Ironracer
Gearhead
Yessir, and I used to know 1 other guy that was local, but he retired and moved away. That's why I bug the piss outta Ya! Lol. Yer a Realist!
Lean pop off idle?
- Thread starter Craig Burriss
- Start date
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I forgot to mention in the original post that I had the heads shaved down to bump up the compression. The pistons are .030 down in the hole at TDC. The stock pistons I pulled out were like .500ish in the hole at TDC
I should have some time to play with the timing some later this week. So hopefully that’s all she needs. Thank you
Ironracer
Gearhead
Above my Grade, but if you advance the cam, you can gain comp. Course, there is you time, materials and then gaskets, ect.
What I’m trying to do? You mean make it idle and drive down the road?
Ironracer
Gearhead
That's a Big Thang to Some of Us!
Well, .500" is 1/2" so we can rule that out. LOL Honestly, I think somehow your measurement is off on the old pistons. It sounds like maybe your new ones are SIx Pack pistons, which do come up in the hole a good bit compared to stock, so it that information is correct, you could have a static compression ratio of around 9:1 give or take. Have you ever run a compression test? That could tell us for sure what we're dealing with and give a better insight as to what to do about a timing curve.
The “measurement” for the original pistons was just an exaggerated eyeball measurement haha. I did actually measure the new piston height when rebuilding it.
I haven’t done a compression test, but if I can find my compression tester I’ll do it next time I’m out there
Wow, 33" tires with a 3.23! That is a lot of load for the engine to turn at low speeds.
Not with an NP435 lol
Ah, did not see that in your original post
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Which one?
6.69-3.34-1.79-1.00 splits of .50-.54-.56, or
4.78-2.39-1.37-1.00 splits of .50-.57-.73(short fourth)
With 33s and 3.23s, the starter gears are equivalent to; 17.68 and 12.63 as compared to typical 27s, in the which 17.68 is insanely low, while the 12.63 is only slightly way out there, like a drag-race starter. But in either case the 50% 1-2 split is not something I'd enjoy. This is one of the reasons I no longer drive the A833od box with it's 54% 1-2split
The one problem I see with that NP435, is the unsynchronized granny-gear, which makes getting back into first a bit of an art, and for sure,,, slow. Most of the time, you will not be going there, which means you will be in Second, which with the 2.39Second, is the equivalent of 2.71s with a regular A833 and 27s. Your 440 is gonna need some grunt to cover that.
I may have been a lil hasty as to not liking your cam;
It occurred to me that the advertised numbers being so very much larger than the typical cam, might not have been ascertained at the usual .006/.008 tappet rise. If those numbers are SAE , well then, I made an ignorant comment. however your idle-vacuum is not inspiring any confidence in this possibility, because with a 260/112 type cam your idle vacuum should be closer to say 17 inches.
But if at 006/008, then I'm not changing my opinion.
The .050 numbers are good for your NP435-combo; how good will depend on your actual cranking cylinder pressure. Certainly in First gear with either starter-gear, low cylinder pressure won't be a problem no matter what.
Typically on a FTH cam, the advertised numbers for .008/.006 will be around 44 to 48 degrees. Your 214/224/112 @.050cam would then be, say
260/270/112, which does not compare at all well to
288/298/112, unless that is SAE; so Ima thinking I mighta screwed up. Rusty, and others seem to know this cam, so I'm just gonna hang around and see what they say.
If it is SAE, I'm just gonna slink away.
However, even then, I still don't like it.
If it was mine, and if the advertised is SAE; I'd probably put some solid lifters on it. The ramps are so long that solids should work just fine and, I bet the engine would pick up some good vacuum with them, in addition to more Cranking Cylinder Pressure. Yeah, that's what I would do ..... if the advertised is SAE.
Finally have some time to play with the RamCharger today. Did a compression test. With the engine cold, all of the cylinders are 175-180psi
Edit: I didn’t have one of the sealing o-rings on the compression tester. It’s actually 210psi across the board
Edit #2: checked the gap of the spark plugs. All at .035
Edit: I didn’t have one of the sealing o-rings on the compression tester. It’s actually 210psi across the board
Edit #2: checked the gap of the spark plugs. All at .035
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Started bumping the initial timing up 1° at a time. I got it up to 22° initial. The stumble is getting better, but is still a problem. I can now hear it starting to ping pretty hard
You certainly don't want it to ping, so bring the timing back down until it does not ping.
I agree. The possible damage from detonation is something you don't want, even if the extra timing helps the pop. That's a LOT of compression pressure. I would be looking for a known GOOD compression gauge, JUST to back up those findings. Once verified, I don't think you're going to need the extra timing due to low cylinder pressure. But it is well worth double checking with another gauge to verify.
Have you put a timing light on the balancer to actually watch when (and if) the mechanical advance is coming in? I'm wondering now if something there isn't amiss. I would try to verify everything with one system (timing) first and move on from there.
An AFR setup would really help you here so that you could actually SEE if it's lean. Have you read the plugs?
Ok, I just went back and read your original post. 87 octane with 210 PSI cranking pressure ain't gonna make it, if that cranking pressure is correct. That's race gas territory. There's no way it's ever going to run right on 87 if those cranking pressure numbers are correct. Just one more reason to verify with another gauge.
I’m doing this all by myself, so it’s difficult to hold the timing light, see it, and rev the engine. But From what I could tell, the mechanical advance starts to come in around 1100, and is maxed out at 3000ish
I have an old AEM wideband I could hook up if I got another O2 bung.
The tank is almost empty so I could put some 93 in it and see how that does, but I didn’t want to go that route with this truck.
I’ll see if I can borrow another compression tester.
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I’m wondering if this carb has some sort of problem. Because I bought it used from a member here (don’t remember who) and when I unboxed it, you could tell that it had been backfired through because of all the burns and “soot” in it.
I’m not blaming anyone but myself for these problems, because I’ve done all the work, and really have no experience with carburetors.
Maybe I should just stick with EFI haha
I’m not blaming anyone but myself for these problems, because I’ve done all the work, and really have no experience with carburetors.
Maybe I should just stick with EFI haha
Interesting about the carburetor. I think I've seen @MOPAROFFICIAL talk badly about them, but I don't remember what, exactly. I tagged him, so maybe he'll chime in. I might be imagining things, but I seem to remember that.
MOPAROFFICIAL
Oogliboogli
Sounds like you need more pump shot.
What color pump cam and # shooter nozzle is on it and what transmission and stall is the car equipped with?
What color pump cam and # shooter nozzle is on it and what transmission and stall is the car equipped with?
Thanks, dork. Been wonderin where you were. Hope yall are ok out there on the leftist coast.
MOPAROFFICIAL
Oogliboogli
Working on my stuff for a change and doing a short vids here n there.
Ironic fact, 92% of my viewers are non subscribers.. Yet they watch it through to the end.
Uncle Bob
Shiny paint causes stress.
That makes two of us so far.
That carb looks new enough that it should have backfire protection in it so it might not have blown the power valve.
Might I make a suggestion? Please work on the volume of your audio. I can barely pick it up.
Don't think the cam is too big at all, from an earlier poster. The 050 numbers are only 2-3 degrees larger than the factory Magnum cam. Unless tappet lift is given, adv numbers are useless. You can pump up the adv #s by using low tappet lift so the mugs will buy the 'big cam'. As another example, how does 346 degrees adv duration sound for a cam that has 254 @ 050.
From the info provided so far, my money is on:
[1] Wiped lobe
[2] Lean under load; PVCR needs enlarging, tested by fitting larger pri jets, about 4 sizes bigger
[3] Sec ign problem. Bad leads, bad coil, bad plug, etc.
From the info provided so far, my money is on:
[1] Wiped lobe
[2] Lean under load; PVCR needs enlarging, tested by fitting larger pri jets, about 4 sizes bigger
[3] Sec ign problem. Bad leads, bad coil, bad plug
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