 get decent gas mileage, and power. It came from a 63 Biscayne, with a Powerglide originally, and I had it supposedly rebuilt in 1996. Now it won't get out of it's own way, and the 6 mpg doesn't work. Would a cam and lifter change help? Also, my carb is currently a rebuilt Carter 500CFM. I was going to sell the 283 and P/G together as they were a matched set, but since I live in an apartment, I can't do an engine swap there. I'm on an extremely limited budget, so I may have to get the parts, then have someone install them. Any help would be GREATLY  appreciated. I have asked about this before on here, but everyone suggested a 350. Believe me, I appreciate all the replies, but things have become worse now , financially, so looking to rebuild the engine on a budget.
Thanks everyone Confused  Frown  

waynep712222 waynep712222
New User | Posts: 48 | Joined: 04/13
Posted: 10/11/13
06:00 PM

what is it in first... so we kinda know...

lets go back to basics..

what kind of ignition system...   window type delco with points..  

did you set the dwell with a dwell meter?? to 30 degrees of dwell before you set the timing???

can you examine the distributor with the cap off..   grab the rotor and twist it in one direction.. then release.. then twist it in the other direction.. and release..

you are probably going to start by twisting the rotor counter clockwise against the advance spring tension.. then release.. it should snap back to the stop..

if the advance weights hang up..  or the second layer of the shaft is seized on the shaft because of the dried grease.. the advance will hang up making the engine hard to start or hard to set the timing..

next...

disconnect the vacuum advance hose at the carb/intake.. apply some suction to the carb end of the hose.. does the upper layer of the breaker plate where the points are mounted move about 1/4 inch..  this proves that the vacuum advance is working..

next...

where is the timing set at???  and are you running manifold vacuum or ported vacuum to the vacuum advance..

manifold vacuum is vacuum at idle.. and is the usual way its run..

..........
if you have a compression tester.. checking all 8 cylinders  140 to 160 pounds is expected..

who knows what was done inside the engine if it was rebuilt..

283 heads do not come with hardened valve seats..  they can be installed.. i am taking that there is probably a small triangle on the ends of the heads. showing those might be powerpack 283 heads... ____/\____

the lack of hard seats can lead to valve seat erosion where the valves actually sink into the heads and limit flow and eventually fail to close as the lifters are bottomed out.....


if everything looks ok... and you have spend the 20 minutes and verified the timing pointer is actually pointing at TDC.. this involves pulling the #1 spark plug and inserting something like a piece of solid conductor copper wire... please pull the distributor cap and only perform this on the top of the compression stroke..

you can rock the crank back and forth to find the highest spot of the piston movement to see if its right in the middle of the timing pointer TDC mark..

there are several different locations...

~~~~~~~~~~~~~~~~  

waynep712222 waynep712222
New User | Posts: 48 | Joined: 04/13
Posted: 10/11/13
06:25 PM

so lets look at the exhaust first...

283 and others have a TRAP DOOR device at the exhaust flange on the manifold.. this diverts hot exhaust across the intake and out the other side to warm the intake and carb for better cool or cold weather operation.  

if the EFE valve we are talking about is stuck closed.. there will be a LOT of exhaust back pressure on one side of the motor.. i found one dodge van that was pieced together.  they were on both sides.. and they were stuck closed.. no wonder that van had little power.. and overheated..


if you have a vacuum gauge.. hook it to manifold vacuum..  where there is vacuum at idle..

slowly increase the engine speed..  the manifold vacuum should NOT drop as you increase the speed..

when you return the engine to idle.. .please note the manifold vacuum reading.. bring the engine speed back up to around 2500 and note what the manifold vacuum is there also...

post these results..

..........


lets look at the carb now..

when the engine warms up.. is the choke blade fully open???? yes or no..

when you turn the idle mixture screws in.. does the engine stall???

lets adjust them..

with the vacuum gauge hooked to manifold vacuum.. start turning one of the idle mixture screws inward. until  the engine is about to stall..  turn it back outward.. until you reach the highest vacuum rating.. turn it in till the vacuum just starts to drop... stop and lets do the other..

turn the other idle mixture screw in until the engine is about to stall..   back it out to reach the highest vacuum..  turn it in until the vacuum starts to drop on the gauge.. and stop there..


are  both screws responding properly??? if not i have a fix...


how fast is the engine running..  can you turn the idle speed down some.. its the screw that holds the lever open..  not the fast idle cam screw..

go thru the idle mixture adjustment again. recheck the idle speed.  as slow as you can go..

back to the idle mixture adjustments one more time.. this time out.. till it won't go any higher..  in till it starts to drop.. stop and do the other screw. out till it won't go any higher.. then in till the manifold vacuum drops about 1/2 inch of vacuum for both screws together..

this is called lean best idle..

if the screws are NOT responding..

take the idle mixture screws out..  with some strong carb cleaner and a spray nozzle.. and compressed air.. spray carb cleaner into the screw openings.. then follow instantly with some compressed air..  put the idle mixture screws back in..

you will have to hold the foot to the floor to get the engine started.. letting up once it starts.. and holding the engine at a moderately fast idle.. to clear out the carbon..

you can go back thru the readjustment of the idle mixture screws again.. and the idle speed screw...


why.. you said you are getting 6MPG..  

waynep712222 waynep712222
New User | Posts: 48 | Joined: 04/13
Posted: 10/11/13
06:27 PM

more to come...  

65chevysub 65chevysub
New User | Posts: 6 | Joined: 10/13
Posted: 10/13/13
08:14 PM

Exhaust is stock ram horns, without the trap door. 21/2" pipes with stock type mufflers exiting behind the rear wheels. I'm thinking the carb is shot. I've been told to run a stock 4bbl Quadrajet. I'll have to check the vacuum and let yo know. Right now the truck is sitting without any gas in it. I've tried to run the idle at the stock 500 rpm, but it won't. Feels like it wants to die. I think it's about 1000 rpms now. When I first drive it in the morning, it runs and starts off ok, but when it gets warm/hot, it has a hesitation at takeoff from a light. Last time i checked the compression, in 2010, all cylinders were at 120psi.Ignition system is an Ignitor system...no points, with a stock distributor. Looking for a small diameter HEI type, but not sure where to get one. I have a Mallory Unilite, that just needs a control module. This is all I can think of right now, so hope this helps. Thanks for the tips. I will go through everything here and start again. My trans is a TH350, and not sure if it's correct, but the serial number on the pan says it's a '78 model. Gears are 3:73's. Normal driving would be about 20 miles one way on the highway between Cottonwood, AZ and Sedona, and about 2-5 miles of city streets. What would be a good gear ratio for this engine and trans combo?  

65chevysub 65chevysub
New User | Posts: 6 | Joined: 10/13
Posted: 10/13/13
09:34 PM

SorryI forgot to post this:
My truck is 1965 Chevrolet Suburban, 1/2 Ton 2wheel drive. Tires are 235 75/R15  

wayne712222 wayne712222
New User | Posts: 37 | Joined: 10/13
Posted: 10/17/13
12:19 AM

When I first drive it in the morning, it runs and starts off ok, but when it gets warm/hot, it has a hesitation at takeoff from a light.


i need the carb number off the side of the carb... stamped in vertical in the drivers side of the float bowl...

either a 7029210 or a 17046210   with a second row of numbers below it..

more than likely.. you are going to need to check the free play in the timing chain.. this involves a 5/8 six point deep socket on the crank bolt. if there is one.. not all 283s had a crank bolt.. and 283s were actually equipped with a rochester 4 bbl..  or 4 jet..

this is what one version of the quadrajet looks like...

Quadrajet 4M Topcover Pontiacversion Zps8d861a46


rochester 4jet

Rochester4jet Zps68b0a9f1  

wayne712222 wayne712222
New User | Posts: 37 | Joined: 10/13
Posted: 10/17/13
12:30 AM

flat spot on acceleration...

several causes...  and your compression is kinda low.. check the timing chain for slack by rocking the crank back and forth... that has a major effect on how the engine runs..


inside the carb...

you could have issues with the accelerator pump circuit... so it does not have enough pump spray as you open the throttle..

that's easy to check.. by just looking down the primary bore and opening the throttle... a nice spray from as soon as you move it to about 3/4 throttle engine off..

if the pump shot is good...

then it could be a clogged idle transition circuit..  idle feed restrictions.. idle air bleeds..

lets figure out which carb you have...

and go from there...