Missing power 440?

Hi

I have been trying to get more power out of my 440 engine. At the moment the power is only in High RPM. Starts to go fast only after 4500rpm???

I have a 68 440 magnum, with forged pistons 10.4 compression. Ported 906 heads, Edelbrock ported Victor intake and 850cfm quickfuel double pumper carb. 284/284 MP cam with 0,484 lift.
2400 stall. Total timing 36

Last fall I had Edelbrock RPM intake and it run really good. Nice bottom end torque also. Dynoed it and it had little over 400hp
I bought victor intake , because I wanted to try it. Now it doesnt seem to work at all

I am gonna change the RPM intake back, but before I´ll do that. I would like to know, that do you guys only use the Victor in a drag cars, because many of my friends are saying that victor should work fine also in street car after 3000rpm. Maybe I would need to change my cam?
I have been recommended Lunati 60303 cam

Many have been wondering the problem I have, because the combo should be ok???

Topi

Sometimes friends are not the best source of advice.

Better not to port the Victor intake unless you are going to use a 2" spacer above 5000 rpm. An unported Victor will make more power than a ported Victor between 3000 and 6000 rpm.

My dyno tests on a 496 stroker showed significant torque loss with ported Victor versus a gasket matched RPM dual plane.

RPM.............. RPM torque..................Ported Victor torque

3000...................543..........................................511
3100...................552..........................................510
3200...................579..........................................525
3300...................603..........................................573
3400...................615..........................................592
3500...................624..........................................604
3600...................632..........................................604
3700...................640..........................................611
3800...................632..........................................608
3900...................633..........................................608
4000...................630..........................................610
4100...................628..........................................609
4200...................624..........................................609
4300...................615..........................................607
4400...................604..........................................604
4500...................604..........................................603

After 4500 the Victor gets better than the RPM intake

What is the initial/idle timing? Total timing is only part of the picture unless you have the distributor locked out.

Combo is not ok in my opinion. You're expecting low end power when you're using high rpm parts. Cam range is 2200-6000 rpm. Intake is 3000+ rpm. And you expect it to make power below 3000? Gotta remember even when a part starts making power, it doesn't reach peak power till well after that. You've built yourself a screamer 440 engine.

My suggestion. Verify compression. If it's correct. Go back to the RPM (1500 rpm). Go with that lunati (1800 rpm). You'll see gobs of low end torque and still have a very similar top end. Should pull hard from 1500/2000 up to 6000 rpm. Tune it right. Run as much initial as you can. Get the carb dialed in. And it should go like a raped ape.

Thank you for the fast reply! I understand really well now, thanks for the good explanation . I will change back to RPM tomorrow and be happy with it!

TTC said:

Thank you for the fast reply! I understand really well now, thanks for the good explanation . I will change back to RPM tomorrow and be happy with it!

Click to expand...

I suspect you have figured out part of the issue, but in the OP you don't mention rear gear.

That also can have an affect on low end if you're running numerically low gears that would be meant for highway cruising..

Classic example of dual plane advantages and where it works. A good friend had a (HEAVY) 70 GTO with a mildly hot 400. We had a 780 Holley with an Edelbrock dual plane on it. It would run 14.20s without the bottle and 12.94 with. He thought it would run better with a single plane and I could not convince him otherwise. Needless to say it did not improve so a gasket set later he sold the intake.

Add a 2" (4 hole if you can find one that fits the 850) spacer and you will notice a little gain....

Hi ! I got my car running with new 60303 Lunati voodoo cam last week. During the week I have been tuning carb and finding the right jets (Quickfuel 850 mechanical double pumper). At the moment it is working best with 75 primary mainjet and 84 secondary main jet. Little bit too rich at top end. I have to admit that I am not happy with the engine at all . Performance is still poor. I even took my car to local mopar performance builder and he checked it also. He said that it is working good but it is not pulling strong. He said also that now parts in my engine are ok and it should perform well!
I have been adjusting ignition and at the moment it is 17 initial and total 37. Vacuum not connected, because of detonation problem.
I am thinking that maybe the reason would be my ignition (PROCOMP 7000 series)
because engine has a flatspot around 3000-4000rpm. ( I have tried to change accelerator pump jets but doesnt help) Biggest effect to reduce this flatspot has been main jets tuning

Before the lunati cam change, I had 284/284 MP cam and car was faster with it

Before I lose my mind and order stroker kit or supercharger, it would be nice to find reason for this . This local engine builder was thinking that maybe porting in my 906 heads are somehow wrong

Summer is short here in Finland, when trying to get the car to work ;)

A 2400TC will make it slow to get going. With 3.23s it will continue to labor to near 41mph.
With a 3500 and 4.10s, it will launch much harder and be be pulling very hard by 32mph
Or a 3800 and 3.91s This will pull hard right off the line and by 32mph you will be hanging on tight.

Yes I have been thinking to upgrade torque conventer. I am running 3.55 gears now.

Is this the cam you currently have?

Product Description

Hydraulic Flat Tappet Cam. The most awesome 268 cam ever produced! Out-powers all others! This High Performance street cam likes 2400 RPM stall, 800 cfm carb, dual plane intake and headers. Makes un-equaled power to 6200 RPM with proper valve springs. Very strong cam with great street manners.

• 
  
  
  • Advertised Duration (Int/Exh): 268/276
  • Duration @ .050 (Int/Exh): 226/234
  • Gross Valve Lift (Int/Exh): .494/.513
  • LSA/ICL: 110/106
  • Valve Lash (Int/Exh): Hyd/Hyd
  • RPM Range: 1800-6200
  • Includes: Cam & Lifters (#71977PR-16)

Part Number: 10230703LK
Previous Part Number: 60303LK

Jobber Price: $207.70

This cam with 3.55s should pull like a freight-train, even with a 2400TC
I had a similar cam in my 367, also with 3.55s and with a 2.66 low 4spd. It would take the 4bbl right off idle, and explode! And I'm at 900ft. There is no good reason your 440 shouldn't do the same or badder(joke),heehee

Now I'm definitely thinking to revisit the cylinder pressure,and/or a leakdown.
This is in an A-body with headers, right ?
But first;have you had it to the track? And how did she do?And how did that compare to other similar combos, in your neighborhood?

A flatspot from 3000 to 4000 is a pretty big hole.And it has nothing to do with the convertor, or gears, at this point.

You say the timing is 36*, but you don't say how early this comes in, nor if the timing is stable all the way out to past 4000.Assuming it is all in by 3000, and stable out past 4000,I have to wonder if just maybe 36* is too much, in this zone.I would be tempted to roll it back some, and if it likes that, then I would recurve it to to come in after 3500, and if it likes that, I would put it back to 36*. And so on.You can't always hear detonation, but it shows up on the plugs,and the performance.

With 10.2Scr, and at 660ft elevation, this new cam(above) should generate about 165psi, and the Dcr rolls in around 8.25. This is just about perfect, for street. So if your compression is up, the hole can pretty much only be due to detonation, or airflow.I'm starting to wonder if your lifter pre-load is off, or unstable.

Thanks for the interesting info! Yes thats the cam I have with Lunati spring kit. I have degreed the cam.
Interesting issue is this lifter preload setting?? I have always had ticking noise in the valvetrain when driving with all the different cams. I have always had to use little shims under rocker arm shaft (0.050inch). If I don´t , valves will be little bit open all the time. All the valves and guides are completely ok and no cylinder leakdown. Vacuum at the idle is 14hg . Can´t get it any higher.
This ticking sound have always been a wonder to me because all the mechanical parts are ok. I think that somebody have milled the deck height which is sad . I have to try to verify the compression by oil but it is difficult when the engine in the car. (Maybe you have good tips, how do this without taking the engine out?? ( I think that all the air is not coming out of the cylinder because of spark plug´s position) Hemi would be much easier with this

I think that I will try to adjust the timing again and try get vcan hooked. Because somehow I think that this has something to do with the ignition and ignition curve like you said.

I haven´t tested it on the track yet, maybe during the summer. I will test cylinder pressure during the week to see the results. With MP cam they were 10.6

You can easily spin wheels (275s) at first gear but when it shifts to second , maybe just a little squeeze . I have new detroit locker

I was told earlier when I was working with the other engine I have ( 400cid, low comp), that when you drain the oil out of the lifter and install it back in its place. You should have around 1/16inch loose until it bottoms.

We got our wires crossed. It's too late to verify the compression ratio.
But you can do a compression test to find the cylinder pressure.
It almost sounds like you do have a lifter pre-load issue which you may have attacked from a wrong angle.
Shims are not used to adjust lifter preload.
Shims are sometimes used to correct rocker arm geometry.
Lifter preload is adjusted by push rod length, AFTER the geometry is corrected.
14 inches of vacuum may or may not be good. It depends on the idle timing and idle rpm at which it was measured. But it certainly is NOT bad.
I think from what you have just revealed, you need to do a complete valve train analyses.If I was there, we would do a compression test and followed by a leakdown test. Then if the LD test was over 4% to 6%;I would take all the valve gear off,and re-do the LD test.If no change you may be in good shape, if the numbers come up reasonably close and reasonably low.
Then I would check the geometry and correct it as needed.It is possible that your shims,if of the correct shape and size, might be correct, but if not, they are gonna be history. .To do this test you will need two adjustable length pushrods.
After that has been corrected, you will use the adjustable length pushrods to determine the correct length pushrods and order some up.
I have adjustable rocker arms so can run whatever, lifter preload I want.I run just a tiny amount (.020) to eliminate problems with lifter pump-up at 7000plus rpm. If you are running at the bottom of the lifter, then that is totally terrible, and is probably your whole problem. You have to run at the very top, less the preload.Without adjustable rocker arms you cannot run as close to the top as I do, cuz soon after break-in or perhaps next summer, the lifter preload will be reduced to zero and then you will have to listen to the clatter destroying your ramps,bit by bit.Typical lifter preload,with non-adjustable arms,is specified at .080
Now here is the big question;
How in the world did you degree in your cam?I wanna hear your method.

The vacuum advance has nothing to do with your problem, I recommend to leave it off for now.

old school ! shims were used for lifter preload on nonadjustable rockers. 0.050 is a little much though.

Yesterday I managed to check the compression test. All the cylinders were between 11.8-11.9bar. (Altitude 330ft). I dont have leakdown gauges(Dual gauge), so this is not familiar to me. I will try to borrow these from somebody.

I am sorry for my mistake. The shims that are in use now under rocker arm shafts are 0,5mm thick (1/64in).
The ticking sound from the valvetrain starts louder after 3000rpm, but doesn´t get any louder after 4000rpm.

I haven´t checked the lifter preload in this engine. I will have to check that also. I was talking in my earlier message about the instructions that I was given before when I worked with my 400cid engine.

Thank you for helping me to find a possible reason for my problem!

Whoa. forget the LD
11.8bar is 175psi,11.9 is 176. So I doubt you have a cylinder leakage issue.At least not at cranking speed.
As to the shims; .5mm is .020, and 1/64 is .016. If those shims are one thickness from end to end , I would try to get rid of them.
Make sure the rocker arms are correctly alternating; lefts and rights and that no pushrods are hitting the sides of the pushrod tunnels, and that every rocker arm is wet with oil, dribbling down over the springs.
What type of lifters did you buy for your new cam; as in are they anti-pump-ups.
The 1/16 you were told about, would be better applied from the top down.1/16 is .0625 or 1.588mm, and would be a good target for lifter preload.Too much for me, but good for stock non-adjustable arms.

Today I checked the lifter preload and results were shocking!. Preload is 3mm (3/32inch)
Thats double, that it should be!
Thank you so much for you information about this preload issue, because I am quite angry for the local "mopar" professionals who does this job for living. They just told me that lifter´s only job is to zero the clearance when I was asking help about the adjustments....

Seems that either my pushrods are too long or somebody have milled cylinder heads or deck. Strange thing is that for example, when I tested this victor intake, it fitted easily without machining and no intake vacuum leaks. So this doesn´t explain the issue, that deck height would be milled

The lifters are from Lunati, that came along with the cam, so they should be ideal for it
All the rockers are well lubricated by oil and also the geometry of the pushrods looks quite straight, far away from the walls.

Tomorrow I will try get adjustable pushrod, that I can see the right lenght for the custom pushrods

Whoa! 3mm is .118 inch. 3/32 is .094 inch. And I run .020!
At 3mm you are more or less at the bottom of the lifter. You need to be more or less at the top of the lifter. The .094 is too heavy for me, but a lot of lifters are designed to run at .080 or therabouts.
The higher you intend to rev it the closer to the top you want to be. I rev 7000 or a little more, so I have minimum preload, so that if the lifters do pump up, They cannot send my valves into the pistons . The penalty for this minimum preload is more frequent valve adjustments, as the parts wear, in the beginning, of their lives.
For you, without adjustability, you don't want to run that close to the top. Further more with that size cam, there is no need to rev 7000, and therefore no need for minimum preload.However, I see two things ;With that much preload, You better have real good lifters cuz there is a very real possibility that the valves may have kissed the pistons, or even that the lifters sent the springs into coil-bind. Your cam is spec'd at .484 lift, right? but if the lifter starts pumping up for any reason, it can add up to those 3mm(.118 inch). Now I am certain that would be a very unlikely situation. But poor low speed performance and the flat spot at 3000 to 4000 could certainly be pump-up. Not likely; but could be.
Here's a bigger question; what if some lifters had run out of room down at the bottom, and were actually keeping the valves open. The results of that would be low compression, and a leakdown test would show a large amount of leakage.And this condition would certainly lead to poor low-rpm performance. After 4500 there may be insufficient time for this leakage to be perceived by the engine so it runs pretty decent. In the 3k to 4k zone the engine is transitioning, from low efficiency running with that cam and running up to peak efficiency, at peak torque.After peak torque she starts to make power.
So in addition to dialing in the rocker arm geometry,I would have to recommend a Leakdown test to prove no valves were bent in this troubling time, and I would be checking the bottoms of every lifter, and I would be checking every spring for proper pressures.While the springs are off you can check the tops of the guides, and the seals, and every pushrod socket in the stamped arms. Oh heck, just check everything.

Yesterday I was working with the car. I managed to adjust the lifter preload around 1mm but it didn´t have any change in engine´s performance or ticking noise. I also installed new msd spark plug wires, because old procomp wires were quite bad. This didn´t have any change either. I also ordered roller rocker arms for the engine, that I can easily adjust the lifter preload more accurate per valve in the future.

But then the shocking news!!!
I have old 750cfm edelbrock carb that I installed in its place.
After start up I immediately recognized that engine was running much better and idle was smoother. Then it was time for the test drive. I felt that it is running lean and I changed bigger jets and needles. I went for proper test drive and WOW!! car is fast!!! It easily spins tires with second gear, no more flatspot around 3000-4000rpm !!.

So mainly the problem has been this new Quickfuel 850cfm double pumper with annular boosters. I have been changing primary and secondary jets back and forth, accelerator pump nozzles and power valves,cleaning and inspecting but no change. Still the flatspot at 3000-4000rpm and rough idle/shaking. So now after I found the problem, local quickfuel salespoint wants to get the carb back and trying to find reason for this. They told me, that this is second time when they hear this same problem... Interesting to see if they will find the problem. I will update when I´ll know more, but now I will do some burnouts!

Thank you everyone for helping me!