Disappointing dyno results

[MopaR&D]

Since you degree'd the cam and installed it straight-up (Post #46) you should be fine there. What was ignition timing for the dyno pulls? You could also try some larger metering rods to lean out the AFR a bit. Might pick up 20-40 HP with the tune but after that your small cam is definitely the limiting factor. That's the sort of cam that belongs in a heavy cruiser or tow rig application for gas mileage and low-end torque.

A cam like the stock 340 grind is good but you could get a little better, something with advertised intake duration similar to or 4-8 degrees more than the cam you have now but with more duration at .050" lift and lift closer to .470-.480" on a 108 degree lobe separation angle (LSA). You don't need to know cam specs to get a good one though, just need to talk to a good cam company that's familiar with Mopar 340 engines (like Oregon or some other smaller ones like Schneider, Racer Brown, Bullet cams). Sounds like the company you got your current one from wanted to play it safe (a little too safe) with street manners and didn't know that even the factory 340 cam was a decent bit bigger than that.

 

[jawbone]

was that engine hp or rear wheel hp?

Engine HP.

 

[jawbone]

Can someone explain this intake CL. Once verified, understand timing is dot to dot. If not, cam can be adjusted accordingly with keyway timing chain set.

 

[Ricks70Duster340]

By going dot to dot, what did I do timing wise. The timing gear allows me to advance or retard timing but did not.

By installing the cam gear "dot to dot" you are assuming the timing gearset is absolutely correct, which many are not. Also that the cam grind is correct, which some are not. There are a lot of posts in this forum about people having performance problems only to find out (when the cam installation is checked using a degree wheel) that it was installed retarded. Think about this for a minute. The engine is a system. All the pieces of the system must work together to achieve the desired end result. All of us have made past mistakes by installing parts that someone recommended only to find out it did not work properly in our build.

 

[MopaR&D]

Can someone explain this intake CL. Once verified, understand timing is dot to dot. If not, cam can be adjusted accordingly with keyway timing chain set.

Intake centerline is the measurement in crankshaft degrees after top dead center on the intake stroke where the centerline of the intake cam lobe is (point of maximum lift). It is generally the cam spec used to verify that the camshaft was ground and phased correctly in relation to the crankshaft. Camshafts are often manufactured off by a bit and need to be advanced or retarded with respect to the crankshaft in order for the ICL when installed to match with the value spec'd by the manufacturer.

 

[mopowers]

Since you degree'd the cam and installed it straight-up (Post #46) you should be fine there.

Just speculating here, but if he's asking what intake centerline means, he probably didn't actually degree the camshaft. That's one of the first things I'd verify.

 

[toolmanmike]

Big valve "O" heads, flat top JE pistons with 2 valve reliefs. Calculated 9.687:1 compression, dynamic at 11.103. cc"d at 65.6 Compression check at 150 after 5 revs.

How close to zero deck are those flat tops?

 

[jawbone]

Intake centerline is the measurement in crankshaft degrees after top dead center on the intake stroke where the centerline of the intake cam lobe is (point of maximum lift). It is generally the cam spec used to verify that the camshaft was ground and phased correctly in relation to the crankshaft. Camshafts are often manufactured off by a bit and need to be advanced or retarded with respect to the crankshaft in order for the ICL when installed to match with the value spec'd by the manufacturer.

So I degreed the crank initially. Sent it back due to errors. Verified ICL on replacement and installed timing dot to dot. Would this not be correct?

 

[jawbone]

If the fore mentioned comment is correct, it goes back to I installed a piece of s*** cam.

 

[jawbone]

And wasted $800.00 on dyno.

 

[67Dart273]

You have me at a disadvantage. I do not understand. Was installed dot to dot.

That is NOT "installing" a performance cam. Performance cams (or really, even stock ones) need to be checked. Google up "degreeing a cam" There are lots of websites and videos, some by the am manufacturers on doing so.

I helped a guy REALLY wake up a 318 that was nearly 12* off optimum. This is due to manufacturing differences in the engine, the cam itself, and the timing drive

 

[dartindanno]

 

[toolmanmike]

That's a pretty slick cam gear.

 

[jawbone]

That is NOT "installing" a performance cam. Performance cams (or really, even stock ones) need to be checked. Google up "degreeing a cam" There are lots of websites and videos, some by the am manufacturers on doing so.

I helped a guy REALLY wake up a 318 that was nearly 12* off optimum. This is due to manufacturing differences in the engine, the cam itself, and the timing drive

Thought I explained the cam was degreed. Why am I getting blasted on doing so?

 

[jawbone]

Want to thank everyone for their input in helping me rectify this issue. Please don't take my previous comment the wrong way. I did degree the cam prior to final install of timing set. Also cc the head and checked valve clearance just for the heck of it. I think the problem has already been identified and that's the cam itself. Any future comments will be appreciated. I never got an answer to my post regarding dot to dot alignment if intake centerline was correct. If this is the proper method would someone please confirm.

 

[Phreakish]

Thought I explained the cam was degreed. Why am I getting blasted on doing so?

I think because some questions about ICL make it sound plausible that it was not. Might be helpful if you describe exactly how you degreed it, just in case the process you used might have induced an error. Worth ruling out, at least?

 

[Phreakish]

Want to thank everyone for their input in helping me rectify this issue. Please don't take my previous comment the wrong way. I did degree the cam prior to final install of timing set. Also cc the head and checked valve clearance just for the heck of it. I think the problem has already been identified and that's the cam itself. Any future comments will be appreciated. I never got an answer to my post regarding dot to dot alignment if intake centerline was correct. If this is the proper method would someone please confirm.

Dot-to-dot doesn't matter. A degree wheel needs to be setup and the timing events checked to the cam card. Your cam has a LSA of 110 and an installed 'centerline' of 106, which should be 4 degrees advanced. Some places grind in that advance, some do not. It should be possible to pull a valve cover and use an indicator on the valve stem or pushrod or rocker to get an idea of where your centerline is currently. It's best to do it at the lifter, but with the engine assembled that's a bit tricky, so do what you can. Your engine guy should be capable of doing this for you as a double check too.

If you did this when the engine was built, describe how you did it and the folks here should be able to tell you whether there's a chance for error or not.

Also, don't feel like you wasted $800. How much more would it cost if you'd gotten the car on the road only to find you hate it? At least you know ahead of time, and it 'only' cost you $800 vs a bunch of exhaust gaskets, fluids, and time to R&R the motor. Depending on how you value your time, that $800 might be considered cheap. I would certainly consider it a cheap reassurance.

As far as the rich condition - swapping the carb may help, but tuning it is likely the better route. That said, trying a carb your engine guy suggests (especially if he has one on the shelf to 'borrow' for the pull) might help show how well the engine SHOULD run if it was tuned right with almost any carb and if those numbers are closer to your expectations then you'll have your answer.

 

[jawbone]

Dot-to-dot doesn't matter. A degree wheel needs to be setup and the timing events checked to the cam card. Your cam has a LSA of 110 and an installed 'centerline' of 106, which should be 4 degrees advanced. Some places grind in that advance, some do not. It should be possible to pull a valve cover and use an indicator on the valve stem or pushrod or rocker to get an idea of where your centerline is currently. It's best to do it at the lifter, but with the engine assembled that's a bit tricky, so do what you can. Your engine guy should be capable of doing this for you as a double check too.

If you did this when the engine was built, describe how you did it and the folks here should be able to tell you whether there's a chance for error or not.

Also, don't feel like you wasted $800. How much more would it cost if you'd gotten the car on the road only to find you hate it? At least you know ahead of time, and it 'only' cost you $800 vs a bunch of exhaust gaskets, fluids, and time to R&R the motor. Depending on how you value your time, that $800 might be considered cheap. I would certainly consider it a cheap reassurance.

As far as the rich condition - swapping the carb may help, but tuning it is likely the better route. That said, trying a carb your engine guy suggests (especially if he has one on the shelf to 'borrow' for the pull) might help show how well the engine SHOULD run if it was tuned right with almost any carb and if those numbers are closer to your expectations then you'll have your answer.

Would I have compression (150-160) if valve timing was off?

 

[Phreakish]

Would I have compression (150-160) if valve timing was off?

It depends on the actual compression, battery charge level, how healthy your starter is, all kinds of things can impact cranking compression. Cranking compression is a guideline, not a hard and fast rule.
So yes, you could have sufficient cranking compression with the valve timing off. There's no way to tell if the valve timing is right except to verify timing events using an indicator and a wheel (or even just a timing tape on the balancer to get close).

 

[ch1ll]

I’m seeing a lot of comments while they are correct, they are not getting to the base of your problem.

First off, figure out your compression ratio. Remove the head on #1 cylinder and find top dead center with a piston stop. Plenty of videos on YouTube showing how to do this. At this time install a degreeing wheel on the cam snout so you can check cam installation. Set a pointer to zero. Then cc the piston to the top of the block with a graduated cylinder and then cc the combustion chamber of of the #1cylinder. Add these two together and figure out your compression ratio. This is the ONLY way to get an accurate CR figure. You cannot just look at piston and head spec sheets. Now turn the crank to 106 ATDC. Your cam should be at its highest lift, on top of the lobe nose on the intake lobe. This is the ICL. There are plenty of YouTube vids showing how to do all this. I have not gone into all the detail how to do this correctly.

A few words on cam selection, engine building and dyno testing.

If you built this engine yourself, you need to find an experienced mopar engine builder cause you didn’t get it right, no offense meant, but I didn’t get it right my first engine either. I now have an experienced engine builder that has built thousands of engines and has experience that I will never have. Reading tech and taking others advice ends up with mis matched parts and trial and error which is right where you are now. My builder has a dyno and knows how to use it. A dyno is used to tune and dial in an engine. If you are just paying for a few pulls and a dyno spec sheet you are not just getting ripped off, but not using the dyno as the tool it was meant to be.

As for the cam, with my limited knowledge and experience, that cam is not opening the intake valve soon enough. It needs to open the valve 20-30 degrees BTDC for a high performance engine. You need to talk to a cam grinder with your engine builder as well, not a salesman from a cam manufacturer. Oregon cam grinders is a good one recommended on fabo and is reasonably priced. Mike Jones is good as well but expensive.

If you want to learn more about about what you and I don’t know about engine and horsepower fundamentals, watch David Vizard on YouTube and buy his books. I do and did. There was so much I didn’t have a clue about and still don’t. David has done thousands and thousands of dyno pull testing for not only for himself and his race cars, but for car manufacturers, and speed part manufacturers. KN, comp cams, Ford and the list goes on forever. Automotive journalist, aerospace engineer, university lecturer, engine builder and race car driver. The guy is accredited.

As for your carb, it is not too big for your engine, it’s not tuned right for your cam and the rest of your combination and that’s your dyno guys job. But I believe the biggest part of your problem is your cam. You have to get your combination right before you tune any carb or you will continue to be disappointed.

 

[67Dart273]

Thought I explained the cam was degreed. Why am I getting blasted on doing so?

Because that is not originally what you said, and it fuzzies up the conversation. Further, the printed specs are not always what you want, depending on the engine build and intended purpose. "Move the HP band." There are guys way more expert on just where to set a particular cam than I. RustyRadRod, Rumble, and Crackedback are a few, there are others.

 

[jawbone]

I’m seeing a lot of comments while they are correct, they are not getting to the base of your problem.

First off, figure out your compression ratio. Remove the head on #1 cylinder and find top dead center with a piston stop. Plenty of videos on YouTube showing how to do this. At this time install a degreeing wheel on the cam snout so you can check cam installation. Set a pointer to zero. Then cc the piston to the top of the block with a graduated cylinder and then cc the combustion chamber of of the #1cylinder. Add these two together and figure out your compression ratio. This is the ONLY way to get an accurate CR figure. You cannot just look at piston and head spec sheets. Now turn the crank to 106 ATDC. Your cam should be at its highest lift, on top of the lobe nose on the intake lobe. This is the ICL. There are plenty of YouTube vids showing how to do all this. I have not gone into all the detail how to do this correctly.

A few words on cam selection, engine building and dyno testing.

If you built this engine yourself, you need to find an experienced mopar engine builder cause you didn’t get it right, no offense meant, but I didn’t get it right my first engine either. I now have an experienced engine builder that has built thousands of engines and has experience that I will never have. Reading tech and taking others advice ends up with mis matched parts and trial and error which is right where you are now. My builder has a dyno and knows how to use it. A dyno is used to tune and dial in an engine. If you are just paying for a few pulls and a dyno spec sheet you are not just getting ripped off, but not using the dyno as the tool it was meant to be.

As for the cam, with my limited knowledge and experience, that cam is not opening the intake valve soon enough. It needs to open the valve 20-30 degrees BTDC for a high performance engine. You need to talk to a cam grinder with your engine builder as well, not a salesman from a cam manufacturer. Oregon cam grinders is a good one recommended on fabo and is reasonably priced. Mike Jones is good as well but expensive.

If you want to learn more about about what you and I don’t know about engine and horsepower fundamentals, watch David Vizard on YouTube and buy his books. I do and did. There was so much I didn’t have a clue about and still don’t. David has done thousands and thousands of dyno pull testing for not only for himself and his race cars, but for car manufacturers, and speed part manufacturers. KN, comp cams, Ford and the list goes on forever. Automotive journalist, aerospace engineer, university lecturer, engine builder and race car driver. The guy is accredited.

As for your carb, it is not too big for your engine, it’s not tuned right for your cam and the rest of your combination and that’s your dyno guys job. But I believe the biggest part of your problem is your cam. You have to get your combination right before you tune any carb or you will continue to be disappointed.

Thanks for the detailed and informative response. I did cc the heads and calculate compression ratio. cc=65.6 CR=9.687:1 This was based off graduated cylinder.
Engine builder said the same regarding intake valve timing. What I do not understand is why stock Mopar 340 intake is at -2 BTDC (@.050), Are you using the advertised value of 26. May be more mis-information.
Do you know what effect leaning A/F ratio will have on numbers.

 

[Inertia]

Horsepower is just a number, - in most cases just a conversation piece. The car will likely drive wonderfully, the only time you may miss h/p is when wide open throttle or showing timeslips, - seriously.
Make up BS horsepower, like most others. lol
Just drive and enjoy it, - make changes at your leisure.
I have always found, "if I could do it again, I'd change this".
You are there . lol
Good luck .

 

[jawbone]

Horsepower is just a number, - in most cases just a conversation piece. The car will likely drive wonderfully, the only time you may miss h/p is when wide open throttle or showing timeslips, - seriously.
Make up BS horsepower, like most others. lol
Just drive and enjoy it, - make changes at your leisure.
I have always found, "if I could do it again, I'd change this".
You are there . lol
Good luck .

Thanks for the words of wisdom. I'm leaning in that direction.

 

[RustyRatRod]

Yall are off the mark, IMO saying that cam isn't a good one. Yall are comparing advertised duration of the 340 cam to the .050" duration of the cam he has. You cannot do that. The .050" duration of the 340 cam was actually very close to what he has now. I doubt very seriously the cam is where the problem is.