I've known I needed to yank the .509 MP cam from my 493 and buy something more modern for a long time. The huge difference between idle vacuum and cruise vacuum made the carb hard to tune, and cams have improved since that cam was introduced. But the endless array of choices made my head hurt, so I did nothing. I think that's called 'analysis paralysis'.

Now I've swapped to EFI, and I made an interesting discovery. I pulled the throttle body yesterday after the engine had been idling for a few minutes and the inside of the intake and the bottom of the throttle body were wet with gasoline... not good! And this is port injection, not TBI. Time to pull the trigger and finally swap the cam.

I figure now that the car has EFI, my camshaft choices have been narrowed. I'm open to flat tappet or roller, mechanical or hydraulic. This is a street car and only sees the strip during fun runs at car shows. Rear gear is 3.54; trans is a Keisler TKO-600. Intake manifold is Edelbrock Victor 440 EFI, and throttle body is a 4-barrel FAST unit. I'm not one of those who is picky about the sound at idle; I want something that'll work well.

Advice is appreciated.

Were you happy with the performance and manners of the EFI'd .509 otherwise? A wider LSA cam should make the EFI happy and help with MPG, which I would expect is a factor with an OD trans and a 3.54 gear.

First of all, it's not that unusual for the inside of the manifold to be wet with gasoline in an MPFI engine. There's a lot more going on in there than we imagine. I have spent hours with carb cleaner getting the varnish off the inside of supposedly dry runners.

Second, you said, "This is a street car and only sees the strip during fun runs at car shows." This tells me you aren't all that interested in a big top end charge, so your 241 duration at 50 cam is way too big. Plus as mentioned above the overdrive transmission and 3.54 gear point to a smaller cam.

Third, if you can afford a hydraulic roller why wouldn't you go to that? You can get big lift with moderate duration. Now, everyone is going to pooh-pooh this suggestion, but I think you'd be really happy with a Hughes SER2226BL3-10. This is 222/226 duration at 0.050 and 0.514/0.520 lift. Your heads are already set up for this amount of lift although I am sure you'll have to change springs to control the heavier lifter.

This site is famous for advising cams on the basis of getting the last tenth in a drag race. So you are going to hear about a lot of bigger cams. Then, you are also going to hear the familiar chorus of having someone pick a custom cam for you, as if the camshaft manufacturers haven't spent dyno time and don't know what they're doing. There's nothing wrong with getting a custom camshaft but understand that the custom cam picker uses standard lobes from the grinder's lobe catalog. So the cam picker picks out one or two lobes and the Lobe Separation Angle and how much the cam is ground advanced or retarded.

R.

Well I'm sure there are a ton of cams that will work so it is just a matter of sorting out what your budget is and how much work you want to do.

A hyd flat tappet cam is the easiest since that is what you have now. So something like a Comp XE285HL should work for you. If it was my engine I'd probably run a Mopar .528 solid flat tappet since I know it works really well for that type of mild stroker engine.

If you're willing to spend more money then a small hyd roller would be a good choice. But they cost about $1000 more and you might not see that big of a difference in performance.

Overall, the EFI tuning is not quite where the carb was yet. But with the carb, you could lug the engine down to 45 MPH in 5th gear (.64 OD), and while it was no powerhouse down there, it would pull smoothly. I'd have to think that a camshaft with a wider LSA would, at the very least, have the potential to match or slightly improve upon this characteristic.

Andy, what sort of idle vacuum would you expect from the .528 cam in a 493? And would you install it straight up?

With the 509, it idles at a whopping 8 - 8.5 in hg. I'd like to see that improve just a bit.

Thanks!

I didn't realize that reversion would cause so much fuel way up to the TB.

In one of the Mopar magazines' test mule '67 R/T, they swapped their .509 for a Comp solid roller with, as I recall, around .550 lift, and less duration and a wider LSA than the .509. They said it idled smoother and pulled more vacuum at idle than the .509, but was a rocket. I've read that our roller lifters (solid or hydraulic) suffer from roller bearing failure when subjected to prolonged periods of idling, and then there's the whole bronze distributor drive and the maintenance requirement on it. I read extensively on roller cams about 5 years ago, and this information might be outdated now. That's another reason I did nothing - the roller sounded great except for those drawbacks, which I consider major. The added cost of a roller is not really an obstacle for me if roller is indeed the best choice, but those two items were a deal breaker for me. Now that it's 2016, I'm willing to consider some sort of roller again.

If you're running a FAST system I'd fire off a PM to MOPARRICH and give him all the motor specs and what you hope to achieve. He'll nail it for ya.

this works well, 248 @ .050 solid flat tappet

So you're saying at lower RPM your carb was performing better than your EFI system is? If that is the case, I think you first need to determine why you are unable to meet or exceed the street manners of the carb. IMO cam selection is not the problem.

You can get EFI to work with any cam, just takes some careful tuning (see below). Left over fuel in the intake is caused by overlap in the cam. It's reversion. But if you are running sequential, which I assume you are because of the coils, you can adjust the injection end angle which FAST calls injector opening retard. This allows you to inject after reversion is over. This has a huge effect on idle with high reversion cams and you'll eliminate the excess fuel in the manifold. It's one of those things that people don't talk about because it only comes up with fully sequential EFI systems. Holley even has a cam page which will compute the correct end angle for you. It's cool, but you can do that with FAST to. With FAST the default opening retard is zero, meaning the injection starts when the system sees the crank ref pulse which is usually 50 degrees BTDC. Change that retard to about 60 to 80 degrees and your excess fuel problem will go away. This will have minimal affect on anything other than idle.

But if you really wanted to smooth things out the major parameter is LSA (lobe separation angle). EFI likes high numbers like 112 and higher. As far as the type of cam, that you have to decide.

BTW: I love the converted Jeep cam sensor :^)

Here is a cam article I wrote a few years back. Any of these cams would work fairly well in your engine. I think I have a few of these cams still sitting on the shelf. The Racer Brown cam for sure and maybe the Comp.

http://www.moparts.org/Tech/Archive/bb/Lobe.html

I run a similar engine on EFI (496, M1 single plane, 1'st gen FAST XFI, 5 speed OD).

The cam is a 243@.050 MM lobe with 108 LSA which is not EFI friendly but gives lots of "area under the curve". The engine runs very well with a wide flat power curve.

Idle vacuum at first fire was about where you are, 9". Some additional ignition advance (20-22 degrees) and tuning the idle AF got it up to 13" which works fine with the PB. It took some time to tune the AF and electronic "pump shot" to get smooth acceleration below 2000 RPM but it works well now. A big SP is tricky at low RPM. I can now accelerate clean from 1200 RPM in OD if I want to. Sounds like it needs more tuning.

A different cam would make it easier and likely give more performance at the same time. I think Andy's 528 recommendation would work well. Enough duration and lift for good power and wider LSA to help FI tuning.

Agreed. I just haven't spent much time tuning yet and I wondered if, since the existing cam was less than ideal, if I'd be better served to change it to something more EFI friendly before spending time trying to tune what I had.

I now know this is an MS installation. I don't know if you can change the injector end angle with the MS, but if you can, then you can tune for any cam and be at least as good as the carburetor was.

Heads up if you're thinking about buying a FAST package... I gotta give big props to Mopar Rich. He thought I had a FAST installation and, without me asking, sent me a long PM with all sorts of advice and offers of help. I told him it was a Megasquirt installation and he still replied with some camshaft advice. Based on this, he gets "good guy" status in my book.

Rich, you can change the injector end angle (one of the features that I have not yet mastered scratched the surface on) in MS... I'm still learning, but that's the fun.

You don't have to go real small on the cam. I have a similar install, sequential mode efi, coil near plug on a 340 with a 227/231 duration at .050 hydraulic roller cam with 110 LSA and it loves it. I have never noticed any wetness in my intake manifold. Your 493 should be able to eat a lot more duration than my 346ci engine anyway.



I haven't touched any of the injector trim angles but the car runs amazing even at low RPM ranges. I'd be curious on what your idle ignition advance is. My car pulls about 13.5 in Hg at idle (900rpm) and has 22 degrees advance at idle.

For tuning in general, do some light driving with the self-learn feature on and then start datalogging when the engine is warm and use the megalogviewer and the VE analyze feature. The more time you spend in the RPM ranges, the better the tune will get on your VE table. Even if I don't get too many hits in an area - I try to smooth it out. So far, it has worked well. In my case, so much better than the carb after only a few hours of driving.