Need Head Opinions and Suggestions! - 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> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 08-27-2010, 11:36 AM
Bonger
 
Join Date: Feb 2010
Location: Canada
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Need Head Opinions and Suggestions!

Hey guys........

Right now I have a 355 in my old 70 GM that I want to make a little more street friendly.........ex - can run at least pump fuel!!!! It was primarily built to be a strip motor so it the compression is way up there at 10.65 - 11:1.

---- I wouldn't mind keeping it as is but access to anything but 91 is pretty slim where I am.......even aviation fuel is tough to come by.

It currently has a set of Vortecs (1.94 intake valve, 1.5 exhaust, 64cc chamber) so I figure that my best bet to knock back the compression into pump gas range would be to go with a different set of heads. I'd love to try and stay with a vortec style head since all my accessories (covers, intake, etc) is of course designed for that style........but I'm pretty sure they don't come any larger than 64cc.........so if anyone knows of some please direct me!!!

SO, since I'm likely going to have to go to a different style head, intake/etc/etc............I'd love to hear some suggestions about what type/brand of heads some of you guys have used and recommend!!!!!!
-------- I don't care about $$$$ so a nice set of aluminum heads would also be in the cards

Based on my current compression......can someone also tell me where I would be (guestimate) based on going with 72cc, 76cc, etc??? I still want to push my hp but just want to be able to fuel up at the pumps!

--- New intake suggestions would also be appreciated but I'd like to go back to a polished or chrome.........just cuz I like to keep it looking shiny under there!!!!

Additional info about what I'm going to be putting together to help suggestions is:

1973 350 4 bolt block, decked, line honed, bored 0.030 - 355cu in
Forged crank .010/.010, Forged Flat Top Pistons, HD stock rods with ARP bolts
CAM - Comp Cam Ex286C, .282/.484 Lobe Center 109, Valve Overlap 64
Rebuilt Holley 650 4777C Double Pumper
GM Stinger HEI Distributor

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 08-27-2010, 11:55 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,548
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
Unless the heads are shaved down the cr is only 10.3:1 (or less)

Don;t invent a problem you don't have. Set the timing at 32deg.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 08-27-2010, 12:31 PM
Bonger
 
Join Date: Feb 2010
Location: Canada
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The guy that built the motor knows his stuff and the heads may have been shaved down since I know he had them pocket ported and bowl hawged and when I talked with him last he told me:

The static comp ratio of the pistons is 11.25/1 and combined with those particular heads and the .040 thick head gaskets it worked out to a real compression ratio of 10.65/1, a little high for 91 octane.

As I said, he had originally built it to be a strip motor, not a street.......I'm really not trying to invent a problem because as it currently sits, on 91 I've adjusted my timing numerous times but the only way I can avoid detonation is to have the motor running like a dog since the timing is too retarded. And I definitly won't claim to be any expert which is why I'm looking for opinions, but with the compression ratio that high (and I have no reason not to believe him since he's been nothing but helpful) all I've seen is that lower octane like 91 is just going to be a problem unless it's being mixed with 100 or 110.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 08-27-2010, 01:27 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,548
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
a 62cc vortec head on a o decked flat top piston 355 with a .038" gasket gives you 10.63:1
What cam is in this motor?
It may be over advanced. (typical on dirt track motors)
The motor is a dog cause the distributor timing advance curve is all wrong for the high perf cam.
A stock HEI distributor timing curve will not work. When you recurve it as follows, it will perform without detonation.
The motor needs more initial base timing at idle 24-26deg , yet only 31-32-34deg at max advance. (vortec motors often don't need more than 31deg for max perf, especially with high compression.)
Shorten the advance from stock 20deg to 10deg limit to allow this. (limit the mech advance travel)

The vacuum advance will also have to be limited and adjusted for rate.
8-10deg vac adv max added at hiway cruise, ....not at idle.

use champion RS9yc spark plugs in vortec heads. Incorrect plugs will make it ping.
When you set it up like this it will not be a dog and will not ping.
If oil is migrating into the intake manifold
it will ping...manifold leak, PCV baffling.

Why are you not useing Sunoco 94?

What is the cranking cylinder pressure PSI?
Check the carb jetting .. should be 67-68pri and 77sec
This motor is not going to work with a stock torque converter low gears or in a truck.

Last edited by F-BIRD'88; 08-27-2010 at 01:37 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 08-27-2010, 01:51 PM
Bonger
 
Join Date: Feb 2010
Location: Canada
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
10.63 is about where the engine builder was guessing so you're spot on F-bird!

I'm actually up in Canada and the availability of decent fuel is pretty F'n lousy. Especially in my area...........so 91 is pretty much going to be it at the pumps. I haven't done a total search of in the city yet but my hopes of finding 93 are slim. The airport can hook me up with 20 gallon jugs of 100 but thats as good as I'm going to get!

And the distributor suggestions are something I'll surely look at ASAP. It does make alot of sense because even when I was doing adjustments on my timing it didn't seem to make alot of sense (how it was reacting).

Plugs were going to be up for a change as well. I have my headers off right now being modified to accomodate for the spark plug wire looms since the bolt holes on the sides of the heads weren't accessible with the headers on so I'll try that as well.

Just re-installed the intake but it was clean underneath and seemed to be sealed well...........carb right now is at 69 primary and 78 secondary.

******THANKS A TON for the info though F-bird!!! I'll start with my Distributor and plugs for sure. Before this I was actually just using a 600cfm Edelbrock performer as well and since have installed a Mallory GP140 electric pump and regulator to use with the 650.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 08-27-2010, 02:19 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,548
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
I got a problem with a engine buider that guesses at a compression ratio.

If this motor has a domed piston the cr very well could be just too high.
if this motor has a flat top piston the cr is not likely excessive unless the heads were
milled a lot or angled milled to max the cr out for racing.

i checked your other posts. A 2400 stall is not really enough for a cammed up motor. a 3500 stall is better.
Clairify the camshaft... Comp does not have a off the shelf hyd cam on a 109 LSA.
They have a 286 with .490 lift a 280 with 480 a 288 with 483 etc
all are on 110 or 108 or unless custom ordered.

There is a crane 284 with 484 lift on 106 or 112

Reguardless, all these cams are going to be troublesome with a near stock 2400 stall converter. needs 3200++ Recurving the distributor will help a ton.
You can even try it locked out if you want. Its easy to lock out a GM HEI distributor by removing he weights and springs and tie wrapping the advance mechanism fully locked with two common zip tie wraps. This will allow plenty of low rpm response and a clean idle yet you can go easy on the spark advance. try locked out with the frozen timing set accurately at 30-32deg BTDC. Make sure the timing tab TDC location is accurate. They are always out a bit and often a lot.
It will have plenty of snap set up like this and will not ping with conservative timing.
A stock fixed vacuum advance canistor is not going to work for this one.
You will need a fully adjustable and limitable one ( crane, MR gasket) as well as recurve the mechanical advance.
All Pioneer gas stations sell 93 octane premimum, Sunoco 94 is the best by far.
some 91 pump gas can be troublesome.

A simple engine cranking compression test will tell the tale if it workable.
Anything under 200psi should be work able on pump gas with minimum compromise.
Where are you that you cannot get decent gas?
it would be a shame to have to pull off the vortec heads from this motor.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 08-27-2010, 04:10 PM
Bonger
 
Join Date: Feb 2010
Location: Canada
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Once again, thanks a ton F-bird!

It's not that the builder doesn't know whats up.......it's just a matter of getting all the info from him as he doesn't live in town and internet is not really his friend if you know what I mean! He's more of a have coffee and we'll sort it out since the e-mails that I receive do not have a single period or spaces.......tough to sort through.

The pistons are flat tops but I don't know exactly what other machining was done to the heads..........so they may have actually been milled down.

BUT, I will get the exact cam as this was info I got off a pile of papers that I had sitting in my desk.

As for the stall, 2400 was what I had available when the trans was rebuilt so I could definitely look at getting a higher converter. But I am trying to keep the truck fairly streetable and I've heard that 3000+ aren't as friendly for the average drive. Even as is right now........I'm hesitant to believe it's actually working properly! It seems to be fully locked up at alot lower RPM than 2000.

But if I do need to upgrade the converter.........it shall be done!

As for the fuel, I've been checking myself and just quizzed a buddy who says that one station in town carries 94. I haven't seen any Sonoco or Pioneer stations in Canada at all! They may be around.......but not here in Alberta so we get stuck with Husky, Shell, etc. The Husky is where it's supposedly 93 or 94, but thats an ethanol blend as well.

------Lastly, I'd rather not be pulling the heads either since I've already been spending an abundance of $$$ on the old girl already!!!! So if I can get it running primo with no detonation I"ll be smiling.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 08-27-2010, 04:50 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,548
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
Husky out west, is the same as Pioneer here. I believe the Husky 94 is equal to the Sunoco 94 here.

Never mind what you heard...I cringe every time I hear this.. A cam like that needs a 2800stall minimum and a 3500 stall is not too much. I recomend not less than 3200 stall (10") for this one.

A "2400 stall" is a stock 12" GM converter with the fines bet a bit more to tweek the stall. Basicly a waste of money as the stock GM 12" converter gives 2100 to 2200 stall behind a 350.

Get a real 10" high stall converter Available in a "3200 stall" tight design or 3500-3600 stall looser design.
The truck is going to want a stiff rear gear 3.73-4.10 minimum with a short tire and 4.56++ with a tall tire.

As long as you don't mismatch the high stall converter with a hiway gear it will "drive fine"
For this one you want a 3000rpm minimum cruise rpm @60MPH Pick the gear and tire diameter accordingly. if you under gear this heavy truck with a cammed up motor, its going to be a dog. Tall tires need big gears. High perf motor with a big cam want rpm. Let it rev.

post back after you fix the distributor.
A Proform HP style center body is a nice simple upgrade to the 650DP carb.
The rpm style hi rise vortec manifold is a ton better than the lowly Performer low rise.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 08-27-2010, 04:55 PM
bigdog7373's Avatar
Of course it's fast
 
Last photo:
Join Date: May 2010
Location: florida
Posts: 2,673
Wiki Edits: 0

Thanks: 13
Thanked 49 Times in 49 Posts
If you're looking for large chamber heads, Patriot makes aluminum heads with 72cc chambers. Jegs sells them, here's the link: http://www.jegs.com/i/Patriot+Perfor.../2171/10002/-1
They're worth a look and they are a reasonable price.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 08-27-2010, 08:36 PM
Member
 
Last photo:
Join Date: Aug 2010
Location: Missouri
Posts: 466
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Everything fbird posted is spot on. I'll only add that polishing the chambers can turn a 62cc head to a 66-68cc head if your fairly aggressive. That'll be better across the board if done right. Another option is a smaller carb with annular boosters- more finely atomized fuel helps some, and a restricted intake helps lower the cylinder pressure.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 08-27-2010, 10:59 PM
Duntov's Avatar
Visit the NASCAR Hall of Fame
 
Join Date: Jun 2010
Location: Near Charlotte
Posts: 411
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by turbolover
Everything fbird posted is spot on. I'll only add that polishing the chambers can turn a 62cc head to a 66-68cc head if your fairly aggressive. That'll be better across the board if done right. Another option is a smaller carb with annular boosters- more finely atomized fuel helps some, and a restricted intake helps lower the cylinder pressure.
All good advice here. Have you considered Aluminum heads? they're getting cheaper and vortecs Ebay good...

Ps Aluminum is generally considered to reduce octane requirement equal to nearly full cr point.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 08-28-2010, 11:34 AM
Bonger
 
Join Date: Feb 2010
Location: Canada
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I'll try and get on top of getting my Distributor set up in the next couple days if I can get ahold of a limitable/adjustable vac can and then I'll limit the mech advance, check my timing tab, change out to a cooler plug, and go from there.

The 2400 converter is coming out and I"ll see what timeline I can have at the trans man in town to get ahold of a 10" stall, 3200 minimum.

The rear end is a 3:73 locker, with 275/60R15 (approx 27").

Lastly, thanks again to all, especially F-bird and I'll get back on here to post after I get everything back in place. It might still be with the 2400 for the time being but at least I can verify that I'm going to be able to run these heads!

------- It's the first project of this type for me since so thanks for the patience! Loving it though and can't wait to get everything on the road. I'll post a pic of the old girl in my profile so you guys can check out what I'm up to!
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 08-28-2010, 03:06 PM
Duntov's Avatar
Visit the NASCAR Hall of Fame
 
Join Date: Jun 2010
Location: Near Charlotte
Posts: 411
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Bonger6
The 2400 converter is coming out and I"ll see what timeline I can have at the trans man in town to get ahold of a 10" stall, 3200 minimum.
I missed it if you said what transmission you have?
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 08-28-2010, 04:14 PM
Bonger
 
Join Date: Feb 2010
Location: Canada
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
TH350, Stage 2 Shift kit and the 2400
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 08-28-2010, 05:25 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,548
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
I use and recomend this converter
B&M #20425 "Holeshot 3600" The exact observed max stall speed will vary abit with engine torque output and tire traction.
http://www.bmracing.com/PRODUCTS/HoleShot-3600

ATI makes a really good converter too.
They prefer that you call them directly to get the right converter.
www.atiperformance.com

They have three slightly different 10" street converters "superstreetmaster"
http://www.atiracing.com/products/tc/smtcprices.htm

Call them and they will help.

In Canada (Mississauga)
http://www.api-racing.com/

Last edited by F-BIRD'88; 08-28-2010 at 05:32 PM.
Reply With Quote Quick reply to this message

Recent Engine 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
Which Head Gaskets? 65malibuSS Engine 4 08-18-2010 02:53 PM
383 stroker built...now need cam suggestions Astrodokk Engine 8 01-31-2009 02:53 PM
New Engine Combo - Your Opinions 300Deluxe Engine 25 07-14-2008 06:57 PM
Head and Cam opinions please.... getsome82AA Engine 11 08-26-2007 12:15 PM
possible twin turbo diesel project......suggestions opinions Chevrolet4x4s Hotrodders' Lounge 15 08-25-2007 07:56 PM


All times are GMT -6. The time now is 01:25 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.