340 build up

[BC*73Duster*]

I am soon starting to build up my 340 that had to be taken out because of low oil pressure( fuel got into oil via flooded demon carb..
what kind of work would I be looking at to put a bigger then 500 lift camshaft on my 340

MY 340 has 360 magnum heads on it, forged flat tops, forged 68 340 rods, and soon to have a new forged crank being installed during rebuild..






it also has a nos sniper kit good for 50-150hp shots Id like to use.

SO what cam can I use , what mods are needed to heads, and still a street strip machine at heart. Its got manual steering and power brakes...

 

[1973dusterkid]

I am soon starting to build up my 340 that had to be taken out because of low oil pressure( fuel got into oil via flooded demon carb..
what kind of work would I be looking at to put a bigger then 500 lift camshaft on my 340

MY 340 has 360 magnum heads on it, forged flat tops, forged 68 340 rods, and soon to have a new forged crank being installed during rebuild..






it also has a nos sniper kit good for 50-150hp shots Id like to use.

SO what cam can I use , what mods are needed to heads, and still a street strip machine at heart. Its got manual steering and power brakes...

If you running power brakes you have to watch the cam because it wont crate vacuum to run power brakes. Also why over 500 lift (for sound) as much as I love the sound bigger it not always better. and a 500 lift cam is not always going to sound better then a lower lift duration and lsa come into account on that. For example when I swapped from a .484 lift cam to a .506 the .484 had a hole lot meaner idle, but the duration and lsa was different.

 

[BC*73Duster*]

I plan on quarter mile the car, while also driving it around town and to car shows and cruises..

what would I have to modify to run roller cam/lifters with my 360 magnum heads who have 1.6 ratio... it has a 3000 b&m holeshot converter plus 50-150 nitrous when on the quarter mile I might spray it..

so I think I will buck up and goto hydraulic roller setup.. lunati? or comp? or who?

 

[BC*73Duster*]

is there not some sort of vacume booster setup available with electric pump or something?

 

[txstang84]

The lift of a given camshaft isn't the deciding factor for idle quality. You said you have a 340 with 360 magnum heads and forged flat tops? Are they the 68-71 style flat tops that actually stand proud of the deck surface? Gotta make sure you have proper piston to head clearance with those...and Magnum heads are close chambered.

Before anyone can reasonably suggest a cam, you might want to define your hp or ET goals...you won't really need a vacuum booster unless you're swinging a pretty good sized cam or one that's just a poor grind. I was able to run power brakes on my Mustang with a 284/292 Lunati roller grind without any problems and it would pull about 13-15" at idle.

As far as mods to the heads, again, you kinda need to let people know what all you expect. I would venture to say though, if those heads are stock, make sure they have no cracks around the seats...apparently, mag heads are known for that, and nitrous has a tendency to exacerbate problems like that.

Help us out...what's your end game?

 

[txstang84]

...being that you want to spray it, you might want to call one of the engine builders here on the site and maybe discuss a custom grind...

 

[BC*73Duster*]

you can hear car run in my youtube video link in my signature

750 demon,
air gap style intake from mopar performance bolted to 360 magnum heads fully built, non ported

10:5-1 comp with forged flat tops in .40 over 340 block original to the duster..

car ran good, but got fuel in oil and was ran without oil change, hence bearings got chewed,..

It has a mopar performance purple shaft in it, but not sure which one, I would guess by the power and sound of car it was the biggest at 484 lift, but I have researched it is not a very good racing cam, and I want to race, with nitrous..

I will be doing main studs, head studs, possibly splaying caps, what else can I do for it
should I just go stroker?

whats involved with that? ( ie , other expenses)

 

[txstang84]

...what else can I do for it
should I just go stroker?

whats involved with that? ( ie , other expenses)

Boy you just opened Pandora's box here, didn't you?

You're right in that there are better cams available, but with better cams come better springs and making sure the heads are properly configured for the cam you choose (you say fully built, but that's not very explanatory to me).

If you're talking about using splayed caps, can I guess you're wanting to make somewhere north of 500fwhp? Installing new caps is a little expensive the last time I looked...your machinist has to machine in new cap registers with the proper amount of interference, depth, etc, plus line bore/hone work...and of course the cost of the caps themselves.

To go stroker, of course, there's the reciprocating assembly...I think a good one goes for essentially $2k by the time you buy the parts, and have them checked and balanced. I'll recommend you be a little cynical of the kit and have it verified by your machinist. Plus machine work to the block to have it cleaned, and if it needs bored/honed, etc...

 

[SleeperScamp]

I would hate to grenade that original 340.. I would bench that thing and build a 360.. but that's just me...

 

[crackedback]

Splayed Caps?

This isn't a SB chevy. You don't need them! Run stock caps with main studs and you're good to go. The splayed bolts weaken the main webbing in your block = BAD!