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MOPARJ

MOPARJ

What can I upgrade now?
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Getting ready to start searching for ways to squeeze some more power out of my 340. The date on the block is 10-16-70, so i assume that it is the higher compression version. It is in a 69 Formula S Cuda. It has 3.23 gearing behind a rebuilt 727 with a shift kit( a kit not of my liking). I believe the internals are basically stock for the engine's date.

I want to change the cam out to something a little more radical. I would like to keep some of the bottom end, but it is a 340 and can rev higher than a 318, so i don't mind stepping it up. I want to have a cam with a lopey, rumpity rump idle that retains great power. I believe it still has a close to stock converter for the 340, maybe a tad more aggressive than that if i can remember correctly from when i bought it.

What grind, duration, type of cams would best fit what im looking for?

Also, it's not the main question, but will an RPM or Airgap intake fit under the stock 69 Cuda hood with a Carter carb and 3" air cleaner? What carb cfm?
Thanks again everyone.
 
If you don't mind me asking - why can it rev higher than a 318?

I just installed the CCams Nastolgia 340 cam in a 340 for a customer - he wanted the rumpity rumpity idle sound and add some go - the smile has not left his face 222/226 @50, 464 lift.
 
With a date code of 10-16-70 it could very well be a '71 low comp motor, this is probably the case being '71 model and not '70 model cars are being built at that date or later. This is assuming that it has not been touched by anyone.

Chuck
 
Verify when you take off the cylinder head. If it is a high comp. engine, the pistons will pop out of the block a little bit.

Do you have headers?
Do you mind changing converters?
Or gears for this swap?

Best is also an opinion. Unless someone dyno'd a buch of shafts to compare.

A cam in the area of 218 - 224 should do well with the stock converter. I'd look for a duration split of approx. 8*-10* with stock unported heads. 6*-8* for light porting. A centerline of 110 will have a chop to the idle. Quicker ramp cams add to the sound.
 
340mopar said:
With a date code of 10-16-70 it could very well be a '71 low comp motor, this is probably the case being '71 model and not '70 model cars are being built at that date or later. This is assuming that it has not been touched by anyone.

Chuck
Click to expand...

'71's had 10.5 to 1 compression also,they did'nt drop the compression till '72 model year....
 
Yeah, i do believe they didn'tdrop the compression to 8:5:1 until 72 or 73. The motor has 340 hi flow manifolds, edelbrock 600 carb, the rest looks stock from the outside. The idle is rather smooth right now, so i believe it has the stock .450 or so lift cam in it.
 
I had a '69 340 I ran a Comp 268H High Energy cam in for years. It pulled great even with a heaavy car and mild gearing, and even passed emmisions in CT for 3 years. It did have a nice rummble to it too. I had headers, factory iron intake and Thermoquad.
 
So would an XE268 give it that choppy, rumpity cam or would another grind, based on the fact that it is a stock internal block?
 
MOPARJ said:
Yeah, i do believe they didn'tdrop the compression to 8:5:1 until 72 or 73. The motor has 340 hi flow manifolds, edelbrock 600 carb, the rest looks stock from the outside. The idle is rather smooth right now, so i believe it has the stock .450 or so lift cam in it.
Click to expand...

If it still has the factory cam it'll be .430/.444 lift......
 
MOPARJ said:
So would an XE268 give it that choppy, rumpity cam or would another grind, based on the fact that it is a stock internal block?
Click to expand...

I am running an XE268H in a 360 and it is basically a smooth idling cam in a 10.6:1 360. It runs like stink though from 1500-6500 rpm.

Remember "that choppy, rumpity" idle is caused by overlap and inefficient burning of the mixture in the lower rpms which means you are giving up bottom end.
 
Not to stray to far off the original question but I really got into 340s and found it interesting almost every non machined high compression 340 I have seen are off on the factory rating of 10.5 compression-more like 9.2-9.8 range.Chrysler specified the compression rating based on the piston being .018 above deck and using the factory thin steel gaskets and small chamber heads.The head ccs are greater than the factory advertised,then you have the head gaskets wich unless untouched are now averaging .040 compressed,and every unmachined factory 340 Ive taken apart/inspected (69-72) had the factory pistons right at zero deck or a couple thousandths above.My machinist whos raced 340s for years intially told me about this.Regarding the cam my opinion is you couldnt go wrong with a xe-268 for the street-or for the real wicked idle a isky 270 wich has a 108 lobe seperation but moderate duration.
 
lead, that's true with every engine Mopar built. Factory specs are out the window when the real parts are measured. NO engine was 10.5:1, even tho they all were rated for it...lol.

MoparJ, the cam I ran was not an XE. they didnt have that line yet. It's the old High Energy series 268H. They do still make them. It had some overlap, but as I said, it passed emmissions for 3 years in CT. It wasn't bad at all. The Extreme Energy XE268H will idle like a kitten like Dave said.
 
Who's Dave?

Want a choppy idle. Like an axe wacking attack? The numerically smaller centerline cams give it. Most cams are on a 110. And they chop.
The newwer line of cams have a slower closing rate.
 
how about a 292 comp cam? will there be some "rumpity" "rump rump"?

was not me rumble
 
HA ha ha hah , I didn't think it was you since you didn't post yet.

I ran the Mopar 292. Very similar to the Comp cam. It was very rumpity.
 
rumblefish360 said:
HA ha ha hah , I didn't think it was you since you didn't post yet.

I ran the Mopar 292. Very similar to the Comp cam. It was very rumpity.
Click to expand...

nice. did it run well for you? hoping it will be a good cam for my setup.:lol:
 
Well, it was about as dead as a door nail under/about 3,000 RPM. Then it woke up. Made me pay attention.
What size rear tire are you running?
 
Sorry, DGC333 is Dave... Unless that's an alias..

The Comp 292 will have a smoother idle than the MP 292. I use that grind a lot in mild 440s. you'll know it's in there, but the power comes in faster than the MP.
 
dgc333 = David G Clement III

I have been using that user name for at least 15 years.
 
Thanks Rumble and Moper,
I didn't build this engine. I bought it complete from a motivated seller, so I'm hoping for the best. I've just changed a few bolt on items. It was built by Magnum Superchargers in Michigan. Anyone ever heard of them?

rumblefish360 said:
Well, it was about as dead as a door nail under/about 3,000 RPM. Then it woke up. Made me pay attention.
What size rear tire are you running?
Click to expand...

I want to run a 235/60/15 instead of the 205/60/15s I have now. So going from a 24.6 tire to a 26.1 diamter tire. I may run the BF goodrich drag radial or the MT drag radial in that size for the track. I'm thinking of having a separate set of rear tires and wheels for the track.
 
Daves66,I have a friend that ran the comp 292 in his car with a 360,it ran good but it wasnt equal to the all around performance of a modern xe seiries or custom cam,it also had really poor vaccum.IMO the amount of driveabilty loss as well as the limited power range make it a race only grind but he did drive his on the street,he had 4.10s and 28in. tire with a 11in. convertor.Not to say its all bad-it ran good but its just not the optimum cam for a dual purpose machine but I know about the run what youve got thing lol.One interesting note comparing mopars cams to the comps is the mopar 292 has a tighter 108 ls and larger .050 numbers then the comp.It seems mopar cams were always larger at .050 vs. advertised when compared to other companies.
 
I built one 340 using different type variations of cam, intake, carb, etc...... it ran good but felt that there was more to get....if you know what I mean. SO, I built the second 340 using the specs that were dyno proven by Edelbrock. I pretty much held to their list of parts except for the carb, I used a Holley Street Avenger & the headers I used were from TTI, Keith Black Aluminum pistons, comp cam 1.5 ratio roller rockers were added. Their cam listed is a 308/318 with a 112° centerline.....NOW, this motor 'ROCKS' :burnout: This motor is by far stronger than the first I had built because of trying to adhere to a proven setup.
Here's the link to the Edelbrock site where the specs are listed.
http://www.edelbrock.com/automotive/7176pp.html
Also, the cam has a really nice 'rumpty rump'. I'm always getting comments on the 'great sound' that it has and I must agree, it sounds outstanding.
But, that's my 2 cents worth. :supz:
Good luck and I hope maybe what I've listed may be something to think about.
:thumbup:
Greg
 
I have a Hughes 515 /504 Lift ,228/232 Duration @.050 on 108 Lobe centers, in my 69 dart 360 and it has a nice lope to it but is still very easy to drive and makes good power
 
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