Valve Guides

Jyrki

Jyrki

Team Member
Moderator
Anybody know where to get bronze valve guides for the 320, preferably for smaller 11/32" or 5/16" stems?
 
I had been considering doing a 263 head with bronze guides, but was just going to get the common .502 od 11/32 bronze guides and drilling them into the current guides. The idea was to use at least the chevy exhaust.

What have you got in mind?
 
Jyrki

Good to hear from you again.

I was going to do the same as Bob and drill the stock guides and press in the chevy bronze guides.
We might even turn the bronze guide OD down so the hole in the stock guide is smaller.

What are you doing to the head?
Did you determine why there was so much leakdown on the engine?

Paul
 
I swapped my dual-carb intake for a spare '49 320 head, and are looking to swap 1.880 and 1.500 valves with 11/32 stems in place of the stock 1.780 and 1.450 3/8 valves. I'm going to let a professional porter take a look at the head and see what he can do. As a side note, the valve spring seat pressure of my 1946 head is just 50 lbs, while the '49 has 75 lbs (the '49 coil wire is actually thicker). I will post the stock flow numbers here when I get them. For your information, the stock retainer hits the stock valve guide at .400" lift. The stock lift is .347"

Manley seems to have bronze inserts that you can use to renew old, worn guides, and oversize liners to swap valve stem sizes. It smells like the K-line valve guide liners that my dad used in the 80's when he owned an automotive machine shop. The K-Liners require special tooling, though. See http://klineind.com/Guide-Liners-R.html

I haven't decided if I'm going to pop off the head of my existing '46 engine, of if I'm going to build another engine from scratch. A year ago I purchased a "320" engine from this forum, which turned out to be a '34 233 - a bummer. Sometime earlier, I was able to get my hands on a local '49 320 short block, which had a bearing failure and had been left in the rain for years, without the head. Imagine how it looked like. I just managed to get the head of that engine, too (storaged inside). The owner wouldn't trade it for money, but would trade it for the dual-carb intake!
 
Last edited:
bronze valve guide

Hi, My name is Russell Martin from Centerville Auto, many of you may already know me from the nailhead yahoo group. Bronze guides are not something you want on a street engine unless you have roller tipped rockers. When used on a Nailhead they will be gone in 100 miles and I expect the same with the straight 8. THe best valve guide material is iron, it is hard wearing and holds oil. As far as valve seals they should never be used on the exhaust, the piston is moving up when the exhaust valve is open so it is not sucking oil in and the little bit of oil there will help lube the stem. Chevy's, Pontiac's and Ford's flood your top ends with oil to keep those cheap ball pivot rockers from wearing out so they need seals on the exhaust valves.. May parts used on racing engines have to place in a street engine and bronze guides are one of those parts.. Russ
 
Russell, thanks for your input. I don't want to question your experience with Nailheads and bronze guides, but I have to believe there's something more to it than just the material. Maybe the guides were cut too short? The straight-8 guide is miles long, as is the valve. I don't think side loading will be detrimental.

I think bronze guides have been used in aluminum heads for ages. You also have to remember that iron guides and stainless stems don't jive together. Then again, the most common stainless valves have hard chromed stems.

I totally agree with you about the seals. It's the intake guide that sucks oil. And from what I've heard, the exhaust will burn away even teflon.
 
Stock Head Flow

I promised to provide the flow specs of a stock head, so I'm trying to attach a PDF here. It's in Finnish but you'll get the picture. The retainer bottoms out at .400 lift, so that's the maximum lift we used. The flow was measured at 28" water. These numbers are with stock head and stock tulipped 1.780 intake and stock 1.450 exhaust valves. The cylinder bore we used was 3.600 which is what I'm shooting for.

Intake 134.4 cfm @ .400
Exhaust 95.7 cfm @ .400

Theoretical max horsepower = 276
 

Attachments

  • Buick-suora8.pdf
    17.6 KB · Views: 40
Since the guides are SO long why not cut them down like I do on the "Nails". Stock the "Nails" can only get about .500" lift max stock. The '66 Nail intake guides were shorter because of the seals on the intake. As the norm when I do "Nail" heads I have cut the guides an average of .125"+ during a normal rebuild. On a Race engine I will cut .225" off for intake seal installation & a lift capable of at least .675" with a seal on the intake.
 
Jyrki said:
I promised to provide the flow specs of a stock head, so I'm trying to attach a PDF here. It's in Finnish but you'll get the picture. The retainer bottoms out at .400 lift, so that's the maximum lift we used. The flow was measured at 28" water. These numbers are with stock head and stock tulipped 1.780 intake and stock 1.450 exhaust valves. The cylinder bore we used was 3.600 which is what I'm shooting for.

Intake 134.4 cfm @ .400
Exhaust 95.7 cfm @ .400

Theoretical max horsepower = 276
Click to expand...
Jyrki, you'd be surprised how much gain in flow can be had by just going to a smaller valve stem size. The norm for most all racing types nowadays is 7mm, even on 9000+ RPM Big Blocks Chevy's in NHRA Pro Stock with 2.450" size valves.
 
Spring pressure

A question to those who have revved your engines past 5000 rpm: how much spring pressure have you been running, seat & open ?
And I mean straight 320 with the stock valves or similar weight (around 120 grams)
 
Bronze Guides

buickrodder said:
Hi, My name is Russell Martin from Centerville Auto, many of you may already know me from the nailhead yahoo group. Bronze guides are not something you want on a street engine unless you have roller tipped rockers. When used on a Nailhead they will be gone in 100 miles and I expect the same with the straight 8. THe best valve guide material is iron, it is hard wearing and holds oil. As far as valve seals they should never be used on the exhaust, the piston is moving up when the exhaust valve is open so it is not sucking oil in and the little bit of oil there will help lube the stem. Chevy's, Pontiac's and Ford's flood your top ends with oil to keep those cheap ball pivot rockers from wearing out so they need seals on the exhaust valves.. May parts used on racing engines have to place in a street engine and bronze guides are one of those parts.. Russ
Click to expand...

You have to remember that all aftermarket heads are fitted with bronze guides, so they can't be that bad. Wear (due to side load) is also subject to spring pressure. And there are many different bronze alloys to choose from. That said, some VW engines have guides so short that they wear out by 100.000 kilometers
 
bronze guides for the nailhead

I think the reason the bronze guides do not last on the nailhead is they have very short rockers, they move in a tighter radius than the longer straight 8 rockers, that is why I would only use them with roller rockers on the nailhead.
 
Many early vintage engines have very poor rocker geometry, this leads to many of the issues we know of and see today, but wasn't that well known to the engineers back in the day. Many times we fail to even check the simple and basic things such as rocker geometry when rebuilding these engines, and then attach blame to things that are really not the cause of these problems when they have accelerated wear, like the machine shop or the parts when it really is bad design or the engineering involved. Most hot rods today are driven more in a years time than the average guy drove the same car when it was new 40 or 50 years ago, so these issues become apparent to us more quickly than they did 50 years ago, and were likely accepted as normal wear because it took longer to appear than it does in todays driving conditions.
 
Last edited:
valve guides

I understand what you are saying but I don't think the design was bad for the time, the valve lifts were much lower back then, some things that work on race engines do not work well on the street and bronze guides are one of them. They are not for a 100K motor and that is proven by how much longer the iron guide lasts over other materials, why fix something that is really not broke? There is no benefit to using the bronze guides, if there is I would like to know.. Russ
 
Well, with that same thinking, why is a bronze guide more desireable for a race engine? Bronze is much more costly to produce than a cast iron valve guide is, and there isn't an aluminum performance cylinder head(street or race) that is made with a cast iron guide. So what advantage would bronze have over a cast iron guide just because its on a race engine. Many times when you pull the heads off even a 50-75K mileage engine that has valvetrain issues, you not only have to replace the guides, but the valves too because the stems are worn badly. Bronze guides/liners don't wear the valve stems like a cast iron guide will, so you typically have to replace guides and valves when heads have cast iron guides. Also, the Nailhead has a common problem similar to many inlines, and that is the valve inclination is straight up and doesn't get additional oiling benefits like most other V engines where the valves are layed down at an angle. If you have ever used bronze guides in a Nailhead and had wear issues, it again could be pointed back to another problem not realized totally like oiling, or geometry, and not necessarily from what the guide is made out of.
 
valve guides

They must have less friction? like I said the short rocker arm just plays hell with bronze guides and ad a high lift cam even more so..
Race motors use forged pistons, cast will last longer in a street engine because they fit tighter and don't rattle in the cylinders when cold plus better ring seal, just because racers use them it don't make them better for every aplication..If you use bronze use roller rockers and you will be fine..
 
You must log in or register to reply here.
Back
Top