Gen 6, 454 Rebuild(long)

If you not already have done it, i would try to adjust the rockers/lifter preload to near zero with the motor running, hot, just to see if it changes anything.
Also, does late BBC cams have a different firing order? Like the Vortec 8100? Could the cam have the wrong firing order by mistake?
Just guessing.
 
The rockers are net lash. No adjustment available.
It has the normal gm v8 firing order. 1-8-4-3-6-5-7-2
 
Can you identify the cylinder that is missing? When does it miss? Is it continuous?

Have you checked the valve train for clearances?

reasonably safe valve train clearance for new 383 sbc cam instal

how much lift can one safly in a 383 with speed pro flat top with 2 valve relief pistons with a quench of .038 before you have to really worry about PVC. i know you should really check any time you change to a bigger cam my buddy has a vega with a 383 in it and its a pain to get engine out. its...
garage.grumpysperformance.com

valve train clearances and problems

you might want to read thru these links and sub links it will help you avoid costly mistakes http://www.summitracing.com/parts/pro-66830/overview/ https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html...
garage.grumpysperformance.com

Do you have the cam card for the ES-5183 Engine Tech camshaft? When does the intake valve close on the seat. The best I could find was on Rock Auto which is obviously WRONG, the Advertised Duration and the Duration at .050" CANNOT be the same.

1680455094286.png
 
yes , obviously you drop back and check all the basics,
yes this may require partial engine dis-assembly to verify everything was done correctly
so your not guessing , but working with valid numbers/info verify the engine has adequate fuel pressure and no vacume leaks
and the ignition timings set correctly and TDC is correct, if you have issues drop to the basics
ideally you own a timing degree wheel that you can use on the damper bolt thats about 8--9 inches in diameter
a long damper bolt a few washers and a pointer (you can make from a clean arc welding rod,
you bend to fit and secure to a water pump bolt, or other bot location,
depending on the degree you need to remove the engine accessories or timing chain cover to verify the cams degreed in correctly,
www.summitracing.com

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youll start with having a compression/leak down test ,
during the assembly process you did verify the piston to valve clearance... didin't you

checking piston to valve clearances

this is an old post I got asked to repost, naturally the first step is to install and correctly degree in your cam, http://garage.grumpysperformance.com/index.php?threads/measuring-piston-dome-volume.17255/...
garage.grumpysperformance.com
all cylinders should be well under a 7% -8% on the variation in cylinders compression on a new engine
and verifying the cams been properly degreed in correctly, you used a degree wheel did you not??

degree it in correctly and get it to last,cam install info,

IM frequently asked (why bother degreeing in a cam, the timing set comes with index marks to install it?) it basically comes down to, a question of do you accept a random install where the timing can be almost any place randomly or do you insist on maximizing the engines potential and know...
garage.grumpysperformance.com

Do You Stop And Logically Isolate And Test Or Just Start Swapping Parts?

Honestly, I have to wonder at times about the thought process or in many cases the lack of thought and research that I see going on.I don,t know about the guys you might know, but it seems all too common for guys I know to find something amiss, or out of adjustment and they immediately just...
garage.grumpysperformance.com

needs to know why 454, bbc, just not running up to expectations

I’m new to this forum thing so hello, I need help building a basic engine so I’m gonna provide as much information possibly for you knowledge people. I’ve recenty bought a 1991 Chevy single cab RWD and it has a 454 that was swapped into it. Not original engine, looked up my casting numbers and...
garage.grumpysperformance.com

otc-5609_w.jpg

verify ignition and valve timing by verifying TDC
(top dead center) on the damper and timing tab agree,)
verify your fuel pressure and oil pressure
verify the ignition wire and firing order match the cam lobe firing order
18436572 on most SBC & BBC chevy v8 's there are 4-7 swap cams (you don't have one do you..???)
now back off all the rockers, until they are all loose, no mater how far you rotate the engine,
turn the dampper to tdc, rotate the engine until your damper indicates its moved 45 degrees and tighten all your rockers only until they are
no longer floppy loose, turn the crank 45 degrees further and tighten any rocker thats now
now floppy loose, turn the crank 45 degrees further and tighten any rocker thats now floppy loose, repeat 16 times,
45 degrees at a time
at this point you can test fire the engine and properly adjust the rockers

correctly adjusting valves

this is an area that causes many newer guys problems ,a slight clicking noise at idle in any hydraulic or solid lifter valve train is usually the result of clearances in the valve train, obviously you should have, some clearance, to allow oil flow thru the lifters to provide lubrication on...
garage.grumpysperformance.com

let us know what you find up to this point and we can continue isolating your potential problems if they are not obvious yet
 
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thats rather normal (having a range of exhaust temps,)
( but most should be near the average temp and more than a 50F difference might signify having a problem)
 
Spareparts said:
Here is the cam with specs.
Click to expand...
They don't provide enough info to calculate an accurate DCR, but estimating by adding 15° to the duration at .050" of lift. I get a DCR of 8.83. I doubt that's going to run on 93 octane with normal ignition timing without detonating. some of time.

Now this makes NO sense with your compression test of 155/160 psi ???????
You can't go by the calculators "Cranking Pressure", it has proven to be inconstant, but you should be higher than you are.

1680470813303.png
 
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I have tried 3 different compression gauges and get 3 different reading. Looks like i may need to break down and actually buy a decent one. Used old tools are not that reliable it seems.
 

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it looks like jegs sells the same tool for $33 thats listed for $20 on amazon

but you might consider a compression/leakdown tester as a more useful toll purchase
shop very carefully many cheaper leak down testers are only able to handle 100 psi max

 
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I bought a OTC leak down tester that seems to work good.
I tested at 100 psi and it passed the leak down test.
I will check out that compression gauge.
I think the problem with some compression gauges is the rubber hose expands not allowing a proper reading.
 
I have not gotten a new compression gauge yet but here is my thinking.
Ignition is totally new, Everything. Using a timing light all cylinders are getting a nice rhythmic flash as you would expect.
It passes a leak down test on each cylinder at 100 psi.
Injectors all test fine flowing the same and not bleeding off using a injector tester. Fuel pressure is within spec at 58PSI.
Vacuum is a nice steady 19inhg with no twitching of the needle.
I believe there is something going on with the valve train. What i dunno.
Maybe lifters are bleeding down, camshaft not ground properly. All rocker arms appear to move properly when watching the engine run.
Here is a short video of the only odd noise i hear with the engine running and the only way you can hear it.
 
since the sound seems to be related to the valve train on a single cylinder,
Id suggest you, remove the valve covers ,
AND PLACE YOUR HAND FIRMLY AND FLAT, to exert a bit of pressure
ON EACH PAIR OF ROCKER ARMS ,in sequence
and listen for the sound to change
(it will be obvious to your feel of the rockers and ears once located)
when you locate the offending / problem cylinder
once its located , you'll want to change out or adjust the defective or mis adjusted components
damn I wish I was local, as solving issues hands on is far easier than dealing with a key board diagnosis
 
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Hands on is for sure way easier!. and a second knowledgeable opinion is always welcome!
So im thinking that little noise you can hear is a valve problem of some sort. and i think cylinder #7 as that one has the most misfires and #4 is second although the others misfire also because the computer is pulling - 18% fuel
When i put this engine together it was with a new stock cam and old stock springs.(funds) I always had plans on upgrading it and the springs to a more "RV" style cam.
Since it passes a leak down test im assuming the valves/heads are good.
It's pretty obvious the intake is coming off in all likelihood so now that i have the funds i went ahead and ordered this cam and these springs and the related necessary parts.
Im guessing im going to find lifters are leaking down, a bad lifter that has wiped out the cam or even what i found in the old engine.
 

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That was after i ordered mine. I got the last one, will be delivered Tuesday.
Thursday they had 6 left by Friday night there was only 1.
 
No idea actually.
I don't know how to figure the Intake valve closing angle. I also don't know if the cam is advanced, retarded or straight up.
 
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