piston/cylinder head question

[abdywgn]

had a Dart with a 68 340,headers,484 DC cam,LD-340 with 3310,3.23 gears and 4-spd. car ran 13.18 @108 with 7 X 27" cheater slicks.I could not shift, never used 4th gear, valve guides were sloppy because the heads had been surfaced and I never checked clearances. SO, now, I would like to replicate this combo using a 360. ? is,do I use pop-up pistons with the 587 open chamber heads OR use flat-top pistons with a smaller chamber? I see where the flat-top set-up would probably be better, but my 1st 340 Dart had old TRW pop-ups and also ran 108 in the 1/4...but only had power in 1st and 2nd because the fuel system was not up to snuff. this is more of a what would it have done as anything else. wanna run pump gas only, not E85,yet. and since I'm not gettin any younger...whatcha all think? Thanks! Bob

 

[jefflock]

You sound like me in my late teen early 20's. 69 Dart GTS 340, 4 speed, 750dp, ld340, headers, 4.10 suregrip, sig erson cam 300dur/500lift,TRW pop up's. The only clutch I could keep in it was a DC race clutch and pressure plate, SS springs and Sox & Martin pinion snubber. Ran like a stripped a## ape. Man I wish I had that car back. A little trip down memory lane.

 

[moper]

If you have to stick with open chambered heads then there isnt much to be said. That's because a mild to midrange cam will ping with more than about 9.8:1 static. You have to run a larger cam to get the cylinder pressure down and a dynamic compression figure of less than 8.25:1. If you go with a closed chamber design, the parts and be changed to get a dynamic closer to 8.5:1 (static around 10.7:1 and cam in the 228°*@.050 or so will get around this) which will mean more power on cheaper fuel. I use 8.5 dynamic as a max for pump fuel and iron closed chamber. 8.75 as max with aluminum closed chamber. 8.25 max with open chamber iron.

 

[abdywgn]

jefflock, I had the Hays street/strip gold set-up,listed at 3400 lbs,used tge 10.95 pressure plate and 10.5 disc. It was a great feeling to side step the clutch at 4000 or so...with the 3310, I used the black secondary spring;secondaries never fully opened but it just kept pullin' and pullin'!

moper,guess I wanted what I had, cake and eat it too! probably the best for now would be the dished 360 pistons already in use along with a set of Magnum heads. cam accordingly and be able to use a full advance curve instead of cutting back on it to stop knock.

OR- pop-up pistons, oc heads,big cam,pump gas and water/alcohol injection!!!

maybe down the road. Thanks for the input! Bob

 

[jefflock]

Get the car rolling backwards then floor it and side step the clutch. Oooo What a feeling!
I just happen to have a set of those old heavy dc/trw 12.5-1 pistons.

 

[green1]

Get the car rolling backwards then floor it and side step the clutch. Oooo What a feeling!
I just happen to have a set of those old heavy dc/trw 12.5-1 pistons.

Yeah, if your initials are JJ, you can leave them burnt into the road, lol.
Of course, back in the '60's, I watched people nail reverse, and metal down, hit drive. Sometimes it was funny, especially when a guy with a Ford c-4 tried it.