Search



Go Back   Third Generation F-Body Message Boards > Tech Boards > Engine Swap
Register Forgot Password?

Engine Swap Everything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 11-29-2010, 01:57 PM   #1
Junior Member
 
isr85-T/A's Avatar
 
Join Date: Aug 2010
Location: Santa Maria ,CA
Posts: 7
Car: 1985 Pontiac Trans Am
Engine: 4 bolt main 350ci. LG4,
Transmission: 700r4
Axle/Gears: stock

Classifieds Rating: (0)
305 heads on 350 block?

i was told you can put the heads of the 305 onto a 350 block and it will increase hp on the engine. and if it is true would that combination be able to pass smog in california?
isr85-T/A is offline vBGarage Page   Reply With Quote
Old 11-29-2010, 02:06 PM   #2
Supreme Member
 
zraffz's Avatar
 
Join Date: Mar 2009
Location: Sussex County, NJ
Posts: 1,264
Car: 1994 Z28
Engine: 355 LT1
Transmission: T56
Axle/Gears: 3.42

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Search it, I know it has been asked many times.

Yes you can do it. Will it increase power? Yes, it depends on the heads and chamber size but mainly it will increase low end power. I did it, car had descent low end grunt and nothing after like 5 grand. Running with 2nd gear grinding badly and without 3rd gear in a T5, 3.73's, two burnt wires, open dif, and a vacuum leak between carb and intake manifold I put down a mid 14 second pass. Running right we figured a mid to high 13. It was also my first time ever running a manual trans at the track (my experience driving a manual is also very limited). All I was running was a mild cam and a set of hand ported 58cc heads.

I think you are better off porting the heads you have and camming it. The only reason they run 305 heads is some of the heads have smaller chambers, increasing compression. Most 305 heads flow terribly though. I wouldn't do it again unless I was putting the motor into a truck.
zraffz is offline vBGarage Page   Reply With Quote
Old 11-29-2010, 02:34 PM   #3
Supreme Member
 
Join Date: Dec 2005
Location: Northern CT
Posts: 2,269
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's

Classifieds Rating: (8)
Re: 305 heads on 350 block?

It's not worth it IMO. The 305 heads will SLIGHTLY increase your compression ratio, but they flow horribly and will kill any top end. A freind of mine put some on his carbed, cammed 350 and my TPI 305 with a small cam ran circles around his car. You are basically choking out the motor. If you're doing all the work to pull the old heads off, at least throw something good on there.....or have the stock ones ported. Plus 305 heads have smaller intake valves than 350 heads.
__________________
1986 Trans Am, 2005 5.3, 317 heads, LS6 intake, LS6 cam and valve springs, Turbonetics T76 turbo, viper spec T56 transmission, BMR everything
whitedevilTA is offline vBGarage Page   Reply With Quote
Old 11-29-2010, 07:26 PM   #4
Member
 
iroc-z_23's Avatar
 
Join Date: Apr 2009
Location: Hermann, MISSOURI
Posts: 379
Car: 1986 Iroc-z Camaro t-top
Engine: 355 SBC
Transmission: 700r4 TCI const. Pres. Valve body
Axle/Gears: 3.73 posi/mosuer axles

Classifieds Rating: (1)
Re: 305 heads on 350 block?

Quote:
Originally Posted by isr85-T/A View Post
i was told you can put the heads of the 305 onto a 350 block and it will increase hp on the engine. and if it is true would that combination be able to pass smog in california?
would not recommend this, it causes hot spots on your pistons from the cylinder heads. will it raise compression yes, but flow, no.
iroc-z_23 is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 12:23 AM   #5
Moderator
 
Apeiron's Avatar
 
Join Date: Jan 2000
Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,979
Car: 1984 Z28 Hardtop / 1988 IROC T-top
Engine: 383 Carb / 305 TPI
Transmission: 4L60 / T-5
Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt

Classifieds Rating: (0)

Re: 305 heads on 350 block?

Lots of misinformation here.

The only difference between a 305 head and an equivalent 350 head is the chamber size, and the size of the intake valve they come with from the factory. The ports are the same. Put a larger intake valve in, and it'll have just the same flow as the 350 head, with higher compression. They don't kill flow, and they don't cause hot spots on pistons. It's possible to do some dumb things, like replace 350 L98 heads for 305 LO3 heads, but the power loss there isn't due to any 305/350 distinction.

Technically by the letter of the law, putting 305 heads on a 350 would not be emissions legal in California. Then again, neither is the 350 block in an 85 to begin with.
Apeiron is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 01:49 AM   #6
Member
 
Join Date: Nov 2009
Location: Georgia, USA!
Posts: 162
Car: 86 Camaro IROC-Z28
Engine: 4.8 LS 68mm turbo
Transmission: Turbo 350
Axle/Gears: 3.08 10 bolt

Classifieds Rating: (1)
Re: 305 heads on 350 block?

We put 305 heads (601 castings) on my buddy's 350. We were both surprised how well it pulls down low with the performer eps intake, and a mildish 224/235 480/488 113lsa cam. It will scoot up a hill no problem and put you in the seat on the way up if you do it right. Just my experience with the swap.
Kyle86 is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 02:25 AM   #7
Senior Member
 
Doom86's Avatar
 
Join Date: Oct 2004
Location: SE, Ohio
Posts: 965
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73

Classifieds Rating: (0)
Re: 305 heads on 350 block?

If you over come the only draw back of a 305 head by putting bigger valves in you will have a far better head then it's 350 equivalent because of the valve job and 55cc chambers.

If you took it a bit further with stainless back cut valves and the bowls blended you would have a much better head then any cast GM or it's era.
Doom86 is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 12:08 PM   #8
Supreme Member
 
zraffz's Avatar
 
Join Date: Mar 2009
Location: Sussex County, NJ
Posts: 1,264
Car: 1994 Z28
Engine: 355 LT1
Transmission: T56
Axle/Gears: 3.42

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Quote:
Originally Posted by Kyle86 View Post
We put 305 heads (601 castings) on my buddy's 350. We were both surprised how well it pulls down low with the performer eps intake, and a mildish 224/235 480/488 113lsa cam. It will scoot up a hill no problem and put you in the seat on the way up if you do it right. Just my experience with the swap.
Yeah I dont remember the casting I ran but they were ported on a comparable cam. It moved but it didn't have much top end. It was putting down 14 second passes at like 72 or 74 MPH... it wasn't running right as previously stated though.
zraffz is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 12:25 PM   #9
Member
 
iroc-z_23's Avatar
 
Join Date: Apr 2009
Location: Hermann, MISSOURI
Posts: 379
Car: 1986 Iroc-z Camaro t-top
Engine: 355 SBC
Transmission: 700r4 TCI const. Pres. Valve body
Axle/Gears: 3.73 posi/mosuer axles

Classifieds Rating: (1)
Re: 305 heads on 350 block?

Well I've seen the hot spots on the pistons from a 305 head. I've also heard that from multiple machinist. Chance it if you want but really I don't think it's worth it to put them on.
__________________
iroc-z_23 is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 12:29 PM   #10
Member
 
iroc-z_23's Avatar
 
Join Date: Apr 2009
Location: Hermann, MISSOURI
Posts: 379
Car: 1986 Iroc-z Camaro t-top
Engine: 355 SBC
Transmission: 700r4 TCI const. Pres. Valve body
Axle/Gears: 3.73 posi/mosuer axles

Classifieds Rating: (1)
Re: 305 heads on 350 block?

Maybe after you changed valves it would eliminate that problem I guess, rather thann just sticking a bone stock head on.
__________________
iroc-z_23 is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 01:12 PM   #11
Moderator
 
Apeiron's Avatar
 
Join Date: Jan 2000
Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,979
Car: 1984 Z28 Hardtop / 1988 IROC T-top
Engine: 383 Carb / 305 TPI
Transmission: 4L60 / T-5
Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt

Classifieds Rating: (0)

Re: 305 heads on 350 block?

Quote:
Originally Posted by iroc-z_23 View Post
Well I've seen the hot spots on the pistons from a 305 head. I've also heard that from multiple machinist. Chance it if you want but really I don't think it's worth it to put them on.
I'm sure you believe you have. Find some better machinists, though.
Apeiron is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 02:27 PM   #12
Senior Member
 
Doom86's Avatar
 
Join Date: Oct 2004
Location: SE, Ohio
Posts: 965
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Quote:
Originally Posted by zraffz View Post
Yeah I dont remember the casting I ran but they were ported on a comparable cam. It moved but it didn't have much top end. It was putting down 14 second passes at like 72 or 74 MPH... it wasn't running right as previously stated though.
It looks like a dump truck from the times. Somethings wrong though, my LG4 305 with headers was +18mph faster.

As pointed out before the casting you start with would change results considerably though. L03 heads would not be a good choice unless ported by a pro. But I think in general when people are talking about "305 heads" they usually mean 416, 601, 081 castings.
Doom86 is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 11:39 PM   #13
Moderator
 
Air_Adam's Avatar
 
Join Date: Oct 2002
Location: Saskatoon, SK, Canada
Posts: 9,067
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi

Classifieds Rating: (0)

Send a message via MSN to Air_Adam
Re: 305 heads on 350 block?

I used a set of 601 castings on my 350, which replaced a set of 882s. The 601s had 1.94/1.60 valves in it, along with screw-in studs and guideplates. No port work, only a little unshrouding of the intake valve in the chambers. The top end power was a little better, but the low and mid-range power increase was HUGE! The mid-range punch was awesome, and the throttle response bordered on ESP lol. The heads were milled a little bit just to get them flat, but my calculated CR went from 9:1 to a little over 11:1.

It was a VERY good upgrade - highly recommend it... and I've actually done it, so I actually have a 'before/after' unlike alot of the speculators in this thread (no offence intended).

You could pass california smog with them, as long as you have the right valve cover bolt pattern ('86-earlier perimiter bolts, use casting 601 or 416, '87+ centerbolts use casting 081) because they look the same as a 350 head externally, and the casting number is hidden under the valve cover.

Last edited by Air_Adam; 11-30-2010 at 11:43 PM.
Air_Adam is offline vBGarage Page   Reply With Quote
Old 11-30-2010, 11:58 PM   #14
Supreme Member
 
zraffz's Avatar
 
Join Date: Mar 2009
Location: Sussex County, NJ
Posts: 1,264
Car: 1994 Z28
Engine: 355 LT1
Transmission: T56
Axle/Gears: 3.42

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Quote:
Originally Posted by Doom86 View Post
It looks like a dump truck from the times. Somethings wrong though, my LG4 305 with headers was +18mph faster.

As pointed out before the casting you start with would change results considerably though. L03 heads would not be a good choice unless ported by a pro. But I think in general when people are talking about "305 heads" they usually mean 416, 601, 081 castings.
Yeah well I previously stated when I pulled the motor I realized it had 2 burnt wires and a vacuum leak between the manifold and carb... not sure if the wires were burnt at the time of running it but it had a very bad vacuum leak. It took off very, very hard for the little bit of money into the motor. I talked to a local shop, I replicated a motor the motor from one of his low dollar builds and I think I recall he said it put a Nova into the mid-high 13's.
zraffz is offline vBGarage Page   Reply With Quote
Old 12-01-2010, 01:38 AM   #15
Junior Member
 
crazyman's Avatar
 
Join Date: Oct 2010
Posts: 7

Classifieds Rating: (0)
Re: 305 heads on 350 block?

There is a difference between centerbolt and perimeter bolt heads.. If you're talking the perimeter to perimeter style, do it. Centerbolt? Nightmarish ramps in the intake port either way that slow flow.

I had an 82 GMC 3/4 ton 2wd 350 that had nothing more than perimeter 305 heads, a 204/214 cam, th350, 3.73's, performer intake, quadrajet, and 31 inch tires that was the terror of my highschool and averaged 19mpg.... Cast ex. manifolds too.

One thing that most people neglect to realize when putting 305 heads on a 350 is that you gain an 1/8" wide squish band around 80% of the chamber, which is beneficial to power, mileage, and efficiency...

Not to mention, that combo spun up to 7,600 RPM during one burnout.... Sounded nascar like, but died three weeks later due to rod clatter. It wasn't the combo that killed it, just rpm and being a junkyard engine that had 1/8" play between the piston and bore, every cylinder. Too tired for 7,600 RPM..

Really, just the heads is like going from a stock cam to a 204/214 cam. Your butt will feel it. So will your gas gauge.

Too many people will say no, because there are expensive bolt-on go fast parts available to make huge power, but if you're on a budget, and you have them, do it. You'll learn, and have fun in the process....

Last edited by crazyman; 12-01-2010 at 02:11 AM.
crazyman is offline vBGarage Page   Reply With Quote
Old 12-01-2010, 03:07 AM   #16
Moderator
 
Apeiron's Avatar
 
Join Date: Jan 2000
Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,979
Car: 1984 Z28 Hardtop / 1988 IROC T-top
Engine: 383 Carb / 305 TPI
Transmission: 4L60 / T-5
Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt

Classifieds Rating: (0)

Re: 305 heads on 350 block?

Quote:
Originally Posted by crazyman View Post
There is a difference between centerbolt and perimeter bolt heads.. If you're talking the perimeter to perimeter style, do it. Centerbolt? Nightmarish ramps in the intake port either way that slow flow.
That ramp has nothing to do with whether it's center or perimeter bolt. It's a feature of the swirl-port TBI heads. Other centerbolt heads don't have it.
Apeiron is offline vBGarage Page   Reply With Quote
Old 12-01-2010, 03:26 PM   #17
Junior Member
 
crazyman's Avatar
 
Join Date: Oct 2010
Posts: 7

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Quote:
Originally Posted by Apeiron View Post
That ramp has nothing to do with whether it's center or perimeter bolt. It's a feature of the swirl-port TBI heads. Other centerbolt heads don't have it.
I did not know that. Thank you. I've only messed with one set of centerbolt heads.
crazyman is offline vBGarage Page   Reply With Quote
Old 12-01-2010, 09:12 PM   #18
Moderator
 
Air_Adam's Avatar
 
Join Date: Oct 2002
Location: Saskatoon, SK, Canada
Posts: 9,067
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi

Classifieds Rating: (0)

Send a message via MSN to Air_Adam
Re: 305 heads on 350 block?

All SBC heads from '87-on are centerbolt heads, including Vortecs and LT1/LT4 heads.
Air_Adam is offline vBGarage Page   Reply With Quote
Old 12-02-2010, 07:46 AM   #19
Member
 
Join Date: Aug 2009
Location: AZ
Posts: 332
Car: 1978 Chevrolet impala
Engine: 350ci 300hp/356tq pace crate
Transmission: 700r4
Axle/Gears: 3.42 Yukon posi

Classifieds Rating: (0)
Re: 305 heads on 350 block?

What are the stats on the "Vortec 5000" 5.0L cylinder heads? I bet a set of those on a 350 would be murderous.

EDIT: Did some searching, came up with this:

http://www.hotrodders.com/forum/vort...ine+305+vortec

Last edited by Grumbles; 12-02-2010 at 08:30 AM.
Grumbles is offline vBGarage Page   Reply With Quote
Old 12-02-2010, 04:26 PM   #20
Supreme Member
 
zraffz's Avatar
 
Join Date: Mar 2009
Location: Sussex County, NJ
Posts: 1,264
Car: 1994 Z28
Engine: 355 LT1
Transmission: T56
Axle/Gears: 3.42

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Quote:
Originally Posted by Grumbles View Post
What are the stats on the "Vortec 5000" 5.0L cylinder heads? I bet a set of those on a 350 would be murderous.

EDIT: Did some searching, came up with this:

http://www.hotrodders.com/forum/vort...ine+305+vortec
The chambers are the same size as the 5.7 Vortec heads.
zraffz is offline vBGarage Page   Reply With Quote
Old 12-03-2010, 02:34 AM   #21
Member
 
Join Date: Aug 2009
Location: AZ
Posts: 332
Car: 1978 Chevrolet impala
Engine: 350ci 300hp/356tq pace crate
Transmission: 700r4
Axle/Gears: 3.42 Yukon posi

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Quote:
Originally Posted by zraffz View Post
The chambers are the same size as the 5.7 Vortec heads.

It actually says in that article that they are 55-58cc
Grumbles is offline vBGarage Page   Reply With Quote
Old 12-03-2010, 03:27 PM   #22
Senior Member
 
Doom86's Avatar
 
Join Date: Oct 2004
Location: SE, Ohio
Posts: 965
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73

Classifieds Rating: (0)
Re: 305 heads on 350 block?

Aren't those the same heads Fast355 used to build the 356rwhp 305?

Never used them my self but people who have say they are 55cc chambers.
Doom86 is offline vBGarage Page   Reply With Quote
Old 12-03-2010, 03:38 PM   #23
Moderator
 
five7kid's Avatar
 
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 42,137
Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 10B-3.73/9"-3.89

Classifieds Rating: (14)

I thought he used 601's.
five7kid is online now vBGarage Page   Reply With Quote
Old 12-03-2010, 04:59 PM   #24
Senior Member
 
Doom86's Avatar
 
Join Date: Oct 2004
Location: SE, Ohio
Posts: 965
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73

Classifieds Rating: (0)
Re: 305 heads on 350 block?

I had to dig it up to check (since he's got a motor a month habit, hard to keep track of )and it's the 059 Vortec 305 heads he used.
Doom86 is offline vBGarage Page   Reply With Quote
Old 12-03-2010, 04:59 PM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > Engine Swap

Tags
305, 350, block, engine, heads, hot, hp, increase, power, put, putting, rating, running, runs, sbc
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 11:42 PM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
All content copyright 1997 - 2014 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details