Disappointing dyno results

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jawbone said:
I was at the mercy of the cam supplier. As I said, not a cam guy. Got tired of reading comments on cams so did the best I could. Still at a loss and don't know what to do. If I were to purchase another cam would be the same story. Thanks for your comments.
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I get it, and I truly don’t mean to rub salt in your wounds. The cam that you were supplied is an offense to what the 340 stands for. A stock replacement cam would have been a better choice, but the fact of the matter is that is in the past.

You will never be happy with that motor until you get a better cam. Nothing you can do, short of forced induction(nitrous,supercharger) will give you the power one would expect from a freshly built 340.

Who supplied the cam? And can we get the part number or actual specs posted? Until you can verify exactly what cam you have, this is all speculation.
 
mcodecuda said:
A simple jet or metering change can correct your air/fuel ratio issue. If your “engine guy” is suggesting that the stock carb is too big then ask him why did he select components that resulted in an engine that made less horsepower than stock.
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It was not the engine guy that selected the cam. It was the cam manufacturer. The engine guy is running the dyno.
 
jawbone said:
I was at the mercy of the cam supplier. As I said, not a cam guy. Got tired of reading comments on cams so did the best I could. Still at a loss and don't know what to do. If I were to purchase another cam would be the same story. Thanks for your comments.
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Leave it the way it's built or change things. Those are your choices.
 
What pistons did you use? Just curious what other parts were used that can cause a loss of power. Which heads are you using?
 
toolmanmike said:
What pistons did you use? Just curious what other parts were used that can cause a loss of power. Which heads are you using?
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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.
 
seeing as how torque is done by 2500 and hp isn’t rising till 5000, could the cam be installed a few degrees retarded? It could explain the 150 psi.
 
Mopar44134 said:
seeing as how torque is done by 2500 and hp isn’t rising till 5000, could the cam be installed a few degrees retarded? It could explain the 150 psi.
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Cam was not installed retarded. It may be a retarded cam but that is not the case. Thanks for the comment.
 
MidnightSwinger said:
I get it, and I truly don’t mean to rub salt in your wounds. The cam that you were supplied is an offense to what the 340 stands for. A stock replacement cam would have been a better choice, but the fact of the matter is that is in the past.

You will never be happy with that motor until you get a better cam. Nothing you can do, short of forced induction(nitrous,supercharger) will give you the power one would expect from a freshly built 340.

Who supplied the cam? And can we get the part number or actual specs posted? Until you can verify exactly what cam you have, this is all speculation.
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Cam was supplied by Camcraft.

20230914_092659.jpg
 
jawbone said:
Intake centerline is 106.
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BUT IS IT ACTUALLY installed there? Throwing it in the engine "by the dots" is not doing so

Also I'm not sure I agree the carb is too big. The entire point of vacuum secondary type carbs is that they self regulate. Ma Chrysler put 360 style Thermoquads on 318s in later years. It may need adjustment and tuning, OK, but likely is not actually too big.
 
Well it's obvious I need a different cam. While I have everyone's attention, I understand Oregon Cam Grinding has the template for 68 340 4 speed cam.
 
Was cam timing verified?? I.e., was the cam degreed, or simply installed "dot to dot"? Maybe it's just way retarded like someone mentioned. You won't know unless you check it.

Something's obviously way off. I agree with Toolman - you've gotta get back to basics and look at everything objectively.
 
mopowers said:
Was cam timing verified?? I.e., was the cam degreed, or simply installed "dot to dot"? Maybe it's just way retarded like someone mentioned. You won't know unless you check it.

Something's obviously way off. I agree with Toolman - you've gotta get back to basics and look at everything objectively.
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I degreed the cam initially. Grind was incorrect so sent it back. The replacement was correct.
 
jawbone said:
Well it's obvious I need a different cam. While I have everyone's attention, I understand Oregon Cam Grinding has the template for 68 340 4 speed cam.
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Yeah man, they are a solid vendor too. But I’m going to echo what the others are saying about your cam timing. You need to verify, if you accidentally put it in retarded(no big deal, regular mistake)by going dot to dot. I would double check everything before you start spending money.
 
MidnightSwinger said:
Yeah man, they are a solid vendor too. But I’m going to echo what the others are saying about your cam timing. You need to verify, if you accidentally put it in retarded(no big deal, regular mistake)by going dot to dot. I would double check everything before you start spending money.
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By going dot to dot, what did I do timing wise. The timing gear allows me to advance or retard timing but did not.
 
Stock 340 was .429, .444 w /.210 and .220 duration and produced about 275 hp and 340 lb. ft.
You are pretty close to stock but there is something not quite right...you should be up about another 45.
I don't think the problem is cam selection. Give us the dyno details and compression height?
...you have duplicated a lo compression 340 numbers?
 
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