Hi everybody! I just grooved my 85 Chevy suburban. It has a 454 with an edelbrock 1406 carb. I'm trying to figure out what to do with the pcv system. I have a pcv valve in each valve cover with hoses meeting in the middle at a t where it plugs into the pcv vacuum port on the carb.
I tried pulling that hose off the pcv port on carb, and hooked it to air cleaner, then capped pcv vacuum port on carb. This makes the engine stutter and soon die, also I now get lots of blue smoke from exhaust when I did not before.
I think this might mean that the pcv valves, and/or their seal in the valve cover, were leaky, and the carb and distributor were tuned for that.
Does that all sound right? And if so do I need to adjust both distributor and carb springs for the higher vacuum?
Hi Geronimo, was cool talking to ya while I was up on a mountain today- I'm sitting on a log about 300 feet from a big cell tower, drinking from a canteen and my phone rings!
Anyhow thanks for the pics this helps heaps. OK first your Grooves look good far as I can see. Large bit, full width, next time the carb is loose take the large bit and check that the bit cutter bottoms out in both Grooves all the way through, known as checking for full depth of cut. The cutter ball should bottom out so the shaft taper behind the cutter is touching the bore wall. In your case there IS no bore left at bottom of Grooves, just try to judge it, if it isnt full depth you can retouch it, be careful not to over-do it.
Next thing I see- the thick fiber carb base gasket/spacer, is it pliable or hard/dry? IF dried out it can leak vacuum. The Edelbrock Performer intakes usually are made such that the opening at top goes wider to accept the stock Quadrajet carb secondaries. A flat spacer like you used can cover the wider secondary section of the plenum opening. Edelbrock makes a flat thin metal adapter plate to be used in applications like yours here. You use a thin carb. base gasket, open style, then the metal adapter plate, then another thin open carb base gasket, stacked bottom-up. Go to any parts store look for a Holley 4 bbl square bore open center base gasket, that's the style to use, just put the Edelbrock metal plate between 2 of these gaskets. This ensures a good carb to intake manifold seal. You can put additional spacers atop this stack if wanted. I have found those thick fiber carb base gaskets like yours to be unreliable, they can leak vacuum, and don't seal that well.Those compression limiter rings at the bolt holes exacerbate the issue. Look on Summit Racing's online site you will see the Edelbrock adapter plate, anf mayber copies of it it's not expensive, that's the only way I will setup an Edelbrock/AFB carb on the Performer intakes.
Next of course is the issue of the PCV/ crankase breather, and doing the PCV re-route to it. I'm not absolutely certain, but the Driver side valve cover might have originally had the breather tube that went to the stock air cleaner. Having 2 PCv valves w/ no crankcase ventilation breather provision is a no-no. See if the driver side grommet is a larger diameter than the pass. side. The larger diameter grommet would be the breather side. Check the air cleaner base plate, seeif there is a provision to add any fittings to it, many aftermarket ones have this. What is needed to do a "correct" PCV re-route is: New pliable grommets for both valve cover holes, a 90 degree fitting to fit the driver side grommet hole ( Look in a "HELP" section at parts store, or boneyard) or it might have had a metal pipe w/ the 90 deg. bend in it, look at other Chevy's. A knockout plug or just a drilled hole to fit the aircleaner base, to take a fiitting the same size ID as the hose that will come from the driver side valve cover. There's supposed to be a hose, that connects from inboard of the air filter element, to direct fresh filtered air to the fitting on the Driver side valve cover. This is the MAke-up air side of the Crankcase Ventilation system. The PCV on the other valve cover, goes to the carb base of course (Capt. Obvious here). The manifold vacuum sucks the crankcase gasses thru the PCV Valve to the carb base, the Breather side lets in the fresh Make Up air, see?
With all that said, get a breather hose done from the driver valve cover to air cleaner base, opening inboard of the filter. THEN---Cap the PCV tube at carb base, run PCV valve hose over and tee it into the new Breather hose. That's It.
I've never seen an engine w/ 2 PCV valves!
IT is possible as you say that some tuning was done before to compensate for this unusual setup. Somebody just took a shortcut w/ the crankcase vent. system. I'm not surprised I've seen lots of stuff like this before. The details on setting up aftermarket carbs, hoses, vacuum lines etc. etc., are sniggly. I dont think it's going to be possible to troubleshoot this engine until the carb base gasket and PCV/Breather stuff is right.
And I notice the nice MSD upgrades, very nice! (IGnition Freak here!) As well as the Magnetic stuff. LAstly, Gernimo, maybe while you re-do the carb base setup and the carb is off, get the Edelbrock torque specs and sequence info- and check the intake bolt torque's. The Edelbrock torque values will prob. be different from Factory Specs, pay attention here. But Don't loosen the bolts all the way, unless you partially drain the coolant dont want coolant leaking at manifold/ head junction. IT's a goood idea to do an intake man. re-torque, I proved it again earlier this summer on a Lincoln w/a Ford 460, original, 40 yrs old.
Out for now, thanks for the posts and great pics, Geronimo!
Founder and Constant Aide to Gadgetman
Gadgetman Reno, NV
OK, I plan on doing all that tonight. Now, since this all will just increase the vacuum pressure, I will still need to figure out why capping the pcv port stalls the engine, right? So after that's all done, where do I adjust for this? I would guess that I need to adjust the distributor by turning it a little. Or is it going to be the rods in the carb ?
Also, the groove is definitely not full depth, I didn't want to go too deep. Has anybody cut it too deep on the bottom of groove and would know exactly how deep to go there?
And I'm hoping my angle is correct. Watching Ron's video on same carb he closed butterfly as far as it'll go, including moving the lever below the throttle lever to close it even more. This is what I did, and kept the front of the bit flat on the butterfly. It seems to contradict what he said in other videos about the groove not "engaging" till butterfly opens just pay throttle. As I see it, in this case, the butterfly at idle position is already halfway into groove. Hopefully I'm doing this right!
Any constructive criticism appreciated
Geronimo, the Groove needs to be full depth to work right. Ive done 2 Performers like yours there was enough material there to be OK. These Grooves look smooth, but I can't see the flat floor part. One thing that's contradictory about Grooving- you want full depth Grooves that are "smooth" but you do not want to go too far trying to make them perfect. Mine never are perfect, and remember what Ron teaches about not 'Penciling" with the bit. Some of the best results I've ever had came from crummy lookin' Grooves..
With a LArge bit Groove in the Performer, there's only so much room under these throttle blades, it's likely the throttle blades will be engaged in the Grooves at curb idle speed, at least some. Remember also, this is the smaller CFM Performer on a Rat motor. The bigger 750 CFM one,that has primary bores as big as the secondaries,. would likely need less throttle opening to get a proper idle speed. I'm still up a tree with the whole capped PCV port/no idle issue. Something basic is wrong here. Does this 454 have the Performer cam or another non-stock cam? I'm assuming this is a stock docile engine, is there anything more hot-roddish in it's build?
I also noticed the fuel press. regulator you have-I had one of those on my Subaru Weber, beware, mine developed a bad leak, I caught and fixed it at a gas station, but it was close...
Sometimes when stuff gets weird w/ a carburetor and some mods, I have found it good to get things back to either stock type configurations (crankcase vent. system) or back to what it liked before then try to untangle the knot. Have ya tried w/ the PCV port capped, cranking in the idle speed screw to get an idle? Maybe it was getting lots of its idle airflow from the dual PCV setup, enough that capping the port starves the engine for idle air. How much initial timing is in the dist., w/vacuum advance capped? I see you are using manifold vac port on the carb, not "ported" vacuum to the dist. Here in Reno at 4500-5000 ft elev. most carbureted engines like at least 12 deg initial advance, w/ dist. vacuum capped off to set timing.
I had the opposite thing happen to my Dodge Slant Six- it had crummy idle quality Forever, until I capped the PCV hose port on the Carter BBD, and did a PCV re-route. THAt cured it and gave a nice idle quality, the PCV acted as a huge man. vac. leak.
It can be trickier to get a carbureted engine in the Groove,'cause you can adjust more stuff manually, therefore we WILL adjust more stuff, often sending us over the "fence". IF this thing has had the dual PCV's since ya got it, and doesnt like having that port capped, something is off. If YOU did the dual PCV's, did you have to adjust something else to get it to idle?
BTW, here is the Edelbrock manifold adapter plate I was speaking of...
it covers the secondary side wider plenum opening nicely, always worked well for me.
Founder and Constant Aide to Gadgetman
Gadgetman Reno, NV