YAC (Yet another combo) question

[ab7fh]

Ok, I'm starting from scratch and my goal is to run low to mid 10s in a stripped out Dart.

I have 2 bare 400 blocks. I plan on choosing the best looking block and stuffing it with a 512 440Source kit.

I've already bought a set of Stealth Heads and will port them to meet the requirements of the motor.

What I would like is suggestions on compression ratio, cam specs, oiling system recommendations, and main cap/girdle recommendations.

Regarding the main caps why is aluminum used in a place where high strength is far more important than light weight? Don't aluminum caps fatigue like aluminum rods do?

Oh yeah... this motor will only see track time, no street use, so racing fuel will be used 100% of the time.

I have already chosen Caltrac monoleafs, bars and a Mopar relocation kit for my rear suspension setup. I've just completed the mini-tub as well.

Transmission will be a 727 with manual valve body and race converter. I'm still up in the air as to which rear axle to run. Right now all I have is an 8/34 housing with no center, so I may end up with a D60.

I'm not sure what kind of RPMs the 512 will need to make to get the results I'm after. Any help with that would be greatly appreciated as well since I need that to choose gear ratio, cam profile etc.

Thanks in advance for your help!

[73swinger]

I think aluminum main caps are used because they act sort of like a shock absorber in a nitrous motor. The hammering of detonation (which I believe all N20 motors do to some extent) is absorbed by the more flexible aluminum in stead of cracking your steel caps

[bOb shingler]

14-1 comp ratio, have the valves back cut, .700" + or - lift roller cam @290* + or - at .050", the same girdle as steve detar uses, aluminum rods, lite pistons and the .990" tapered lite pins, 4.30-4.56 gear, if your gone to use the 8 3/4" use the aluminum center, 29"-31"x10.5" slicks, milodon duel swinging pick-up with a mancine 12quart supperstaock pan, 1150 dominator on a single plane intake, 9 1/2"-8" convertor. with the compression up that high you also have the choice of using alcohol for fuel but the carb will have to be set up for it or better yet use mechanical stack (which has the wow factor) or hat injuetion.

[68_Val_Sedan]

12 to 1 comp with a 650 to 690 lift roller will more than get you there especially in a stripped out car ... 4.30 gear wit ha 30 inch tire would be max gear with that much torque in a light car ... any girdle will work no alluminum caps ... no aluminum rods ... and a 9.5 inch converter

[ab7fh]

Thanks for the info. I was thinking closer to the second setup than the first as far as comp, cam specs and rods. I don't want a mid 9sec car that I have to slow down to run in the 10s;) If I do that then I'll end up having to get a certified chassis, etc.

What kind of RPMs would I be turning at the top end with a 30" tire 4:30s?

[bOb shingler]

6000 @ 124

[68_Val_Sedan]

6000 @ 124

 

I used to turn about 6100 rpms on a 10.20 / 126 mph  automatic car with the above mention setup.   the car weighed 3800 with me in, it had a set off edelbrock heads opened up to MW ports with a factory stage III intake and (2) 750 edelbrock carbs no scoop, 2" headers and full 3" exhaust ...

[ab7fh]

I'm getting a bit ahead of myself, but I was wondering if there are any mufflers that bolt directly to header collectors? I don't think the neighbors would like me after breaking in the motor without mufflers:D

[ksdartguy]

There are header mufflers. I would go Dana on the rear, for
reliability. Cost is about a wash to build something you wont break.
Rick

[bOb shingler]

14-1 comp ratio, have the valves back cut, .700" + or - lift roller cam @290* + or - at .050", the same girdle as steve detar uses, aluminum rods, lite pistons and the .990" tapered lite pins, 4.30-4.56 gear, if your gone to use the 8 3/4" use the aluminum center, 29"-31"x10.5" slicks, milodon duel swinging pick-up with a mancine 12quart supperstaock pan, 1150 dominator on a single plane intake, 9 1/2"-8" convertor. with the compression up that high you also have the choice of using alcohol for fuel but the carb will have to be set up for it or better yet use mechanical stack (which has the wow factor) or hat injuetion.

12 to 1 comp with a 650 to 690 lift roller will more than get you there especially in a stripped out car ... 4.30 gear wit ha 30 inch tire would be max gear with that much torque in a light car ... any girdle will work no alluminum caps ... no aluminum rods ... and a 9.5 inch converter

both motors will cost the just about the same.

[ab7fh]

I just received my bottom end parts today. I bought a 440Source kit with I-Beam rods, 7/16 ARP bolts, and 14:1 compression with their Stealth heads. Now I need to choose an oiling system, and cam.

[bOb shingler]

milodon external dual line swinging pick-up.

[Womanator]

They have mufflers that go right into the collector,they look like spark arresters.

[ab7fh]

Whose aluminum main caps would you recommend? Mancini Racing?

[wild383]

The BCR cap&girdle set-up is super strong. Willie  http://www.bcrproducts.com/

[chryco]

I'm getting a bit ahead of myself, but I was wondering if there are any mufflers that bolt directly to header collectors? I don't think the neighbors would like me after breaking in the motor without mufflers:D

Naw ! They`ll love it !

[dusterdarryl]

I just received my bottom end parts today. I bought a 440Source kit with I-Beam rods, 7/16 ARP bolts, and 14:1 compression with their Stealth heads. Now I need to choose an oiling system, and cam.

14 to 1 with stealth heads what a waste, it would be like trying to sprint down the street with a sock in your mouth, you want 440-1s and that will then make for serious power

[fasttcars]

considering the stealth heads stall at about 600 lift  no need to run   much more then that....duration at 0.050  should be around  270  int  278  exhaust...a good cam   would be   crane   cam  part#  688811.....which is   268 at  0.050 int...278 at 0.050 exhaust...with  0.630   lift  int and exhaust  with a 108   lsa......i would   also fill those   stealth heads   with a 2.25 intake  valve  to fatten them up  along with  the appropriate  porting  {carefull short turn work  to wake up the top end numbers will be critical}....  the engine   will make peak  power at about   6200 rpm   so   a  milidon  single line   external sysyem is all that's needed   go  with  the milodon part #  21110....or if using a motor  plate  part#  21100........of the header   you'll want to run at least   a 16 inch  extention  before any muffler is placed.....

[fasttcars]

I have 2 bare 400 blocks. I plan on choosing the best looking block and stuffing it with a 512 440Source kit.

i wouldn't choose the prettiest  block  but the one  with the thickest and most consistent  cylinder walls

[ab7fh]

14 to 1 with stealth heads what a waste, it would be like trying to sprint down the street with a sock in your mouth, you want 440-1s and that will then make for serious power

I planned on porting them, I'm not going to use them out of the box...

[ab7fh]

the engine   will make peak  power at about   6200 rpm   so   a  milidon  single line   external sysyem is all that's needed   go  with  the milodon using a motor  plate  part#  21100...

Do you recommend the Milodon rear sump pan with that setup for use in an '70 A body with motor plate and stock k member?

[fasttcars]

it won't be a rear sump pan  it's considered a center sump.....with the external line  you won't be able to use the low  profile pan because of how the sides are angled...but   milidon pan part# 31015{with a hole provision allready for the pickup}...will  work   you might  have  to do  just a quick  grind  to the k member at the very front corners of the pan

[dusterdarryl]

with 14 to 1 you will be best to look at the big port window of EZs, and or  -1s and realy see some power come home with those cubes, with 500+ odd cubes stealths or eddys are going choke it

[fasttcars]

with 14 to 1 you will be best to look at the big port window of EZs, and or  -1s and realy see some power come home with those cubes, with 500+ odd cubes stealths or eddys are going choke it

true  if he's  looking to make  750hp plus....but  with  proper  work  to those stealths   he will  have the potential  to knock  on 700 hps  door   but   with a real fat curve and low  shift points....i've made over 700 hp  with   a worked set of rpms  before  and  since the stealths  aren't any  different he should able to get  to his  goal  of low   tens  very   easily...

[dusterdarryl]

ok then with those cubes he should be able to back it off to 11.5

[fasttcars]

oh  ya  really  only  about  11.5:1   is  all that's   gona be needed  to make the required power to run the #..it's  gona  be  hard to actually keep it out of the nines ....and  a lot of attention  with every aspect ..........

ab7fh  do your  pistons  have a +14cc  dome on them?

[ab7fh]

There's a method to my madness... I hope;)

I'm shooting for a low to mid ten second car to start with. I don't want to overshoot my goal, but I want to build a bottom end that will support more cam, heads etc to eventually run faster. It's not going to be fed anything but racing fuel, so I figured why not run all the compression I can, with a comparatively mild top end to "slow it down".

Honestly I'm not certain of the size of the dome, but it's definitely quite large and not just a raised "flat" section.

I've been out of the sport for 20 years. 10s will be plenty fast to start with. The car is just going to be for fun more than anything else. A little bracket racing a couple times a month at the most is all it's going to see.

[ab7fh]

I just checked my invoice. Yes it's a 14cc dome.

[dusterdarryl]

14cc domes!  what size chambers?  84cc on the stealths arint they? I thint you may be over 12.5 to 1 already

[ab7fh]

Yes the Stealth's chambers are 84cc.

[dusterdarryl]

fastcars is right, your going to have trouble keeping out of the nines, should be good fun, whats the pistons part # you have? sounds like a weapon

[ab7fh]

440Source part # 7000 "Platinum Series Pistons 4.375 +14 Domed"

[ab7fh]

A couple more questions... What would you recommend for a cam gear drive, and a harmonic balancer?? There's so many choices