Piston recommendations?

C

Chris S

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I've finally got my engine combo figured out.  All that is left do decide on for sure are the pistons.

I'm leaning towards  KB's for the 76cc heads (10.2-1 comp without decking I assume)

Depending on what everything measures out at this will get decked for optimal quench.
Otherwise stock blueprinted bottom end.  Good flowing 76cc heads with 272/276 @.050 cam 110ls, shaft rockers, Edlebrock intake, carb shop stage IV q-jet or 850 holley (have both), unequal length 460 doug thorly 1 7/8" into 3" headers, 3" to x-pipe and not sure on mufflers.  Chassis will be set on "vampire"

This goes into the '81 Grand Prix with '70 GTO 12-bolt posi (fits nicely) 3.07 gears for now. Caged but not stripped.

Input on piston options, anyone? 

I'm betting Terry says stick with the stockers flipped..... :beer:

Thanks

Chris
 
It depends on your budget, personally i would use the KB's,  That duration sounds like a lot for a 10 to 1 motor in my opinion    :twocents:
 
10.2-1, but that's before decking. 

Cam was priced right and can always be changed down later - - -  :bs:

Let's just pretend that budget isn't a factor.

By the way, is there a floating pin option or do the KB's press on?

Chris
 
I'm using the Kb's , they can be either press on or floating. If your gonna go floating you should probably hone the rod small end for a bushing. Its definitly better than press on but costs more. I went press on. I think the 10.2 CR assumes zero deck and a true 76cc head. By the way if your gonna use 455 olds rods you need to mill approx. .022 off the decks but measure to be sure
good luck
Brian
 
Chris-
    You owe me a  :beer: :yes: I'm going to say Olds 455 rods with KB's as my preferance,and the Ross pistons from Maddog Racing in Florida ($500 on Ebay) if you want the real stuff and are willing to go the extra $. (Remember,you said to pretend budget was no object)
    The only reason I have the stock( Silvolite replacement) pistons in the T are because I had them already,the block was already bored to fit them,the rings on them were usable,and they already had valve reliefs cut in them.It was just too much for a CSOB to resist..... ;) And to either prove or disprove :weeping: a point,I match weighted and resized a set of stock rods with ARP bolts and hung the cheapo slugs on 'em.Maybe I'll get away with it,maybe not,but I don't have much in it and I'll know better next time and so will all you guys.
    That's a lot of cam at 10 or 10.5,but the cad likes a lot of cam. You'll need quite a bit of converter and 3.50+ gears though,I'll bet.This isn't going to be a mild mannered Caddy,by the way..... :yikes:
        Terry
 
Terry, :beer: :beer: There's one for each of us and more in the fridge! 

I'll go you another that you do get away with it... :shhh: :thumbup:

I'm figuring the cam's duration is kinda a relief-valve, won't let cylinder pressure get too high. :-\

I'm willing to give up some already excessive torque at the bottom for more at the top.  Air pumps need to breathe right? :eyebrow:    Got the converter and gears can come after I see where it crosses at.

I hope its not Sunday driver material!  Mild-mannered is not my style anyways, in junkyard disguise maybe, but sedate?  No thanks...
:cloud9:

Chris
 
  I'll gladly buy you that  :beer: if I get away with it. :thumbup:
  What kind of fuel do you want to run? I'm assuming pump premium,but are you planning on something more?
  I agree on the relief valve statement,trick is to make sure the relief valve isn't too big and lets too much good stuff get away. It really is tougher to build a fast street/strip engine than a race engine.Lots more to consider,all a big balancing act with a fine line.
    I really like stuff like you are doing here.Gives us an opportunity to see combinations that we might not get to see otherwise,because it's outside the box.As long as one is willing to take a chance and not be disappointed if it fails,no sweat!
    You have me thinking. :scratchchin: My gut says more compression with that cam,but I'm going to think about it some more.Any chance you could post all the cam specs?
      I'm thinking this thing needs to be 6000+ rpm capable,so good rods will be a good idea."Do as I say,not as I do"...... lol. One time bomb is enough. :beer:
        Terry
 
Well, while the price of pump gas isn't exactly appealling, I'm sure race fuel will be on the same scale.

But I already have to mix the sandrail's at least 1/2 racing and 1/2 premium. (of course, its really almost always 100% funny fuel anyways!)  So having another like that in the herd wouldn't be a huge inconvience....

My wife thinks I need to be in a box sometimes, but that's different - I think?

If it fails, next time I'll do more.  I honestly think the stock rods are extremely underrated.  I'm not saying that cast parts are as strong as forged, but it you put enough meat on something it doesn't matter if it's made out of silly putty. 

I agree that cam would love more comp, but these will be my "baby steps".  I doubt I'll go with less cam though, if you get my drift.......

I'll get those cam specs tomorrow....don't have them with me.

Chris
 
those cam specs sound alot like Mikes comp piece. if it is its not going to work right with that low a comp rate unless your going to spray it every run, which from the sounds of it your not going to. now have you gotten rockers yet? if not really dont use it, the intake has a .388 intake lobe & the exh has .400 lobe it will beat them up pretty quick. lastly a minimum of at least 3.73's to 4.10's will be needed without the comp to match that piece. the heads Mike had where good hopefully you have them but that piece will not make good torque. get a smaller piece.
 
I've got adjustable RAS shaft roller rockers.  They'll hold it...... ;)  Those stock pieces are a joke! lol lol
Seriously I figure if they are the weak link then that needs to be fixed first - and I LIKE adjustable rockers.  A lot.  That's what all my beloved VW's come with afterall :beer:   

I'm willing to sacrifice torque.  I won't be taking Grandma to pick up her hi-strung poodle from the groomers with this car so if it has to wind up above an idle before it goes I'm cool with that.  Maybe some higher $ headers would help out some? :P

What specs would you recommend, Tiny?  I was e-mailing JW about options a few months ago - he said wait till we get to that point. :banghead:

I'm sure a gear change is in the future, but I'll try it out first to see where the numbers fall and then compute what to change to from there. :yes:



Terry, the cam is .688/.692 lift, 272/276@.050 110ls.  Can't make power without airflow. :D

Chris
 
This set-up is close to what I'm trying to build up.  I am looking for high torque low in the rpm range say, around 2500-3500.  What do you guys recommend for a cam in that situation? This is going in a 74 Cadillac hearse burn out machine.

Wild Wild West.
 
wildwildwest_11 said:
This set-up is close to what I'm trying to build up.  I am looking for high torque low in the rpm range say, around 2500-3500.  What do you guys recommend for a cam in that situation? This is going in a 74 Cadillac hearse burn out machine.

Wild Wild West.
Click to expand...
:yikes:
There are lots of different opinions here on cams. Your best bet is to read as much as you can about how cams work and make your own informed decision.
Do a search here.....I'm sure you come up with some interesting threads. :devil:
 
I think we'd all agree that if you are looking for high torque low on the rpm scale, you do NOT want a cam that even remotely resembles what I'm doing.

Try something that is in the 220/230 range @ .050

My car will be streetable with some trade offs.  Mainly milage, bottom end, and manners. :mischievous:

On the Ross pistons, I really don't hear much about them on here.  I don't find a listing for them on their site, looks like they would all be custom ordered?  After reading the Big Inch book I was under the impression that they would be an item?

If they are available off the shelf what has to be done to fit them? Would they fit stock rods? (I know, if you go that far why not do forged rods...) Decking ballpark #?

Chris
 
Just my input, but unless you have around 330 cfm of air @ 28" and 13 to 1 compression or a 540ci motor your probably gonna be disapointed in that cam, but if the price was right go with it. I dont want to start another heated discussion on cams, we all know how that turns out   lol   What do the heads flow? Just curious    Man......thats some huge lift  :yikes:                      good luck on you combo DV8  
 
Keep it simple if you want something off the shelf, Ide go with the good KB hyperutectics and recondition the caddy rods w/ arp bolts and balance the assembly    :twocents: :D
 
They flow over 300cfm. 

I know I'm giving up some and that there is room for improvement.  That's part of the fun. :scratchchin:

I'm leaning even stronger towards the KB's and ARP bolts in stock rods.  (I forgot to mention the ARP bolt part before.)

Thanks for the luck Shawn! :beer:

Chris
 
if your trying to save a few bucks a set of the ross  ebay pistons will be more than enough

in talks with cooke he indicated that he had to sink the valves to make them work right
seems like a good candidate for seats, guides and smaller 2.19/1.81-1.84 valves
the low lift airflow would help and you could get rid of the manhole cover valves in the heads now..well worth the effort...TI
 
Those ross ebay pistons look like a pretty good deal.  Just overbore .030 and put them in?  Anyone have experience on where deck heigth ends up on stock rods?

Did I ever say I had Cooke's heads?    Everyone has this figured out but me..... :boggled:

I'd like to hear on the Torque Inc theory as it pertains to airflow.  I understand how the short duration on the exhaust helps pressurize the cylinder, and keeps the intake charge from being drawn through.  Don't give away your secrets, but maybe tell us more on what makes it work.  Is it just that the exhaust ports flow so good as cast and even better with a little work?  And that's how you can get away with the early closing?  Kinda helps the lesser flow of the intake?

(not being antagonistic, just like learing more.)

Chris
 
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