383 problems

[getstroked]

I have a 383 stroker. It seems to have good power but not like it used to. the problem is that i have changed many parts since i put it away for the winter. I went from a stock q-jet and manifold to an edlbrock 750 carb. and performer rpm manifold. factory ex manifolds to headers 3in collecters 1 5/8 in primaries witch inturn ment new 2.5in flowmasters. i changed out the steel rockers for 1.5 roller rockers. and then i finally went from a 245/60 15 tire and 2.56 gears to a posi 3.42 posi with 275/60/15 tires. the engine is all scat bottom end w/ speed pro flat top pistons. a comp cam (12-246-3) .490 single pattern 106 in center line 110lobe separation [email protected] is 230in and 236ex. the heads are called thunder series heads that i guess dart makes? they are told to flow 205 i think(2.02/1.6valves). i also gaskett matched the intake and heads. please help me b4 i go even more crazy!!!

[maxwedge]

Originally Posted by getstroked

I have a 383 stroker. It seems to have good power but not like it used to. the problem is that i have changed many parts since i put it away for the winter. I went from a stock q-jet and manifold to an edlbrock 750 carb. and performer rpm manifold. factory ex manifolds to headers 3in collecters 1 5/8 in primaries witch inturn ment new 2.5in flowmasters. i changed out the steel rockers for 1.5 roller rockers. and then i finally went from a 245/60 15 tire and 2.56 gears to a posi 3.42 posi with 275/60/15 tires. the engine is all scat bottom end w/ speed pro flat top pistons. a comp cam (12-246-3) .490 single pattern 106 in center line 110lobe separation [email protected] is 230in and 236ex. the heads are called thunder series heads that i guess dart makes? they are told to flow 205 i think(2.02/1.6valves). i also gaskett matched the intake and heads. please help me b4 i go even more crazy!!!

How about the power brake/ convertor issue, get that resolved? There is no way in this forum anyone can suggest what this vague complaint 'of it doesn't have the power it used to 'constitutes. Go over the fine tuning try bumping the timing a little, what is the compression ratio, gasoline quality can be a probelm and on and on.

[jveik]

is it in a heavy car? i have heard that the carb you use can affect performance in heavier vehicles... simple rule of thumb vaccuum secondaries for heavy cars and mechanical secondaries for lighter cars

[getstroked]

after the weather finally got nice again i finally got my malibu out and tuned it. i adj the timeing, new spark plugs, adj. the carb witch all help alot. it is a 9.2:1 compression motor. yes it is a heavy car the registation says 3846lbs. is there anyway i can get the secondary's to open faster on my edl performer carb.?

[richtazz]

Are you sure the secondaries aren't opening too soon? Are you running rich or lean? The vacuum secondaries respond to low vacuum (WOT has lower vacuum than at idle). Since your engine produces very little vacuum, an edelbrock carb set up with stock jets and vacuum secondary springs may have the secondaries slightly open at idle/ just off idle. This would cause the off idle stumble and a rich mixture.

BTW, if you don't hammer this car above 5500 rpm, you have too much carb and WAY too much cam for such a heavy car.

[getstroked]

i dont understand how do i have to much cam for a heavy car?
so would the motor be much better in a lighter car?(besides the power to weight ratio efect)
i am shifting the car at about 5500. If i have to much carb. then how come a 650 q-jet made things worse? is that too small now?

[getstroked]

?anything to say?

[richtazz]

First, I need more info, gear ratio, trans used, do you have headers, intake, what plugs, etc... before I can make an assessment. For a cam like yours, you should be running 3.42:1 or numerically higher rear gear, a 3,000 stall and a 650 carb should be about right (if the carb is good). As I stated before, a 350ci engine only draws 595 cfm at 6,000 rpm. Most people buy too big a cam and carb for the way they will use the car. Your driveability issues and lack of vacuum are proof your cam is too big for your intended use. I'm not trying to beat you up here, just stating fact.

[getstroked]

it has 3.42 gears w/ posi, 350th trans (stock), 1 5/8 primary 3in collecter 2.5 in from then on out,acdelco 45 plugs, stock gm distributor(rebuilt)w/ 40,000v accel coil,taylor wires, dart180heads(76cc),

the rest of the info should be above

[richtazz]

If you put a 2,500-3,000 stall in that car, it should scream. I still say, since you have a long stroke motor, you should put a cam in it that works better at lower RPM (1500-5500 range). Then your car would launch like a titan rocket and pull like a freight train.

[maxwedge]

Originally Posted by richtazz

If you put a 2,500-3,000 stall in that car, it should scream. I still say, since you have a long stroke motor, you should put a cam in it that works better at lower RPM (1500-5500 range). Then your car would launch like a titan rocket and pull like a freight train.

Rich is right here, way too big a cam for that gearing and stock convertor and weight, at minumum call a high perf tc mfg and give them your combo and let them suggest a tc, the carb will be close to ok with more stall speed, or back up on the cam and carb and leave gearing and tc stock. Got to be one or the other or this thing will not deliver the performance you want. Be careful with multiple parts/tuning changes without a definitive plan, this makes it very hard to back track if the car slows down.

[getstroked]

well i broke down called about a tc and got brought on to a holeshot 2400 witch i just ordered! i hope this works out lol. i am also going to rebuild the tranny w/ a shift kit just to be safe.