I'm not going to be running any blower combinations any time soon, not saying i wont ever want to because i am thinking about it later on after the motor's broken in. I'm building the motor now and i'm ready to buy my rods, pistons, and crank. So i have to look into what heads first. What should i do here? I havent been taught much on the rotating assembly/cc and matching things on the bottom end. I looked into rotating assemblies and havent really found much. I'm shooting high.

 

Cam heads and pistons must match crucially.
It's hard to say which you should buy first, i'd say cam then heads, then pick pistons to match. (or heads-> cam).
Eitherway, what is the outcome of the engine? pure street? want to run pump premium fuel, no race gas? Hot street though? High RPM, or torque?

Probably in the range of 190CC intake, 64CC chambers. That's my

 

everyone tells me, start with the bottom end first. So I am. Yes on pump gas probably 93 . Would like to spark on race gas at the track. Its going to be a weekend car. Some daily driving but only to work which is 5 min away. Its a hyd roller set up so i dont plan to go real high in the rpm range.

So like 195 cc afr heads would be just right?

Whats a go Cr to go with in this situation and if you can, please explain to me how i get the Cr desired. thanks man

 

If your buying an after market rotating assembly you'd be crazy not to just go with a 383. Get the whole assembly with about -15 cc reverse domes and get the 68cc chambered AFR 195's. Depending on piston to head clearance you'll be @ about 10:1. I would use a comp xe276hr in it for a street car.

 

10:1 is horrible for a n/a car isnt it? Forget me even mentioning the forced induction part. And if i was to go 383, whats the benifit compared to a 350. Wont i have to get my stock 350 bore, bored out now.

 

well you could leave it unbored and go with the 377 or whatever it comes out too.

No offense but, your being to vague as to what you want for any1 to give you an accurate description but, i'd have to agre if you're buying an aftermarket rotating assembly going with a 383.

With a 383 your building a stroked sbc that's bored 30 over.... Not much i can tell you about it other than your gaining cubes so more power is easer attainable.

If you gave us an idea on hp goal say 500hp or so i'm guessing we could be of more help, either that or a cam or compression ratio to work around.

 

k my bad 10.1 is good.

So a

10:1 CR
195cc afr heads

Mine as well go 383. Anyone know of a good 383 rotating assembly, i'll start looking but if anyone knows off hand thatd be awesome.

I'm shooting for 500+ btw. Around there

 

I strongly agree with the 383 recom above. More cubes, more torque. A 383 is gotten by boring the 350 block 30 over...
That is, the stock 350 block bore is 4.000", the 383 bore is 4.03".
The pistons are then 30 over also. The stroke of the crank is 3.75"... (If you do not want to bore the block, then you will have a 377 instead of a 383.)

Now you need to decide what rod length you want, either 5.85" or 6.00" is good. I would go with the 5.85".

Having choosen the rod length, now you can calulate the piston compression heigth. Adding half of the stroke + rod length + piston compression heigth should equal 9.000"...

There is alot of rotating assemblies on the web, do a search on the web for "chevy rotating assembly". I did this for my engine biuld of a stroker engine. I have maybe 10 sites bookmarked.

With that decided, choose a good CR for your purpose. Do you want to run on pump gas, yes I think, therefore a streetable CR is 10.5 max,,,(10.0 as recom above might be better.) This should work with 93 octane and aluminum heads.

An excellent choice for heads is the 195 AFRs 2nd maybe the 195 Trick Flows heads. Also, you should check out the new heads from Patriot Performance for SBCs. I just received my LS1 heads from Patriot Performance, they look awesome.

 

One thing to remember when looking for heads is the flow numbers to port volume. I have a set of 185cc trick flows that I've got some nice numbers from.

 

Opened up my summit and found the eagle competition assemblies. I'm not sure what rear seal i have on my block? And doc, It doesn't say the piston compreition heighth.

I see this

3.750 stroke

6.0 or 5.7 rod length

and pistons come in -16cc invrt. dome for 10.4:1 Cr with 64 cc head

or -5cc flat for an 11.8:1 which is too much compretion.



And here's a paragraph taken from afr's site

These heads feature a 74cc or 68cc combustion chamber with a 64cc exhaust port and a 3/4” thick head deck (ideal for nitrous or blower applications). The 68cc chambers are designed for flat top or dished pistons; domed pistons will require additional machining.

So invrt dome pistons wont work?

The competition kits with eagle are 1900.00 around there. I'm not sure with the info i'm finding if this will work.

 

What induction is this supposed to be working with? TPI? Carb?

 

sure not tpi, either carbed or HSR

 

The -16 cc inverted dome's should work, look at an inverted dome as an up-side down dome. Those heads require extra machining for domed or up-side UP domed pistons. Hope i cleared up some confunsion.

 

so the -16 inverted dome pistons are like a stretched out "U".

So since their inverted dome and not domel does this mean i dont need to have the heads machined? Wouldnt an inverted dome be considered a dished piston? I wouldnt want to machine the head if alls i need is a differnent type of piston

 

Okay, well I would decide on that first.
The suggestion to build a 383 is sound. Most rebuilds go .030" over anyway. The price of stroker assemblies is reasonable.

You can get away with a little more head, cam, and intake if you go with MPFI. Once you know the engine size and induction type you can better figure which parts will suit you best.
For instance the same 215cc port aluminum head may work great on a HSR 383, but be very lazy on a carbureted 355.

FYI, inverted domes are dished.
A flattop piston with two valve reliefs works very well with a 383 & 64cc chambers. It's around 11:1 give or take and is what you'll want with aluminum heads.

 

ehh, i was told around 10.1 by many people

 

hmm, is this the rotating assembly I should go with?



These heads feature a 74cc or 68cc combustion chamber with a 64cc exhaust port and a 3/4” thick head deck (ideal for nitrous or blower applications). The 68cc chambers are designed for flat top or dished pistons; domed pistons will require additional machining.

So how do i figure out my Cr with the given information? Say i go with a 68cc and a 64 cc exhaust. Then i get this assembly

Pn# Esp-B12110030 at summit , is for a 1- peice rear main seal, 3.750 stroke, a 6.00 rod length, -16cc invrt. dome. With a 64 cc head it calls for 10.4:1 compretion. Well i dont have a 64cc head. I'm confused here, please help. And no machining needed on the head correct?

 

I would suggest using flat-top pistons with valve reliefs, and the 68cc heads. Zero-deck the block to the pistons and use a standard FelPro .039" head gasket (1004). This will give somewhere around 10.5 - 10.6:1 with the correct "quench", without any machining on the heads.

That's this kit right here.

You'll want a cam somewhere in the neighborhood of something like a Comp XR282HR.

 

Thats perfect. One problem, how are you getting those Cr numbers. I never have known how to calculate them but found a calculator on the net. I took a pic of it just to see if i was entering everything right. And I would like to keep down on the machine work, already looking at 1400 just to get the bottom end in not including parts.

 

just make sure your deck, and piston volume are correct in +/-, some calcs use piston volume POSITIVE means dome, some that means dish...deck height as well. hopefully there's info above that to clarify, but it looks ok otherwise.

Or just try swapping piston volume to negative, if CR goes down, then you should use negative. (deck height too)

remember, .025" deck height, plus .039 gasket gives .064" quench, a bit high. If you can get the machine shop to deck the block to 0, then you'd have .039" quench. Look for larger dished pistons.

$1400 in machine work to the block, with no parts? That sounds quite high, care to clarify?

 

sure can

to bore .30 over =204.00

Splay my 2 bolt into 4 bolt mains=500-600.00

Bottom end ballanced and assembled=400

And a bit to have the area clearanced for the 3.75 crank

 

alright here it is, with the .039 head gasket i'm putting out

10.076:1 whats the smallest gasket i can use? You guys are being a great help thanks a lot

 

or should i just keep it at 10:1

 

The above posts are right on. It is best not to go over .045" quench to be able to run a higher compression ratio on pump gas. .039" is even better. So zero deck the block and use the .039 head gasket and you will be there.

 

without zero decking the block i'm already at 10.1:1

 

i thought 10:1 was perfect?

 

I'm running 10.5:1 with my Trickflow heads and 91 octane gas with no problems. With my next rebuild and .038" quench I'm going to bump it up a tad to 10.8:1. We will be using a .028" head gasket and have the piston -.010" in the hole. This will be with the Comp Cams XFI268HR-13 cam.

 

hmm, if i decked the block to zero, it looks like i would be at 10.6:1 thats good for adjustment. How much is it to get the block decked to zero usually. And would i feel a gain compared to running at 10:1 then 10.8:1 on pump gas.

89 gta whats -.010" in the hole mean?

and whats quench referring to, gasket thickness?

 

If I put my numbers into my compression calculator wrong like you're doing, I can come up with strange numbers like that too.

You're telling your calculator that your pistons are .025" ABOVE the deck, not BELOW the deck (i.e. sticking out the top of the block); and that you have a 5cc DOME instead of a 5cc DISH.

.010" in the hole means, .010" of deck clearance. That's how far below the deck the top of the piston will be when at TDC.

Quench refers to how close the piston top comes, to the non-chamber part of the head above the cyl. Ideally you want the piston to come as close as possible to that part of the head without touching it. It is equal to gasket thickness ONLY IF the pistons have exactly zero deck clearance. The higher the compression is, the more it matters; that is, it's a non-issue on a 8:1 motor, but ABSOLUTELY CRUCIAL on one where you want the highest possible CR on the lowest quality of fuel. It can make a BIG DIFFERENCE to the engine's tendency toward detonation. Given the amount of flexing and heat-induced size changes of all the parts and such, about .025" - .030" on paper is as close as you dare to get, in the real world. .035" - .040" is about ideal... which is exactly what you get with a zero-decked block and a .039" gasket.

As far as the cost, ask your machinist. Usually it's pretty cheap to actually do it. What costs money, is the measuring and setting up.

Yes you would "feel" a gain, by going from 10:1 to 10.6:1.

10:1 might be perfect for some motors; might be too much for others; might be too little for yet others. It's all in the combo.

 

I'd recommend getting it decked and going with the slightly higher CR. You're going to be using a rather large cam right? I'll say it like this, 10.6:1 CR with perfect quench is better then 10:1 with .070 quench IMHO. If you haven't absolutely decided on that rotating assembly combo, you may still be able to replace those pistons with ones with a larger dish, 10cc maybe?

oh ok, forgot about the splaying, that is pretty pricey, that includes the caps I hope?

decking shouldn't cost much more then $100 or so.

 

Ok there's stuff i'm getting here and stuff that's confusing me. Lets start back to what dock said at the top. Hopefully you guys have the time to help me and clear it up.

DOCK="Having choosen the rod length, now you can calulate the piston compression heigth. Adding half of the stroke + rod length + piston compression heigth should equal 9.000"

1)What's the 9 representing here? The length of what? Why should it equal 9? I did this and got 8.375 . Can i subtract that number with a different number and that tell me how close my quench is? How do i find quench and also so my valves dont smack the piston. Is there a way to check those clearances with numbers. Gotta be i just dont know it. Please help there

2)He also stated that the max on 93 octane fuel would be 10.5:1 also said 10:1 is perfect. I'd be at 10.6:1 with a .039 gasket! I hope thats ok

I understand quench now and no i do not want a detonation of valves smacking into my pistons then 2k rotating assembly or pistons smacking the head.



Hey sonix, going with a larger cc dish will just lower my compression. What are you thinken? The 10.6:1 is perfect for pump gas, I can still up the compretion if i wanted to with a smaller head gasket. I like how the set up sounds. why get a bigger dish , dont make no sence there.

 

You know with all the money your going to put into machine work and stroker kit you can buy a forged short block shipped to your door step.
For the same price or less with a warrenty! Ebay sell 383 short blocks with forged pistons, rods and nodular crank for $1500. Several adds in car mags sells them from $1200 to $1800.
If you want to enjoy building a engine yourself thats understandable but if you brake something good luck getting a refund on your parts.

 

that eagle rotating assembly is way better then their "lt1 connecting rods" Also a 12 month warrenty. I doubt i can finish this motor in 12 months because i'm still in school. Not working like i was during the summer. My splayed 2 into a 4bolt with be much stronger, the internals will be better then what ebay is supplying. And i know my machinest(friends of my dad) that everything will be assembled/ballanced together using my clutch, etc correctly. 2k for the assy. like 1600 for the caps and machine work. Now i might get a brake cause i think he already has a block over there ready for a 383 that he may cut me a price on and trade. I'll have to check.

 

ebay doesn't "sell" short blocks. Or anything else, for that matter.

PEOPLE sell their stuff, using ebay. All of the usual things to watch out for, apply to stuff that people sell on ebay. You can get some great stuff there, and you can get some REAL CRAP. The mere fact that it's on ebay doesn't mean a thing, as far as whether it's actually something you'd want to spend your money on.

Short blocks are kind of a commodity. You gotta come up with a core, buy some parts, do some machine work. There are costs associated with each of those things. Everybody knows what those things cost. People can't sell their stuff on ebay for less than what it costs them to build it. On top of just the costs, those people are mostly there to make a profit; so what you pay, is GREATER THAN just the raw costs. You know as well as I do, that Eagle, or Clevite, or SRP, or Comp, or whoever, isn't going to give away their stuff to that guy on ebay; so basically, if you see a business advertising their product for some impossibly low price, then either they are hiding something about aspects of the product that you can't see (the quality of their machine work, for example), or the parts they're using that aren't on the list they show you, or machine work you might "assume" they're doing but they're really not (re-sizing the rods for example), or whatever. They're sure as hell not going to buy a bunch of parts, do a bunch of work, and then give them away for a loss; they won't be in business long doing that.

There's no such thing as a free lunch. Somebody ALWAYS pays for it.

The same rules that apply to any other source of short blocks, apply to ones that people are selling via ebay. One of those rules is, "if it sounds too good to be true, it probably is".

On the other hand, there are also some high-end machine shops selling race-prepped motors on ebay; and people who just have them and want to sell them for whatever reason. But those aren't the $1500 bottom-feeder ones, either. ebay isn't a "vendor". It's just like your local Yellow Pages; it's just a forum to sell stuff. Just because somebody is in the Yellow Pages doesn't mean their stuff is good, and the same thing applies to ebay. You gotta evaluate each individual item to see if it fits your needs and if it's a good deal FOR YOU. Even if it's a "good deal", it may or may not be the one YOU need for what YOU are doing.

Anyway, all that aside:

The 9.000" comes from the fact that the spec dimension for a SBC from the centerline of the main bore to the deck surface, is 9.000" -.000" +.030". In other words, that's how "tall" the block is. Your rotating parts are supposed to exactly fit in that space.

You find "quench" by measuring and machining your block, to exactly fit your rotating assembly. No rot assy is perfect; pistons vary slightly, rod lengths are slightly different from each other, etc. The often-abused term "blueprinting" an engine, means measuring each and every dimension of each and every part, and making each and every one to be what you want; be it the factory spec, or your own custom spec, or some tighter tolerance, ot whatever. "Blueprinting" a short block might include such things as making the main bores exactly straight and the exact right diameter; squaring the bores so they point exactly at the crank cenerline, exactly perpendicular to it, and are exactly 90 degrees apart (factory blocks almost never are like that, sometimes are VERY far from it); squaring the decks so that they're exactly parallel to the crank centerline, and exactly perpendicular to the bores, and exactly 9.000" (or whatever you choose) from the crank centerline; grinding the crank so that all rod throws are exactly the same distance from the crank centerline, exactly 90 degrees apart, and exactly the right diameter; and so on. I could fill up a whole page listing all the things I can think of that you might want to check and/or perfect.

And of course, that doesn't include all the steps that a more conscientious machine shop might take; removing all oil passage plugs, running a rifle brush through them all to dislodge any metal shavings or casting sand, tapping ALL holes and Heli-Coiling any defective ones, deburring and removing casting flash, etc. etc.

Incidentally, you can bet your sweet hind end, no $1500 short block you're going to find on ebay (or anywhere else) from somebody making a profit off of it, has that kind of work done to it.

It's all but impossible to predict valve-piston clearance from the "specs" of your parts. There's too many variables in assembly. Rest assured though, with flat-top pistons, and valves in their normal stock places and so forth, it won't be a problem with any cam anywhere near the ballpark of what I suggested.

 

I was suggesting a bigger dish in the piston to lower your compression ratio, while maintaining that quench valve. (ie, instead of not decking the block).
I think 10.6CR is a bit on the high side, and i'd rather lose the 4% power or less to be closer to 10:1, rather then be dangeriously close to pinging all the time. Just my opinion, depends on the size of your cam, which i've forgotten already. Your other choice, and the main point of this thread a while ago, would be which cc head to choose. You can always bring that up.

a lot of pistons don't show the compression height in the ad. (also because it's usually a constant value between most 350 pistons). Hence why a lot of people aren't doing the math to achieve the 9.0" value there, too many variables, as sofa mentioned. I'd just buy the pistons, then install into block, then measure the depth below deck, cc the heads, and do the math to get my quench and CR from there. Then if desired I can go get the block decked, mill the heads, etc.

 

You don't want a bigger dish. You don't want to lower the CR. 10.6:1 is about perfect for aluminum heads and a cam in the ballpark that I suggested. In fact it's already kind of on the low side for such a cam, which is about the size cam (RPM range) that those heads are designed for. Lower is bad.

I'd stick with the flat-tops with valve reliefs, 68cc heads, .039" head gasket, and the block zero-decked to the rotating assembly.

 

I spent about 1700 on block work. I had it 30 over with plate, alignhoned for studs, tanked, washed, decked, drill and tap from oil plug bolts, clearanced for the 3.75 stroke. Internally balanced, piston assembly onto rods and a bunch of other stuff that adds up. I had them also put together the lower end since I'm not good with it and the total bill was about 2300 with tax. Parts ran me about 900 so it was a 3200 buck shortblock. But you get what you pay for.

 

Save yourself some time and money and go with the 195 Trick Flows or the 195 Cannfields. They are almost just as good but for a few hundred $ less. You also will not have to wait to get them. You also will not have to pay extra to get the accesory holes drilled and tapped. If you have ever seen either pair in person, you have seen how mush they can be safly ported. The exhaust side can really be opened up on the TFS's.

Have you mentioned how you are going to tune this?

 

So how will my block be zero decked to the rotating assembly if i have 8.375 and i take away .025 from 9 which equals 8.975. My piston still has .6 untill its at the top of the deck at TDC. So I'm not getting why its called zero decked.


Thanks sofa kingdom for the help. But i'm still not sure why he said it SHOULD =9. Cause i'm not getting 9.

 

i'm just not sure, cause isn't a 383 set up further up the bore then a normal 350 set up. So the clearances would be different. I'm confused here. Does zero decked really mean my pistons at TDC will come to the very top of the deck?

 

I don't know where you're getting 8.375" from.

A 383 with 6" rods should consist of parts with the following dimensions:

Half the stroke (half of 3.75") = 1.875"
Rod length = 6" (duh)
Piston pin height = 1.125"

Add those up, should be 9.000".

A 383 doesn't put the piston farther up in the bore than a 350. It puts it to exactly the same place, plus or minus these tolerances we've been talking about.... that place being, almost flush with the deck.

Unfortunately I can't look up the specs on the parts in question, because they're in pdf files, and pdfs are broken on my machine. I bet it has to do with that wmf file exploit, because they worked yesterday, but my machine got pushed the fix this morning, and now they don't.... even after de- and re-installing Acrobat. Oh well.

Look up whatever specs you have for your parts, and see if those are the numbers.

Yes, zero deck means exactly that: the pistons will come up to exactly flush with the top of the deck.

 

oh i'm sorry sofa, piston pin height. I didn't know where to get that number, how did you get it? 1.125 that is. I probably did some wack number equation and pulled out a number, wups. thanks for helpen me.

So wow the only thing from stopping my piston from hitting the head is a head gasket. oh my. And then that head gasket thickness will be what my quench is since i'll be zero decked. The 282 hr xe cam is what i was originally going to use like way back. But i always thought the bigger the cam the better. I'd like to get a really nice lope and a very mean sounding idle. But have a decent power curve ya know. What we all want lol. Any expeirence with that cam? What would you say i'm looking at power wise .

You have helped me tonz sofaking thx and all you others also!
(sofa wrote the most, : ) ) thanks

 

It's listed in the specs for the piston. Be sure and check it for the different pistons you look at, because it may not be the same from one piston to the next (close, but not the same). This would affect how much (or how much less) you would have to mill off the deck.

 

Eh it doesn't say

http://store.summitracing.com/defaul...SP%2DB12111030

 

You'd have to call and get the part # for the piston in the kit.

Here is an example for a different piston:



SRP-138093 $499.69
Estimated Ship Date: 1/16/06
Application Show All

Brand: Sportman Racing Products
Product Line: SRP Pistons
Bore (in): 4.030
Piston Material: Forged aluminum
Piston Style: Flat

*****Compression Distance (in): 1.125 *****

Dish Volume (cc): 5.00
Valve Reliefs: Two
Wrist Pin Style: Press fit or floating
Pin Diameter (in): 0.927
Top Ring Thickness: 1/16 in.
Second Ring Thickness: 1/16 in.
Oil Ring Thickness: 3/16 in.
Quantity: Sold as a set of 8.
Notes: Gram weight: 416. Oil support rails included.

Pistons, Forged, Flat Top, 4.030 in. Bore, 1/16 in., 1/16 in., 3/16 in. Ring Grooves, Chevy, 350, Set of 8

 

yeah that's what i was thinking.. Wa la, thanks man i understand most of this CR stuff now.

 

Actually, that might not be a "different" piston at all; seems like Eagle puts SRP pistons in their "kits", and that would be the one that matches the specs for the kit. So Lo-Tec might very well have posted the exact specs for what comes in that Eagle kit.

Now if only I could open pdfs again....

 

Yeah, I was thinking the same thing sofaking. Hmm, I wonder if that's the biggest cam I can go with. The xe282hr. Yes streetable, but a mean *** lope, and power curve. I'm not sure if bigger the better in this scenario. Will the valves actually open past the chamber deck of the head? I wish I knew how close it was. Is there ever a valve open at TDC? I forget, i'm off to bed tty'sl

 

Save yourself the trouble and just get this:

http://cgi.ebay.com/ebaymotors/SBC-c...27703451QQrdZ1

If 500hp is all your gunning for then just get this:

http://cgi.ebay.com/ebaymotors/SBC-3...27703446QQrdZ1

The guys a pro builder and he can sell his stuff for whatever price because he gets his parts in bulk. He has over 3000 positive feedbacks call him at 702-567-3035. I'm not saying go to ebay and look up somebody's peice of crap short block sitting in their back yard thats stupid.

Ebay is more than a place where people sell their junk there are certified engine builders who see it as a good place for advertising.

There are hundreds of engine builders across the country with great prices that you never hear of if your not looking for them.

I've built engines but when it comes down to it I rather buy one already made with a warrenty. I bought mine on ebay from a pro and all I did was put a set of Trick flow heads on it an been killing mustangs ever since.

Do yourself a favor and buy the $1599 short block and use the rest of your money on a set of AFR heads. That engine is 2 times stronger than any stock engine and I bet it will out last the rest of your drivetrain.

 

Here's some feedback on one of there $1500 specials:

"Motor was poorly built, machine work sloppy, Owner very arrogant / incompetent

Reply by dynoflo1: engine was straight up, customer is in over his head, on a 1500.00 engine Jul-16-05 11:47

Follow-up by hotzr1: Had 2 machinist verify. Scot ,you got caught and now your exposed. Sorry"

Link to another: http://home.comcast.net/~britz5/Dyn.htm

I don't know this company, and they might be great, however add a couple hundred for shipping to that 1500 when you buy it, and a couple hundred to ship it back if there's a problem, plus a couple hundred to ship it back to you after it's fixed, etc......

As already pointed out by sofakingdom, you get what you pay for.

At least by keeping it local, you can throw your engine or part of it in the back of a pickup and have your machinist look at it immediately instead of having to call ROADWAY for a pickup. And who knows how long that would take to get it back.

EDIT-just reread the add....says nothing about a warranty, just that the engine comes with "very high perormance dyno-flo stickers."