Moparts
why would a stock street hemi have only 5in vacuum ?
Posted By: ogopogo
why would a stock street hemi have only 5in vacuum ? - 11/14/13 06:19 AM
I have been fighting for a while now with a poor running stock rebuilt 426 hemi i have.it runs pig rich and has no power.it was rebuilt in 2005-06 to stock specs and the car has basicly sat most of the time since.i have switched out carbs,every single component of the ignition system as well as corrected an incorrect timing mark and replaced the exhaust pushrods that were too long,replaced the ebay rockers with OEM chryslers etc etc.I was working on it tonight and discovered it is only making 5-6 in of vacuum at idle which seems way too low.
Im starting to wonder if it could have an incorrectly degreed cam,an RB cam,or the cam has gone flat.
The engine leak tested perfect(under 15%) and compression is 140psi across the board.
Posted By: dartman366
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 06:50 AM
where is the ignition timing set at and have you tried to increase the initial and re check the vac.?
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 07:53 AM
Quote:
I have been fighting for a while now with a poor running stock rebuilt 426 hemi i have.it runs pig rich and has no power.it was rebuilt in 2005-06 to stock specs and the car has basicly sat most of the time since.i have switched out carbs,every single component of the ignition system as well as corrected an incorrect timing mark and replaced the exhaust pushrods that were too long,replaced the ebay rockers with OEM chryslers etc etc.I was working on it tonight and discovered it is only making 5-6 in of vacuum at idle which seems way too low.
Im starting to wonder if it could have an incorrectly degreed cam,an RB cam,or the cam has gone flat.
The engine leak tested perfect(under 15%) and compression is 140psi across the board.
Check the valve lash, if it has excessive lash on one or two lobes maybe the cam is going flat. More than likely whoever assemble the motor did not degree the cam, they stuck it in and aligned the dots 
Posted By: Dragula
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 02:33 PM
Low initial timing...
Posted By: Crizila
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 04:43 PM
Quote:
I have been fighting for a while now with a poor running stock rebuilt 426 hemi i have.it runs pig rich and has no power.it was rebuilt in 2005-06 to stock specs and the car has basicly sat most of the time since.i have switched out carbs,every single component of the ignition system as well as corrected an incorrect timing mark and replaced the exhaust pushrods that were too long,replaced the ebay rockers with OEM chryslers etc etc.I was working on it tonight and discovered it is only making 5-6 in of vacuum at idle which seems way too low.
Im starting to wonder if it could have an incorrectly degreed cam,an RB cam,or the cam has gone flat.
The engine leak tested perfect(under 15%) and compression is 140psi across the board.
1. VACUUM LEAK. 2. timing retarded. 3. cam in wrong.
Posted By: RUNCHARGER
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 04:45 PM
Give it 18 initial with 34 total, works good on this gas Dean. Then take it for a rip.
Sheldon
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 05:06 PM
Timing is set at 18deg initial and 36 total.Spark plugs are always completely black and sooty,dry,but sooty.
No indication of any vac leaks.while engine is running i can pull the hose off of the brake booster and the RPM's climb,it wants more air.
the cam being in wrong would not surprise me just because the the engine builder had exhaust pushrods in the motor that were .210 too long (sloppy workmanship)
Posted By: dartman366
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 05:57 PM
I think that I would verify the cam setting first,then if that don't do the trick then I would go to the carb next and make sure it is in top notch shape with that said make sure the carb power valve is not blown if one is used in that carb also the it might be the idle air bleeds are not right for that motor, where are the idle air screws set at and do they make a difference when you screw them in or out there are a lot of little things that can cause it to not run right, is the motor rich at just idle or all the way thru the rpm range,i worked on a buddys 440 roadrunner for days, and he had the same problem but the car would die when you put it in gear only to find out that he had a cam with a lot of duration and was trying to use it with a stock torque converter
Posted By: ScottSmith_Harms
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 06:29 PM
Trust me, the carbs are fine, I recently test ran them. That's the very last thing Id mess with on your setup. Just be sure there are no unplugged vacuum ports, carb gasket leaks, or any other possible installation mistakes. BTW its VERY common for Hemi intake gaskets to leak, usually due to some spec being wrong during a rebuild or just a sloppy installation.
Posted By: DodgeCharger
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 06:42 PM
Quote:
Trust me, the carbs are fine, I recently test ran them. That's the very last thing Id mess with on your setup. Just be sure there are no unplugged vacuum ports, carb gasket leaks, or any other possible installation mistakes. BTW its VERY common for Hemi intake gaskets to leak, usually due to some spec being wrong during a rebuild or just a sloppy installation.
Maybe an intake leak and the black plugs are from pulling oil from the valve galley?
If the heads where trued up to make them flat it changes the angles one the surfaces where the intake manifold mates.
The intake can bottom out on the ends and not be sealed at the intake ports
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 06:58 PM
If its an intake vacuum leak wouldnt the engine be smoking and wouldnt the plugs be oil fouled and wet? i will post a pic or 2 of the plugs later today.
i have not had excessive valve lash at any time to indicate a bad cam but that could have occured before i owned the engine.
Sounds like i will be pulling the intake next.......
Posted By: dartman366
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 07:03 PM
Quote:
Trust me, the carbs are fine, I recently test ran them. That's the very last thing Id mess with on your setup. Just be sure there are no unplugged vacuum ports, carb gasket leaks, or any other possible installation mistakes. BTW its VERY common for Hemi intake gaskets to leak, usually due to some spec being wrong during a rebuild or just a sloppy installation.
gotcha', not knowing the history of them was my reasoning for my comments,,,now I know and can rule that out, at least we are eliminating possibilitys.
Posted By: Dragula
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 09:44 PM
Intake leak is also a strong possiblity with the stock intake pattern, we always glue ours in place first.
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 10:42 PM
Posted By: BradH
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 11:22 PM
Quote:
The engine leak tested perfect(under 15%) and compression is 140psi across the board.
Neither of those #s look good to me. IMO, a good leak test for a reasonbly fresh engine would have been 5%, and unless you've got some mongo-huge cam in their killing all the cranking pressure, 140 psi is what I'd expect out of a stock 383.
Posted By: WO23Coronet
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 11:27 PM
Quote:
Low initial timing...
Why would low initial timing affect vacum if the idle RPM is set proper? Isn't vacum dependent on the mechanical specs of the cam? What does it matter to vacum where the plug fires?
Posted By: Challenger 1
Re: why would a stock street hemi have only 5in vacuum ? - 11/14/13 11:29 PM
Quote:
Quote:
Low initial timing...
Why would low initial timing affect vacuum if the idle RPM is set proper? Isn't vacuum dependent on the mechanical specs of the cam? What does it matter to vacuum where the plug fires?
OH yea it matters big time.
I have to question the if it really has 18 degrees of timing at 900-1000rpms? Are you sure?
140 psi on the compression test would make want to check the cam also, to see if it's in right, unless it has really low compression pistons in it.
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 12:08 AM
ive pulled the intake and dont see any indication of oil being sucked in,ports are wet from fuel but not oily.
if anyone has a completly stock street hemi they dont mind throwing a vac gauge on i am curious what the reading should be.
i wasnt impressed with 140 psi comp reading until i checked the service manual and it says 110 psi is the acceptable minimum.cam lobes appear fine at a glance. i think i will pull the timing cover next.
Posted By: cudaman1969
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 12:12 AM
Sounds like you have carter carbs yes? If so the low vac. is not keeping the needles in the seats, thus very rich. I would check how big that cam is and where it's degree in at, sounds like a 110• or lower centerline.
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 12:27 AM
i was just thinking that exact thought,its super rich because the metering rods arent being sucked down in the carters.
Posted By: therocks
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 12:56 AM
With pushrods being almost 1/4 inch too long the valves might be bent a bit.It dosent take much to have them not seating completley.That compression is low also.Thats a lot of extra lift.Rocky
Posted By: pacifica
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 03:26 AM
Quote:
ive pulled the intake and dont see any indication of oil being sucked in,ports are wet from fuel but not oily.
if anyone has a completly stock street hemi they dont mind throwing a vac gauge on i am curious what the reading should be.
i wasnt impressed with 140 psi comp reading until i checked the service manual and it says 110 psi is the acceptable minimum.cam lobes appear fine at a glance. i think i will pull the timing cover next.
I just did a compression check beginning of October on a stock hemi, standard bore, resto cam, ect.
It reads 160# - 175# all 8 cylinders.
Posted By: ScottSmith_Harms
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 04:22 AM
Quote:
and over until they don't take any more movement with a good inch lb. torque wrench, same thing after running the motor to warm it up, retighten those bolts many times until they stop tightening
I agree, just be sure to use an INCH LB wrench, I believe the spec is only 12 inch lbs? It isn't much that's for sure! You don't want to break off a chunk of cylinder head by over torqueing the intake bolts.
I also agree on the low vacuum failing to pull down the metering rods, no vacuum will = pig rich with those carbs.
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 04:54 AM
Quote:
Quote:
and over until they don't take any more movement with a good inch lb. torque wrench, same thing after running the motor to warm it up, retighten those bolts many times until they stop tightening
I agree, just be sure to use an INCH LB wrench, I believe the spec is only 12 inch lbs? It isn't much that's for sure! You don't want to break off a chunk of cylinder head by over torqueing the intake bolts.
I also agree on the low vacuum failing to pull down the metering rods, no vacuum will = pig rich with those carbs.
The FSM calls for 72 inch lbs(6 ft. lbs) on the center four intake bolts on both sides and 48 inch lbs(4 ft. lbs.) on the rest of the outer bolts and studs 
Posted By: ScottSmith_Harms
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 05:23 AM
Thanks Burge, I couldn't remember for sure, I just recalled it wasn't much!
Posted By: SNK-EYZ
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 06:13 AM
Quote:
Sounds like you have carter carbs yes? If so the low vac. is not keeping the needles in the seats, thus very rich. I would check how big that cam is and where it's degree in at, sounds like a 110• or lower centerline.
I just went through changing the springs on the metering rods on the edelbrock's/afb's (750's) on mine.
It took changing to the blue springs (weakest) on mine to get them to stay closed at idle.
It will now idles fine in gear at 700 rpm and it quit gas fouling the plugs. Installing an MSD-6 AL2 helped alot with the idle too.
Posted By: B G Racing
Re: why would a stock street hemi have only 5in vacuum ? - 11/15/13 04:51 PM
Don't over think the situation,start with the obivious things that can cause the problem.
a.check all carb areas for vacume leaks and mixture settings.
b.check intake for the same(tighten by hand,side to side and repeat till the bolts refuse to turn) use a small 1/4 ratch and socket.
c.Check all electrical for voltage and strong spark and firing order.
d.Check distributer for solid timing results.Set timing at 35* at 3000 RPM and no fluctuation at lower RPMs.
e.Check valve settings
f.If everything checks out,look to cam timing.
We have seen bad fuel cause issues also.Cam design,cam timing,distributer timing,valve timing and compression can all effect engine vacume.If you can idle the engine at low RPMs then it is usually not a vacume leak unless the intake is pulling air from the crankcase and then you should see oil foul and smoke.If it shuts off at low idle the leak is above the manifold(carbs).Occasionally if you have a leak and adjust the blades open too far and uncover the idle slots the engine will siphon from the main jet wells and cause an overrich condition.
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 02:20 AM
so i spent the afternoon measuring lobe lift and duration,and checked degreeing of the cam and have determined I have a comp 292 in here,it appears to be out 2 degrees as well (timing events are 2 deg late) ,,specs:
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=754&sb=0
Posted By: RUNCHARGER
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 05:22 AM
Decent cam and 2 degrees late shouldn't be terrible. You're welcome to try my carbs if you want, they work terrific.
Sheldon
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 08:49 AM
thanks Sheldon,I actually have 3,yes 3, pairs of restored hemi carbs right now and I have tried all three on the car with no difference.I think im going to install a smaller cam (comp 278) and im going to carefully check the intake manifold fitment tomorrow.i have to assume the intake must have been leaking to cause the low vacuum.
im thinking the comp 292 is too big for a 100% completely stock car with auto trans,stock converter and 3:23 gearing
Posted By: RUNCHARGER
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 05:48 PM
It is a shiver big but should come on strong around 4000. Obviously you checked for cracks in the intake and the old gaskets showed nice imprints from the castings, puzzling. I wonder if the head studs into the ports are leaking, but I've never seen them create this problem.
Sheldon
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 06:26 PM
Intake is perfect I even pressure tested the exhaust crossover.head studs dont appear to have sealer on them and I plan to remove them one by one today and seal them up.Block may have been decked so I'm going to check intake fitment as well.
I dont think this trailer queen will ever see over 4000 rpm anyway unless the next owner actually drives it.I can use the comp 292 in the engine Im building for my challenger (4 speed car w 4:10's)
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 06:37 PM
Quote:
so i spent the afternoon measuring lobe lift and duration,and checked degreeing of the cam and have determined I have a comp 292 in here,it appears to be out 2 degrees as well (timing events are 2 deg late) ,,specs:
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=754&sb=0
When you say late cam timing are you referring to opening and closing or te lobe seperation angle? If the cam has the intake lobe installed at max lift at 110 degrees after top dead center move it so it is at 104 to 106 before top dead center In other words if the cam is opening the intake lifters two degree later(closer to top dead center) than on the cam card move it forward (away from top dead center) to open sooner 6 to 8 degrees to help it have more bottome end I've never had any type of Mopar V8 motor like having the cam timing late, on the dyno or at the track Having the cam retarded will kill the bottom end dramatically Try moving it before replacing it That grind is not that big, trust me on that Hemiroid motor need an love more air to make more power 
Posted By: Twostick
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 06:46 PM
What does a "stock" factory street hemi cam spec at for duration and overlap and what does a "stock" Hemi have for idle vacuum? If the Comp 292 is anything close to the MP 292 cam, spec wise, I wouldn't expect idle vacuum to be much higher than you are at 426 cubes.
Probably an apples to oranges comparison but my 493 wedge has an MP509 that has 76 deg of overlap which is the same as the MP 292 Hemi cam. It idles at 7-8" at 1100 RPM.
As for 15% leakdown, my builder considers anything over 10% worn out on a competition build.
Kevin
Posted By: Dave Watt
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 07:16 PM
Everything sounds good that you've checked.
I'm wondering if the carb base gaskets are causing a leak which in turn draws more fuel into the engine?
Posted By: B G Racing
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 08:21 PM
The Comp 292 cam you show isn't much different than the Mopar Hemi 292,510/512 cam used in the 4 speed cars.They usually carry 12 to 15 inches of vacume.I have used the Comp Cam in many street applications and have all carried good vacume to operate vacume assist brakes.
You have an issue that needs to found and corrected.Did you remove the pan from the bottom of the intake and check for leaks at the core plug or for any cracks?Did you check for timing fluctuation?
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 08:36 PM
Cab,
yes by late timing I mean the intake is opening at 35-36 btdc when it should be 38 btdc.
I have checked the plug on the bottom of the intake.Timing was a little erratic with the oem dual point but i replaced it and timing is good now.
How much of a vaccum loss would I see if the brake booster was bad?
what do you guys recommend to seal the head stud threads?
Posted By: dartman366
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 08:42 PM
Quote:
Cab,
yes by late timing I mean the intake is opening at 35-36 btdc when it should be 38 btdc.
I have checked the plug on the bottom of the intake.Timing was a little erratic with the oem dual point but i replaced it and timing is good now.
How much of a vaccum loss would I see if the brake booster was bad?
what do you guys recommend to seal the head stud threads?
pull the hose to the booster and plug it. that will tell if it is .
Posted By: racerhog
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 09:11 PM
I would move it one tooth and see how it reads....
Posted By: TRENDZ
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 11:07 PM
You say it's running rich, and you said the rpms climb with the booster vacuum line open.
It's to rich. the engine wont run well if its blackening the plugs. Find somone that knows how to tune these carbs ON THE CAR.
Everything you've stated tells that the engine wants more air.
Get the Air/Fuel ratio where it needs to be, change the engine oil, and maybe the leak down numbers will also improve. You are chasing a tuning problem, not a mechanical issue.
Posted By: cudaman1969
Re: why would a stock street hemi have only 5in vacuum ? - 11/17/13 11:33 PM
From the 69 service manual, cam- 284 deg. 467 lift not even close to a 292 cam. cranking pressure 150-205 psi. Change that cam!
Posted By: Hemi Allstate
Re: why would a stock street hemi have only 5in vacuum ? - 11/18/13 02:52 AM
Quote:
Cab,
yes by late timing I mean the intake is opening at 35-36 btdc when it should be 38 btdc.
I have checked the plug on the bottom of the intake.Timing was a little erratic with the oem dual point but i replaced it and timing is good now.
How much of a vaccum loss would I see if the brake booster was bad?
what do you guys recommend to seal the head stud threads?
Permatex makes a white thread sealer that I use.
Permatex # PX 56521
If the studs are not sealed, you will draw oil passed the threads that you will see in the intake ports.
Any chance the valves are adjusted too tight?
Posted By: superwrench
Re: why would a stock street hemi have only 5in vacuum ? - 11/18/13 04:39 AM
Just to give you a comparison of sorts.....I have a Racer Brown SSH-44 for a Hemi sitting on my shop shelf. It's a hydraulic 292* .510 lift cam that Direct Connection had 30 years ago.
The reason it's on the shelf is for the very reason's you have pointed out in your post.....NO vacuum, pig rich running at idle and low speed, and all the other associated woes that a cam like that creates.
My hemi car doesn't have Power brakes,but the 6" of vacuum that I had wouldn't have run them anyways.
My
is you need a cam down in the 276*-280* maximum (Not at .050 either)
That cam made the car haul like hell up top, but you couldn't poke around town with it and enjoy the car.
Just the stock solid in the car now, and that's what's staying in it.
Posted By: B G Racing
Re: why would a stock street hemi have only 5in vacuum ? - 11/18/13 03:36 PM
With most cams you won't see much change unless you move it 3 to 4 degrees.One tooth can be a large move in degrees.If your going to move the cam do it correctly.Advancing moves the intake valve closser to the piston,retarding moves the exhaust closer to the piston.Don't guess at it.
Posted By: GTX MATT
Re: why would a stock street hemi have only 5in vacuum ? - 11/18/13 04:15 PM
Quote:
With most cams you won't see much change unless you move it 3 to 4 degrees.One tooth can be a large move in degrees.If your going to move the cam do it correctly.Advancing moves the intake valve closser to the piston,retarding moves the exhaust closer to the piston.Don't guess at it.
I believe one cam tooth is something like 15 degrees, at least thats what I've heard and it seems to make sense
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/26/13 10:53 PM
ok my comp 278 will be here this afternoon,comp recommends cl @ 108, does that sound good for this cam?
specs
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=753&sb=0
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/27/13 02:45 AM
Quote:
ok my comp 278 will be here this afternoon,comp recommends cl @ 108, does that sound good for this cam?
specs
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=753&sb=0
Nope 
Put it in at 102 to 105
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/27/13 04:42 AM
Ok, well I just degreed it and it came in at 107.I can move it in 4 degree increments if i want.this is a stock engine keep in mind in a street only car.
The comp lifters are kinda strange,the pushrod cup sits down farther in the lifter and is loose,you can rattle it.the pushrod cup sits .087 lower down than the cup in the lifters im replacing so that is going to affect my pushrod length again..............
Posted By: cudaman1969
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 05:29 AM
I don't think you will see any more vacuum with that cam then the one you had. You need at least 112 or more centerline. Just a street engine-right?
Posted By: Twostick
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 05:42 AM
Going from 76 deg of overlap to 62 has got to help.
Kevin
Posted By: cudaman1969
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 06:07 AM
I put one in my 440 and with the crane bleed off lifters only got 9-10 inchs of vacuum. Brake booster was marginal and carb needed work. So I put stock cam back in.
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 02:19 PM
I did some online research before buying this cam and two moparts members have it in stock resto cars and are happy with it,I thought it speced out fairly mild?
Sooo,Cab says I should install it at 102 and cudaman is saying 112?
Im getting confused here !
My local engine guy as well as BGR are saying 108 is good!
Posted By: MR_P_BODY
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 04:16 PM
Quote:
I did some online research before buying this cam and two moparts members have it in stock resto cars and are happy with it,I thought it speced out fairly mild?
Sooo,Cab says I should install it at 102 and cudaman is saying 112?
Im getting confused here !
My local engine guy as well as BGR are saying 108 is good!
NO NO... they are talking 2 different things... Cab
is saying to INSTALL at 102.. Cuda is talking LSA
(lobe separation angle).... from your initial post
you said you moved the timing pointer.... if thats
the case your timing would be based on the od pointer...
when installing a cam you set TDC on the piston then
slide the cover on to verify the zero... so if you moved
the pointer you changed a lot of factors.... back
to the cam numbers... like Cab said I would INSTALL
it at 102 or so for the lower end torque
A cam that is installed retarded(as in 109 or higher)
will have low vac
Posted By: sr4440
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 04:17 PM
Quote:
Quote:
With most cams you won't see much change unless you move it 3 to 4 degrees.One tooth can be a large move in degrees.If your going to move the cam do it correctly.Advancing moves the intake valve closser to the piston,retarding moves the exhaust closer to the piston.Don't guess at it.
I believe one cam tooth is something like 15 degrees, at least thats what I've heard and it seems to make sense
very close, 14.4 degrees (25 crank teeth / 360 degrees)or (50 cam teeth / 720 degrees)
Joe
Posted By: cudaman1969
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 05:25 PM
Quote:
I did some online research before buying this cam and two moparts members have it in stock resto cars and are happy with it,I thought it speced out fairly mild?
Sooo,Cab says I should install it at 102 and cudaman is saying 112?
Im getting confused here !
My local engine guy as well as BGR are saying 108 is good!
Just looked at some cams and Crane has a 660091 cam,284-294 with 112 lobe separation - 1500-5200 rpm great idle. This is what I'm saying, a good street cam that will give you the vacuum you need for stock carbs.
Posted By: Dodgem
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 05:29 PM
Quote:
I did some online research before buying this cam and two moparts members have it in stock resto cars and are happy with it,I thought it speced out fairly mild?
Sooo,Cab says I should install it at 102 and cudaman is saying 112?
Im getting confused here !
My local engine guy as well as BGR are saying 108 is good!
I would install that cam 102 to 105
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 06:55 PM
Quote:
Quote:
I did some online research before buying this cam and two moparts members have it in stock resto cars and are happy with it,I thought it speced out fairly mild?
Sooo,Cab says I should install it at 102 and cudaman is saying 112?
Im getting confused here !
My local engine guy as well as BGR are saying 108 is good!
Just looked at some cams and Crane has a 660091 cam,284-294 with 112 lobe separation - 1500-5200 rpm great idle. This is what I'm saying, a good street cam that will give you the vacuum you need for stock carbs.
Hemiroid motors don't like wide lobe seperation angles like above 110, even a street blower motor Same thing on close lobe centers(closer than 106), them dang hemirod motors are a pain to get right 
Posted By: dvw
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 07:39 PM
Quote:
Quote:
Quote:
I did some online research before buying this cam and two moparts members have it in stock resto cars and are happy with it,I thought it speced out fairly mild?
Sooo,Cab says I should install it at 102 and cudaman is saying 112?
Im getting confused here !
My local engine guy as well as BGR are saying 108 is good!
Just looked at some cams and Crane has a 660091 cam,284-294 with 112 lobe separation - 1500-5200 rpm great idle. This is what I'm saying, a good street cam that will give you the vacuum you need for stock carbs.
Hemiroid motors don't like wide lobe seperation angles like above 110, even a street blower motor Same thing on close lobe centers(closer than 106), them dang hemirod motors are a pain to get right
I built a Hemi for my buddy's 69 Road Runner. A friend recommended a cam with a 114 LCA. The car Idles like a 318. Has great low end and pulls to 6000. All stock (still has the original exhaust from 69) 13.00@107. I would have never chosen this cam but he swore it would work. He was correct.
Doug
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/28/13 07:44 PM
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/29/13 01:58 AM
Posted By: scatpacktom
Re: why would a stock street hemi have only 5in vacuum ? - 11/29/13 05:42 AM
I just went from 114 to 111 and it didn't seem to care at all
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 11/29/13 03:26 PM
Quote:
I just went from 114 to 111 and it didn't seem to care at all
Try 110 to 108 LSA cams with the intake lobes at 104 to 106
Posted By: Teamx
Re: why would a stock street hemi have only 5in vacuum ? - 12/01/13 04:27 AM
It depends on what you are trying to acheive, The OP stated this is a resto car so ET at the track may not be his main consideration. A cam with around 220>225 @ .050 on 110>112 lobe seperation installed 2 to 4 degrees advanced will give a nice stong vaccum signal to the carbs enhancing tuning and also make plenty of vaccum to operate the power brakes.Oh and it wont burn your eyes out as much as a tight lobe cam!
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 12/01/13 07:03 AM
Quote:
It depends on what you are trying to acheive, The OP stated this is a resto car so ET at the track may not be his main consideration. A cam with around 220>225 @ .050 on 110>112 lobe seperation installed 2 to 4 degrees advanced will give a nice stong vaccum signal to the carbs enhancing tuning and also make plenty of vaccum to operate the power brakes.Oh and it wont burn your eyes out as much as a tight lobe cam!
I've never seen Eyeballs damaged by camshaft lobe centers, ever Rich mixtures are another subject entirely Carbs. may need modifying, tuning, when you change any of the stock parts to non stock parts, just like adding headers usually requires leaning down the carbs on all the pertinent circiuts, idle, transistion, main and sometimes the secondary jetting also That is if you want the best results from your changes You can lean the idle circuits down two diffeent ways, restrict the idle fuel feed or open up the idle bleeds to reduce the vacume signal too the idle circuits, sometimes doing both is the best answer
Posted By: JAKE68
Re: why would a stock street hemi have only 5in vacuum ? - 12/01/13 08:24 AM
Quote:
It depends on what you are trying to acheive, The OP stated this is a resto car so ET at the track may not be his main consideration. A cam with around 220>225 @ .050 on 110>112 lobe seperation installed 2 to 4 degrees advanced will give a nice stong vaccum signal to the carbs enhancing tuning and also make plenty of vaccum to operate the power brakes.Oh and it wont burn your eyes out as much as a tight lobe cam!
I understand what your saying. It's not about rich or lean carbs its about high hydrocarbons . That's what burns your eyes. And yes engine with big aggressive cams will do that.
Posted By: dvw
Re: why would a stock street hemi have only 5in vacuum ? - 12/01/13 05:11 PM
Quote:
I dont think this trailer queen will ever see over 4000 rpm anyway unless the next owner actually drives it.I can use the comp 292 in the engine Im building for my challenger (4 speed car w 4:10's)
The OP stated this is a resto car so ET at the track may not be his main consideration.
My point exactly
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 12/02/13 09:33 PM
A quick update,I just broke in the new cam and the car is running fantastic,its a whole different car now.Idles nice with a slight lope and its making 12in vacuum at idle.
I did install the cam 4 deg advanced(at 103), and the moral of the story is dont install a comp 292 cam,4 degrees retarded,in your bone stock,auto trans,3:23 geared hemi car!
Thanks to everyone who helped me out!
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 12/02/13 09:48 PM
Posted By: scatpacktom
Re: why would a stock street hemi have only 5in vacuum ? - 12/02/13 09:51 PM
Quote:
A quick update,I just broke in the new cam and the car is running fantastic,its a whole different car now.Idles nice with a slight lope and its making 12in vacuum at idle.
I did install the cam 4 deg advanced(at 103), and the moral of the story is dont install a comp 292 cam,4 degrees retarded,in your bone stock,auto trans,3:23 geared hemi car!
Thanks to everyone who helped me out!
AND THAT FOLKS IS HOW HEMI'S BECOME DUDS
Posted By: RUNCHARGER
Re: why would a stock street hemi have only 5in vacuum ? - 12/03/13 04:10 AM
Glad you sorted it Dean.
Sheldon
Posted By: ScottSmith_Harms
Re: why would a stock street hemi have only 5in vacuum ? - 12/03/13 04:14 AM
Quote:
A quick update,I just broke in the new cam and the car is running fantastic,its a whole different car now.Idles nice with a slight lope and its making 12in vacuum at idle.
I did install the cam 4 deg advanced(at 103), and the moral of the story is dont install a comp 292 cam,4 degrees retarded,in your bone stock,auto trans,3:23 geared hemi car!
Thanks to everyone who helped me out!
Great news!
Posted By: goldmember
Re: why would a stock street hemi have only 5in vacuum ? - 12/03/13 04:21 AM
Quote:
Isn't it amazing the differences a small change like that can make 
How bad do the rear tires spin now
It's far from a SMALL change but NOT unexpected.
Posted By: MR_P_BODY
Re: why would a stock street hemi have only 5in vacuum ? - 12/03/13 04:38 AM
Quote:
A quick update,I just broke in the new cam and the car is running fantastic,its a whole different car now.Idles nice with a slight lope and its making 12in vacuum at idle.
I did install the cam 4 deg advanced(at 103), and the moral of the story is dont install a comp 292 cam,4 degrees retarded,in your bone stock,auto trans,3:23 geared hemi car!
Thanks to everyone who helped me out!
I'm sure the cam timing was suggested to check... but
was it degreed when you installed the cam(I dont recall)
or was it the timing pointer was moved... which shouldnt
have changed the cam timing but would have on spark
timing.... anyways.... glad you found your lost
power and vac
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 12/04/13 01:34 AM
Quote:
How bad do the rear tires spin now
Cmon Cab,this is an all #s matching low mile restored 71 hemi car,it is much too rare valuable etc etc to be spinning the tires.it is for static display use only !!
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Seriously though,it spins 'em real good now !
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 12/04/13 01:42 AM
I spent several hours today driving the car and it runs great,really a treat to drive an auto trans car,I cant remember the last time I owned one its been so long.To my knowledge this is the first time since 1971/72 this car has been driven, at all..it was taken off the road sometime in 71 or 72.
Posted By: cudaman1969
Re: why would a stock street hemi have only 5in vacuum ? - 12/04/13 01:47 AM
Quote:
Quote:
How bad do the rear tires spin now
Cmon Cab,this is an all #s matching low mile restored 71 hemi car,it is much too rare valuable etc etc to be spinning the tires.it is for static display use only !!
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Seriously though,it spins 'em real good now !
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 12/06/13 06:59 AM
Ha ha,dont need the snow tires yet but it is getting chilly here now!
these motors LOVE cold air!
Posted By: Cab_Burge
Re: why would a stock street hemi have only 5in vacuum ? - 12/06/13 08:08 AM
Quote:
Ha ha,dont need the snow tires yet but it is getting chilly here now!
these motors LOVE cold air!
Dat be true Thats one of the reason I dyno test in the winter, cold and dry with high B.P. 
Posted By: cudaman1969
Re: why would a stock street hemi have only 5in vacuum ? - 12/06/13 03:51 PM
Quote:
Ha ha,dont need the snow tires yet but it is getting chilly here now!
these motors LOVE cold air!
Chilly??? Looks like snow on the ground now lol. 
Posted By: Tempest
Re: why would a stock street hemi have only 5in vacuum ? - 12/06/13 04:22 PM
Quote:
Quote:
How bad do the rear tires spin now
Cmon Cab,this is an all #s matching low mile restored 71 hemi car,it is much too rare valuable etc etc to be spinning the tires.it is for static display use only !!
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Seriously though,it spins 'em real good now !
Please tell me you washed all that salt off after the drive??? You can see it on the road.
Posted By: ogopogo
Re: why would a stock street hemi have only 5in vacuum ? - 12/06/13 06:58 PM
Quote:
Please tell me you washed all that salt off after the drive??? You can see it on the road.
relax ,the only salty portion of road is the 200ft stretch where I was doing the burnout,the rest of our streets are snow and salt free so far this year.and yes,i did wash the car after just to be safe!
Posted By: B G Racing
Re: why would a stock street hemi have only 5in vacuum ? - 12/07/13 12:44 PM
Quote:
Quote:
Please tell me you washed all that salt off after the drive??? You can see it on the road.
relax ,the only salty portion of road is the 200ft stretch where I was doing the burnout,the rest of our streets are snow and salt free so far this year.and yes,i did wash the car after just to be safe!
