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problem with 383 stroker

 
y96for96
I love my Chevy Chevette!
Posts: 2
Joined: 07/07
Posted: 07/16/07 02:04 PM

i have a problem with a new 383 stroker. engine stalls when put into gear. here is my set-up: 383 crank, comp cams magnum 270h cam, dart iron heads--small valves--1.94i/1.5ex 72cc chambers 165 intake runner, airgap intake, q-jet carb, msd dist.,headers. engine needed 15degrees initial advance to idle well, 32 at 3000rpm with vacuum advance blocked off.  have only 10lbs vacuum at 900 rpm. steady vacuum needle. checked for leaks.  engine will not idle when put into gear. have to set idle speed up to 1000rpm to get it to not stall in drive. 700r trans just rebuilt with new converter stock stall speed. questions: is this a normal amount of vacuum with the 270 cam?  is 15 degrees of initial advance not too high?  (will not idle well in park with 10-12 degrees)  the tech line at comp cams suggested initial advance of 12 degrees and said the 270h cam does not require a high stall converter, was not concerned with only 10lbs of vacuum.  could i have a bad converter?  1000 rpm idle speed is not going to work!  

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55Guy
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Posted: 07/17/07 05:02 AM

Before giving you detailed advice, I need the specs on your cam. What's the part no., lift int./exh., lobe sep. angle, and duration?

10 lbs. of vacuum at idle sounds too low for a street cam. You should be pulling 14-16 at idle, depending on the cam specs.

As for the stalling when you put the car in gear, it sounds like it oculd be because of the low vacuum problem you're having. The carb's not hitting the fast idle circuit when you put the car in gear. This could also be an adjustment issue with the carb.

Write back with your cam specs, and we'll go from there.  

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y96for96
I love my Chevy Chevette!
Posts: 2
Joined: 07/07
Posted: 07/17/07 08:09 AM

comp cams part 12-211-2    duration at 0.05lift 224 for both intake and exhaust, valve lift 0.470 centerline 110   this is a 270H magnum comp cam. dart iron eagle heads 165cc runner 72cc chamber 1.94 intake 1.5 exhaust   msd hei type dist. 16 degrees initial and 32 degrees in at 3000rpm with vacuum advance plugged. engine will idle at about 800 rpm with some lope.  requires 1000 plus to run in gear.    q-jet  with 73 primary jet   50n rod  silver spring  da secondary rod  idle feed res. 0.038   i hope you can help and thanks for your time!  

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55Guy
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Posted: 07/18/07 05:02 AM

Ok. That cam is mild enough, you should be pulling 15-16 psi of vacuum.

Did you assemble the motor yourself? If yes, how much lifter preload did you use? If you've got too much preload, the valves won't fully close and you'll lose vacuum, and the motor will have trouble at idle, and when a load is put on it.  

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73nova
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Posts: 10
Joined: 02/08
Posted: 03/30/08 01:55 PM

Hey might be a crazy idea but i think you should try a little looser converter with that cam.
Question for you,When you put the car in gear does it pull you forward hard so that you have to put allot of pressure on the brake pedal so that the car doesnt move.?  

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racechevy7
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Joined: 06/08
Posted: 06/05/08 05:39 AM

The tech line said that it didin't require a HIGH stall speed.  Whats high?  1800, 2400, 3800?  High to them night not mean you don't need a mild converter up grade.  I would think 2200-2400 would fit you application well and would add to the torque curve of the 383.  

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55Guy
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Posted: 06/05/08 11:40 AM

I'm gonna go back to my earlier question, how much lifter preload was applied when the motor was put together?  

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stempak
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Posted: 11/15/08 11:11 AM

You have a 500-600hp motor it's going to be a little tempramental.  

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Pontiacman2
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Posted: 11/15/08 01:46 PM

500-600 horsepower I very much doubt it will have that much at all more like around 430-450hp.  
Pontiacman2
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chevytrucks92
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Posted: 11/15/08 02:11 PM

What does the cam call for the valves to be set on?  May have them off.  

1000 rpms doesn't really sound too high to idle IMO, but if you don't think its right then its yours so you got to make it satisfy you.  

I would guess even less then 430 hp as far as that goes.  
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JW454
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Joined: 08/08
Posted: 11/15/08 05:06 PM

Some wildly imaginative horsepower figures out there, glad to see some corrective reality. Your cam should have a little lope at idle, but should pull at least 15 in. vaccum at idle. Like 55 said, I dont think you have the valves adjusted right. No more than one half turn after the pushrod has slight turning resistance.  

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stempak
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Posted: 11/15/08 09:56 PM

just about any cam with "lope" will need atleast 800rpm up to 1100 or 1200 and will suffer low to no vacumm and is the reason for vacumm boosters. And is the reason stock auto transmission coupled to a "hotrod" motor doesn't mix well, you may have to loosen up your converter and whatever else is the problem.  Don't forget a shift kit and tranny cooler, big power kills stock trannies.

Quadra jet carbs are junk period and could be your problem right there. you'd be better of with a holley or better a demon series carb  

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