a good combo?

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jakemary

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im building a 340 .030 over 10.5 :1 magnum 360 heads airgap intank 700cfm carb a voodoo 226/234 .494 / 513" 1800 rpm to 6200rpm
headers i dont have yet
it is going into my 1970 340 duster 3speed
 
jakemary said:
im building a 340 .030 over 10.5 :1 magnum 360 heads airgap intank 700cfm carb a voodoo 226/234 .494 / 513" 1800 rpm to 6200rpm
headers i dont have yet
it is going into my 1970 340 duster 3speed
Click to expand...

Is the lift on that cam the advertised lift with 1.5:1 rockers, or 1.6:1? If that's the lift with 1.5, then that will put it at .547 on the exhaust side with 1.6 rockers, which is pushing it for stock magnum heads.
 
jakemary said:
im building a 340 .030 over 10.5 :1 magnum 360 heads airgap intank 700cfm carb a voodoo 226/234 .494 / 513" 1800 rpm to 6200rpm
headers i dont have yet
it is going into my 1970 340 duster 3speed
Click to expand...

what converter/ rear end
 
64physhy said:
Is the lift on that cam the advertised lift with 1.5:1 rockers, or 1.6:1? If that's the lift with 1.5, then that will put it at .547 on the exhaust side, which is pushing it for stock magnum heads.
Click to expand...

Good point, you may be exceeding the max lift of the stock valve train - I calculated a maximum of .520 lift on my magnum heads allowing .050 before coil bind

Better check it out
 
I am running almost .500" of lift on my stock magnums and springs look pretty tight to me.
 
Badart said:
I am running almost .500" of lift on my stock magnums and springs look pretty tight to me.
Click to expand...

There are so many different spring choices out there, everything from rates to material to number of coils - there will be lots of variation in the heads too which will affect individual builds differently

Which springs are you running badart, what is the installed height and coil bind height?
 
octanejunkie said:
There are so many different spring choices out there, everything from rates to material to number of coils - there will be lots of variation in the heads too which will affect individual builds differently

Which springs are you running badart, what is the installed height and coil bind height?
Click to expand...

I am running the GM 3100 bee hive springs and retainers. There are a few threads about them over at Moparts. They are good for a moderate cam and around .500" lift. I can't recall the installed height off of the top of my head. It was a cheaper alternative to the MP stuff. I am only into them $115 for everything and I just picked them up from the dealer. So far so good with no issues. I am also running 1.6 ratio chevy roller rockers.

Here is a pic.

Rockers.jpg
 
right now im getting the heads checked out for cracks. so the springs I'll have to look at and rockers not sure yet. the car would be driven on sunny fridays droping the kids off and picking up at school and to the north st.paul car show that are held every friday. but I do what to take it to the strip.
and it is a stick car. gears not sure. thanks for the input. the car has been on the back burner for 11 years now.
 
Then I'd say, as long as the gear ratio isn't a 2.76 Hwy. gear, it'll be OK. 3.23 and a stock tire, 3.55's and a slight oversized tire at best, 3.90 and up would need a bigger tire. (Ops, AKA, taller.)
 
Sounds to me like it should work good as long as you have half way decent gears in it (3:23 or lower). The J heads will be lower compression but with open chambers you'll need it. I'm running a 360 with X heads and the next step up Lunati (234/242 @ .050) and compression figured in at 9.85 to 1. It won't take any more than 35 degrees of total timing without spark knock running 93 octane so I run it at 34 total to be safe. You should be about that same place with your build cause your compression should be a smidge lower than mine due to the less cubes therefore it should work about the same.
 
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