Vacuum on 1968 GTS 340 4 spd.

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I'm wrong Felpro 1008 are .039. The eddy and felpro 8553pt are one and the same. Edelbrok just puts them in their packaging.
 
All I can think of now is maybe a mis-packaged (cc) head ? I'm disgusted and have to walk away from it right now.
 
Hmmmmm.... 145 to 175 is about 1.5 points in compression ratio! That's gonna take a lot more than a coupla cc's from .010" difference in head gasket thickness, or the 2 cc's chamber difference in the 2 SBM Edelbrock head types. That is more than 10 cc's of difference...which would be greater than .050" of deck difference, or something in the valvetrain on one side versus the other.

Did you record the actual compression numbers? If so, it might help the list them so we might spot another pattern in the numbers.

Was the right bank where the shims were placed? If so, then the lifters on the side with the shims would be pumped up higher. If you then took the shims out, and did the compression test without running the engine first, then the lifters on that side could all be hung open and ruining the compression on that side. Oh, maybe not....sounds like you re-started the engine after removing the shims.

BTW, the .030" shims would have opened up the pushrod side lengths by the rocker ratio times .030" , or about .045".
 
.045 would tell me I'm good on the pushrods then. Yes I started the engine after shim removal then decided to pull plugs and do the compression test. There is a 58 cc head as well. Maybe 1 58 & 1 65 or maybe head with roller springs ? Test results are at home I'm at work but I will post tomorrow. Can't get back to car until Saturday to work on it.
 
Roger.... I will have to look up that small head. But that still is not enough of a cc difference for 1.5 points in CR. Roller springs are just the springs/retainers. It would have to stack up with head gaskets and deck height differences. This is very unusual.... like you don't already know.

Maybe OK with the .045" extra (with shims). If the pushrods were still just touching the lifters after they pumped up, then yes. If they were loose then that clearance is deducted from the .045" to get the preload. And the 2 sides can be different.
 
I might shim the other side just to see the results. And yes very unusual . I fix other peoples stuff without a hitch but when it comes to my stuff all hell breaks loose! Just call me Ziggy lol or as I've often said :I'm still a Grizwald (Vacation).
 
Too Much !!! I got home from work and wife was out so I shimmed the right side. Same results. I did check my vacuum and saw a 2" increase from 8 to 10 .I decided to do a comp check on #2 by starting engine and had100 PSI Compression. Revved up some and gauge was getting hung up trying to increase . It's Junk ! I bought it and used it when I did my 500 stroker 4 years ago and seldom used it since.Kept inside in a case. I think I have to get new test equipment.Can't believe this. Thought this tester looked decent when I bought it.I will get some new readings when I can. Milton Industries S-1251
 
Ahah.... that would do it! Not the first error in a compression tester. My 40 year old NAPA tester keeps giving good results so 'knock on wood'....

BTW, you mentioned a 8 to 10 in vacuum increase... was this with the right side shimmed up or ???

As for cartoon characters.... this reminds me Joe Btfsplk, the world's worst jinx, from Little Abner.. that was the guy who walked around with the rain cloud over his head all the time... LOL
Btfsplk
 
Well I took tester to work. Gave it good cleaning and blowing out Shrader valves and such. Took out plugs and hooked up battery charger and set to 40Amps as it was cranking a little slow. Cranked until I saw oil pressure come up. I did it all cold and came up with #1 163 #2 163 #3 163 #4 163 #5 160 #6 165 #7 160 #8 170 . 163 sounds a little too consistent with issues I just had with the tester . I am looking to borrow a tester from a buddy so I can compare. The tester climbed smooth and wasn't erratic like yesterday. I still think I'm getting too much water out the exhaust . It doesn't smell like anti-freeze but not sure. Dip stick looks semi clear, still break in oil but I unscrewed oil filter and looked at oil there and it looks more muddy. I wanted to leave water in it till I figured this out but cant risk it as I pull the car out to work on other stuff and wont risk the freezing temps.Even though I tested for vacuum for leaks my gut tells me there's an intake issue. I'm contemplating Pulling the intake to see if I can find any clues and check pre load with a adj. push rod. If I get stonewalled on this.
 
Vacuum sounds low for a stock camshaft unless the idle is really slow.
 
Kendog 170 said:
Sorry Meant increased vacuum while shimmed and ticking.
Click to expand...
I guess that is plausible with the valves on that side being opened at a smaller duration (and thus overlap).

Looks like pretty good compression readings now.

What carb? Is the secondary stop crew way open? That'll drop vacuum.
 
Secondary seemed fine but I will double check. The motor ran the same with my original AVS 600 cfm before I put the rebuilt Eddy 625 that's on it now.
 
Not sure. You wouldn't know a part # for a replacement ? I might still have my old one kicking around to compare with but not sure.
 
All I can think of at the moment is that there is an MP part that transitions from idle flow to full flow at a lower vacuum level. Maybe someone will know it and post the PN here. The stock one (like off of a 318) transitions at something like 14-15 in, so if that is in there, the PCV will be wide open at idle and will drop your intake vacuum a couple of inches. With the age of these cars, it is hard to know what it in them.

Easy to check: Idle the engine, and pull the PCV valve out while still connected to the hose to the carb; if it is wide open, I will make a very noticeable 'whooshing' sound. And if you put your finger over the end of the PCV valve, to close it off, the vacuum will jump up a few inches if the valve was wide open.
 
I already blocked it off with no real change a while back. But still will replace as Rock auto lists the same PVC valve for all the mopar small blocks. I only have a few months left in my house and won't have a garage for at least a couple years. I'm ready to pull out this thing and dis-assemble and have a machine shop check out everything and balance as I only had it bored and pistons (KB Hyper. and yes filed to correct gap.) hone fitted. Now I have oil under car and I hope I didn't blow out rear main seal sealing the motor and running for intake leak test. I know there's a cam plug and two galley plugs which I did do all new plugs. I've got no one around here to help me out as all my mopar buddys live out of state. One guy I sold parts to is a mechanic and I may call him and see what he can do for me if anything.
 
OK, good you tested that. I'd not use the RockAuto PCV; I would bet it will be wide open at the cruise flow opening with the lower idle your cam. I've used a Fram 191 (made for factory cammed-up GM's, that transitions at the 11-12 in range) but those are for larger valve cover grommets than the stock SBM grommet.
 
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So this is a stock 340 cam? Also I went back through and didn’t see what your total timing number is? I know that the springs on those heads are kinda marginal, but with stock cam the should be enough. It just doesn’t pull right?
 
I bought the car with a 110K on it. The owner said it was bone stock other than a valve job. Always ran good but was getting a little tired. You could push down on the valve spring with the palm of your hand! Now Only 8 in vacuum . Car wont stay running unless partial choked until it is completely warmed up. Original carb worked fine before rebuild. Now has a used 600 Eddy I bought and rebuilt . Then I rebuilt and tried the original carb and had the same results so I put the Eddy back on.Car does idle smooth no mis-fire but stumbles when trying to open secondary s. Timing now initial 12 total 35
 
Since you say you have proven the intake is not getting un-authorized air;
I'm gonna guess that your ignition timing ain't what you think it is and you have the additional problem of either;a lazy accelerator-pump system, and or a problem in the metering rod system, OR seriously wrong cam-timing.
Sometimes additional idle-speed can help, up to 750, but if that upsets the T-slot sync, then it just makes it worse.
I wanna go with cam-timing because Ignition timing alone won't usually cause this kind of issue. I say this because I have a dash-mounted, Dial-back, timing control with a range of 15 degrees, and when it comes to taking throttle,my engine cares not a bit about initial timing. The only thing that changes, with the T-slot sync properly set, is the idle speed and resultanant manifold vacuum.

nm9 outlined a nice test to check split overlap.This should always occur within about 5degrees of TDC on any one piston. I use #6, because of the ease of accessibility and the marks on the balancer are correct to be read there as well,after I have proved them to be exactly correct.The only street cams that might not be pidgeon-holed within 5 degrees are the thumper-style cams.If your Split-Overlap is outside the 5* then something is wrong.
I pull the intake, then lay a straightedge across the lifter bodies, leaning against the pushrods. Other guys turn the lifters upside down; that's just wrong. I move the crank back and forth until the straightedge contacts in 4 places, two on each lifter, then simply read the known-to-be-accurate balancer, looking for it to be in the target zone.
I know it's a lotta work, but after this, I don't have to wonder about it any more.
There is one wild card,
And I wouldn't have known about if it hadna happened to me.
If the you have a Mopar Electronic Ignition system; there are two types of pick-ups to signal the ECU. If you have yours wired in reverse polarity,you can make it idle, altho the reluctor will end up in an odd-sync. But it will not take much throttle and kindof stall there with some stuttering going on. As you relax the throttle everything returns to normal.
If you have your timing light hooked up, you can see what's going on. As the engine is being reved up the spark advance will go crazy firing at a multitude of wrong times, then when returned to idle, everything seems normal.
This problem is instant proof of a wrong polarity pick-up.
The pick-ups are color-coded , and the factory SMALL-block ones have one Orange wire and the other I have seen either black or gray. If at least one of them is Orange, then it is correct, and you can prove it by the spark pattern.

Good luck
 
The motor ran good before the rebuild. The dist. is the same along with the orange box ignition. I did inspect when this began . Bought new cap rotor and wires. Same coil. I can say I've proven intake but my vacuum gauge was messed up. My gut tells me intake. I might pull it and go from there or I might register it and bring it somewhere just not sure yet.
 
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