Now i have a few more questions now that i got it to the shop. They checked the bore for me and my 402 has already been bored out .030 over. So now I'm going to have it bored .060 over. The new questions are... what's the best pistons to go with (ie. dome size, hyper, etc). I'm trying to find a whole rotating assembly for this size but havent had any luck, any suggestions or part #'s? Also will this increase in size drastically change my cam setup. I just bought my new cam so there shouldnt be a problem returning it. Here's the actual setup:

402 BBC
290 heads going to be ported and polished
2.19/1.88 valves to be installed
roller rockers w/Lunati cam 232/239 @ .05 .549/.558 110 LSA
performer rpm air gap
holley 750 dp
th-400
3000 stall converter
eaton posi

Lookin to run low 12's, maybe 11's in the future. Not going to be raced, but will see the strip every once in a while for fun. Thanks for any advice!

Matt

Cam is fine, you want forged pistons, builder ought to be able to recommend dome you need for 10-10.5-1 max. Mid low 12's ought to be doable. What gears?

I'm running 4.10's in the rearend. Any suggestions on the dome size so that I can get a couple different opinions, one from the shop and some from others?

Matt

considering recent trends in the oil and gasoline business I'd be very conservative on the CR. Iron heads and a reasonable street cam, keep it about 10:1 or lower. You don't get that much power out of half-point or full point of compression, and if running it causes you to have to run the timing retarded from what it could be it'll be a dog that runs hot a lot. Cars drive much better with more timing, snappy and sharp. lazy timing = lazy car. The guys that recommend you run a bunch of compression, do you think they'll bring you 55 gallon drums of race gas if it pings so bad you can't really drive it? Or maybe they'll show up with a set of low-compression pistons and install them for you? Doubtful at best, right.

I'm running the TRWL2354 .030's (19.8CC) with 290 heads that finished out at 104CC after install of bigger valves and some minor combustion chmaber work to unshroud valves. Compression with .014 deck and .041 gasket is right at 9.5/1. This combo could go to about 9.8/1 with the GM .022 factory steel gasket. You can also go with a 396 .060 piston for a .001 smaller bore (4.184). these are standard in I think 22CC domes, which would yield close to 10-10.25/1 depending on how much cleanup you do on the heads.

im gonna need the 402 0.060 over, anyone know of a complete assembly kit?

Matt,
Have you asked your machine shop if they can get you the parts ? When you say "an entire rotating assembly" do you mean crankshaft, rods and pistons ?

Sticky, you can use a 396 + .090 piston, same as a 402 +.060 less .001". If you do need a whole rotating assembly (including crank) I would look into making it a 440CI motor - .060 over 4.185 bore w/ 454 4" crank. Keith Black makes the piston as a stock item to do this.

I haven't talked to the shop yet about gettin the parts, I figured I could probably find them cheaper on my own, maybe not? Also, I don't NEED a new crank, its a stock crank, will it hold up? i was just thinking that I was getting all other new parts, may as well strengthen the crank. Is my thinking wrong? If it is strong enough, thats extra money that i can save and use elsewhere, any opinions? how well will the 440 perform? Is that frequently done?

Been doin a lil browsing and found some rods and pistons, want to see what some of you think. Also, isn't the standard rod length 6.135"? Heres what I found:

Keith Black hyper. Pistons part number KB160
4.185" bore
0.180 dome -17cc
1.765 compression height
floating pin
rings are 5/64, 5/64, 3/16


Eagle Rods ESP-6135B
6.135" I-beam
Forged 5140 steel
floating wrist pin
big end bore 2.2"
pin end 0.99"

The wrist pin style must match up correct? Seeing that both are floating wrist pins, they should work? So what are your opinions on this choice? Thanks for the advice!!

Just got my setup rom Summit Racing. Comes with forged pistons, and all the bearings, rings, etc. Decent price, I think. Unless your going racing, it will probably be a fine setup.

Anyone know where to find forged pistons for 4.185 bore? I just read up on the hypers and want to find some forged pistons.

any opinions on these two pistons from speed pro:

TRW-L2383
0.110 dome height

vs.

TRW-L2328
0.319 dome height

I was hoping for about 10:1 maybe a lil more and am thinking the .319 dome is gonna give me too much even with work done to the heads. but at the same time, i dont think the .110 will give me enough. any suggestions?

I know I've asked alot of questions and may be a little annoying to some, but you guys have been great!! If you could just give me some feedback on the last problem I would be so thankful. :)

Well, with 4.185 x 3.75, .040 gasket, .014 deck, 20cc dome and 105cc head I get 9.7:1. With iron heads and the size cam you're looking at I'd stay right about there. I predict that much more it'll ping, you'll be in rich-n-retarded mode and it won't run sharp and need a lot of spark plugs. Just IMHO, YMMV, all that. What do you think the gas will be like in 5 years? Better or worse?

And your gonna buy these parts and ask the machine shop to install them and guarentee their work and parts, See where I'm going with this, a reason BillK said you should have the machine shop get the parts for you. Give the local business some of your hard earned cash and build some kind of relationship with the machine shop and owner. Proper machine shop work isn't the place to scrimp on things.

Leo, I am definitely going to let the shop order the pistons and install them, I was just wondering what everyones opinions were on whats out there so that I have some information for when the shop makes a recomendation. This is the first build and definitely first time ordering pistons. I have yet to use this shop, but it has come recomended to me and see no reason why they would lead me astray. Like I said earlier, this site has been a huge help and I respect everything everyone has to say. I will be on the phone tomorrow with them ordering the pistons and rods. Thanks again.

I hope I didn't come on too strong, just better to let the machine shop do the parts ordering after they do the machine work, they know how to make sure the parts are correct and can send anything back that is wrong or damaged to get the good, correct parts for your build.

http://www.speedomotive.com/BBC%20396%20CID%20ALL%20FORGED%20CRANK%20KIT.htm

I apprecitate that link but do you know if they make the pistons +.090 to come to a 4.185 bore?

Just to let you know I've heard too many horror stories on speedomotive. Might want to beware with those guys.

junkyard,

your post is exactly what is meant by our rule anbout vendor bashing. just a nasty negative statement about a company with no examples, no proof and no opportunity for them to give their side of the story. there's thousands of horror stories about all the major vendors floating around out there, most of them just BS being repeated by people who were never involved in the original transaction. I've bought lots of stuff from them with no problems over a period of 25 years.

We had a customer bring in a set of rods, crank, pistons, rings and bearings all balanced form Speed-O-Motive a few years ago and we checked the rods for for size and we found them off .003 form low to the high and the rods were never checked for bend and twist and the crank was never balanced as the cutomer paid good money for things that were never done. And I might add the rods were some of the earlier rods and some were the later GM rods.

If I had not looked the stuff over the customer would have got shafted, The end result was they refunded his money and took the parts back no questions asked after I had a disscussion with them.

That isn't the first time we have rejected parts from magazines as there seems to be no quality just quanity as they figure no one will ever check there work.

Matt, 290's are closed chamber heads, right? Make sure the pistons you choose will work with closed chambers too, the domes have to fit up into the chambers. This will limit your piston choice somewhat. If you get your chamber size down to about 100cc, you can use a flat top piston and change around some head gaskets to fine tune your c/r....

the chambers are at 101 right now and they are going to have some work done to them so im guessing its going to push that up to about 106? but there are a limited number of 4.185 pistons out there and my machine shop hasnt gotten back to me yet so im getting a little ancy.

i cant find the web site that has info on deck hight but i think you want .030 total with gasket included it will raise compression but you will get less detonation because increases turbulance in the combustion chamber or [squish] do a search on it and ask your machine shop
Curt

BTW, a stock crank and rods will work fine with your setup. You don't need fancy $550-$700 rods, just properly rebuilt/resized stock ones. If they have a Sunnen rod machine, it's all they'll need. May make it easier to balance as well. Stock cranks are fine, in fact, some say the cast cranks are less prone to cracking anyway.

4cc in the chamber is alot of hogging out. Not likely unless they are putting bigger valves in.

Be conservative on the compression as Tom indicates. Be sure you tell them to install the camshaft advanced 4 to 6 degrees. If its one of Harold's grinds it will prefer that phasing. I cut it too close on compression, and am picking up some new heads to help that out. I suspect 93 octane today is barely 93 and a different mix than a year or two ago. OR its stale due to sitting around the tanks too long due to high $$. Either way, $4/gal racefuel is an expensive additive.

Oh, and NO high volume oil pumps allowed!

For comparison, my 290's finished up at 104CC. Went with 2.19 int / 1.72 exh. Unshrouded both intake & exh and polished combustion chamber. I was surprised when these ended up as 104CC. Didn't expect them to get that large - doesn't take much.

My CR is right on 9.5/1 though. 19.8CC piston, 104CC head, .014 deck, .041 gasket.

Anyone have any luck with custom made pistons?

looks like its custom pistons, either that or the KB hypers, or the forged .319 dome to give me almost 11:1 CR which i dont want. any suggestions/comments on ordering custom pistons or should i just try the hypers for 700$ less?

The .319 dome forgings are TRW L2328-060's ??. Most likely a solid dome piston. If so these can be turned in a lathe or milled to .200 - .250 ht. without any problem. Rotating assembly has to be balanced anyway. The L2354 is a .188" dome / 19.8CC piston. You should be able to get the .319's down to about 23 -25CC without much effort. Any machine shop can do this.

i wasnt sure about that, but if thats the case, then i will definitely go with those. i appreciate all the help!