My 340 build

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MoparMark91

MoparMark91

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Hey guys so i know you guys have been seeing my post's on my build and concerns in various places so i thought i would make my own thread so im not interfering with other post's. I will post pictures along with photos as i go for progression. I will edit and add details as i get more time.

So here are the specs

1973 340 block
Bored 30 over
Scat crank 3.58 stroke

Edelbrock closed chamber heads
XE268H comp cam hyd flat tappet
Air gap intake
Holley 650 vac secondarys
Headers-undecided
Distributor-undecided
Scat rotating assembly
Icon pistons
Total seal rings
Scat i beam rods
Arp main studs
Arp head studs
Trickflow balancer
 
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Progress so far

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My questiom is when im rotating the crankshaft with a breaker bar, 1st time it was really tough then as i moved it more it went easier. How tough should it be to spin it when all pistons and rods are in? I know my clearances on majority mains are .0015 but was told its good to run it in my past posts
 
Building essentially a 360 in a 340 block, 372ish cubes. Should be good for 375hp and close to 400+ish if the heads are touched up lightly.

What is the anticipated compression with those pistons and Ede heads? Have to be careful with the pump swill in CA. Probably close to 10.5:1 which may not be a good level with your cam choice.

Nice OSHA approved footwear.
 
crackedback said:
Building essentially a 360 in a 340 block, 372ish cubes. Should be good for 375hp and close to 400+ish if the heads are touched up lightly.

What is the anticipated compression with those pistons and Ede heads? Have to be careful with the pump swill in CA. Probably close to 10.5:1 which may not be a good level with your cam choice.

Nice OSHA approved footwear.
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Lol that would be my dad with the approved OSHA footwear lol. And it should be 10.5 to 1, or 10 to 1. Is it normal for when rotating crankshaft it takes some force? Just wondering? 4.07 bore ring end gap is .018-.020 i believe
 
Gap is about .018 with those for a hot street/ race set up. I think they recommend .004 factor per bore inch. You have .0045. If it's done there, don't sweat it.

Detonation is going to be something to watch out for. Cylinder pressure is going to be high with that camshaft. I would NOT install it advanced. I like that cam with 9.5 max static compression.
 
crackedback said:
Gap is about .018 with those for a hot street/ race set up. I think they recommend .004 factor per bore inch. You have .0045. If it's done there, don't sweat it.

Detonation is going to be something to watch out for. Cylinder pressure is going to be high with that camshaft. I would NOT install it advanced. I like that cam with 9.5 max static compression.
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Even though i already got this camshaft, what would be your recomended cam?
 
Call a custom grinder like bullet...give them specs and goals for the car.I ran an xe 268 in warm 340 and it needed a converter with more than stock stall regardless of what comp say.In all fairness i was running 3.23 gears and a 27" tire but it was lazy at lo rpm until i installed a dynamic 9 1/2 converter.
From mid range up the power seemed limitless!
 
There is a rotating torque spec with torque wrench on balancer bolt. Sorry I cant remember, but its light I think like 25 lb/ft ? I could be wrong tho.
 
So maybe i should nit run the xe268h and just bite the bullet and buy the voodoo
Hmm? Any opinions or input guys buttoning it up Wednesday
 
You will have to go bigger on the cam to keep the cylinder pressure down. I think the biggest voodoo 05 hyd if that's what you want to run or something in the 285+ advertised area.

The tune is going to need to be REALLY good regardless what you do.
 
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crackedback said:
You will have to go bigger on the cam to keep the cylinder pressure down. I think the biggest voodoo 05 hyd if that's what you want to run or something in the 285+ advertised area.

The tune is going to need to be REALLY good regardless what you do.
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So what would be the cam you would recommend from lunati
 
RustyRatRod said:
He told you. The 05. One step bigger than what I said. lol
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Hmmm okay i didnt realize, any other recommendations off shelf lunati or comp as im hoping to button the whole bottom end and front end on Wednesday

Says that lunati wouldnt ship till later in month :(
 
MoparMark91 said:
Hmmm okay i didnt realize, any other recommendations off shelf lunati or comp as im hoping to button the whole bottom end and front end on Wednesday

Says that lunati wouldnt ship till later in month :(
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What about the 04? I think either would do the job.
 
ir3333 said:
Call a custom grinder like bullet...give them specs and goals for the car.I ran an xe 268 in warm 340 and it needed a converter with more than stock stall regardless of what comp say.In all fairness i was running 3.23 gears and a 27" tire but it was lazy at lo rpm until i installed a dynamic 9 1/2 converter.
From mid range up the power seemed limitless!
Click to expand...
What stall rpm did you go with?
 
Don't forget my engine was a 340 with a tall tire and 3.23 gear...the extra cubes in a 372 with a taller gear may be a good fit for the xe268
 
The thumpr goes in at 102 IIRC. That will defeat any reduction of dynamic. Isn't the thumpr more deigned to help low compression engines, same as winding a 284/484 way ahead of the XE268H? It does have more duration but it also 4* ahead. Maybe installing it at 107 might be OK.

If anything I think this has to go the other wider LSA and install closer to straight up. You want the intake closing late here.
 
crackedback said:
The thumpr goes in at 102 IIRC. That will defeat any reduction of dynamic. Isn't the thumpr more deigned to help low compression engines, same as winding a 284/484 way ahead of the XE268H? It does have more duration but it also 4* ahead. Maybe installing it at 107 might be OK.

If anything I think this has to go the other wider LSA and install closer to straight up. You want the intake closing late here.
Click to expand...

I don't know. I've not seen where Comp advertises them for low compression......they're similar to the Whiplash cams and they do advertise for low compression, so you're probably right.
 
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