Pennock's Fiero Forum
  Technical Discussion & Questions
  head rebuild

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
head rebuild by dhen
Started on: 03-01-2014 01:20 AM
Replies: 13 (344 views)
Last post by: Brucepts on 03-06-2014 09:18 PM
dhen
Member
Posts: 50
From:
Registered: Nov 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post03-01-2014 01:20 AM Click Here to See the Profile for dhenClick Here to Email dhenSend a Private Message to dhenEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have the cylinder heads off and I want to get a valve job. I will probably install a VS cam later, but I still haven't decided. This is a long term project.

A couple of questions:

1) ZZP says you can use stock valve springs with the VS cam. Any advantage to using heavier springs other than being able to shift at a higher RPM?

2) If I don't end up doing the VS cam, is there any disadvantage to heavier springs (other than noise?)

3) My machinist charges twice as much for a 3-angle valve job than a standard one. Is it worth it?

Thanks

[This message has been edited by dhen (edited 03-01-2014).]

IP: Logged
PFF
System Bot
Arns85GT
Member
Posts: 11147
From: London, Ontario, Canada
Registered: Jul 2003


Feedback score: (1)
Leave feedback





Total ratings: 200
Rate this member

Report this Post03-01-2014 06:46 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
When doing the heads, good quality stock springs do the job, even with the 1.6 lift rockers.

More critical is doing a good porting job.

my old porting thread should help you some.

I used OE springs with 1.6 rockers on a fully ported and long tube headered engine and they performed perfectly. In theory, you can spend allot on springs and they are better, but in real world performance, if you are not on a closed circuit race track, you will not notice the difference for the money.

Arn
IP: Logged
zkhennings
Member
Posts: 1491
From: Massachusetts, USA
Registered: Oct 2010


Feedback score: (3)
Leave feedback

Rate this member

Report this Post03-02-2014 10:04 PM Click Here to See the Profile for zkhenningsSend a Private Message to zkhenningsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Arns85GT:

When doing the heads, good quality stock springs do the job, even with the 1.6 lift rockers.

More critical is doing a good porting job.

my old porting thread should help you some.

I used OE springs with 1.6 rockers on a fully ported and long tube headered engine and they performed perfectly. In theory, you can spend allot on springs and they are better, but in real world performance, if you are not on a closed circuit race track, you will not notice the difference for the money.

Arn


Yea I have a compcams 260H cam with 0.440 inches of lift (around what upgrading to 1.6 rockers will do, I think a little less) and I have stock springs, and I dyno'd my car, and I make peak horsepower at 5500 rpms where it then flattens out. If I had valve float the HP would drop off. So in my opinion, the stock springs will be fine for your application. I might upgrade to 1.6 ratio rockers on the stock springs in addition to my cam.
IP: Logged
dhen
Member
Posts: 50
From:
Registered: Nov 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post03-03-2014 12:16 AM Click Here to See the Profile for dhenClick Here to Email dhenSend a Private Message to dhenEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks. It's good to know that I can use stock. Makes it easier.

[This message has been edited by dhen (edited 03-03-2014).]

IP: Logged
zkhennings
Member
Posts: 1491
From: Massachusetts, USA
Registered: Oct 2010


Feedback score: (3)
Leave feedback

Rate this member

Report this Post03-03-2014 01:36 AM Click Here to See the Profile for zkhenningsSend a Private Message to zkhenningsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dhen:

Thanks. It's good to know that I can use stock. Makes it easier.



Sorry, I only read Arn's post, I was referring to the 2.8!
IP: Logged
Lou6t4gto
Member
Posts: 8421
From: Ocala, FL USA
Registered: May 2008


Feedback score:    (7)
Leave feedback

Rate this member

Report this Post03-03-2014 01:16 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
heavier Springs will make the Cam Wear Faster unless it's roller cam. Most decent springs are good for .550 lift . twice as much for a 3 angle ? compare d to how much ? a 3 angle , 4 angle, what ever ( most shops do a "undercut" Behind the valve and is included in the price ( depending where you live) for about $150 pair. + resurfacing (about $50)
IP: Logged
lou_dias
Member
Posts: 5070
From: Warwick, RI
Registered: Jun 2000


Feedback score: (3)
Leave feedback





Total ratings: 65
Rate this member

Report this Post03-03-2014 01:45 PM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
I thought stock springs bind somewhere around .460" lift ... The Crane or Comp Cams "double" springs are good for .500" lift.
The max lift supported by iron heads before kissing the flat-top piston is .510" lift unless you get custom ones with valve reliefs...

Usually when going to max lift, the seats are machined to accept V8 springs which would support the .510" lift and not float at high rpm.
IP: Logged
sco77
Member
Posts: 711
From: MD
Registered: Nov 2011


Feedback score: (1)
Leave feedback

Rate this member

Report this Post03-03-2014 06:36 PM Click Here to See the Profile for sco77Click Here to Email sco77Send a Private Message to sco77Edit/Delete MessageReply w/QuoteDirect Link to This Post
For mild cam I would go with S1X instead, I think if I could go back I would have went that route also.

------------------
86 Fiero GT 4spd - L67 swap: VS cam, GenV
98 GTP - Some mods

IP: Logged
daveg
Member
Posts: 193
From: Barrie, Ontario, Canada
Registered: May 2004


Feedback score: N/A
Leave feedback

Rate this member

Report this Post03-05-2014 07:11 AM Click Here to See the Profile for davegSend a Private Message to davegEdit/Delete MessageReply w/QuoteDirect Link to This Post
The best thing to do is talk to your engine builder .That is what they do. Choose your rocker arms, check cam specs for max lift, and choose springs that work within the range you need.

With my build, the Crane dual springs kept failing - we were just too close to bind. that gets expensive really fast. ask your builder about beehive springs, which offer higher lift range without the need for a second spring.

dave
IP: Logged
KurtAKX
Member
Posts: 4006
From: West Bloomfield, MI
Registered: Feb 2002


Feedback score:    (9)
Leave feedback





Total ratings: 128
Rate this member

Report this Post03-05-2014 03:15 PM Click Here to See the Profile for KurtAKXSend a Private Message to KurtAKXEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dhen:

3) My machinist charges twice as much for a 3-angle valve job than a standard one. Is it worth it?

Thanks



Yes. Valve job has more effect than port shape when the valve lift is under roughly .200" lift. As it turns out, the valve spends a great deal of time between .000 and .200" lift.
IP: Logged
trotterlg
Member
Posts: 1378
From: WA
Registered: Aug 2011


Feedback score: (2)
Leave feedback

Rate this member

Report this Post03-05-2014 11:52 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
3) My machinist charges twice as much for a 3-angle valve job than a standard one. Is it worth it?



Don't know if it is worth it or not, but he should probably charge you three times as much, he has to grind 3 angles instead of one. Larry

IP: Logged
PFF
System Bot
dhen
Member
Posts: 50
From:
Registered: Nov 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post03-05-2014 11:54 PM Click Here to See the Profile for dhenClick Here to Email dhenSend a Private Message to dhenEdit/Delete MessageReply w/QuoteDirect Link to This Post
The machinist is a good guy and I'm not questioning the price. I meant more if it's worth it if you're not doing a race build. I probably wasn't clear.
IP: Logged
Arns85GT
Member
Posts: 11147
From: London, Ontario, Canada
Registered: Jul 2003


Feedback score: (1)
Leave feedback





Total ratings: 200
Rate this member

Report this Post03-06-2014 09:30 AM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
the 3 angle is the superior seal. Yes it is a bit better

Arn
IP: Logged
Brucepts
Member
Posts: 314
From: Denver PA
Registered: May 2001


Feedback score: (1)
Leave feedback

Rate this member

Report this Post03-06-2014 09:18 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Arns85GT:

the 3 angle is the superior seal. Yes it is a bit better

Arn


Not sure why the 3 angle gives a better seal? A single or three angle valve job only seals on one angle. A 3 angle simply changes the airflow above and below the seat.

If he is cutting the seats with a single blade cutter (Serdi style) and it's ground for multiple angles it takes very little more time than a single angle cut. If he is grinding 3 angles then it would be taking more time to change stones and then control the depth of cut so each seat is at the same height. Most shops would have separate stone holders for each angle with dressing of the stone between seats.

I have 2 stone dressers I setup for the seat cut and top cut so all my seats are ground at the exact same angle on a set of heads. The bottom cut simply blends into the port so it's not as critical if I'm off between seats. A Serdi style single cutter setup is the way to go though, find what angles/widths work for flow and then have a cutter ground to do the seats. This is the most expensive setup though.

------------------
"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock