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340 running like a lame duck

Started by Rdchallenger, September 24, 2022, 01:36:46 PM

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crackedback

my favorite horsecrap hp claiming article for a street build...

check float level and no dripping fuel while running in the throats of carb.

Look at the plugs and see if they are black...  that would be the first thing to do, IMO

Lining up the cam dot to dot can create a few issues.  Have to verify cam installed centerline to rule out a retarded cam install.  Advance more than  suggested is usually not an issue as long as it is reasonable. 

That cam works well in stockish type builds.

Good luck.

torredcuda

Degreeing the cam is always recomended but if it`s only a few degrees off shouldn`t be a huge loos of power, in fact advacing or retarding the cam can sometimes be beneficial and change where in the rpm range the engine makes power. "According to Comp Cams Valvetrain Engineering Group Manager Billy Godbold, "If your cam phasing is off 4 degrees, the loss of performance is going to be in the neighborhood of 10 lb-ft on a 400 lb-ft/400 hp application, but only on the ends of the torque curve. This is a big deal in racing, but probably not dramatically bad on the street."
Jeff   `72 Barracuda 340/4spd
https://www.facebook.com/jeffrey.hunt.750

Northeast Mighty Mopar Club
https://www.facebook.com/groups/1486087201685038/



chargerdon

#18
This is more of a question than a statement.   But stock timing chain sprockets are NON adjustable.   If your using a stock type timing sprockets then just what does degreeing it in mean?  How could you change it if necessary ?

I put a Lunati 703 cam in my 360.   I have the double roller sprockets that have no adjustment...i.e only one keyway position that you line up the upper and lower sprockets on the little circles.    Buddy of mine had a degree wheel and so while installing just to be sure, we went thru the degreeing checking process and found that it was within 1 degree of what Lunati's Cam card said it should be for intake and exhaust opening.   So, that was that.   I mean if your using quality components why wouldn't it be on ?   Oh, and this is with a Scat brand stroker kit as well...   So mixing and matching Scat and Lunati and still it was within 1 degree...

PS, on my 360 stroked to 408 engine, i read about 190-195 PSI compression the Compression ratio was calculated at 9.75 static during the build.  With an Edlebrock air gap, and an Edlebrock 600 CFM carb that i know Chycro hates (thank you for the Lunati 703 suggestion), Patriot headers and only a 3.23 sure grip with automatic and 14" wheels, i CAN NOT floor it in first at anything less than 15 MPH without the tires going up in smoke.   I recently used Track Addict cell phone app, and recorded a 0-60 in 4.99 and an 1/8 mile in 8.6 at 84 mph.   

Rdchallenger

So I'm getting a game plan together. Since the fun for the year has wound down.

Going to call lunati tomorrow for a cam suggestion I'm thinking about their 10200702 hydraulic cam.
Getting a degree wheel
Changing out valve springs with the tool from Mancini so I can keep the heads on and put on roller rockers
Compression check, leak down, and vacuum check.
Rejet carb if needed. 
And now fix an exhaust manifold leak that has recently appeared lol

Anything else anyone can think?
When I broke in this cam, my oil pump shaft snapped out of the drive which I'm thinking affected this cam. So even if it passes the check I'm yanking it.

torredcuda

Quote from: chargerdon on October 09, 2022, 06:57:16 AM
This is more of a question than a statement.   But stock timing chain sprockets are NON adjustable.   If your using a stock type timing sprockets then just what does degreeing it in mean?  How could you change it if necessary ?

I put a Lunati 703 cam in my 360.   I have the double roller sprockets that have no adjustment...i.e only one keyway position that you line up the upper and lower sprockets on the little circles.    Buddy of mine had a degree wheel and so while installing just to be sure, we went thru the degreeing checking process and found that it was within 1 degree of what Lunati's Cam card said it should be for intake and exhaust opening.   So, that was that.   I mean if your using quality components why wouldn't it be on ?   Oh, and this is with a Scat brand stroker kit as well...   So mixing and matching Scat and Lunati and still it was within 1 degree...

PS, on my 360 stroked to 408 engine, i read about 190-195 PSI compression the Compression ratio was calculated at 9.75 static during the build.  With an Edlebrock air gap, and an Edlebrock 600 CFM carb that i know Chycro hates (thank you for the Lunati 703 suggestion), Patriot headers and only a 3.23 sure grip with automatic and 14" wheels, i CAN NOT floor it in first at anything less than 15 MPH without the tires going up in smoke.   I recently used Track Addict cell phone app, and recorded a 0-60 in 4.99 and an 1/8 mile in 8.6 at 84 mph.   

Offset crank keys are used to adjust timing - https://www.summitracing.com/parts/dcc-5249600
Jeff   `72 Barracuda 340/4spd
https://www.facebook.com/jeffrey.hunt.750

Northeast Mighty Mopar Club
https://www.facebook.com/groups/1486087201685038/

chargerdon

Thanks Torredcuda...didnt know offset keyways existed.   Glad mine was about right on anyways.