i want to build a 421.does anyone know what stroke i will need and what kind of pistons? i know this is'nt a high rpm motor but i should have torque out the ass should'nt i?any in put would be welcomed and thanks.

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Yes.U should have torq out the ass.Depending on cam choice.Be more specific of what combo you have in mind,and what parts you intend to use.

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DVC-98.Racing
482 cubes of fogger injected thunder in a 71 z.
racing@mbox303.swipnet.se (http://racing@mbox303.swipnet.se)

well racing,right now i have a 408 in a '72 camaro with a turbo 350 trans..the mighty mouse sports a set of dart heads with 2.02 & 1.60 valves,total roller setup(lunati cam (.555 ) & lifters with crane roller rockers).on top sets a 750 holley double pumper above a edelbrock performer intake and all of that is backed up with a 2800 stall with power being planted thru a 4:11 posi. unit.sounds like i should be happy with what i have,huh?i pretty much want to stay with the basics. all i want to change is the cam(lift).i'm not going to tear this block down,i have a 4 bolt main that i'm going to attempt to bring to life.i know that the block is going to be bored .40 over and that my stroke is going to be 3.875 with 6" rods.the lift i want to use is .600 or.640.i might even up the size of the carb.so what do you think of my little monster?i know that there's no replacement for displacement but i'm a mouse man.looking forward to your reply....soon.thanks,duzzit.

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I´ve run as much as 4" of stroke in the mouse,with good results.Come to think of it the mouse is happy as long as you have a positive r ratio between bore and stroke.

You don´t mention what Dart heads you´re running.?
The motor will be head limited anyways,if you haven´t had a good porter look at them,so that´s what you need to adress.

421cid consumes a LOT of air bro,so i think you should get another cam spec too.At least if you want to make them cid´s do any good.

Mechanical roller is the way to go,and i´d shoot for something like 260/270@05 and just over 600 lift.

Don´t forget to look at the intake manifold while you´re in contact with your porter.Either a Victor jr or a team G in my book.Forget about the performer if you want that motor to breathe!
I´d say you need a "built" 4150 series carb or a dominator to keep that puppy happy.I think i´d opt for the built 4150(Need flow around 1000 cfm minimum)
Hedder primary would have to be 2".

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DVC-98.Racing
482 cubes of fogger injected thunder in a 71 z.
racing@mbox303.swipnet.se (http://racing@mbox303.swipnet.se)

thanks for the input.i built the 408 and had stock heads with a little work done to them.i sold the car and the guy i sold it to went right out and starting racing and had great sucess with it.i guess he wanted more power so he bought the dart heads and put them on.i really don't know which heads(dart) he got,so i how can i tell?he fell on hard times and i got a chance to get the car back,so i did(bought it back 500.00 cheaper than i sold it.i know they are dart heads because my mechanic did all the work on the car for the other guy).i thought the victor jr and team g were high rpm intakes but i guess just because they are built for hi r's don't mean you have to push it that hard,huh?the cam i thought about using has a duration of 258/268 and a gross lift of 600/618,what do you think?the victor jr would be my choice of intakes and as far as the carb, the 4150 sounds great.the performer works good on the 408 but do you think the victor jr would be better(i have a new torker still in the box).i made a mistake on what the block would be bored,it's 30 over instead of 40 but i guess you caught that.i don't mind spending the money to build this motor,i just don't want to have to do it twice due to a screw up or something.i'm still in the dark on what pistons i should use,any thoughts?the car runs damn good now but there are still some people who still have doubts about it and i'm going to sneak the 421 in on them to put a stop to the rumors once and for all.also thinking of trying a set of afterburner headers.look to hear from you soon,thanks duzzit!!!!!!!!!!!!!

The victor type manifolds are made for higher rpms for a 355 style engine.Put things in a perspective here.You´ve added a LOT of cid:s,and it´s safe to say that "eats" a lot of air that neither the manifold or heads are made for.
To get the REAL performance benefits from that motor,you need to get in contact with a good headporter.He´ll take care of your manifold too.
I´d guess you´d end up with intake port volumes around the 280-300 mark to get any real perfomance... http://www.camaros.net/forum/wink.gifThat´s a liiiiiiittle more then any stock Dart casting will deliver.Actually it´s a LOT more http://www.camaros.net/forum/smile.gif

Remember to keep the revs down on that mouse.With a stroke as long as the one you´re thinking of i´d safe line it a 6500.Might even be conservative and say 6200.
You´ll make power enough anyways....he he.

With the heads you´re running you wont be able to run anything but flattop pistons.Might have to use dished even.Ill get back to you on that.You wouldn´t happen to know if the heads are 64 or 76 cc?
As for piston brand,well..I prefer wisecos.Can´t really reason why.Just the way things have settled for me i guess.

Understand that the 750cfm carb you´re thinking of will basically strangle that motor.You need to think BIG here.

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DVC-98.Racing
482 cubes of fogger injected thunder in a 71 z.
racing@mbox303.swipnet.se (http://racing@mbox303.swipnet.se)

first i want to say thanks for all the info.i've got a good porter in mind so that shouldn't be too big of a problem.i still need or should i say want to know what kind of heads i have.what is the best way to find out?victor jr and 4150(1000+) are a must.i visited your home page last night.nice ass car.you need to to give up the front end secrets to a fellow 2nd generation owner.again thanks for all the info and if you find out how i can tell what type of darts i have, drop me a line at duzzit@ftc-i.net or post it here so others will know for future projects.duzzit!!!!!!!!!!!!!!!!