Bigger valves

[Coach23]

Need help understanding 

I have a 430 big block

went to machine shop 

wanted hard seats ( take Reg fuel)

wanted bigger valves

 

machine shop said they didn’t want to drill because they were scared of getting to water..Soooo..basically no one with a 430 hase bigger valves, because there’s no room to drill..or they are jus being on the safe side ?

[John348]

I found that there is no need to use hardened seats 

[Coach23]

Why is that ?

[Matt Harwood]

I presume you're talking about a 430 Buick, correct? Buicks used high-nickel content iron in their blocks and heads. Installing hardened valve seats is often more trouble than it's worth and I doubt you'll see valve seat recession using unleaded fuel unless you're building a race motor. For normal driving, there's no need to cut and modify the seats. The risk, beyond possibly cutting into a water jacket, is that the seat inserts can sometimes come loose and cause catastrophic failure. Given the quality of the Buick hardware, a regular valve job should be more than adequate and you should not see problems for many years, if ever. The whole fear of "valve seat damage" from unleaded fuel in older engines was pure BS. It was a lie floated by the oil companies to delay the changeover to unleaded fuel in the early 1970s. Lead was first and foremost an octane booster and no engineer ever designed an engine that needed lead to "cushion" the valves.

 

As far as bigger valves, why? As I said, unless you're building a race motor, there's really no need and I doubt it will make any difference you will feel. You can buy high performance cams that will make better use of what is there without clearance issues or extra machine work. You're still going to be limited by valvetrain geometry so shoving bigger valves in there doesn't necessarily make more horsepower and may even make it run worse, not better.

 

Always listen to the guys building your engine because they're going to be the ones to warranty it. The minute you start asking them to do things they don't want to do, they'll either toss you and your engine out the door, or refuse to warranty anything if you have a problem later. Neither situation is one you want, right?

 

Even if it's not a Buick (a Lincoln? A Mopar?) most of this still applies. Trying to out-smart the factory, particularly on a street engine that will be driven modestly, is either money unnecessarily spent or an expensive mistake that you'll only regret later.

[joe_padavano]

I don't have any first-hand experience with Buick motors, but bigger valves are usually an advantage. The important metric is valve curtain area, the cylindrical area formed by the valve diameter and lift. Actually, the important metric is integrated curtain area over the duration of the valve event. Yes, you can get equivalent curtain area with a higher lift cam with more aggressive ramps. The problem is that this puts additional loading on the valvetrain, potentially requires different springs, causes piston-to-valve clearance problems, etc, etc. Proper valvetrain design requires consideration of all of these effects - along with the actual airflow of the rest of the port, since it's meaningless to improve flow at the valve head if there is more restriction in the port further upstream.

 

As for this particular situation, I'm sure the machine shop is trying to avoid any possible liability for turning your vintage heads into scrap. I'd suggest asking a forum more attuned to performance mods on Nailheads, like v8buick.com.

[lump]

Coach23, 

Over many years I have assembled several engines myself, and I have also had engines built by pros as projects for articles which I wrote for major car magazines, including MUSCLE CAR REVIEW, MOPAR MUSCLE, and CAR CRAFT. Perhaps the MOST important thing I learned about increasing performance in any engine was to STOP doing things like a I had done as a teenage hot rodder (IE: buying "hot" parts at speed shops on a whim, or having machine shop work done ala carte, based on hearsay about what needed to be done).

 

Writing and photographing engine build-up articles professionally placed me inside the shops with top engine builders and performance experts for many days in a row. They showed me many techniques and "tricks" I had never thought of. But the MOST important trick that I learned from that experience was for me to tell them what I was trying to achieve, and what I had to work with, and then allow THEM to "design" the project for me.

 

THEY recommended which mods to make to my engines. THEY selected parts for me to use...ALL AS A PART OF A COMPREHENSIVE PLAN. This proved SO much more effective than me listening to buddies, or reading articles, or buying really cool parts that looked so great on the speed shop wall. And the results were amazing.

 

Keep in mind that a bunch of "better-than-OEM" parts thrown in a box, and various modifications based on what you have read or been told or experienced a few times yourself, do not often add together to make a much-improved engine. Even if we are brilliant mechanically, we can't match the experience that a well-experienced full-time engine builder has. If you find one who is especially good at what he does, AND who cares about the results of his work, AND whom you have shown courtesy and respect to, you might reach that golden situation, in which he really WANTS to use his knowledge, skills, equipment, and experience to help you achieve your engine performance goals. 

 

Summing up my opinion: Before you go telling them to install larger valves or seats in your engine, consult a respected professional full-time engine builder in your area. Tell him or her your very specific performance goals, let him examine your project engine, and then listen carefully when he tells you what needs to be done to your engine to achieve your goals. 

[lump]

By the way, my comments above are applicable whether you are trying to "soup up" an engine, or just rebuild it basically stock with any needed refinements for smooth reliable original performance. 

[Pfeil]

34 minutes ago, joe_padavano said:

I don't have any first-hand experience with Buick motors, but bigger valves are usually an advantage. The important metric is valve curtain area, the cylindrical area formed by the valve diameter and lift. Actually, the important metric is integrated curtain area over the duration of the valve event. Yes, you can get equivalent curtain area with a higher lift cam with more aggressive ramps. The problem is that this puts additional loading on the valvetrain, potentially requires different springs, causes piston-to-valve clearance problems, etc, etc. Proper valvetrain design requires consideration of all of these effects - along with the actual airflow of the rest of the port, since it's meaningless to improve flow at the valve head if there is more restriction in the port further upstream.

 

As for this particular situation, I'm sure the machine shop is trying to avoid any possible liability for turning your vintage heads into scrap. I'd suggest asking a forum more attuned to performance mods on Nailheads, like v8buick.com.

 

You could go the way Pontiac did from the beginning of their V-8 back in 53. Pontiac cut their intake valves at 30 degrees to fill the cylinders faster at low lift and therefore most Pontiac cams ( even high performance ) aren't beyond .406 lift. There is only one hydraulic cam that is over .406, the 041 cam is .469.It was only used for a couple of years because it couldn't pass emissions.

Pontiac's solid lifter cams of the late 50's and early 60's for drag racing and NASCAR compared to other cars had relatively low lift because of the 30 degree intake valves and they were all .445 lift with 1.65 rockers. Also remember that the 421 NASCAR engine while rated at a low 410HP and was making close to 600HP only used 2.02 intakes and 1.76 exhaust valves. Sort of a far cry from the street Ram Air engine of 2.11 intake, 1.77 exhaust on my 455 engine.

  FYI, If you ever cut Pontiac intakes at 45 degrees you will loose roughly 50HP on a 300HP engine.

 There is also something else to consider. Some engines can get away with smaller valves by using intake and head ports that have a venturi effect which gives the charge a high velocity for filling the chamber. 

 

BTW after Pontiac, Ford started using 30 degree intakes of the FE Series engine 352, 390, 406, & 427

 

[Pfeil]

30 minutes ago, lump said:

Coach23, 

 

 

Summing up my opinion: Before you go telling them to install larger valves or seats in your engine, consult a respected professional full-time engine builder in your area. Tell him or her your very specific performance goals, let him examine your project engine, and then listen carefully when he tells you what needs to be done to your engine to achieve your goals. 

 

You want to pick a engine builder that is familiar and successful with the engine  (brand). What works on a Chevy, valve wise, cam wise etc. will NOT work on a Pontiac or Olds or Buick or Cadillac, not to mention other manufacturers. Just be aware of that.

Going the 30 degree route on a Buick might not work. It does for Pontiac for which I'm very familiar.

 Just a FYI about 8-10 years back I had a friend who was running in the STOCK 36HP VW Bus class at Bonneville. VW intakes and exhaust are ground at 45 degrees. and their cams are very low lift for durability and as a way of governing engine speed and HP. We ground the intakes on that engine at 30 degrees and picked up 20% more horsepower-that's all we did to the engine.   

 

Edited January 20, 2020 by Pfeil (see edit history)

[60FlatTop]

2 hours ago, Matt Harwood said:

The whole fear of "valve seat damage" from unleaded fuel in older engines was pure BS

 

Does this group look familiar in any way?

 

We had two unleaded fuel stations in my little village all through the 1960's. The group like the picture hung out and the leaded Gulf station and rarely had a positive word about anything.

 

Emissions controls made things different in the 1970's, lots of evil stories. The engines did run hotter. And if you commuted from Rochester to Syracuse everyday, yes, valve seat recession could be a remote possibility. But most of those modifications, like many, are peer pressure driven. Or documented by an automotive writer who needs to get a couple bags of groceries on the table. The use our cars get would hardly ever hit the radar.I watch the tach's on my cars from time to time, 3500 RPM does show much unless I'm being a real Yahoo. no often.

If I had some Stellite seats installed my big worry would be shutting the car off some hot day and having the ring drop down on an open valve.

I agree, hogging out for and larger valve and then going deeper for a seat is a risk. I'd tell you to just get a 455.

 

That group in the picture was around when I was learning. I listened and bought books. And read them. When the conversation of leaded fuel came up I would ask "Would replacing the Tetraethyl  lead with Trcressyl phosphate be a better additive?" They'd go Har. Har. and the one in the bib overalls would bray and tell me I was wet behind the ears.

Edited January 20, 2020 by 60FlatTop (see edit history)

[bryankazmer]

 I hope this is not a hi-jacking, but my recollection is that the weak point of the 430 was failure of a polyamide (nylon) timing gear, and that there is now a stronger metal replacxement.  Perhaps this is already on your "to do" list

[Pfeil]

21 minutes ago, bryankazmer said:

 I hope this is not a hi-jacking, but my recollection is that the weak point of the 430 was failure of a polyamide (nylon) timing gear, and that there is now a stronger metal replacxement.  Perhaps this is already on your "to do" list

It's a weak point on Chevy, Pontiac, Olds, Buick and Cadillac. Ironically  nylon gears came on the 425HP 427 FE Ford.

[joe_padavano]

41 minutes ago, bryankazmer said:

 I hope this is not a hi-jacking,

 

Well, changing the thread topic from valve size to timing gears...

[lump]

Coach23, how about unraveling one part of the mystery here, and confirming for us which engine you have? We are ASSUMING it is a 430 cubic inch Buick. 

 

 

[Pfeil]

 On Pontiac engines it is possible to swap heads for compression and valve sizes. Example; I have a 455" Pontiac engine  with 400" Pontiac heads to give me large valves 2.11" In. and 1.77"Ex.and a desired compression ratio. Pontiac also says you can't install big valve heads on a small bore 3.88" Pontiac 350" engine ( really a 355" ) but the bore centers are the same and the 355 uses the same crank as the 400 Soooo all you need to do is notch the block bore to allow the big valves to enter the bore-which Pontiac did do on the 350 H-O engine.

 

So I also understand Buick like Pontiac has the same bore center. On Buick it's the 400, 430 and 455.

The 400- 430 Buick has 2.0" intakes and 1.625" exhaust valves and the 455 Buick has 2.125" intake and 1.75" exhaust valves.

Now you need to know if 455 heads will bolt onto a 430 and if they do will they need to be notched, and if the head chamber volume is too large giving too low compression, now if someone can make you a set of pistons to raise the compression us satisfactorily you might have something to work with.....and later year 455's already have hardened seats! 

[Coach23]

2 hours ago, lump said:

Coach23, how about unraveling one part of the mystery here, and confirming for us which engine you have? We are ASSUMING it is a 430 cubic inch Buick. 

 

 

I mentioned that in the initial post..but yes it’s a Buick 430

[Guest]

Only slightly off topic (not engine but differential).  I worked in a GM Buick Cadillac dealership in the 60's.  Our shop foreman was a better engineer than GM's so he believed.  He was a long time employee and was ordering a new Buick to tow his trailer with.  He wanted a different rear end ratio than was available on his wagon.  GM Oshawa said no, that it would not accomplish what he thought it would.  Finally between the Principal, sales Manager and parts Manager it was agreed that he would order the Wagon with GM's recommended ratio and we would trade C&P's.  The wagon arrived, C&P's were swapped and he went on a trip with his trailer in tow.  When he returned he wanted to swap back as his ratio was terrible on the road.  The Principal and the parts Manager said he could buy a C&P and pay the shop to change it.  No credit for the "used" one.  He paid to have it changed and even this did not cure him from his superior attitude and only convinced him that his superiors wern't.

[Pfeil]

2 hours ago, Pfeil said:

 On Pontiac engines it is possible to swap heads for compression and valve sizes. Example; I have a 455" Pontiac engine  with 400" Pontiac heads to give me large valves 2.11" In. and 1.77"Ex.and a desired compression ratio. Pontiac also says you can't install big valve heads on a small bore 3.88" Pontiac 350" engine ( really a 355" ) but the bore centers are the same and the 355 uses the same crank as the 400 Soooo all you need to do is notch the block bore to allow the big valves to enter the bore-which Pontiac did do on the 350 H-O engine.

 

So I also understand Buick like Pontiac has the same bore center. On Buick it's the 400, 430 and 455.

The 400- 430 Buick has 2.0" intakes and 1.625" exhaust valves and the 455 Buick has 2.125" intake and 1.75" exhaust valves.

Now you need to know if 455 heads will bolt onto a 430 and if they do will they need to be notched, and if the head chamber volume is too large giving too low compression, now if someone can make you a set of pistons to raise the compression us satisfactorily you might have something to work with.....and later year 455's already have hardened seats! 

 

In addition to this I found; You certainly can install the 455 Buick head with Big Valves and hardened seats already in it. on a Buick 430. It's not just a swap like in the Pontiac engine but is easily doable.

 

 It's absolutely wonderful that all or most of this information is at our fingertips on the internet for those who want to pursue it.

 

 

Here is what I found out.

 Background: When first developed, the 400/430 motors oiled the rockers thru two holes in the block, one in each deck surface, to corresponding holes in the heads. When the factory went to pushrod oiling in 1970, they eliminated the hole in the passenger side of the engine, but had to keep the one in the driver side, as this hole, on the other end of it, is the hole that allows oil to feed to the driver main galley, across the front cam bearing. Since drill bits make straight holes, we end up with a pressurized oil hole at the deck, that head gasket has to seal. No real problem with that at 45psi, but when you push the oil pressures up to 75+, it can leak oil out the head gasket.

The 400/430 oiled the rockers through the head to the shafts, the 455 oil up the hollow pushrods to the rockers.....if using 455 lifters with the 400/430 rockers you need to hollow pushrods with the correct size ball on the end....the earlier pushrods used bigger balls

Edited January 20, 2020 by Pfeil (see edit history)

[lump]

3 hours ago, Coach23 said:

I mentioned that in the initial post..but yes it’s a Buick 430

Sorry, but no matter how many times I read that initial post, I keep missing the word "Buick." I see only "big block." My bad. 

[Pfeil]

3 hours ago, Coach23 said:

I mentioned that in the initial post..but yes it’s a Buick 430

 

So did we answer your question??