Another "what will it make", but a little different

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metallidart

metallidart

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Kids are watching Spongebob, so I am stuck sitting and thinking about my engine. I figured I would bounce some ideas off of you guys.

The engine : 1970 340 block, bored/plate honed, decked for zero deck, line honed, main studs/girdle, JE flattops, Eagle H-beams, Scat 4 " forged crank, balanced, lifter bores bushed, etc. Compression will be about 10.75 or so,comp custom grind solid 275/288 adv, 250/254@. 050, 104ls,. 584/. 568 lift with 1.6 rockers. I bought it barely used with just a little dyno time. I talked to a guy from comp, and he said he couldn't recommend a better cam, especially for lowering my cylinder pressure to help it run on pump gas.
Heads will be a set of 1973 587 heads. I will be doing the port work, but I will have them cut for 2.02/1. 625 valves. I have done a few sets of heads, and always had good results, so I amgoing to try to go all out on these. Also got some good head-porting threads on here to refer to!
Intake is an LD340 that I will port match.

Now my questions.
-would I be better off with 2.05 valves?
-should I just use 1.5 rockers? I will be buying the Hughes rollers.
-what size carb would you guys recommend?

And lastly, what kind of numbers do you guys think?

Car is a 1973 Dart Sport 340, 904 with a 3300 stall (but that was with my mild 360, I am sure it will be higher now), and 3.23 gears, for now.
Any quarter mile guesses?
 
metallidart said:
Kids are watching Spongebob, so I am stuck sitting and thinking about my engine. I figured I would bounce some ideas off of you guys.

The engine : 1970 340 block, bored/plate honed, decked for zero deck, line honed, main studs/girdle, JE flattops, Eagle H-beams, Scat 4 " forged crank, balanced, lifter bores bushed, etc. Compression will be about 10.75 or so,comp custom grind solid 275/288 adv, 250/254@. 050, 104ls,. 584/. 568 lift with 1.6 rockers. I bought it barely used with just a little dyno time. I talked to a guy from comp, and he said he couldn't recommend a better cam, especially for lowering my cylinder pressure to help it run on pump gas.
Heads will be a set of 1973 587 heads. I will be doing the port work, but I will have them cut for 2.02/1. 625 valves. I have done a few sets of heads, and always had good results, so I amgoing to try to go all out on these. Also got some good head-porting threads on here to refer to!
Intake is an LD340 that I will port match.


Now my questions.
-would I be better off with 2.05 valves?
-should I just use 1.5 rockers? I will be buying the Hughes rollers.
-what size carb would you guys recommend?

And lastly, what kind of numbers do you guys think?


Car is a 1973 Dart Sport 340, 904 with a 3300 stall (but that was with my mild 360, I am sure it will be higher now), and 3.23 gears, for now.
Any quarter mile guesses?
Click to expand...

With a flattop piston, you'll need at least 75cc chambers!
 
I think your pump gas ambitions are going to be crushed unless you use aluminum heads and try for about .040 quench.
You could open up the chambers , but that is going backwards sort of.
 
Well crap. Lol. Well, for now, I will try it, it's all I have for now. I would like to get another set of aluminum heads, really like those airwolf heads. I will just open the chambers up, maybe try concentrate on the area around the intakes to unshroud the valve a little along with dropping the compression?

What kind of numbers do you guys think, even if I have to run a little bit of race gas?
 
FelPro 8553 head gasket.......12cc
typical valve notch volume......6cc
587 head nominal volume.......72cc
total TDC volume of..............90cc

90cc TDC volume in a 416 will yield 10.4-10.5
if you can open the heads to 75cc you'll have 10.1
sink the valves a bit, along with deshrouding cuts, and blend the chamber to the valve job/deshrouding work will probably increase the volume by 3-4cc
 
I've taken 7 cc's out of LA open chambers before, but careful where u grind it from, start off by sticking the heads on the bored block and from underneathe/crank side of the bore scribe the overhanging deck of the heads 'the chambers are always smaller in circumference than the bores themselves' . Starting that way and remeasuring will hold off on changing the chamber design/overall shape which will effect flame travel , possibly in a negative way.

When does the intake valve close with that cam?
I think the cam will be a really nice in a street car with that @.050 duration.
 
Cool, that would make me happy! I didn't even think about how opening the chambers up might affect flame travel. My shortblock is already assembled, but I may be able to make a template on top of the block and use that.

For this combo, is the 2.02/1.625 good? Or would 1.6 be good enough?

I had waaay different plans for this engine, but I just bought a house, and remodeling is taking most of my money lol. So, I am using what I got.

The cam timing specs @.050 are:intake open 24, close 46. Exhaust open 54, close 20. Cl is 101.
 
46* close is trapping A LOT of cyl psi.

Make sure you make very accurate placements of the dowel pin locations, otherwise you will have chambers misplaced over the bores...and end up too big on one side or the other.
And leave the chambers just a c hair smaller, like .010-.015 smaller around.

Also know that in your ragged edge compression will benifit from not having the chambers edge massively overhanging in to cyl which will turn into hot spot for preignition.
 
I like what you did, skrews, with smart porting on factory castings that most don't even realize have a lot of potential. Good job.

Here's a pic off my phone of my 915 j heads, I left the guides, just narrowed them a lot and raised the roof quite a bit, 186cc measured. They flow over 270cfm after final touch ups and [email protected], [email protected], [email protected], and 250 by .400 lift! The chambers are 60' cc in this pic.
 

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1wild&crazyguy said:
I like what you did, skrews, with smart porting on factory castings that most don't even realize have a lot of potential. Good job.

Here's a pic off my phone of my 915 j heads, I left the guides, just narrowed them a lot and raised the roof quite a bit, 186cc measured. They flow over 270cfm after final touch ups and [email protected], [email protected], [email protected], and 250 by .400 lift! The chambers are 60' cc in this pic.
Click to expand...

Thanks, yours look sweet too. Not many guys doing max effort port jobs on OE castings anymore. I got more work to do on those. Going to tube the pushrod pinch and add an 86* bowl cut. I think they can peak over 290 cfm. Hope it don't go backwards.:D
 
If it was me I'd run the 2.05/1.60 setup. I'd also look for another cam. By adding 10° of duration at .050 you can be a bit safer without getting funky by sinking valves or enlarging chambers. You'll also get more power out of it.
 
moper said:
If it was me I'd run the 2.05/1.60 setup. I'd also look for another cam. By adding 10° of duration at .050 you can be a bit safer without getting funky by sinking valves or enlarging chambers. You'll also get more power out of it.
Click to expand...

I like this idea also.....and you can definitely use as much head flow as you can get plus you've got the bones to turn some decent rpms for a stroker.

Although known for big torque, with good head flow, going a little bigger with the cam, and at some point, a good single plane, you can make some big HP numbers with that setup.

A good suspension with some bite, can get you deep into the 11s, and with a spot on converter.....maybe the 10's.
 
Thanks everyone for the input so far! Definitely giving me alot of ideas, and new ways to look at my engine.

I did some research on my cam, and the actual numbers for the valve timing, not the @. 050 numbers, are as follows :
Intake open :36.5
Closes 58.5
Exhaust open: 71
Close 37
Overlap is 73.5

Those numbers seem a little more reasonable to me,lol.

The head info and pics help tremendously, I will probably be using what you guys did as a guide!
Still on the fence about the valve size, for some reason I just want to run the bigger valves, but you guys seem to be getting some serious numbers without going bigger.

I was leaning towards an 850 dp, glad to hear that is a good idea too.

Down the road, it might change to a larger roller, aluminum heads, and a single plane. Actually, that's what I had until I sold it all for the down payment on the house. Now I got this weird compulsion to go with a dual plane, stock valve covers and air cleaner, paint it blue, just so it looks like a mild stock engine.

I might have missed some stuff tonight, but I will be rereading this thread often. Been a long day, my oldest son had his 12th birthday party and the kids wore me out!
 
All this stuff is always controversial as all of us have had different experiences. Just take the comments as the're intended, to try and help you out. In the end, you'll figure out what's best. :D

Also, tell that young man Happy Birthday from OldmanRick...:eek:ccasion:
 
Thanks oldmanrick, he got a kick out of reading that! What you said pretty much sums up my reason for starting the thread, alot of these guys really know their stuff! I just realized I already subscribed to the link that skrews posted just because of the phenomenal job he did on those heads, and I always look forward to reading what 1wild&crazyguy posts. Same with moper, and ou812.
 
Good thread. Like the 2.05,or 10 degrees extra duration. Very cool info.
 
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