The build: 1967 273, Stock heads, 10.5 Egge pistons .040 over, Lunati matched cam, hydraulic lifters & springs, LD4B intake with
Holley 4160.
if a 750 this is just too much! Duration
@ .050-IN 213 EX 220 lift IN .454 EX .475, LSA 112. About 2 hours total run time,
150# compression on last check.
Good stuff
The tune: Stock distributor with Pertronix conversion, coil & wires , distributor
recurved to 34 total from 12 initial all in at 2500. Hot in gear,
idle at 700 rpm with 8" of vacuum. In neutral idle goes to 1000.rpm,
With this cam size;A 300 rpm spread points to a problem.This speaks to a too-tight TC or a vacuum issue; possibly due to too much lifter preload, or a too-big carb, or to just a plain old vacuum leak.
forgot to check vacuum.
I have not checked jets size but the factory AFB wanted .089 mains and .073 secondary's.
Just wondering about the vacuum, seems a little low and I will be changing power valve based on hot idle vacuum.
Insight welcome as always-------------Cheers---------DR
Went through the drill again this morning. Reset initial to 17 degrees and set idle at 700 rpm hot in gear and reset the idle mixture screws. Finished up with
11" vacuum hot in gear at 700 rpm and 16" hot in neutral at 900 rpm. At 2000 rpm it is pulling 19" of vacuum and sounds like it wants to be let loose!
Now at 200rpm, the split is much better Next step, check jet size against the FSM callout for the AFB and if a change take place, I will leave the initial alone (it really likes it there) and readjust the idle circuit.
Why are you tumbling about AFB and PVs? AFBs dont have PVs so do you in fact have a 4160 up there? Or an AFB? which is it ? You cannot compare jets between these two in any way!Plugs have been running black and I suspect it is a bit rich but the float level is correct
This speaks to a faulty T-port sync! so I have to sort that out and probably change the power valve to a 5.5 or 6.5.
I know the valve adjustment is correct and the timing marks and TDC are all correct. You know this because?Thinking about putting it on the ground and test driving it this weekend. (no front fenders or front or rear glass
Chime in if you feel like it, I think the indicators are good. I have decided to fabricate my own fan shroud as the available ones seem flakey to me.
Cheers to all--------------DR--------------
Hang on a sec, if all the tuning you've been doing so far has been with the engine running under no load then I'd just wait until you can test-drive the car before you start changing jets. Definitely good idea to know what you have in there but until the engine is seeing realistic load and driving conditions you won't be able to tune anything except the idle mixture correctly...
At 30 mph you may not even be on the main jet.
Don't use the carter jetting for any kind of reference on a holley.
Find the LIST # on your holley and start with the factory jetting.
30 mph in low is not a normal driving condition and little if nothing you see regarding plugs/jetting should be considred.
Too cold. Screw in a set of RN12YC Champions and see how it acts. RN12YCs I did the same with my 273 buikld but tried Autolites. Too cold for the less than 10.5 compression the Egge pistons give you. I chased a rough/rich idle condition for a year until I switched plugs and it has been perfect since.
I have never hooked vacuum to the distributor. It is set at 17/18 initial now. Limiter plate gives it 38 all in at 3000 rpm. With pcv valve connected and all other vacuum plugged I have 14" vacuum at 800 rpm in neutral. I re-read my research in this thread and it was 60 for the primaries and 66 for the secondaries that may be a starting point. I have a wideband O2 sensor but I have to weld in the bung and plug in a fuse to activate it. Then all I know is that 14.5 seems to be a number that people strive for but that will be another learning project for me. I do know that the effin thing is running raw fuel out the tailpipe now. Are you sure it's gas or are you assuming?If true, this is a very serious issue.Just trying to fix it before it ruins my motor.
I'm so effing done----DR out-maybe for good------
You are getting closer.
back in post #2, barnet468, was trying to teach you most of what you need to do. It's called setting the T-port sync. You may wish to read about it in my sig. below. The T-port sync sets the stage for all the low speed functions. You have to get this right before you ever leave home.You just have to.
So this 213 cam is pretty tame. It should be a piece of cake to tune, once the T-port sync is set.
-The engine will run at part throttle with the powervalve completely plugged, to perhaps even 50 or 60 mph. It just won't get there in any hurry. It will also get there with the PV plugged and a wrong size MJ so stop groaning over what size to put in. In fact, the lowspeed circuit can probably get you to 30mph all by itself. And one more; the mainjets could be completely removed, and if you were careful you could probably get it up to 30 mph as well. What I'm saying is, that if the engine is torquey enough it will get to 30 mph on the low speed circuit alone.So
-The low-speed circuit is what is giving you fits. And the way to get that really,really, close is to set the T-port sync.
-The three digit holley jets are precision calibrated jets. The first two digits (51 in your 512s) is the base number, and the following is a method of telling how close the jet is to the next size. I forget the exact way it is used, but I know that a 514 is ever so slightly richer than a 512. For most of us this way more precision than we need.A 51 could be somewhere between 50.5 say and 51.5, but a 512 might be bang on 51.2IDK
-Now personally I think 17/18 is way too much initial for this size cam, but that will work itself out when you fully understand how to set-up the T-port sync. Ima thinking 14 is plenty, but if the vacuum falls under 12 at 750, with that cam, and it is installed correctly; then you may have a valve lash issue or a vacuum issue, but again that will work itself out during the T-port synchronization.
-This engine should not require a shroud, and it should keep it's cool with a 180 stat easy enough. I of course would try to run a minimum water temperature of 200.And it should do this with a 5 blade all-steel fan on a thermostatic clutch.And a 7 psi cap. Unless you have a really small rad. A clean factory 26" will do this easy. A factory 22" might need a 7-blade, but I doubt it. I wouldn't be spending my time building a shroud for this one.At least not yet. Getting the timing and fueling right will do wonders for keeping the heat down. And as the rings break in, the heat will go down too.
-If you are a novice, I would block the secondaries closed until you get the primaries bugged out. I would also recommend to keep the PV blocked until you see how the MJ works. And I would recommend to start the jetting with the factory jets for the carb. On Holleys they are usually pretty close on tame cams such as the 213. The jetting is more related to the carb than it is to the engine under it.
-These systems all overlap and until you experience how the engine responds as it moves from one circuit to the next, you might as well take baby steps.
- I think somebody mentioned to be sure that your timing mark is where it's supposed to be.If it lies to you, it is possible to lose an engine.I like your power timing all in at 3000;that seems like a good starting point. I've never owned a 273 for very long and cannot speak to 38* being ok, but it seems high to me.I like to sneak up on the power timing. I'd say the spread (between initial and power) is pretty good, but I'd back it up to 34* and that will also back up the initial to 14ish, which seems about right to me; but again, let the t-port sync determine the idle timing. I myself would be trying to idle that beast down to 600 in gear or even less. I would try for 550/500. Once the sync is in and if it won't go there, I would be hunting for a vacuum leak or too-tight a valve lash/lifter preload.If that 4160 is a 750 it's too big and there's your problem right there. A 500/450 would be a much better match.See with the low vacuum signal those large venturies just won't respond properly, unless you jack a bunch of timing into it, and then the Sync takes a dump. Also with the small engine under a 750 the low-speed calibration is all wrong.And that's not easily changed. I did run a 650 Metering-block on a 750 once with a 223 cam in my 367. It worked ok but A750DP was better! I have a stick-car, so the stall was whatever I felt like;heehee.
- Oh yeah, the transfer circuit is the low-speed circuit.Remember that. And the calibration is in the block,where you cannot see it. The transfer circuit is augmented by the idle circuit at idle, and as it transitions to off-idle. So if you get the timing too far off, then the butterflies get messed up throwing the sync off, and then you can get several different problems.Many times too much idle timing kills the transfer circuit. Since this circuit is probably used for over 70 to 90 percent of all driving, you need to get it right.
- You can also get plenty of help at the Holley website.
But yeah if thats a 750 get rid of it. Even a 650 is too big. 450/500 is what you need on a 150psi-273 to keep the velocity through the booster up, and thus the fuel will follow. Yeah some guy will tell how he "made a 750 work" but it aintagonna work on you combo, as it now sits. You will need more cam, more compression and a much higher stall TC. Besides 750s are for racecars right? Heehee.....
Awright that's my opinion, and Ima sticking to it. AJs out for now..........
