340 buildup advice

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Lil Demon

Lil Demon

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Laredo, Texas
I am currently building up a 340 I found on Craigslist for $300.00! I think I scored pretty good on this find. Once we removed the massive amount of rust built up on the motor, I found a stock bore 7/69 340, steel crank, floating rods, untouched X heads with the 2.02 intakes. Needless to say I am pumped about building up a nice 340. The block has been decked and bored out in .030 installed some SRP forged pistons, reworked the heads and installed 11/32 valves with a multi-angle valve job. The crank went 20/20. I had it fully balanced and setup for 10.4:1 compression. I am looking for experienced opinions for cam selection and carb setup. I have narrowed my cam selections down to the following:

CC PP284 Hydraulic .484/.484 239/246 108 centerline 2500-6400

CC XE284 Hydraulic .507/.510 240/246 110 centerline 2300-6500

I want a nasty idling high winding motor, that will cruise "great" and enjoy blasts down the 1/4 once in a while.

As far as carb setup I don't know whether to go six pack or a good 'ol single 4 bbl sitting atop a performer RPM intake. Obviously the six pack gets all the looks and maybe more valuable?
 
There is a EFI version of a six pack if you want to go that route. A member on here has the setup and really likes it.
 
what are you running for transmission/converter and rear gears?
 
well...both of those cams have alot of duration and are going to want a "loose" converter and more gearing to get into their operating range or the engine will be a dog.
 
What do you suppose cruise rpm would be with 4.10's? I was counting on a 3000 stall converter.
 
Im doing a similar build with same intentions. I have 4:10s in my 65 Barracuda, Im intersested in the combos as well
 
Cruise will depend not only on your gears but the height of your rear tire as well. I have 3.91s and with 255/60/15's Im right around 2900 at 55.
 
Lil Demon said:
What do you suppose cruise rpm would be with 4.10's? I was counting on a 3000 stall converter.
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for converter....called a converter company...such as dynamic or ptc...just dont buy an off the shelf 3000 converter...as you will soon find out it does not stall to 3k...
 
If you look up member Mopar To Ya, he's putting a GM 200R4 tranny in his car. The 200R4 is smaller then a 727 plus the 200R4 is an overdrive tranny with a final gear ratio of .67. Just something to think about.
 
I build a lot of customer's muscle cars with the 700R4. I did not know there was a 2004R conversion for the LA. Who sells the adaptor plate? Is the crossmember just modified? I definately like the idea. The 200 is a great and strong tranny.
 
Lil Demon said:
I build a lot of customer's muscle cars with the 700R4. I did not know there was a 2004R conversion for the LA. Who sells the adaptor plate? Is the crossmember just modified? I definately like the idea. The 200 is a great and strong tranny.
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Wilcap and tci sell the adaptor (though you have to trim the tci adaptor to fit) and you jus have to mod the bolt in cross member.
 
Back to the question at hand, anyone have experience with either cam? Sixpack or single 4bbl? Feedback appreciated.
 
Does anyone here have any experience with these cams? Sixpack or 4bbl? C'mon guys!, you guys gotta have some feedback on these questions, thanks.
 
Unless you are a true carb wizard, I'd stick with a four barrel. The six pack is an eye catcher, but is a PITA to tune for the street. JMO
 
Cam choice should be done before the machine work. If you choose a cam that needs the pistons to be fly cut being the block was decked . You will need to reduce the bob weight. Just a thought. Why pay to have it balanced twice. I would go with the second choice wider band and a 3000- 3500 converter would work with it for the street.

You got a good deal on the motor I just sold a 71 with adjustable rockers for $500
 
I used the comp XE284H cam in a 9:1 360. It is not "nasty" at idle by any stretch of my imagination. Idled around 800 rpm if memory serves. It worked good, I didnt love it but didnt hate it either. I never had the carb issues worked out before I changed my setup but I hear, yea one of those stories, that a friend of a friend is one in a 10:1 360 with stock j heads in a challenger going mid-high 12's. I dont know the full rundown of his combo.
 
Thanks for the feedback guys, I likely will go with the PP284 camshaft and a single carb setup. I really want the idle more than true 1/4 mile performance. With a 340, Hp/Tq won't be weak either way.
 
Personally I think it's a mistake with that cam. If you have to have the idle, run something like the 20-600-4. I never like the idea of buying a camshaft for the sound.. So this is not what I would recommend in terms of overall performance. But, it will idle like crap... er... like you want...lol.
 
The 108 will give it more power vs a 112 cl but the idle will be rough-weak, like it wants to stall out.

You want a wide 112--114 cl and around that much duration. Won't be the quickest in the 1/4 mile but have the idle sound you are looking for and be nice and strong-steady..it pull very strong on the top end

Edit, 4.10-4.56 gears will perform much stronger vs 3.23--3.55

Only thing is 3.23--3.55's are nicer gears part throttle--90% of the time it be over geared and be sucking the $5 a gallon gas up

You could put a more mellow cam in--like the factory 340 cam and 3.23 gears and pull a vacuum hose, ha ha, to get that rump-rump sound. I knew kids in high school who did that, with a loud exhaust its really noticeable

But wide open throttle it won't pull for crap, its bark would be worst then its bite
 
I guess I needed to truly define the idle quality I wanted. I am going for the 108 because it produces a more "erratic" idle and as far as track performance it definately produces more power, peakier than a 112-114 which are "mellow" in my definition of idle. Again we all have our own personal taste. To build up the low end for cruising I will be using 4.10's likely and I will likely also be using an overdrive tranny with a 3500 stall, again we all have our own definitions of street cruisers. I have plenty of other toys I use strictly for drag racing and that's how they are setup. This is just a bad little cruiser I want to build.
 
I personally like your pick ...a lot of guys are all about the new grinds but a hot rod should sound bad ***. that is A cam that was what helped build the ledgen and a lot more people hear my car than race it .
 
the 2nd cam on a 110 will make more power.imo

Really....the last engle grind i had 'though it was a solid' would be perfect imo for you

252* @.050 .573 lift 284* 110*....lumpy idle with big power everywhere.

The old MP.557 solid would also be real nice....or for a hyd, the mp .533 lift
 
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