bad Mopar 340 • The Dodge Challenger Message Board

by **Brant** » 16 Jul 2004 0:32

Hi,

I've been learing tons from these forums - and there helping me make something from nothing.

I'm restifying a challenger with a early '72 340 forged crank, low compression engine with matching 4 speed thermocarb, 4 speed set up. Rear end is the 489 casting-3:23. I've spent the last year learning body work and sanding.

My engine runs real strong, as it was honestly rebuilt (new guides, seats, high V-oil P). My plan was to swap out components this winter to match the early model 340's. I've purchased some badger (got cheap) 10.3:1 flat top pistons .020 over. I will bore my block to match. Buy some x or j heads w/2.02's, and a mild cam. Maybe port match and polish.

Most other postings are for radical horsepower. What make cam would you recommend for an even + of torque/horsepower? Sound is very important as well. I would sacrifice top end for sound. I want my freinds to say ‘I wish my car sounded like Brants 340‘.

I would love to hear from anyone. I've been reading everynight - learning about this stuff, but it gets confusing. I need dialog - if that makes sense!

Thanks guys.

by **Brant** » 16 Jul 2004 0:39

Oh,

I have so much info on lift, duration, lobe and what not. I guess even though I've studied this stuff I need advise. Do I go Mopar purple, or do I go comp nastalga, or is it Hughes (or something) I'm freak'n confused already. Do I need to swap out my lifters and get diff spring.

thanks

by **dave-r** » 16 Jul 2004 10:49

Power is made by the heads and cam together. So they have to match.

So with near stock heads like these you cannot go too wild. The rear gears you have would suit a milder cam too.

However with a mild cam your cylinder pressure is going to be high with those pistons you are thinking of fitting.

So on balance I would say a cam like Hughes HEH 2832 AL with 0.524/0.540 valve lift and 228/232 duration as it will give you that idle sound you want. Check with them as you might need to cut the valve guides shorter with that much lift.

Use roller tip adjustable rockers, a good exhaust system and fit 3.91:1 rear gears. It will run and sound strong.

It would be MUCH better with a pair of edelbrock heads though. Just bolt them on and they will work well with this cam and those pistons you bought.

by **Brant** » 16 Jul 2004 17:54

Hi Dave.

Thanks for the great advice dave.
Will this cam/stock head/combo be alright for some highway? If you were me, would you invest the money into building this 340 (new heads, boring block, new roller rockers, and gears) or would you build a 440 while driving the 340? Just a question. It seems people want $400-800 for X/J heads. I think I can find a 440 carb to pan for $500-700. Then just do everything to the 440 as I would the 340. hot tank, magnaflux, bore, cam ect.

I'm told it costs roughly the same to build a 440 as a 340? Then I could sell the 340 after or keep it. I ask because I know you have a 440. I can't imagen what that would be like. My chev friend went in a 440 six pack chally with a real low gear ratio. He said he was honestly scared. He said it was unbelievable. The torque was close to 495 he stated.

Just talk'n.

by **dave-r** » 16 Jul 2004 19:27

If I were you?

I would not bother with a 440 at all.
The only reason I have a 440 is that I wanted a real 440 Challenger R/T because of what it represents.

If I had bought a Challenger with any other engine i would build either a stroked 340/360 (for street use, great handling and loads of power) or a stroked 400 b-block (just to go as fast as possible at the drags while still being streetable).

The 340 is a kick-ass engine. No need to stroke it at all really. It is possible to make just as much power with one of these as you could with a 440. It would cost more to get the same power levels though.

I personally would use a 4-inch stroke crank in the 340 to give 416 cubic inches of light weight fun. You can get a streetable 500hp from a small block like this.

If I wanted all-out power I would fit a 440 crank in a 400 (cheap way for getting 451 inches) or I would go for any of the 3.9, 4.15 or 4.25 inch stoker cranks to give anything up to 500 inches. A 500 inch big block will make 600 easy streetable HP. More if you wanted. That is enough to make the car very dangerous to drive in anything other than very good weather conditions.

But you give me the impression you are more interested in looks, sound, showing off etc than you are in actually going so fast you foul your trousers.

So put a lumpy cam in the 340. Fit a 3-inch exhaust system. Have fun. That way you will have money left over for dirty women and beer. :wink:

by **insuranceguy** » 16 Jul 2004 20:40

I second Dave's opinion! With the savings you could get Dave to give you a ride through the suburbs... According to a previous Video clip, that would be quite the trouser filler :shock:

by **Brant** » 19 Jul 2004 23:35

Really appreciate the feedback guy's - thanks. Your right about the show but really I need something to keep me busy this winter, so I thought I'd through $1500 at the engine. (it's the learning process I'm after)

I read about stroking the 340 with the 4'' crank about a month ago. Also, the fella that will help with the work on my engine suggested I do the bottom end. I'm going to look in to this more, as I'm assuming gas would be rediculious with a stroked engine.

Hey, dave - how 'bout that ride in the suburbs :shock:

by **insuranceguy** » 20 Jul 2004 22:06

I get 10mpg with a stroked 360. That's after I tuned the carb :roll:

by **Kevin** » 18 Oct 2004 21:09

I just wanted to bring this thread back up to the top, as I am curious what you have decided. Dave has some great points.

Opinions, well everyone has one, and here's mine

. I would stick with the 340. Wonderful engine, revs like there's no tomorrow, and even with the stock displacement you can build a very streetable 400+hp and 400ft/lb. There are SOOOOO many factors to consider when building an engine, that it's nearly impossible to cover all of them here. I would start by prepping the block (hot tank or magnaflux, deburr, bore, hone, align-bore, chamfer, and deck). Run a tap through all threaded holes, check all water passages and oil passages for blockage, then clean, clean, clean, and re-clean! Don't forget to blow out all nooks and crannies with an air hose.

I would rework the old crank (magnaflux, chamfer, polish, and balance) if it magnaflux's ok. Scat 4340 forged crank, if your old one is bad. New rods (I like the Scat 4340 forged for the price, Manley 4340 if your wallet is fat this month), and forged flattops (Ross or SRP...TRW's are unnecessarily heavy IMHO). Speed-Pro moly rings, Clevite 77 bearings, and Fel-Pro gaskets. If money permits, Edelbrock's RPM heads are great. The 63cc chamber with the SRP flattops yield a static comp. of approx. 10.1-1. Edelbrock RPM intake, Edelbrock 750 carb (#1407), MPP elec. conversion, 1-3/4" headers (TTI's fit the best, but $$), new timing set, new oil pump and pickup (braze the pickup to the pump), new fuel and water pumps, and good open element air cleaner.

Cam? It's the biggest choice you'll make. The cam needs to match well with rear gears, torque convertor (if it's an auto.), and intake. I would go with a good all-around 3.55 gear, with a 2200 stall convertor, and a CompCam Magnum 270H or XE274H. The main difference in these two cams, as I see it, is the XE's have a broader RPM range (good), but also a quicker ramp up (bad, as they could wear out more quickly). An Edelbrock RPM cam would be a good match with the rest of the components, but I think they're a little heavy on duration for my taste. Good if you like that "rumpty-rump" sound for the car shows. Don't forget to degree the cam once it's installed.

Whew! Ok, I'm done now! :shock:

That should be enough to keep you working those overtime hours through the winter!

Kevin

by **dave-r** » 19 Oct 2004 7:43

Yeah but I would feel like a wimp with only 400hp. :wink:

by **Kevin** » 19 Oct 2004 19:35

Sounds like a little confidence problem, Dave! :wink:

In all seriousness, a 416 storker kit and a bump in cam (say, to a CompCams XE284) would bring those numbers closer to 500 each. Am I beginning to gain your respect back now?

Kevin

by **dave-r** » 20 Oct 2004 7:54

I wouldn't get out of bed for less than 500hp.

by **72 Challenger (Hans)** » 20 Oct 2004 17:09

Oh, we're gonna talk like that guys... Hmmm, no I can resist it and won't say anything. Not before I hear mine running!! :lol:

by **Brant** » 24 Oct 2004 19:48

Kevin, Thanks for your advice. I feel bad for not being able to answer many of the postings - In time!
I am starting to decide what my game plan is now. It's important to note that most of my choices consider price - probably more than the next guy. I'm mostly doing this to learn.

So far this is what's happening. Car will be driven 90% on street, and will see the high way once a month. These are the parts I have.

virgin 340 block
(20 over) cast 10.3:1 flat top Badger pistons - floating
2.02 J heads (3 angle to be done, minor port and polish, gasket match)
orig forged crank -
3:23, 8 3/4 suregrip
4 speed
stock dual plain
340 rods

Is this compression to high & will a .040 head gasket lower this any?
Should I get gaskets that have a steel ring built in?
What does ‘braze the pickup to the pump’ mean?
I thought quick ramps up were good, and that's what I should want for my mopar?
Dave mentioned a Hughes cam with 0.524/0.540 lift. Will my heads flow this?
I'm also open to switching gears but not right away. Seams like a lot of money.

Anything you write, I print out - compare to other combos - it's the only way I can learn this stuff.

Oh, and to me - 400 hp is plenty. could I get my torque up close to this too? could I drive this around every other day?

Thanks

by **Kevin** » 25 Oct 2004 18:06

Brant, sounds like you're on somewhat of a budget. Not that that is bad, just one factor that needs to be considered. Again, opinions are "a dime a dozen", but you can certainly use the block, crank, rods, and heads you have...given they magnaflux ok. How about prepping these components as described above (installing ARP bolts in those rods). The only major questions to be answered then are the pistons (to acquire a "liveable" CR for today's gas) and the cam.

The cam is a little easier, now that we know some of the other components and how you intend to drive. Here is a link to CompCams: http://www.compcams.com/Technical/Curre ... /32-43.asp. There are other good manufacturers (Crane, Racer Brown, Isky), but I have always received good service from Comp. Their sight even has a "recommendation form" you can complete and fax to them for their recommendation. If you're keeping the stock intake (which I wouldn't, as an Edelbrock aluminum dual plane is inexpensive, flows better, and saves weight), you may want to use a retro. 340/275hp cam (CompCams #268AH10). With an Edelbrock RPM intake, the CompCams #270H or #XE268H are still probably the max. you will want to go, considering the 3.23 gears. Btw, there's nothing wrong with faster ramp up cams (e.g. the XE series), IMO. I haven't had any problems with them, but some people claim the lobes wear out more quickly.

The pistons? I know nothing about Badger pistons. We would need to know the manufacturer's recommendation for deck height, the "J" head's combustion chamber size (probably 68cc, but who knows for sure?), the piston's dome volume, etc., in order to get a true "final" CR. Here is a link that will help you in determining the final CR, once you know all of these factors: http://www.csgnetwork.com/compcalc.html
IMHO, with the stock cast iron heads, you will probably want the "final" CR to be at or under 9.5-1. With aluminum heads, like the Edelbrocks, you should be able to run in the 10.5-1 range, and still run 92 octane with no timing retard (aluminum disipates heat more efficiently).

Don't know if this helped, but hope it did some. Good luck!

by **dave-r** » 26 Oct 2004 12:53

Fast rate of lift lobes are bad for Chevys and Fords but Mopars have no trouble with them and can use much higher rates of lift than other makes. I have been using a Hughes fast lift cam for years in my Challenger with no sign of wear at all after about 15,000 miles?

Put simply the faster the rate of lift the more power you will tend to make over the whole rpm range for the same duration. The duration fixes what rpm your power will be made at so with those gears you don't want too much duration. Or too much compression ratio!

A good way to compare cams made by different people is to look at two with about the same duration. Always go for the cam with more lift for the same duration. It will simply make more power.

by **Kevin** » 26 Oct 2004 15:12

Brant, I agree with Dave 100%. Choose a cam that will match well with the rest of your components. Because you have a manual trans., you have no torque converter (stall) to worry with. I don't think it's your heads that are limiting your cam selection either. I think it's the 3.23's. Hence, I suggested cams that work with gears in the 3.23-3.55 range. If it were me, I wouldn't eat out for a couple of months, take the $ saved and buy a set of 3.91's. These gears, with an Eddy RPM intake and some mild head work, would put you smack-dab in the middle of some good cam options.

Kevin

by **dave-r** » 26 Oct 2004 17:00

And steer well clear of Mopar Performance cams!

Not only are they out-of-date 40 year old efforts but we also had two cars at our EuroNats that lost a cam lobe on MP cams after just a few hundred miles. I saw one of them. It looked completely rounded! :shock:

When we mentioned this to '60s factory team Drag racer Al "The Lawman" Ekstrand (he lives in the UK during the summer) he confirmed that he had heard there were major problems with MP cams lately.

by **Brant** » 27 Oct 2004 18:30

O.K. this is the plan. All to happen over winter.
I'm grabb'n some J's and having them worked over - three angle, hardened seats. I know another guy who sais I can have his extra J's, 2.02, w/hardened seats - ready to bolt on for $400. Sais I don't need to do anything to them. He races – not that that means anything.
I know the gears are limiting my cam selection. Will 3.91's allow some high way, what would the revs be like at 60 m/h? I know people who have 4.11's in there bow ties and they rev way high. I'm not against changing the gears, I just don't want to make a mistake. Is there any point in changing to 3.55's?

Sorry, with all the questions - I want to get my engine on paper in front of me, so I can start gathering parts. Your first hand experience and advice helps tremendously. Thanks

by **dave-r** » 27 Oct 2004 19:13

Have you got Microsoft Excel on your computer?

Play around with this and you will see what mph vs rpms you can expect for any tyre or gear combination.

http://www.challenger440.pwp.blueyonder ... Dchart.xls

by **dave-r** » 27 Oct 2004 19:22

I should add that the lower the rear gear the more torque you have at the wheels.

Example. If you had a top speed of 180mph and 300lbs/ft of torque at the rear wheels with 2.5:1 rear gears.

Changing to 5.0:1 gears (double the number of teeth on the gear) you will half your top speed (now 90mph) but double the amount of torque at the rear wheels (600lbs/ft) so the car will launch twice as hard.

You should aim to pick a gear to match your cam power band though.

by **aarcuda** » 28 Oct 2004 5:57

I have a 340 motor and i am hopeing to find out what the numbers mean on it. FW340P29290019. The heads on the motor are X heads #3531894d Anyone has any info at all that would be great.

by **dave-r** » 28 Oct 2004 8:19

F = 1970.
W = Windsor, Ontario production plant.
340 = Displacement.
P = Premium fuel.
2929 = Date code (10,000 day calender)
0019 = 19th engine built that day.

A "10,000-day calender" is comprised of that many days, giving each day a unique number. As a point of reference, January 1st, 1967 was the 1,983rd day on Chrysler's 10,000-day calender. With a calculator and a calender you should be able to convert your code to a standard date. Don't forget leap years ('64, '68, '72).

Heads. Your head number will be 2531894. I don't have any reference material to hand on these at the moment but they have 63.3cc chambers.

It was rated at 275hp if it was a Carter AVS carb on manifold #3462848.

10.5:1 compression ratio.

by **aarcuda** » 28 Oct 2004 12:10

thanks dave.
thank you for the info.

by **Brant** » 28 Oct 2004 13:39

Dave - you rule! that's so useful! also thanks agian for the advice. I'm going to start pricing things now. Thanks and cheers

by **dave-r** » 28 Oct 2004 21:07

I don't have much info on small block heads (me being a big block person :wink:

) and the little I have is conflicting.

Some info I have says all 1968-71 340s had 2.02 intakes and 1.6 exhausts.

Other info I have says the 2531894 1968-1971 heads have 1.78/1.50 valves.

I don't know which is correct. Sorry!

Ask me one about big blocks!

by **aarcuda** » 29 Oct 2004 3:21

The LA engine has used three different intake valve sizes and two exhaurst valve sizes. The 273 and 318 have a 1.50 diameter exhaust valve while the 340 and 360 use a 1.60 exhaust valve (PN 2863521). Tthe 273 and 318 use a 1.78 diameter intake valve and the 340 ('72-73) and the 360 have a 1.88 intake valve (PN 3418688) as standard. The early 340 ('68-71) used a 2.02 intake valve (PN 2863520).

I hope this may be some help.

Darryl.

by **dave-r** » 29 Oct 2004 7:33

That is what one of my references says. Good. Now I know which one is correct. Ta. :wink:

by **aarcuda** » 29 Oct 2004 8:19

I found that in a old book from direct connection called 273 318 340 360 racing manual.

Darryl.

by **Brant** » 01 Mar 2005 1:34

Just to conclude my opening of this thread, this is what I decided on. So much for my initial $1500 dollar project. Next time I'll know better. Oh well. Car will be driven street and will encounter many long distance weekend cruisen (cottage, beach)

FRESH
340, bored/honed 30 over, decked, line bored,
stock crank, deburred, checked, balanced, clevite bearings
stock rods, ARP rod bolts, balanced
forged pistons flat top, two valve relief, full floating, (TRW? I think)
moly rings,

SOON
x-heads, mild porting, gasket match, decked 20 thous ( to reach 10.2:1 compression – will cc heads)

Edelbrock Air gap intake
Holley Double pump 750
4 speed
3:23 gear ratio

Mopar electronic Ignition ?
Is this too much carb, would 700 be better?

Camshaft
this weekend I'm going to run some cams through a dyno to see where I'm at. Most the machining has been completed to my bottom end, now need to start designing this baby. The guy who's helping me has already chosen a cam for me, but I'm going to look at a few others as previously suggested – thanks guys – Dave, kevin and Insuranceguy

Anyways, Does anyone have a cam card for the Direct Connection Purple shaft 280/280 advertised, 238 @ .50, .475/.475 lift cam. I'm having a hell of a time finding the specs on when the intake and exhaust open and close. I need this for the dyno my friend has. This info will provide a more accurate look on the dyno for my friend and I.

I've called Summit and a few other places - no one can help.

Thanks for letting me ramble. I figure this combo has been done a billion times before - someone might have the specs.