DZ 302 Engine Build Feedback- DCR, Quench, etc. - Hot Rod Forum : Hotrodders Bulletin Board
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> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 11-24-2011, 04:38 PM
Registered User
 
Join Date: Nov 2011
Location: San Diego
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
DZ 302 Engine Build Feedback- DCR, Quench, etc.

I was analyzing my DZ engine build and found some interesting posts regarding DCR and cam profile relationships and so I thought I would post my build goals and assumptions for input/advice on how to improve the performance.

The car is a stock 69 Z28 with a four speed and 3:73'S and runs through the stock cast iron manifolds and dual pipe/single transverse muffler system. I also considered putting on the AIR system. The motor in the car is 11:1 and requires racing gas to boost the octane (I live in Calif. where the premium is not very good). I would like to consider the use of pump gas only for this build but it is not critical. The motor will be a "period correct" setup so that limits the modification options for the block (the block is an original DZ stamp so it can't be decked) and the use of the cast iron heads and intake manifold/carb setup. I am going to upgrade the internals of the engine and that's what I was trying to figure out when I came across this site.

The engine specs currently are:

-010 block with a 4.030 bore

-186 cast iron heads with 2.02/1.60 valves, screw in studs and guide plates. Three angle valve job with mild porting and valve unshrouding (heads were original 1.94/1.50)

-JE 202890 pistons with a 10.4 comp., with a 64 cc head, 1.8 comp. height and a 6.5 cc dome volume. This piston is meant to be used with a deck height of 9.00" which is less than the standard 9.025" factory deck height.

-Crower Sportsman 5.7" rods

-Head gasket is open at this point but the assumption is a .041" thickness with a 4.166 hole.

-Duntov 30-30 Camshaft with the following specs:

Intake opens BTDC 60:50
Intake closes ABDC 105:23
Intake Duration 346:13
Intake Lobe Center (112)
Intake Lift .485"
Exhaust open BBDC 108:50
Exhaust close ATDC 57:23
Exhaust Duration 346:13
Exhaust Lobe Center (64)
Exhaust lift .485"
Distance between centers (132)
Overlap 118:13

I used Pat Kelley's DCR and compression calculators and with this setup the DCR seemed very low at 7.05, probably due to the lower dome height of the JE piston, the higher factory deck height and the head gasket thickness ( I believe that I have calced it correctly but I have never done this before so all caveats apply).

I started to research how to get the DCR up to around 8:1 and if this cam would still work, and if not what would be as close to the sound and characteristic of that sweet revving 302. I don't believe that I can go to a thinner head gasket due to one of the pistions only being about .024" in the hole so the next thinner gasket I found was .015" which would be below the threshhold of .040" for piston/valve clearance. I found that advancing this cam at least 4 degrees would help the situation, but there seems to be more to it than that. That's when I decided to post my build. If I have left anything out let me know, otherwise thanks in advance for the feedback.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-24-2011, 07:11 PM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,643
Wiki Edits: 0

Thanks: 13
Thanked 56 Times in 53 Posts
Mr. Gasket carries a head gasket thru Summit racing that is .028 thickness.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-25-2011, 01:17 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
Quote:
Originally Posted by clm69z28
I was analyzing my DZ engine build and found some interesting posts regarding DCR and cam profile relationships and so I thought I would post my build goals and assumptions for input/advice on how to improve the performance.

The car is a stock 69 Z28 with a four speed and 3:73'S and runs through the stock cast iron manifolds and dual pipe/single transverse muffler system. I also considered putting on the AIR system. The motor in the car is 11:1 and requires racing gas to boost the octane (I live in Calif. where the premium is not very good). I would like to consider the use of pump gas only for this build but it is not critical. The motor will be a "period correct" setup so that limits the modification options for the block (the block is an original DZ stamp so it can't be decked) and the use of the cast iron heads and intake manifold/carb setup. I am going to upgrade the internals of the engine and that's what I was trying to figure out when I came across this site.

The engine specs currently are:

-010 block with a 4.030 bore

-186 cast iron heads with 2.02/1.60 valves, screw in studs and guide plates. Three angle valve job with mild porting and valve unshrouding (heads were original 1.94/1.50)

-JE 202890 pistons with a 10.4 comp., with a 64 cc head, 1.8 comp. height and a 6.5 cc dome volume. This piston is meant to be used with a deck height of 9.00" which is less than the standard 9.025" factory deck height.

-Crower Sportsman 5.7" rods

-Head gasket is open at this point but the assumption is a .041" thickness with a 4.166 hole.

-Duntov 30-30 Camshaft with the following specs:

Intake opens BTDC 60:50
Intake closes ABDC 105:23
Intake Duration 346:13
Intake Lobe Center (112)
Intake Lift .485"
Exhaust open BBDC 108:50
Exhaust close ATDC 57:23
Exhaust Duration 346:13
Exhaust Lobe Center (64)
Exhaust lift .485"
Distance between centers (132)
Overlap 118:13

I used Pat Kelley's DCR and compression calculators and with this setup the DCR seemed very low at 7.05, probably due to the lower dome height of the JE piston, the higher factory deck height and the head gasket thickness ( I believe that I have calced it correctly but I have never done this before so all caveats apply).

I started to research how to get the DCR up to around 8:1 and if this cam would still work, and if not what would be as close to the sound and characteristic of that sweet revving 302. I don't believe that I can go to a thinner head gasket due to one of the pistions only being about .024" in the hole so the next thinner gasket I found was .015" which would be below the threshhold of .040" for piston/valve clearance. I found that advancing this cam at least 4 degrees would help the situation, but there seems to be more to it than that. That's when I decided to post my build. If I have left anything out let me know, otherwise thanks in advance for the feedback.
Given the figures:
• 4.030" bore x 3" stroke
• head gasket 0.041" thick x 4.1" bore diameter (you need not use a HG w/ 4.166" bore)
• deck 0.025" in the hole
• 64cc chambers (you have to verify this! Often undecked heads will be larger than 64cc)
• dome of 6.5cc,

I get 9.76:1 compression ratio. But this runs the quench out to an unacceptable 0.066". To get the CR up and quench distance down, a thinner HG is needed. There are various high quality gaskets available that are composite construction (composite gaskets makes sealing to an uncut deck more positive) that might work well for you, like:

• Victor Reinz Nitroseal p/n 5746- Compressed thickness is 0.025", 4.1” bore. NAPA carries Victor.
• GM 10105117- Multi-layered stainless steel gasket with a 4.1 bore, .028" thick, will handle some surface irregularities of the deck and head surfaces (supposed to be the “revised” gasket, better seal- Post #23 ). $21/ea. @ Summit.
• GM 14096405- Stainless steel layers over a graphite core (or graphite on one side, SS on the other), is .028" thick, 4.1” bore.

Shim type gaskets w/the rubber coating are a bit more forgiving than the uncoated gaskets. You can sometimes take an ever-so-light skim off the block and retain the suffix, or have the decking done in such a way that that area is left untouched. This will allow the use of a shim HG w/a lot better chance of no sealing problems.

So, using a 0.015" shim HG puts you at 10.5:1 w/quench at an "ideal" 0.040".
Using a 0.025" HG, the CR becomes 10.2:1 and the quench would be 0.050". The 0.028 gasket will give you 10.1:1 CR and a quench of 0.052".

I'll leave the DCR calculations up to you. But I do have to say there are other solid lifter flat tappet camshafts that I believe would be a better choice unless authenticity takes precedence over more efficient power production.

Heck, you could run a stout hydraulic cam w/Rhodes hydraulic lifters and have better power and still the tickety-tick of solids. Blasphemy, I know. Just saying'.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-25-2011, 07:25 PM
Registered User
 
Join Date: Nov 2011
Location: San Diego
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by cobalt327
Given the figures:
� 4.030" bore x 3" stroke
� head gasket 0.041" thick x 4.1" bore diameter (you need not use a HG w/ 4.166" bore)
� deck 0.025" in the hole
� 64cc chambers (you have to verify this! Often undecked heads will be larger than 64cc)
� dome of 6.5cc,

I get 9.76:1 compression ratio. But this runs the quench out to an unacceptable 0.066". To get the CR up and quench distance down, a thinner HG is needed. There are various high quality gaskets available that are composite construction (composite gaskets makes sealing to an uncut deck more positive) that might work well for you, like:

� Victor Reinz Nitroseal p/n 5746- Compressed thickness is 0.025", 4.1� bore. NAPA carries Victor.
� GM 10105117- Multi-layered stainless steel gasket with a 4.1 bore, .028" thick, will handle some surface irregularities of the deck and head surfaces (supposed to be the �revised� gasket, better seal- Post #23 ). $21/ea. @ Summit.
� GM 14096405- Stainless steel layers over a graphite core (or graphite on one side, SS on the other), is .028" thick, 4.1� bore.

Shim type gaskets w/the rubber coating are a bit more forgiving than the uncoated gaskets. You can sometimes take an ever-so-light skim off the block and retain the suffix, or have the decking done in such a way that that area is left untouched. This will allow the use of a shim HG w/a lot better chance of no sealing problems.

So, using a 0.015" shim HG puts you at 10.5:1 w/quench at an "ideal" 0.040".
Using a 0.025" HG, the CR becomes 10.2:1 and the quench would be 0.050". The 0.028 gasket will give you 10.1:1 CR and a quench of 0.052".

I'll leave the DCR calculations up to you. But I do have to say there are other solid lifter flat tappet camshafts that I believe would be a better choice unless authenticity takes precedence over more efficient power production.

Heck, you could run a stout hydraulic cam w/Rhodes hydraulic lifters and have better power and still the tickety-tick of solids. Blasphemy, I know. Just saying'.
Thanks Cobalt327 for the great information. Given that the originality of the block is a big limiting factor, the head gasket seems to be of even more importance given it's impact on quench, clearance, etc. The issue with the block is the fact that the drivers side bank all measures about .026" in the hole. The pass side starts at about .024" and grows to .030" in the back. The engine builder wants to use the Fel Pro 1103 head gasket given that the block surface won't be perfect. I found a Mr. Gasket head gasket that might work and keep me in the safe zone for clearance and a good quench, but it is a metal shim construction: 1130G NEW 4.100" .020" Embossed Steel Shim, Elastomer Coated(Not For Use w/Lightweight Head). I will also check into the ones that you listed.

It appears from the product information that this gasket might squish down to a .018" thickness (is that possible?). If so, this would translate to a .044-.048" clearance and quench. Are you familiar with these type gaskets?

With an advance of about 8 degrees with the 30/30 cam, it calcs. at a DCR of 7.63 and an SCR of 10.38. What is the effect of this much advance: does it take away the idle quality, have large impacts on the top end, and is it a problem?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-25-2011, 08:16 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
I have no experience w/the p/n 1130G HG, but if the compressed thickness comes from Mr.G, I would have to assume it's correct.

When you are calculating the DCR are you using a "correction factor" of any kind? Some calculators (it is claimed) are more accurate if the intake closing point is fudged some amount, and this is different between the different calculators. Maybe someone will read this who knows what's up w/ the Pat Kelly calculator and can assist you in getting a correct DCR- not that you are incorrect, it's just that I don't know if you're correct or not w/the calculator you're using.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-25-2011, 10:02 PM
Registered User
 
Join Date: Nov 2011
Location: San Diego
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The calculator I used (Pat Kelley) doesn't have a fudge factor, it requires the use of absolute valve duration, not the durations at some lift e.g. .050". Other than that, I am not aware of any other fudge factor. Maybe it is built into the program?

Do you have any opioion of the type of material between the two gaskets that I mentioned? The composition of the Fel Pro and the Mr. G gaskets are different; do you see any issue substituting one for the other?

And does the cam advance of 8 degrees seem to be problematic? Thanks.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-26-2011, 12:43 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
Quote:
Originally Posted by clm69z28
The calculator I used (Pat Kelley) doesn't have a fudge factor, it requires the use of absolute valve duration, not the durations at some lift e.g. .050". Other than that, I am not aware of any other fudge factor. Maybe it is built into the program?

Do you have any opioion of the type of material between the two gaskets that I mentioned? The composition of the Fel Pro and the Mr. G gaskets are different; do you see any issue substituting one for the other?

And does the cam advance of 8 degrees seem to be problematic? Thanks.
Advancing the cam will put the intake c/l at 104Ί. Not a deal killer, although it also will decrease the valve to piston clearance of the intake valve. As I said earlier, I would spec a cam that did what I needed it to do w/o needing anything even close to a 8 change- but that's me. If you are committed to this cam you have to do what you have to do.

So that said, you still have to degree the cam in to know where you are starting from, in order to to know how much advance you actually need to get some theoretical DCR, so start w/degreeing the cam in.

HERE is a list of valve train points to check.

An embossed, coated shim HG will not be as forgiving as a full composite HG on an unmilled deck surface. I have no idea what a p/n 1103 Felpro fits. Are you talking about a 1003? If so it's a composite 0.041" thick w/a (too large IMO) 4.166" bore diameter. I've said above where a 0.041" compressed thickness HG puts the quench and CR (CR will be a bit lower due to the HG diameter- I computed it using a 4.100" dia.). Personally I would use one of the thinner composite HG's. Why give away CR and quench- when you need more CR and less quench?

Quote:
Distance between centers (132)
What is the LSA really?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-26-2011, 05:05 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,195
Wiki Edits: 326

Thanks: 591
Thanked 756 Times in 646 Posts
Quote:
Originally Posted by cobalt327
What is the LSA really?
Some of the numbers don't prove out in math, but if we use the intake opening and closing figures of 60.5 degrees/105.23 degrees, adding 180 for getting from TDC to BDC, we find an intake duration of 345.73 degrees. On the exhaust side, adding 108.50 degrees/57.23 degrees, adding 180 for getting from BDC to TDC, we find an exhaust duration of 345.73 degrees, same as the intake duration. More than likely, these figures were taken using the old S.A.E. J604d spec. I seem to remember it as 0.004" on the intake and 0.006" on the exhaust. The ramps on these cams were very long. Not having a 0.050" figure in the published data and not having access to the rate of lift, I cannot determine the 0.050" duration. The intake centerline is given as 112, the exhaust centerline as 64. Adding these figures together and dividing by 2, we find a lobe separation angle of 88 degrees.

You also have to take into consideration that the cam was a solid flat tappet, so there is the factor of valve lash to consider.

Personally, I'd wrap the motor/trans up in moisture-proof stuff and build a 383 5-spd for it. Mark hit it right on the money with the Rhodes lifters.

Last edited by techinspector1; 11-26-2011 at 05:23 PM.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-27-2011, 10:07 AM
6426yy's Avatar
Member
 
Last photo:
Join Date: Nov 2003
Location: Macomb Il.
Age: 34
Posts: 536
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
Quote:
Personally, I'd wrap the motor/trans up in moisture-proof stuff and build a 383 5-spd for it. Mark hit it right on the money with the Rhodes lifters.
X2 The value of that engine is IMO too high to risk driving around with. 010 blocks are everyware, then if you have to have one milled just tell everyone that it's the original block when it's really a 350 ot 383 like tech said, or find a 283 crank if you wana stick with a 302.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-28-2011, 08:01 PM
Registered User
 
Join Date: Nov 2011
Location: San Diego
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The actual LSA for this cam is 114 degrees. If the cam is advanced 8 degrees, and the piston deck clearance and the gasket are in excess of .042", does the advance reduce that clearance amount? And if so, what would the loss of clearance be or does it reduce it by some undetermined amount that has to be physically measured?

As to the cam, I am hoping that I can make the 30-30 cam work given the goal of using the factory parts as much as possible. All of the comments on using a different motor are certainly valid and I probably should have considered that more seriously before I started. I don't drive the car that much-about 3K miles in 9 years-so the risks are low on the original stuff.

I wish that I had done all of this upfront and not after the bottom end was pretty far along and the components weren't totally analyzed. Thanks for all of the good input. I certainly enjoy the learning curve.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 11-28-2011, 08:49 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
Quote:
Originally Posted by clm69z28
The actual LSA for this cam is 114 degrees.
Thank you, sir.

Quote:
If the cam is advanced 8 degrees, and the piston deck clearance and the gasket are in excess of .042", does the advance reduce that clearance amount? And if so, what would the loss of clearance be or does it reduce it by some undetermined amount that has to be physically measured?
The deck clearance with the gasket thickness, etc. is describing what makes up the quench distance- the distance between the flat part of the piston deck and the deck of the head. The quench isn't affected by advancing or retarding the cam. In the diagram below, the quench distance is labeled the "Squish Band". Different name, same measurement:



Advancing the cam reduces the intake valve to piston clearance, and this, along w/the exhaust valve to piston clearance would be physically measured during the mock up phase of the build. The closest the valves get to the pistons doesn't happen at TDC like one might expect. Look for the minimum intake valve to piston clearance to be somewhere around 5° to 20° ATDC during valve overlap. The minimum exhaust valve to piston clearance is around 20° to 5° BTDC during valve overlap. The clearance you are looking for with steel rods is generally said to be 0.080" for the intake and 0.100" on the exhaust unless there is some reason to use a different clearance. Add 0.030" for aluminum rods.

HERE is a short page on using the "clay method" for determining the P to V clearance.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 11-28-2011, 11:14 PM
Registered User
 
Join Date: Nov 2011
Location: San Diego
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the excellent info. Learn something new every day. I will dig around some more to see if anybody has info on this cam/advace issue.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 12-01-2011, 10:54 PM
Registered User
 
Join Date: Nov 2011
Location: San Diego
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the excellent info. Learn something new every day. I will dig around some more to see if anybody has info on this cam/advace issue.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 12-02-2011, 06:29 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
You're quite welcome. Let us know what you find.
Reply With Quote Quick reply to this message

Recent Hotrodding Basics posts with photos

Quick Reply
Message:
Options

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
could use some feedback on poping engine awert Engine 4 11-13-2010 04:47 PM
355 vortec build. DCR, SCR, quench, octane confusion thebigblue Engine 20 06-16-2009 01:41 PM
Feedback on engine mount design pcoghlan General Rodding Tech 3 02-01-2009 10:54 AM
squish or quench on a supercharged engine smokin63 Engine 7 03-31-2008 05:41 PM
GM- 454 engine feedback Chris Engine 1 03-13-2002 02:56 PM


All times are GMT -6. The time now is 08:01 PM.


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.