Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine> SBC build questions
User Name
Password
lost password?   |   register now

Thread: SBC build questions Reply to Thread
Title:
  
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Additional Options
Miscellaneous Options

Topic Review (Newest First)
05-02-2011 02:48 PM
stealthy1991 Does anybody have a rocker arm recomendation? If I run roller rockers do I need taller valve covers? I plan on putting the standard old style rocker covers on because the heads are drilled for them.
04-28-2011 03:50 PM
stealthy1991 Sorry forgot to ask about a timing set and cover. I shouldn't need anything special since it's originally a flat tappet block I should be able to use the old style right? With stock cover?
Double roller or gear drive?
04-28-2011 03:44 PM
stealthy1991 Does anyboby have a rocker arm recomendation? If I run roller rockers do I need taller valve covers?
04-22-2011 02:54 PM
68NovaSS What Tech said. However, you have the pistons that came in an assembled short block it sounds like. With a .018 compressed thickness you would have about 10.16.

Here's an online calculator you can use.
04-22-2011 02:44 PM
techinspector1
Quote:
Originally Posted by stealthy1991
Ok I've posted some questions on my build before but have gone a different route since then. I had a newer truck block that ended up being a 2 bolt main so instead I bought a 1974 350 4 bolt main short block .020 over .010 square decked. The pistons are Servolite 1436-020 which are .031 in the hole. So the questions i have are... What kind of compression can I expect with these Vortec heads?
Specs:
190cc Intake Runners, 64cc Chambers, 1 piece stainless valves; 2.02 Intake valves, 1.60 exhaust valves. Flow about 260/180 CFM.
The valve springs have a max lift of .600, open pressure is 325 lbs, closed pressure is 130 lbs.
Straight Plug. 3/8 studs, 5/16 guideplates. Standard accessory bolt holes.
Want to use either this: Howards Cams CL110245-12... Duration 280/292, Lift .501/.509
or Comp Cams SK12-422-8... Duration 270/276, Lift .495/.502.
Can I use the springs that came with the heads for these retrofit roller cams?
What kind of rocker arms should I buy? The screw in studs have a hex on them.
I plan On putting this in a 73 Corvette 4 speed 3:73 gears.
I'm sure I will have more questions.
You have chosen a piston that most of us hotrodders would not have chosen, a rebuilder special with a reduced compression height. Most 350 pistons have a CH of 1.560". Pistons such as you have chosen have a CH of 1.540". This is to allow the machine shop to cut the block decks 0.020" and still have the same piston deck height that the block had from the factory.

Your piston deck height is 0.031", so by the time you add a composition gasket of +/- 0.040", you are at 0.071" squish and have eliminated any chance of generating a good squish to create turbulence in the chamber.

What I would do at this point is to make certain that the block decks and heads are flat enough to use a shim gasket. An 0.016" gasket would yield a squish of 0.047", which would go a long way toward making a good motor out of it in my opinion. I generally shoot for 0.035" to 0.045" on a 350 build.
http://www.summitracing.com/parts/FEL-7733SH1/
Silvolite says there are approximately 6cc's in the piston eyebrows...
http://webpages.charter.net/beckracing/slvpg28.htm
My math tells me there are 6.44cc's in the piston deck height and 3.46cc's in the head gasket. Most all heads will pour a little bigger than advertised, so we'll call the heads 66cc's.
So, here are the values:
723.80 in the cylinder
66 in the chamber
6 in the piston
6.44 in the piston deck height
3.46 in the gasket
Added up, we get 805.7 cc's.
Dropping the cylinder out of the mix, we get 81.9 cc's.
Dividing the larger by the smaller, we get 9.83:1 static compression ratio. I would use a cam with somewhere between 212 and 224 degrees intake duration @0.050" tappet lift, ground on a 112 degree lobe separation angle for good manifold vacuum. A shorter LSA will yield a little more low end power, then peak early and peter out at the top. Counsel closely with the tech at the cam grinder that you choose, as to the suitability of the springs on the heads. The grinder is the guy who has to be satisfied, he's the only guy who will know for sure.

As far as valve to piston clearance, each and every build is unique unto itself and must be closely checked by the builder. Here is some excellent info from Isky for those readers who are unfamiliar with checking for clearances (valve to piston, coil bind, retainer to guide and rocker to stud).....
http://www.iskycams.com/camshaft.php

Bottom line, I like the Howards grind.
04-22-2011 02:17 PM
stealthy1991 Yes that's what the pistons are. What about a thinner head gasket to bring it closer to 10:1? Do you think I'm on the right track with either cam? Any valve to piston interference?
04-22-2011 02:08 PM
68NovaSS With my own calculator, assuming .041 gaskets and flat top pistons, I come up with a static of 10.16:1.

Edit: I see the Silv-O-Lites are flat with valve reliefs, factoring in 5cc for reliefs makes it more like 9.62.
04-22-2011 01:50 PM
stealthy1991
SBC build questions

Ok I've posted some questions on my build before but have gone a different route since then. I had a newer truck block that ended up being a 2 bolt main so instead I bought a 1974 350 4 bolt main short block .020 over .010 square decked. The pistons are Servolite 1436-020 which are .031 in the hole. So the questions i have are... What kind of compression can I expect with these Vortec heads?
Specs:
190cc Intake Runners, 64cc Chambers, 1 piece stainless valves; 2.02 Intake valves, 1.60 exhaust valves. Flow about 260/180 CFM.
The valve springs have a max lift of .600, open pressure is 325 lbs, closed pressure is 130 lbs.
Straight Plug. 3/8 studs, 5/16 guideplates. Standard accessory bolt holes.
Want to use either this: Howards Cams CL110245-12... Duration 280/292, Lift .501/.509
or Comp Cams SK12-422-8... Duration 270/276, Lift .495/.502.
Can I use the springs that came with the heads for these retrofit roller cams?
What kind of rocker arms should I buy? The screw in studs have a hex on them.
I plan On putting this in a 73 Corvette 4 speed 3:73 gears.
I'm sure I will have more questions.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -6. The time now is 09:13 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.