New engine build 300 miles BB396 Holly 4150 HP carb. Car ran better but now is getting worse. 1200 RPM idle in park but in gear the car does not want to idle.Timing looks good 16*in. 36 * total . Plug electrode is white and metal case is black. What do I need to look for ?
1200RPM IDLE /in gear does not want to idle
Rayzz
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New engine build 300 miles BB396 Holly 4150 HP carb. Car ran better but now is getting worse. 1200 RPM idle in park but in gear the car does not want to idle.Timing looks good 16*in. 36 * total . Plug electrode is white and metal case is black. What do I need to look for ?
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vacuum leaks
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I concur, get a spray bottle, cheap maybe dollar store? and spray water on parts of the engine that may be sucking air. I had this problem once. It was a bad leak at the trans...from the manifold
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Timing could be the cause. If it's initial is 16*@1200rpm, it could be falling off when put in gear due to centrifical advance coming back down. If you idle the engine down, does timing fall? If so, it's got to be modified. I had to have mine at 16*@900rpm to not lose but 50rpm in gear. The bigger the cam, the more initial it takes to make it idle.
Ray P. has a very good point. It may very well be also that a vacuum leak is at play. But any time your idle gets high enough to allow the mechanical advance mechanism to start advancing, all sorts of off-idle issues can crop up.
My 355 / THM700R4 setup was pretty ill mannered when I got it. The PO really had things messed up. In my case, replacing the 750cfm holley square bore with a 650cfm, adding vacuum advance, and a few other adjustments really helped. I was able to bring the idle speed back to about 800, and actually sit with the car idleing in gear (warmed up of course). But I need to bump up the stall speed on my converter, or better yet put in a manual. A stock stall speed converter and Edelbrock Performer RPM cam don't play well together.
My 355 / THM700R4 setup was pretty ill mannered when I got it. The PO really had things messed up. In my case, replacing the 750cfm holley square bore with a 650cfm, adding vacuum advance, and a few other adjustments really helped. I was able to bring the idle speed back to about 800, and actually sit with the car idleing in gear (warmed up of course). But I need to bump up the stall speed on my converter, or better yet put in a manual. A stock stall speed converter and Edelbrock Performer RPM cam don't play well together.
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i say its the timing advancing at 1200 idol drops when you put it in gear to say 1050. But now it stops advancing and now there isn't enough timing and the idol keeps droping till it dies or you 2 foot it.
That happend to me and was driving me crazy. So i locked out the timing and love it.
That happend to me and was driving me crazy. So i locked out the timing and love it.
dont put it in gear..
you need to work out the idle quality issues first.do this yourself or a knowledgeable freind. lowering the idle and adjusting the air/fuel mixture and timimg.this means checking the float level as well! after that if it still runs rough you have vacc leaks........i can get really into detail on how to determine if it has them and how to eliminate there possible sources.
you need to work out the idle quality issues first.do this yourself or a knowledgeable freind. lowering the idle and adjusting the air/fuel mixture and timimg.this means checking the float level as well! after that if it still runs rough you have vacc leaks........i can get really into detail on how to determine if it has them and how to eliminate there possible sources.
I have been working and just back to working on car . Cam is a Comp cam 550/552 lift and a TH 350 with 2400 stall converter. I check float level and idle fuel adjustment riched up a little (was only half turn out now one turn). That helped but not alot.
I have MSD distributor and 6AL box so I setup the dist. to have 16*int. and 36* total advance, disconected vac. advance and now it runs great.
Any thoughts on why it runs good like this compared to having vac. advance?
THANKS RAYZZ MY CAMARO LIKES MY MONEY
I have MSD distributor and 6AL box so I setup the dist. to have 16*int. and 36* total advance, disconected vac. advance and now it runs great.
Any thoughts on why it runs good like this compared to having vac. advance?
THANKS RAYZZ MY CAMARO LIKES MY MONEY
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Sometimes cars with a lot of cam & the vac advance connected to full manifold vacaum, putting the car in gear drops the manifold vac enough to pul the advance out.
Best solution would be to get a vac can that will fully depoly at your "in gear" idle vacaum. Another possible solution is to connect the vac can to ported vac.
Best solution would be to get a vac can that will fully depoly at your "in gear" idle vacaum. Another possible solution is to connect the vac can to ported vac.
How do I check how much vaccum I have to operate vac advance? I have a vac gauge. How much vac should I have? Do you check at different RPMS ? I was using ported vac should I use manifold? If manifold vac were should I hook up ?
THANKS RAYZZ MY CAMARO LIKES MY MONEY
THANKS RAYZZ MY CAMARO LIKES MY MONEY
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Disconnect your vacuum advance. Set your timing to your desired initial setting. Measure the manifold vacuum at idle. Get a vacuum can that's all in at this vacuum level.
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To test, check your timing under the following conditions:
Idle in park, vac disconnected
Idle in park, vac connected
Idle in gear, vac connected
Idle in gear, vac disconnected
For the vac connected tests, be sure you are using a port with full manifold vacaum at idle. "ported" vac will not give valid readings.
If you note those 4 readings and study them you will be able to tell if either mechanical or vac advance are providing any timing advance at idle, on or out of gear.
In an ideal world, mechanical advance should be ZERO (you'll read the same initial only timing in both park and in gear with the vac disconnected) and vac advance should provide full advance BOTH in gear and in park (vac connected to full manifold vacaum)
This way, your timing would be the same idling in neutral and in gear.
Idle in park, vac disconnected
Idle in park, vac connected
Idle in gear, vac connected
Idle in gear, vac disconnected
For the vac connected tests, be sure you are using a port with full manifold vacaum at idle. "ported" vac will not give valid readings.
If you note those 4 readings and study them you will be able to tell if either mechanical or vac advance are providing any timing advance at idle, on or out of gear.
In an ideal world, mechanical advance should be ZERO (you'll read the same initial only timing in both park and in gear with the vac disconnected) and vac advance should provide full advance BOTH in gear and in park (vac connected to full manifold vacaum)
This way, your timing would be the same idling in neutral and in gear.
That is only the lift.It's not the important part of the spec's they need.
Give the advertised duration, duration at .050, and the LSA.
Heck I tried to look for that lift in their on line catalog and couldn't find it.
Do you know the grind or gart number?
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