Disappointing dyno results

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jawbone said:
Hi ch1ll. Regarding Carter AVS. Dyno operator only had a lager Holley which yielded similar results. He will receive 600cfm Holley for pull tomorrow if weather permits. Humidity is currently high. Operator does not have any replacement jets or metering rods. The Carter I had rebuilt was stock unit for 68 or 70 340 4 speed application. Can't remember which. Would only think jetting would be correct.

Cam is from Camcraft. I know, you never heard of them. Wish I hadn't. Only looking to make stock horsepower. That's all I can expect using stock engine components.
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Jetting is never correct unless it's been tweaked for current conditions. Yes, that's over over-statement, but it would not be abnormal to see AFR vary from nominal when the cam isn't exactly stock and the exhaust isn't stock, and the air filter is removed, etc. Every carb needs fine tuned to conditions and equipment.
It's a shame the dyno guy doesn't have some AVS parts on-hand to help out, but it sounds like you can rule out the carb as an issue with the 600 holley.
 
Hysteric said:
Don't rush to change things. Take your time and be methodical. Try another carb first or put that AVS on another car and see how it works.
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Good advice. I'm a methodical person by nature. That's why it's taken me so long to get here. Will be attempting another pull with different carb when weather clears. Humidity is currently very high.
 
318willrun said:
Just reading through this and I was like "his cam is very close to a stock 340 cam".... one is advertised and one is @ 050 ... then I see RRR pointed that out...
Carb is not too big.
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It's a stock AVS specific for 340 4 speed.
 
For what it's worth, I don't see either the cam or the carburetor being the problem. Stock cam, stock carb, should make stock horsepower. Unless the cam is not degreed properly, carb has wrong jets or the secondaries aren't opening all the way because they are not adjusted correctly. Or the ignition timing is way off.
 
65 Cuda 340 said:
For what it's worth, I don't see either the cam or the carburetor being the problem. Stock cam, stock carb, should make stock horsepower. Unless the cam is not degreed properly, carb has wrong jets or the secondaries aren't opening all the way because they are not adjusted correctly. Or the ignition timing is way off.
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Hey 65 Cuda 340. Carb, number wise, is for 68 or 70 340 4 speed. Can't remember which. May be someone played with it before I got it and changed jets. We made sure secondaries were opening fully. Will ask operator about timing. Was curious myself where that was set.
 
Do you have a qualified engine builder helping you? I ask because going to 1.6 rockers may be an easy solution. It will simulate a more aggressive cam but you need to have sufficient piston to valve clearance. Will let you keep your carb too.
 
65TerrorCuda said:
View attachment 1716141729
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Is this a graphical representation of the data on the first page? If so your engine is really only accelerating between 3300 and 3800 and then again 4500 and 4800.

There's definitely something funky going on. It looks like its making its best power as the AFR leans out.

What do the plugs look like? Did your dyno guy pull any to check?
 
jawbone said:
Had it restored by Woodruff Carburetor.
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I will say this:
Many times folks build an engine but trust others for setting everything up. When this happens, the guy tuning/setting it up BETTER know what he's doing. Nothing against your guy, I don't know him. I'm just speaking in general. Usually, the biggest disappointments in power output come from these type of builds. I not only recommend, I insist that a person knows how to do basic tuning, carb settings, timing - initial, total, curve and just general understanding of it all. As these cars get older, and the good ole' boys keep leaving us (RIP), there just isn't enough guys out there to get these right. Again, nothing against your tuner at all. He may be great.
 
69conv said:
Do you have a qualified engine builder helping you? I ask because going to 1.6 rockers may be an easy solution. It will simulate a more aggressive cam but you need to have sufficient piston to valve clearance. Will let you keep your carb too.
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Hi 69conv. Now that's a new idea. Have ample clearance it's just that I spent more on adjustable rockers than a cam would cost. Wouldn't have to take the engine apart. The engine builder built my short block and is doing the dyno.
 
Running rich and dismal dyno numbers are clues to retarded ignition timing. Where was initial and total timing set?
 
jawbone said:
Hi 69conv. Now that's a new idea. Have ample clearance it's just that I spent more on adjustable rockers than a cam would cost. Wouldn't have to take the engine apart. The engine builder built my short block and is doing the dyno.
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I wouldn't buy one single part. I'd start with the absolute tune and verify what you already have. Throwing parts and money can lead to driving cost with greater disappointments. If you find a faulty part or a problem, then make a smart purchase.
 
RustyRatRod said:
Running rich and dismal dyno numbers are clues to retarded ignition timing. Where was initial and total timing set?
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Hi Rob, Will get that info for you tomorrow if weather breaks. Will be doing another pull with different carb.
 
For you NCIS fans out there, nice campfire. Thanks for everyone's comments. The response was much more than expected and greatly appreciated.
 
lots of great suggestions here, paramount with starting with a tune and going from there.

however, something i haven't seen is, have you verified the camshaft specs? i know it's been degreed, but have you checked the actual lift numbers and criticals? mistakes happen in grinding. mistakes happen in packaging. mistakes happen in shipping.

given the specs that *should* put down numbers that are very similar to a stock 340, and given the disparity in numbers there something is fundamentally wrong.
 
junkyardhero said:
lots of great suggestions here, paramount with starting with a tune and going from there.

however, something i haven't seen is, have you verified the camshaft specs? i know it's been degreed, but have you checked the actual lift numbers and criticals? mistakes happen in grinding. mistakes happen in packaging. mistakes happen in shipping.

given the specs that *should* put down numbers that are very similar to a stock 340, and given the disparity in numbers there something is fundamentally wrong.
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Great idea but if it was not on youtube, would not begin to suspect it as being an issue. They got my first cam wrong but that is before I knew to advance or retard using adjustable timing set. One could suspect errors in just about any aspect of this magical piece of hardware. I spent untold hours reading trying to grasp how differences affect performance and driveability. After I failed at that, left it up to the experts which is where I am today. Granted I have forgotten all that I understood which was almost nothing. I do remember the idea of scavenging which made sense.

Was told by my engine builder to verify valve timing angles. One would also have to consider the time it would take to verify and how often to get proficient at it.
 
jawbone said:
Great idea but if it was not on youtube, would not begin to suspect it as being an issue. They got my first cam wrong but that is before I knew to advance or retard using adjustable timing set. One could suspect errors in just about any aspect of this magical piece of hardware. I spent untold hours reading trying to grasp how differences affect performance and driveability. After I failed at that, left it up to the experts which is where I am today. Granted I have forgotten all that I understood which was almost nothing. I do remember the idea of scavenging which made sense.

Was told by my engine builder to verify valve timing angles. One would also have to consider the time it would take to verify and how often to get proficient at it.
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you keep mentioning your engine builder here, and i'm failing to grasp what it is that you mean by that or what he actually does, or did in this whole process?

if you employed him to build your engine, then ALL of that cam stuff should come under his purview.

anyway, cam is sus. i would pull it down and verify with a degree wheel, or at least check the lift numbers at the rocker.

one would, indeed have to consider the time it would take to verify the camshaft; and in response one would also have to live with the unknown and poor performance if not verified.

this leads to the conclusion: there is no easy button.
 
junkyardhero said:
you keep mentioning your engine builder here, and i'm failing to grasp what it is that you mean by that or what he actually does, or did in this whole process?

if you employed him to build your engine, then ALL of that cam stuff should come under his purview.

anyway, cam is sus. i would pull it down and verify with a degree wheel, or at least check the lift numbers at the rocker.

one would, indeed have to consider the time it would take to verify the camshaft; and in response one would also have to live with the unknown and poor performance if not verified.

this leads to the conclusion: there is no easy button.
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Engine builder put together the short block minus cam. Think I did check lift which if I recall was a little shy but not by much.
 
jawbone said:
And wasted $800.00 on dyno.
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No … not really . Dyno time is so you can break in the engine , check for leaks and find performance issues before you spend days installing , tuning , diagnosing and then having to pull the engine againe and start all over .
although $800 seams spendy for a dyno shop that wont even rejet your carb muchless redegree your cam or set lash etc….
 
Once again...if you do indeed have a cam with those numbers it is an excellent choice for a 14 inch tire street driven 340, should produce better numbers and pull hard to well past highway speeds. Maybe the cam sent was not the cam you ordered?
Your build makes good sense. I might even suspect you have wiped a few lobes? But there is definately something not right?
 
jawbone said:
Think I'm probably more than two years into this build. Much more than just a steep learning curve. It's like you said; overcoming the frustration that comes with it. I'm not just trying to repair or refurbish an existing engine, it's starting from scratch. Missing everything but the short block. Will say learned a lot and enjoyed most of it. Sure bought my share of parts that I will not use. I'll get over it and get back to it. I was so ready to get engine in car and start work on drivetrain. Don't think I have the strength install cam once engine is in the car. Between the weight of heads and intake manifold, too much for this old man. Thanks for the recommendation on voodoo cam. Will ad it to my new list. What do you have it in? Stock engine components?
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I think it took me about 2 or 3 years to get mine done. I did the same started from scratch. I started with a budget 318 and it was gonna have to he machined so I figured if I'm gonna pay a machine bill might as well go with a 360. I like you bought parts that was wrong for the combo ended up changing the combo a few different times due to parts I couldn't get during the pandemic! Three sets of pistons and about 2 camshafts later It started setting in just how much planning needs to be made before hand lol my engine ended up as a 360 .06 over refurbished stock crank rods and kb 107 pistons ported heads valve job and comp springs voodoo cam factory 71 340 intake and thermoquad carb. It makes 175 psi cylinder pressure and about 10.2 scr. I can't recall the dcr. Somewhere around 9 tho. I wish I had the means to dyno it and tune it on a dyno I have no idea what it makes it might be similar to yours for all I know but I do know it's alot of fun.
 
jawbone said:
Hi ch1ll. Regarding Carter AVS. Dyno operator only had a lager Holley which yielded similar results. He will receive 600cfm Holley for pull tomorrow if weather permits. Humidity is currently high. Operator does not have any replacement jets or metering rods. The Carter I had rebuilt was stock unit for 68 or 70 340 4 speed application. Can't remember which. Would only think jetting would be correct.

Cam is from Camcraft. I know, you never heard of them. Wish I hadn't. Only looking to make stock horsepower. That's all I can expect using stock engine components.
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Your still not telling me if you cc’ed the cylinder with the piston at top dead center. This is going to make a difference in CR. I doubt your going to make stock hp with less than stock compression. Compression is a huge part of the equation.

If he didn’t have jets, he should not have even loaded it on the dyno till he did.

Did you have the advance curve checked?

If anything, your avs is too small. Using a dual plane intake, 4 cylinders are only getting 275-300 cfm. The other 4 are getting the other half of the carb. Think about that.


Did he have jets,air bleeds,power valves to tune the holley he used?
 
Jadaharabi said:
Sounds like you need a new dino man not a smaller carb. The engine will only use as much air flow as it needs. You can put a thousand CFM carburetor on that motor if it needs 600 it's only going to draw 600. Now I'd try a different carburetor sounds like that one was rebuilt screwy.
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Actually a 1000 CFM carb will have very large jets so I would think that even though the engine is only calling for 600 CFM it would still be running rich. While we know most of the details on his motor we still don’t know what part number carb that he is using.
 
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