305 heads on 350 question - 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 07-04-2006, 01:49 PM
Registered User
 
Join Date: Jan 2006
Location: north carolina
Posts: 18
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
305 heads on 350 question

I have a 350 that has a set of 305 heads( #376450)with 350 valves.It also has a ultradyne 276 cam 454 lift,and trw 2256 forged pistons.I have a performer intake.I plan on headers and probably a 650 carb. Any ideas about what my compression would be? Will the 305 setup be OK? What kind of hp ?I'm not going to race or rev above 5000rpm. Just cruise.I bought the engine with little time on rebuild.Going to put it in a 68 Camaro
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-04-2006, 03:22 PM
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
I just put 305 heads on my 350 this spring for my pickup, real tight budget!!
I had the dished stock pistons though, and a GMPP cam 212/222 @ .050 435/460 lift, edelbrock streetmaster intake and a 600 holley with headers and 2.25 duals with flowmasters. The single plane intake is surely hurting low end torque but all in all the engine runs better than I had expected.

Make sure you have the 350 head gaskets on it and you'll be fine. As for power I couldn't tell you some one on here mentioned I'm porbably making around 300 lb/fts. You're probably a little shy of 10 to 1 with the flattops according to Flatlander Racing's website they claim with your pistons and 58cc heads 10.27:1. Let us know how it works out. For a budget these arn't bad engines.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-04-2006, 03:28 PM
Registered User
 
Last photo:
Join Date: Jun 2006
Location: Winnipeg Manitoba
Posts: 33
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
My dad has a 65 Pontiac Acadian Canso with a 350 quite done up, dont know the specs but its over 450hp for sure, he told me that back in the day he tried 305 heads on his 350 and it kicked *****, he said it would go through head gaskets every couple months though. that was a while ago though, maybe gaskets have changed since then, but if anyone knows if 305 heads on a 350 is possible without going through gaskets id like to know too thx, Tim
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-04-2006, 04:21 PM
WakBordr7387's Avatar
Gone fishin'
 
Last wiki edit: Removing stuck fasteners
Last journal entry: blah.......again
Join Date: Sep 2004
Location: Texas Coast
Age: 29
Posts: 667
Wiki Edits: 2

Thanks: 0
Thanked 0 Times in 0 Posts
Ive used 305 heads on a 350 for my truck before.
Ran good for the budget I was on. I was using the stock flatop pistons. Only time I had any pinging or detonation was from timing being off. Of course I also had a big cam to bleed some of the pressure off to.
I never thought about the head gaskets blowing out on an engine like this being a problem for other people to. Mine blew a head gasket before, I thought I fixed the problem. Until a few months later when it blew again and had quite a bit of compression in the radiator (like the overflow tank looking like ol' faithful )
Personally I wouldn't do it again. I only did it because I was on a budget and the 350 heads I had were crap to begin with, and the 305 heads were in great shape.



Brad
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 07-04-2006, 06:25 PM
Marcel
 

Last journal entry: Choo-choo town
Last photo:
Join Date: Feb 2002
Location: adairsville ga.
Age: 71
Posts: 414
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
350 with 305 heads

I had a .040 350 with flat top pistons with 305 heads with 1.94 valves. pinged bad with 93 Oct. gas. Run about 100 mi. and started skipping bad. Tore it down and the first two pistons ( 1 and 3) were cracked from the top of the piston down to the top ring ( broken off in spots). I was told that the comp. was to high (heads were 58 cc) also used shim head gaskets. Changed to new flat top pistons and went to 73 cc 350 heads with 1.94 intake valves with a lunati hyd. cam 00016 with 1.6 rockers and it barks the tire when it shifts( 700r). Alum (chevy ) intake with qua. carb. and headers with 2.5 exhaust pipes ( flow masters) .
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 07-04-2006, 07:12 PM
Mustangsaly's Avatar
Member
 
Last photo:
Join Date: Jan 2005
Location: Nebraska
Posts: 1,071
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
what about the 305 votec heads ? what are they like on a 350 ? any advice from someone that has used them would be great.......



Thanks




Mustangsaly
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 07-04-2006, 09:39 PM
Registered User
 
Last photo:
Join Date: Jun 2006
Location: Winnipeg Manitoba
Posts: 33
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Lanierledford, sorry to hear about your problems with the pistons i have a 350 also bored.040, i run 87 octane, I have hyper eutectic pistons, stock 882 350 heads with 1.5 roller rockers, i have a hydraulic cam thats rated at 300 hp from a corvette, performer intake and a crappy old 6sumthin holley carb and headers also, if you look in my pictures youll see that i drive an old Grand LeMans 4 door Grandpa car! it barks the tires too, just thought id share that info with ya..id say keep 350 parts with 350s and 305's with 305's, cant go wrong...happy motoring
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 07-05-2006, 12:41 AM
Registered User
 
Join Date: Jun 2006
Location: Forest Grove, British Columbia
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hey Buzz, I've heard all kinds of myths about putting 305 heads on a 350. I build engines professionally. Untill I moved about a year ago I was building up to two 350s with 305 heads a month. Never had a problem with any of them. With a standard replacement type flat top piston a 350 with 305 heads will have 10.22 to 1 compression. Thats about as high as you want to go on a street motor. 305 heads are cheap horsepower and work great on a 350. I guarantee you it will blow the doors off a 350 with open chamber 194s. As for you guys who had problems, could it possibly have been something else?
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 07-05-2006, 05:44 AM
Registered User
 
Join Date: Mar 2006
Location: USA
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I've always heard 305 heads don't flow well at all and weren't worth the trouble on a 350.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 07-05-2006, 11:56 AM
Rhansen's Avatar
Footbraker
 
Last photo:
Join Date: Jan 2004
Location: Davenport, Iowa
Age: 44
Posts: 579
Wiki Edits: 0

Thanks: 2
Thanked 3 Times in 3 Posts
Friend of mine did an 86 Monte SS with a set of late model camaro (1987 305) heads on a 350. It made all the right sounds (chirp tires on a gear change, slight lope at idle) but would lay down bad at around 4000 rpm. I got the stopwatch out and timed it 0-60, took a little over 9 seconds - not too impressive in my book.
My understanding is that the 416 casting is the best 305 head to use, but I would rather use vortecs or aftermarket heads any day.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 07-05-2006, 01:40 PM
Registered User
 
Join Date: Jan 2006
Location: north carolina
Posts: 18
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
What would be a good option instead of the 305's. Would like to keep cr down some. What are advantages of aluminum heads?
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 07-05-2006, 02:08 PM
bigbadbowtie's Avatar
Bottle Fed
 
Last photo:
Join Date: Jul 2005
Location: Huntsville Alabama
Age: 40
Posts: 468
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
advantages are.....
easier to repair when it comes apart at 7k.
usually can run 1 more point of compression on pump gas.
lighter by quite a bit.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 07-05-2006, 04:33 PM
King of my Man-cave.
 
Last photo:
Join Date: Nov 2003
Location: Michigan
Age: 55
Posts: 2,836
Wiki Edits: 0

Thanks: 2
Thanked 4 Times in 2 Posts
The head gasket problem is from detonation and/or pre-ignition.

Putting 350 intake valves (1.94") into the small chamber (55cc) 305 heads will not increase breathing because the intake valves are extremely shrouded. The 1.84" valves probably breathe as well or better.

Putting 305 small chamber heads on a flat-top 350 (L2256F-30) yields a comression ratio around 11:1 compression.

Putting 305 larger chamber heads (62.5cc) on a flat-top 350 (L2256F-30) yields a compression of 10.1 compression.

The biggest problem I see with using 305 heads on a 350 is the compression ratio being too high for the application and the fuel/timing combination. Also, too many guys run a "torque" type cam with this combo and run into head gasket and/or broken pistons, etc. (sound familiar?).

Putting 305 heads on a 350 is a quick way to increase compression, but there are better heads for getting decent power from a 350.

tom
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 07-05-2006, 07:00 PM
Registered User
 
Join Date: Jun 2006
Location: Forest Grove, British Columbia
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Machine Shop Tom, I'm the only one who mentioned the word "myth" so I'm assuming your comment was directed at me. I have heard all of the same things about 305 headed 350s. Exactly how many 305 headed 350s have you built? Have you experienced these problems personally? I built one that ran 13.20s at Mission Raceway, Mission B.C.in a '70 Nova with, flat tops, mild cam, dual plane intake and headers. Ran a full season before I lost contact with the customer, No Problems. Also built one that I personally ran in a '78 Regal which went 13.60s, at Eagle Motorplex, Ashcroft, B.C., then installed the motor in a customers '87 S15 Jimmy, again no problems. I built and installed these motors in too many cars list, No Problems. Maybe I hallusinated the last 10 years of my life. Oh by the way, have you heard of a little company called Summit? I used get their catalogues. All of their lower budget engines ran 305 heads on 350s. Also the compression ratio I gave in my last thread was calculated by cc ing the head, measuring the deck height, gasket thickness, cc ing the valve reliefs, with a replacement type flat top piston and 58cc heads, composite head gasket, this was not a guesstimate or something I read somewhere. modelawoody.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 07-05-2006, 07:03 PM
xntrik's Avatar
Save a horse, Ride a Cowboy.
 
Last photo:
Join Date: Jul 2005
Location: Arkansas
Posts: 5,131
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Big valves should be unshrouded .200 minimum or to the cylinder wall, whichever comes first. This will remove a little metal for lowering the compression also.

The right 305 head massaged gently works well on 350s.

Qustion is..... at what point do the Scoggins-Dickey modified Vortecs for $ 620 pair ready to run start to sound like a bargain?
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
Distributor Tuning and Theory - Part 1 Rick WI Engine 35 04-26-2011 12:38 AM
350 sbc..305 heads?? learjet60 Engine 6 01-28-2005 08:28 PM
305 heads on a 350 digitalfrek Engine 4 12-13-2003 05:34 PM
305 vortec heads on a 350 tonylsg Engine 13 09-21-2003 05:54 PM
MAXING OUT A 350 w/ 305 Heads chevyteen17 Engine 4 03-15-2003 09:40 PM


All times are GMT -6. The time now is 04:52 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.