Did someone throw a boat anchor behind my car at 4500?

[max71]

I've been dealing with this since the new engine rebuild. Since then I had the head redone properly back to huffaker specs. Put a new dizzy plate in my dizzy (that was curved to the car per Dave Anton) which helped some of the points bounce. The car has an APT VP11 cam in it.

Here's what happens. The car pulls fine until 4000-4500 them suddenly its as if someone threw a line with a boat anchor behind the car. Completely bogs down. Won't go past 5000. No backfire or carb or other issue. Just won't go.

The car is timed to 32 degrees at 4000RPM. Carbs were rebuilt and I'm pretty sure the mixture is spot on. I have #6 needles in them.

Long ago when I had a Huffaker cam and the head and carbs done by them the car pulled deep into redline like it was yawning. I just don't have any idea. Compression is fine. At least last I did it. 20K since ring job.

[malcolmr18zoy]

Hey Gary,
Well, if your distributor is curved, and working, properly, and your carbs are not leaning out, there's only one thing left. If, and it's a big if, there's nothing wrong with intake, ignition, cam timing, or fuel supply, then it must be a restriction in your exhaust system. Check your exhaust system for damage or blockage. Did this problem happen suddenly, or was it gradual? If it was suddenly, maybe someone lifted the car and squashed the exhaust partially.
Malcolm

[Steve Simmons]

...like that fancy new manifold gasket you installed? Also did you ever try a known good condenser as discussed?

[Jimmy]

If you swap to a 2-cylinder tachometer the engine will appear to rev to 9,000 rpm, which is plenty.

[max71]

Steve. As mentioned put in the new plate which had a new condenser. New intake gasket is ok. Never made any difference between it and the old ones

Malcolm - exhaust is fine. Fairly new and welded by a exhaust shop. Intake was ported to the head when Sean Brown did it. I would think #6 are fine although I did ask the head guy and he said there could be other needles but they found #6 worked best. I have #7s but those may be too rich. I wondered if it was fuel delivery but not sure why it would bog down like that.

Maybe if we have tech day or when we meet up for Burmese food you can drive it and see what you think. I always wondered if we timed the cam wrong but we did it ten times and always came up with the same numbers.

Just don't know.

[malcolmr18zoy]

So what has changed since it revved into the red? what have you, or someone else, changed?
Malcolm

[max71]

The only thing that changed was an engine rebuild.

[Steve Simmons]

Oh, well that isn't much.

[max71]

I knew that would get Simmons.

Ok, yes rebuilt the engine which on the bottom just amounted to re-ringing and new bearings all around. Rod checked and trued if necessary. The whole train balanced.

On the top end it has the APT VP-11 where the worn Huffaker cam was. Cam bearing. I sent the Huffake cam to APT and he said while not the same it was close to the VP-11 which is a mild street cam.

The head was screwed up and then righted by Sean Brown ie all new valves, guides, springs, keepers, reflowed slightly and intake manifold matched to the head.

Not since the rebuild have I been able to get it into he red. The bottom is .30 over and has been for many, many years.

The dizzy was redone as mentioned and curved for the engine.

Today I was at a friend's and he had a MSD coil and I thought I would try it as Steve wondered if mine was running out of juice at the higher RPMs. This coil had an internal ballast and wouldn't work properly. I have a black Bosch or some other brand in my parts bin. I just don't recall if its the proper one but I think the car ran on it for a while. I'll try putting that in and see. I thought coils worked or didn't work. Mine is a fairly new Lucas Sport coil.

[malcolmr18zoy]

Hi Gary,
Well, you've made some significant changes there! Your engine would pull into the red until you changed the camshaft! On top of that, you had your distributor re-curved! Oh,and your cylinder head slightly gas flowed. What was wrong with your camshaft? Why didn't you get another cam the same as the successful one? In the world of camshafts, almost the same doesn't do it! You don't know what the differences in lift,duration, overlap, or profile are, and each one of those differences make a difference. As for your ignition coil, a Lucas sport coil is fine. Should give you about 60 Kv.
Malcolm

[max71]

The Huffaker cam was a special grind by them. I lost the paperwork on the grind numbers. That's when I sent it to Dave Anton. The cam was toast. Lobs were flattening.

The dizzy recurve actually helped well off the line, but even before the curve I couldn't get it into redline with the old dizzy as was. The guy that does them said to send it back and he'll check the springs. Its only had about 20000 miles on it and the bushing is no play at all.

I measured the coil last night after removing all the leads. It measured 3.8 Ohms. Shouldn't it measure no more 3 Ohms?

[malcolmr18zoy]

The lobes were flattening, yet it would still pull into the red? That's amazing. I usually measure coil Kv output rather than resistance. If your engine won't pull into the red, either it's not getting enough combutible charge into the combustion chambers, or not enough reliable sparks at that rpm, or the exhaust is restricted. Those are the three components that control your rev potential. Of course, I'm assuming your tachometer is accurate. The procedure is to eliminate the easy things first. The more complicated issues are, just that, more complicated.
Malcolm
PS
Who told you that your camshaft was toast.

[max71]

I don't think its an restricted exhaust. For boring reasons - defects, got noisy - I've had to replace both resonators and there was no difference in pulling into the red.

I took a picture of the cam and send it to Joe Huffaker who confirmed it was toast as did Hap Waldo and APT. The tach was tested recently and is off a little on the low end but more accurate at the top end. I have a timing gun with a built in tach and it appears to be very close.

I have new spark plugs in and that made no difference. I have them gapped at .025 although I was told I can and have gone up to .030 since I have a sport coil. When I ran .030 I still had the same issue I believe.

[malcolmr18zoy]

The cam was toast, but it would still pull into the red, but with the new cam it only pulls to 4500? That sounds sick. Is the new cam new, or is it a regrind? Silly question, but it has a significant bearing on the subject.
Malcolm

[max71]

Oh I put all my pennies into a new Billet cam version of the APT because "I never wanted to worry about the cam again".

Sean Brown who works with Dave Anton even setup the head to work best with the cam I have.

[Jimmy]

If I remember correctly, a coil will work even when wired wrong...just not well at all.
Could it be that simple?

[malcolmr18zoy]

Yes, Jimmy has a good point there. Is the coil wired reverse polarity? I still dont get it though, why the old worn out cam would rev to red line, but the fancy, new, billet cam just revs to 4500. Will it rev into the red in neutral?
Malcolm

[Steve Simmons]

I can't imagine that the coil being backwards would cause this. It's only a slight bit less efficiency if backwards. The spark will still be there, just not quite as strong. I've wired them backwards on purpose before and felt no difference whatsoever.

[max71]

Coil is wired correctly. Oh man I wish it was that simply. Usually all this stuff comes down to something simple. I'm running out of ideas.

According to the APT site the VP11 is good to 6800 RPM. Here's the specs:

VP11 B-Series Mild Street 260/260 .286/.293 8.9-9.7 1200-6200 6800

I'm going to head over to Steve's and test the coil by putting one in he has. We'll also hook up a tach and see how far off mine is but I'm sure its maybe off a couple thou at most.

I'll also borrow Steve's used 25D and after the holidays I'll send mine back. I really doubt anything is wrong unless the Vac advance is suddenly bad. The plate moves when I suck on the advance. We'll check for sustained movement as well since I didn't do that.

[malcolmr18zoy]

Hey Gary,
I'll ask you one more time, Are you sure that the engine would pull into the red with the old worn out Huffaker cam, but only pulls to 4500 with the new fancy billet cam? The vacuum advance will make absolutely no difference. It is merely an economy device, designed to advance the ignition on a trailing throttle. If you reverse polarise your ignition coil, it means that the current is flowing backwards through your ignition system. That means that thevoltage is flowing through the engine block and jumping the gap to the spark plug electrode.
Malcolm

[malcolmr18zoy]

Just kidding, but reverse polarising your coil does make a difference.
Malcolm

[Steve Simmons]

LOL @ Malcolm! You had me scratching my head there for a minute when you sounded serious!

[max71]

Just got back from Steve's and we thought we had it solved until I drove off. We swapped coils and I took the car for a run on his street. No problem! Went to redline in 1st no problem. Stopped there. Problem solved. We congratulated ourselves. Steve innocently asked if I needed to test the new coil (put a new one from Steve's stock in). I thought it unnecessary.

An hour or so later I take off. 1st to redline no problem. 2nd to redline - what??!!!

So here's the deal. Heavy throttle in 1st no issues. Heavy throttle in 2nd - bogs down again. Same in 3rd.

Heavy throttle in 1st no issues. light steady throttle in 2nd no problem. Same in 3rd.

Something is not recycling fast enough would be my guess. What that is - unknown.

But previously I couldn't even go to redline in 1st.

[Steve Simmons]

Just for kicks, I'd say keep it floored until it bogs down, and cut the ignition while your foot is still on the floor. Then check the float bowls. At least that would rule out an entire system.

The fact that the car runs "smoother and stronger at all revs" as I believe you put it certainly suggests that your old coil was not doing its job.

[Jimmy]

If you reverse polarise your ignition coil, it means that the current is flowing backwards through your ignition system. That means that thevoltage is flowing through the engine block and jumping the gap to the spark plug electrode.
Malcolm

Gary, they do make spark plug cables that connect in reverse, which would compensate for such a reverse flow of current.
But do make sure to increase the size of the ground strap to the motor, and to install it in the correct direction.