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A few more tuning questions?
#1
Ok, I got to the point where my engine fires up good and seems to run well, but have a few questions. First off I notice the valve train is fairly noisy when cold, as it warmed up it did get quieter, I'm guessing this is normal for a full roller valve train? I did listen to it with my stethoscope and their are no "oh my god" noises jumping out at me, just the typical whirring/ticking sounds. Next, my idle still wants to be around 1000 rpm, 8-900 in gear. And my vacuum still wants to stay just under 15" of vacuum, around 13ish. Is this normal vacuum for a higher lift cam? I did spray some starting fluid around the intake ports and such and the motor did not suck it in so I don't think I have a vacuum leak. This is the first engine of this performance level I have ever built and I'm just not familiar enough with them to know what proper tune would be! I'm not saying anything is really wrong, I just want to know if some of these things are "normal"?
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#2
What is the duration @.050" of your cam?

What is your initial timing?

What is your static compression ratio?

What carb?

What intake?

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
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#3
A little Valve train noise that's gone after warm up nothing to worry over. A lot of people over look low vacuum as always the cam fault. Not all PCV valves are the same. Fram # 156 or 181 are the better working valves when running a mild cam. If you have a vac gauge try changing PCV. The 156 seems to work best for me . I always buy 2 or 3 of the same number even since they are same number one always seems to work better. Our 67 with the clever and AOD would stall most of the time when put into gear. Always had to mess with gas pedal to keep running. In park it needed to idle 1500 rpm to make it road friendly. Now it idles in gear at 6 to 700 and out gear under a 1000 rpm using .536/562 lift flat tappet cam. Vac. stays around 14 to 15 in. I could turn the idle down more but the wife happy with it now. No more chugging after turning key off and locking the doors...
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#4
Looks like the duration of your cam is 221/229 @ .050 so I think 13" vacuum is about right. I get about 13" with 225/235 @ .050.

-john
(jbojo)
351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,
C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

Some Mod pictures can be seen at:

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#5
Your not going to get full vacuum on a new motor that hasn't broken in seated the rings-Check back after you put a few thousand miles on it

LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#6
Adv. Dur. In 272 Ex. 280, @.050 In 221 Ex 229, Gross lift In. .594 Ex .611 LSA 112 In. CL 106, Compression around 10.5, Stock dizzy re-curved w/ Pertronix 2, spiral core wires, AP25 plugs, Pro Systems Carb 780XP body w/Venom 2 metering blocks. Air gap intake, Hooker headers. One more question: When I set my lifter preload, I did it with engine cold and turned the engine by hand, I noticed that some of the lifters did not offer much resistance during preload, but a couple did. I did allow 2 minutes for bleed down for each lifter. Is this normal or should I redo my lifter preloads?

I was also thinking to plug off all vacuum accessories and run motor again to see if that changes anything. I have been setting initial @6-8 degrees and it seems to like that.
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#7
You could adjust your timing by putting a vacuum gauge on the engine, turn the distributor until you get maximum vacuum, readjust your idle, again adjust the distributor for maximum vacuum, then back it off about 1-2 degrees and see where you end up at. You could probably go as far as 14-16 degrees with your initial timing. I also like to verify timing at 3000 rpm as not exceeding 36 degrees with the vacuum advance disconnected with a 4V closed Chamber head or 38 with OC heads

If you did not soak your lifters in oil for 24 hours before installation, then it is not unusual for some to be "dry" inside initially. It should resolve itself on your first drive though.

Barnett will be along to disagree with me shortly Big Grin

13-15" of vacuum is about right. If you have power brakes you'll probably need a vacuum canister, make sure it has a proper check valve.

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#8
^^Agree with the above^^

That came will want more than 6-8 degrees I believe and that should pick up the vacuum reading slightly.

Also agree with Scott that the engine needs to be broken in before the tuning can be finalized.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
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#9
.
exactly what lifters do you have?

exactly what spark plugs do you have?

do you have vacuum advance?

if so is it connected to manifold or ported/timed vacuum?

how much advance does it add?

what oil are you using?

the preload should always be set by starting at zero whether the lifter offers a little or a lot of resistance . i sometimes have people use a feeler gauge then set it to .002" then remove the gauge and turn the nut in around 1/2 to 3/4 turn depending on the pitch of their threads . this helps prevent them from over tightening the nut.

with the engine idling, plug the pcv . if the rpm drops by around 100 rpm or more, i would buy an adjustable one.

after that test, plug the pcv until it is properly tuned just to eliminate a variable and possible source of a prob.

plugging the other vacuum sources sure won't hurt and if the rpm drops after you plug one, it has a leak.

unfortunately, just because a distributor has been ecurved, it doesn't mean it has the ideal setting for your engine, and more performance can sometimes be done by testing the timing curve yourself.


remove the front spark plug from each bank and post a photo of it.
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#10
I am using 14* initial timing with similar motor specs.

-john
(jbojo)
351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,
C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

Some Mod pictures can be seen at:

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