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).]

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

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.

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).]

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!

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)

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.

For mild cam I would go with S1X instead, I think if I could go back I would have went that route also.

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

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

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.

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

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.

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

Arn

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.

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