gbak

Background:
For a couple of month ago I bought a 2-bolted 010 block, for a 450-500 hp 383 build.

According to the seller the block was a 4.000 stock, never rebored.
I checked the ridges and they was very small in my opinion.
I didn't measured it, which was my first misstake.

My second misstake was that I found 8 forged Ross Racing pistons +30 on Ebay for a good price, and bought them right away.
The Ross pistons should give me 10.7 in comp, which would be fine for my application.
I have also Trick Flow al heads with 64cc chambers, and a Xtrem Energy mech roller cam CS XR274 R-10 on my shelf.
Spec:
Valve timing at 0.015
Open: Int 31 BTDC, Ext 74 BBDC
Close Int 63 ABDC, Ext 26 ATDC

I also bought a Eagle 383 ESP int crank and 6" Manley (streetmaster) rod's.

So I then went to my machinist with the block.
Last week my machinist called and told me that 3 of the cylinders didn't clear up at +30.
The block was already +20 when he started the machining
He wasn't even shure +40 would be enough!

So I bought forged flat top Probe SRS (12337-060) pistons at +60 just to be on the safe side.
The Probe have a higher comp 11,3/64cc (if decking the block to 9.010) but I took them anyway, but now I'm don't know if the engine can handle this comp without pinging!

Future plan:
Is now to bore the cylinders to +60 and deck the block to 9.020-9.015 use a 0.039 gasket to get comp to a "decent" 10.8-10.9
We got 98 octane here so I think it will work.

How will the crank's bobweight correspond to my other parts?
The reason I selected these parts was that they had a low weight and can handle the hp I aiming for.

Crank is int balanced to the bobwight 1855 gram.
Pistons cpl (inl rings and pin) weights 583 gram.
Rods 593 gram, big end 432 grams, little end 161 grams, bearing 46 gram.

Can you give me some comments on this setup?
Have I overlooked something?

VETDRMS

.060 shouldn't be a problem, does your machinist have a way to measure the cylidner wall thickness?

If you have 98 octane you should be fine with 11.3:1. I wouldn't use the head gasket as the crutch as you'll end up with horrible quench and a better chance of detonation.

I run 10.7:1 compression on my 406 with 91 octane gas and no ping, even with the timing locked out. I run .038" piston to head clearance (quench).

I think the cam is a good choice for the 383, I use the XR280R and it has a good, broad powerband.

I would recommend you use the Polymer gear from Comp, even if Comp says you "don't need to." I went through 1 cam and about 4 timing gears before I switched over to the Polymer gear. It has performed flawlessly. It is now on my Billet grind of the same cam and it has not worn at all over many passes and a lot of hard street miles. Its expensive, but worth it IMHO.

SmokinBBC

[QUOTE=VETDRMS
If you have 98 octane you should be fine with 11.3:1. [/QUOTE]

Is the octane measurement the same in Sweden as in the US? Does 98 octane in Sweden = 98 octane in the US

jackson

I assume you included any pin locks in that 583g. Machine shop's bobweight fixture should work out to about 1700-1710g including allowance for some parasitic oil. Looks like they'll be drilling some mass from the crank ... or possibly machining down the crank counterweight's OD to reduce mass ... or both. VERY unlikely it will need any heavy metal added. The OPTIMAL method for reducing mass here would be to achieve all reduction by machining CW OD ... that brings mass closer to crank centerline; reducing moment of inertia ... results in quicker revs & slightly higher HP potential. That optimal method costs more than simple point drilling and requires much experience to get it right.

gbak

Don't know, must check!
When is the wall to thin then?

It says 95 or 98 on the pump, but might be something else??
How do octane correspond to the comp?

One of the main things with the parts I selected was just to have a quick rev engine, and to avoid the use of heavy metal.
Is it any disadvantage to drill a lot of holes in the crank, except that it will look like a swiss chease?

What is the optimal distance between the piston and head regarding quench?

Here are my Ross pistons #70765, is there someone out there that will buy them?
It really hurts to be forced to sell these nice pistons.

VETDRMS

What else does it say on the pump? US is (Research Octane Number (RON) + Motor Octane Number (MON)) / 2.

Here is a good link with some rating information:
http://en.wikipedia.org/wiki/Octane_rating

This is from that link:
So it looks like the (R+M)/2 rating would be closer to 93-94 US octane, which, if setup correctly could run on 11.3:1 in my opinon.

Optimum quench is from .045-.035 with .035 being tightest you want to run with steel rods. I would shoot for .038-.042.

Wall thickness should be from .100-.125". This is just from memory and I might be off a little but your machinist should know for sure. It is more important when overboring a 400, but I think most 350s can go .060 without a problem.

gbak

You are right VETDRMS!
I have checked the octane now, and the Swedish 98 octane is similar to the US 93 octane.

gbak

Can someone tell me which way to go:

Deck the block to 9.005, piston top will be at 9.000, use a gasket 0.039 and get 0.044 in quench distance with a static comp 11.3 and a dynamic comp to 8.8

or

Deck the block to 9.015, same gasket 0.039 and get 0.054 in quench distance with a static comp 11.0 and a dynamic comp to 8.6

I have asumed that the intake closing point (degrees) ABDC @ 0.050 is 67 degrees, is that right??

jackson

Why not leave yourself some room to change as motor wears/ages?

Probe -4cc w/cd 1.125" + 1/2 stroke 1.875" + 6" rod = 9.000"

Why not use a composition Victor Reinz 5746 gasket (4.100" x 0.026" x 5.4cc) with your alloy heads and deck it to about 9.020"? ... that would yield decent quench of about 0.046" ... & still have great SCR about 11.25:1 ... and leave some meat on block if you need to deck in future. You can always get a thicker gasket for those alloy heads ... but you can never replace meat on block or heads.

FYI ... VR 5746 is the thinnest composition gasket I know of that's recommended for use w/ alloy sbc heads. Someone else may suggest it, but I do not agree with using a steel shim gasket with alloy heads.

BTW ... those probes are made of 2618 alloy which expands a fair amount & needs a fair amount of bore clearance. That will result in more piston rock than other alloys. You must not run too tight a quench where there's much rock or the edge of piston will rock up & smack bottom of head when at running hard at TDC.

David Ey

What is a two bolted block?

I'm Batman

2-bolt mains, I presume.

jackson

I understand he means a block with 2-bolt main caps ... as opposed to 4.

Although the gent is apparently in northern europe, me thinks his english language skills are better than most here in usa.

gbak

Probe recommend a running clearance .002 to .006

http://www.probeindustries.com/Pisto...t/Chev_350.htm

PatsLs1vette

My last motor i did at 60 over,ran it hard on nitrous also and is now running in a 80 vette no trouble with running hot either.

L88Plus

Careful with opening that quench up too much - you'll get more pinging at .055 quench with 11:1 than .035 with 11.3:1.

gbak

jackson:
Seems impossible to find that Victor Reinz 5746 gasket here!
Any specific speedshop in US selling the gasket?

jackson

Yes, Competition Products / Howards cams sells it. So does an NAPA auto parts store here. Give me a minute and I'll try to find the P/N for a VERY similar GM gasket that's 0.028".

jackson

Two GM gaskets ... Scoggin Dickey shows them ... any GM dealer should be able to get them.

1. 0.028" - Composition Small Block Chevy Head Gasket 10105117 $15.45

2. 0.028" Composition w/ Graphite - Small Block Chevy Head Gasket 14096405 $21.00

gbak

Thank you very much for the help jackson!

2000FRCZ19

how much for the ross pistons? i am looking at building close to the same engine and my bore will be 4.030 with an eagle 3.75 stroke crank with a set of 6" rods on a decked block 9.010. thinking of brodix heads and a hyd. roller cam.