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Advice on fresh rebuild

Flyboy1400

Well-Known Member
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11:15 PM
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Location
California
Looking for some advice on tuning my new rebuild. Let me start by saying that this is my first engine build so I don't have a lot of experience to lean on. I've been reading and watching plenty of video's on carb and timing set up, but still a bit unclear on which to adjust and in what order. This is where I am at:

440 .030 over
Stealth Heads
Weiand Action Plus Intake
Edelbrock AVS2 800 cfm
HP Manifolds
Comp CL21-222-4 Cam & Lifters
10.3 to 1 Static CR
Summit Electronic Ignition Conversion

Cam Break in was a little rough, I stabbed the distributer at ~12 degree advanced and it fired almost instantly on the first go, I didn't let it idle at all, went straight to 2000 RPM for the break in. I did have to shut it off twice during break in, once because it sucked the 5 gallon gas can dry at the 18 minute mark. Then after cooling and retorquing the head bolts I restarted it and had a massive valve cover oil leak (split the cork gasket), shut it back off and had to wait a week for parts and time to run it again, primed the oil pump again and ran another 10 minutes (and another 3 gallons of gas). It has between 25 and 30 minutes total of run time above 2000 RPM. When I tried to lower the idle speed screw ( I was using that to keep the RPMs up) it really didn't want to go below 1000 RPM, it ended up running really rough and wanting to stall at around 1000 RPM, I feathered the throttle a bit and got to stay running smooth around 1200-1500 RPM but that seems too fast for a curb idle on a warm engine.

Where should I begin with tuning this? Many of the videos I've watched talk about 30-35 degrees total timing is that with the vacuum advance still unplugged? and at what RPM would I check timing for total?
I've made no adjustments to the carb, I ran it right out of the box. Idle mixture screws are 1.5 turns out and at 2000 RPM it sits right about 20" vacuum.

Also fuel consumption seems excessive to me but then again this is my first big block...but ~7-8 gallons in less than 30 minutes?? It's not leaking anywhere that I can tell.
Any advice, suggestions, or anecdotes appreciated!

Ignore the mess of wiring, most of it is temporary.
20230923_193133.jpg
 
Well I'd start by getting it running, around 900rpm, or 1000 if that's as low as it will go, and get a timing light on it. Will likely enjoy more than 12 degrees of timing with that setup.

Not knowing what advance curve you have, I'd shoot for around 16 degrees of initial to start, 34-36 all in on the mechanical with that compression (others may chime in). Yes, you set this with the vac advance unhooked.

I'd be checking for any vacuum leaks as well, as that can cause rough running too.

I see you have a vacuum gauge, so you'll wanna find your highest vacuum with the mixture screws.

You may also want to pull the air horn & make sure that AVS2 has the floats set properly, since they likely aren't (ask me how I know).

Good luck.
 
Good choice of parts for a mild performance boost!

Check the float level [ 7/16"] in the carb & also check that needles & seats are sealing. Unlike brand H stuff, you will not need gaskets if you are careful removing the top.
I really don't see how 5 gals of fuel could be used in 18 min. There would be black clouds everywhere & hard to breath....maybe there was less than 5 gals in the container?
12* initial timing is ok, but not ideal, but engine should run ok & idle ok.
Rough running/poor idle could be many things:
- carb as above
- carb idle not adjusted properly
- air/vacuum leak
- ign timing. You say 12* but has that been verified? Low timing such as near zero will cause problems
- lifter preload. Lifters have about 0.150" or more internal adjustment. That means when properly adjusted, lifter on the cam base circle, the prod cup in the lifter can be anywhere within just touching the circlip...to 0.150" lower; the lifters will work anywhere within this range.
- the junk lifters today & Comp Cam uses them. They are made of Crapanium [ good news: it is pure Crapanium ]. All the proper installation & break in procedures can be done but the lifters & lobes get wiped because of soft lifters &/or poor or no radius on the lifter base.
 
Not knowing what advance curve you have
The distributer is from the Summit brand conversion kit it claims the mechanical advance to be the same as OEM Chrysler
I'd shoot for around 16 degrees of initial to start, 34-36 all in on the mechanical with that compression (others may chime in). Yes, you set this with the vac advance unhooked.
Assuming the Mechanical advance is the same as OEM, what RPM should the mechanical be 'all in' ?
ign timing. You say 12* but has that been verified? Low timing such as near zero will cause problems
After priming I rotated the engine to 12 degrees advanced and dropped the distributer lining up with #1. I did put a light on it while it was breaking in and it looked like it was at 12-14 degrees maybe.
I'd be checking for any vacuum leaks as well, as that can cause rough running too.
With out a smoke machine, what's the best way to do this? I've heard of brake clean/ carb clean and looking for change in RPM, but that seems like a great way to start a fire where I don't want one.
I really don't see how 5 gals of fuel could be used in 18 min. There would be black clouds everywhere & hard to breath....maybe there was less than 5 gals in the container?
With gas prices for premium here in CA, my wallet is relieved to know this is not to be expected :rofl:

The gas can was full though, and there was no visible leakage or smell anywhere, and also no smoke of any color out of the exhaust...my only thought is that I have a return line plumbed to the tank, maybe some flowed back to the tank. Although it sure sounds empty when I knock on the tank...
lifter preload. Lifters have about 0.150" or more internal adjustment. That means when properly adjusted, lifter on the cam base circle, the prod cup in the lifter can be anywhere within just touching the circlip...to 0.150" lower; the lifters will work anywhere within this range.
This is something that I measured numerous times before ordering pushrods, the paperwork that came with my cam called for .020-.080 preload. With 9.250" pushrods my preload is .050
the junk lifters today & Comp Cam uses them. They are made of Crapanium [ good news: it is pure Crapanium ]. All the proper installation & break in procedures can be done but the lifters & lobes get wiped because of soft lifters &/or poor or no radius on the lifter base.
Yes, I have read and watched enough on this topic to cause mild paranoia and anxiety for me this entire build :praying: LOL.
ALL lifters had a .0025 radius (measured many times), and the cam lobes were also tapered the same 2.5 thou. As far as the metallurgy and hardness, time will tell I suppose, hoping for the best.


I suppose my next move should be to open the carb and check the floats, then verify the timing and advance it a bit, then adjust mixture screws for best vacuum and see if it will idle better then
 
take a look at your oil and check for a strong gasoline smell. no way should it burn 5 gallons in 18 minutes at 2000 rpm. you could easily damage the bearings with a lot of gasoline in the oil. a new engine will have considerable blow-bye until the rings get seated which is bad for the oil anyway. could you have excessive fuel pressure? try about 17-18 degrees of initial timing with no more than 36-38 total. your lifter preload is fine at .050. probably wont idle well below 900,especially before rings are well seated. good luck.
 
Assuming the Mechanical advance is the same as OEM, what RPM should the mechanical be 'all in' ?

I suppose my next move should be to open the carb and check the floats, then verify the timing and advance it a bit, then adjust mixture screws for best vacuum and see if it will idle better then

Mechanical all in @ 3000RPM on a fairly stock build, some like it in by 2500.

And yes, all of those things. My AVS2 floats, out of the box, were not even close to what they should be.
 
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