408w running poorly

82 GT · 08-30-2005, 06:07 PM

Did you check for vacuum leaks? It's sounds as if you have one.
Unplug a vacuum source(creating a vacuum leak). If the idle picks up then you have a vaccum leak somewhere.

rwhite65 · 08-30-2005, 06:20 PM

Timing is set to 5 degrees BTDC, vacuum gauge read 6.5 - 7 inches vacuum. Fluctuated very little to none, basically just between 6 to 7 inches.

What would be an acceptable vacuum source to unplug? The brake booster? That is about the only thing I can think of on this that runs off of vacuum.
Ryan

82 GT · 08-30-2005, 07:14 PM

Add some more advance. I would start at 10* and go in 2* increments until vacuum reading is maxed out at idle.
You have the next step up cam that I have. I have the 274XE cam.
That cam, in that 408, should have tons of torque through the rpm range.

Yes, you can disconnect the brake boost for a leak test.
Here is a helpful link to diagnose possible problems by using a vacuum gauge: http://www.tradervar.com/Engine%20Pe...um%20Gauge.htm

rwhite65 · 08-30-2005, 07:37 PM

disconnected the brake booster....killed it out every time..instead of picking up. got mad, used a can of brake cleaner over the #7 and #8 intake runner near the head, every time I sprayed it there the car would idle great. After a few seconds, it would start to run crappy and I would spray it again....smoothing the idle out.

I am 99% positive it is an intake leak, now here is the next issue. I have never used torque wrenches on intakes. I am thinking I should have with aluminum to aluminum, can I lossen these up and retorque? Or, should I just pull it and use new gaskets and RTV the crap out of them this time? Anyone know what they should be torqued too?

82GT- The car has always had gobbs of torque, just never has revved as we feel it should.

Ryan

lx mike · 08-30-2005, 08:08 PM

you can try loosening all the intake bolts and find the right order and torque them down and see if that'll help but best way would be to use new gaskets and you don't need to go wild with the rtv either.

08-30-2005, 06:07 PM	#1
82 GT Import Slayer Join Date: May 1999 Posts: 2,241	Re: 408w running poorly Did you check for vacuum leaks? It's sounds as if you have one. Unplug a vacuum source(creating a vacuum leak). If the idle picks up then you have a vaccum leak somewhere. __________________ '82 GT 351W (.060)Comp Cams 274* Extreme Energy cam, ported & polished heads w/ 1.94/1.60 valves 10.3:1 flat top pistons,stealth intake, Mallory dizzy,Holley 750dp carb, BBK shorties,Flowmaster exhaust,C-4 with 3700 stall converter, B&M pro shifter,8.8 rear, 4:10's, subframes, electric fan, powermaster alternator, 4 core radiator.

08-30-2005, 06:20 PM	#2
rwhite65 Ride Hard Join Date: Oct 2000 Location: Wyoming IL Posts: 1,094	Re: 408w running poorly Timing is set to 5 degrees BTDC, vacuum gauge read 6.5 - 7 inches vacuum. Fluctuated very little to none, basically just between 6 to 7 inches. What would be an acceptable vacuum source to unplug? The brake booster? That is about the only thing I can think of on this that runs off of vacuum. Ryan __________________ 65 Fastback 91 roller 306, H/C/I AOD-Bauman, PI Stallion, 4.10's and traction loc 04 Grand Cherokee Freedom Edition 79 Ford F-250 4x4 - Restored

08-30-2005, 07:14 PM	#3
82 GT Import Slayer Join Date: May 1999 Posts: 2,241	Re: 408w running poorly Add some more advance. I would start at 10* and go in 2* increments until vacuum reading is maxed out at idle. You have the next step up cam that I have. I have the 274XE cam. That cam, in that 408, should have tons of torque through the rpm range. Yes, you can disconnect the brake boost for a leak test. Here is a helpful link to diagnose possible problems by using a vacuum gauge: http://www.tradervar.com/Engine%20Pe...um%20Gauge.htm __________________ '82 GT 351W (.060)Comp Cams 274* Extreme Energy cam, ported & polished heads w/ 1.94/1.60 valves 10.3:1 flat top pistons,stealth intake, Mallory dizzy,Holley 750dp carb, BBK shorties,Flowmaster exhaust,C-4 with 3700 stall converter, B&M pro shifter,8.8 rear, 4:10's, subframes, electric fan, powermaster alternator, 4 core radiator.

08-30-2005, 07:37 PM	#4
rwhite65 Ride Hard Join Date: Oct 2000 Location: Wyoming IL Posts: 1,094	Re: 408w running poorly disconnected the brake booster....killed it out every time..instead of picking up. got mad, used a can of brake cleaner over the #7 and #8 intake runner near the head, every time I sprayed it there the car would idle great. After a few seconds, it would start to run crappy and I would spray it again....smoothing the idle out. I am 99% positive it is an intake leak, now here is the next issue. I have never used torque wrenches on intakes. I am thinking I should have with aluminum to aluminum, can I lossen these up and retorque? Or, should I just pull it and use new gaskets and RTV the crap out of them this time? Anyone know what they should be torqued too? 82GT- The car has always had gobbs of torque, just never has revved as we feel it should. Ryan __________________ 65 Fastback 91 roller 306, H/C/I AOD-Bauman, PI Stallion, 4.10's and traction loc 04 Grand Cherokee Freedom Edition 79 Ford F-250 4x4 - Restored

08-30-2005, 08:08 PM	#5
lx mike Undescribable Join Date: Sep 1998 Location: Ft Myers Fla Posts: 1,539	Re: 408w running poorly you can try loosening all the intake bolts and find the right order and torque them down and see if that'll help but best way would be to use new gaskets and you don't need to go wild with the rtv either. __________________ Rice Haters Club Member #101

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