View Full Version : no lead cylinder head conversiom

04-25-2005, 08:35 PM
Does anyone have any experience with hardened valves seats and guides?

04-25-2005, 09:29 PM
No replies yet? Well I'm sure many will follow my remarks.

The hardened seats for a no-lead head are generally added only to the exhaust ports. I've never heard of hardened guides. Generally there are choices in grades of bronze or cast iron. I polled the Mini commumity about this two years ago and got mixed answers. Racers seemed to push the bronze guides while street drivers said the original cast iron guides were OK on street machines.

Do you need to convert you cylinder head? I was faced with that question and my answer came during a rebuild for the entire engine. The old head was beyond reason to upgrade so I moved up to a later head with the exhaust seats already installed. If your engine is currently in good shape without too much wear in the guides and seats, I'd just buy RedLine additive and wait until a rebuild for other reasons becomes necessary.

04-25-2005, 09:37 PM
The rebuild started out as just the bottom end to seal the many oil leaks but grew in scope when I found a head cheap.

04-26-2005, 09:32 AM
Still no replies?

Since the engine is apart, this would be a good time to go for the no-lead head conversion. With new guides and a 3-angle valve job you'll be very pleased with how the rebuilt engine will run.

Have you considered doing any port work? If so, research this and get that work done before the hardened seats and new guides are installed.

04-26-2005, 10:05 AM
I agree with Doug, if the engine is already apart AND you put a fair amount of miles on your car, then I would have it fitted with hardened seats. I really don't think the upgrade is that neccessary for cars that don't seen much road time.

04-26-2005, 02:05 PM
I just got my engine back from the machine shop and I was going to have the hardened seats installed, but my machinist and several others all agreed that unless your going to run the car hard (autocrossing) or something, there is no need to have the seats hardened. It does require a fair amount of additional work and machining. I've rebuilt several older American engines in the past and never had the seats changed and never had any trouble. I did add a lead additive about every 3-5 fill ups, but considering I was only driving these cars in the summer for fun, I think the lead additive cost about 5 dollars a summer. Just something to think about.

04-26-2005, 06:13 PM
Driving my TR6 I annually add 2,500 miles. This is mainly in the mountains and some interstate driving. Last January I drove my TR6 from Spartanburg, SC to Charleston, SC with the local British Car Club. During the drive back the 6 was loosing power and running lousy. You could hear a difference in the exhaust and once I arrived home I checked the engine compression. # 3 cylinder compression was very low and all others within 5 lbs of each other. After removing the head and valves, the #3 exhaust seat was pitted enough to loose compression. The other exhaust seats were beginning to pit. I installed nickel chrome seats and new stellite exhaust valves. Problem solved and I will do the same modification to my AH 3000 when I get around to doing the engine. While your engine is apart I would definitely install the hard seats and stellite valves. Another member of the club on the January drive also experienced problems with his TR6 head and has also installed hard seats and stellite valves.
Mistake with annual milage... Sorry

04-27-2005, 04:56 AM
What car? TR4? I looked at your profile and hope that my response is talking about the right car.

If we're talking TR4s, the heads do surprisingly well on unleaded gas. The metal Triumph used to cast them is more resistant to valve recession than some others.

Just last week, among other things, I was discussing unleaded conversion with Ken Gillanders, Triumph Frame and Engine. He's a master machinist and has been racing and building TR engines since these cars were new. In fact, I have to remember the next time I speak with him to ask if he still has his '55 TR2. At one time, it was believed to be the oldest TR still in the hands of the original purchaser. I trust Ken's opinion since it's based upon lots and lots of experience, his own and that of the folks at Triumphtune, Racestorations, Revington TR and other highly experienced TR tuners.

All in all, I wouldn't tear apart a TR4 engine just to make unleaded gas changes.

However, that said, I'll soon be doing a major rebuild on my '62 TR4's motor and will definitely put in exhaust valve seats. It just makes sense to spend a little extra to have the job out of the way and not have to pull the head again later to do it.

Possibly of more concern than the valve seats, you might want to consider replacing the valves themselves with improved, more unleaded compatible type. These come in both standard grade and more expensive Stellite faced (hardened). Also there are gas flowed and oversize varieties available. Increased hardening, gas flowed and oversize all add to the price, of course.

If we're talking about a TR4 #21,000 (approx) or earlier, the exhaust valves have triple springs and a 3/8" stem. There are easy conversions available for both, to 5/16" stem and double springs as used on later TR4/TR4A. The primary reason for doing this is a modest performance upgrade, but it's essentially "no cost" if valves and/or springs are being replaced anyway.

Due to the close positioning of the valves in the 4 cylinder head, it's not possible to run certain oversize valves with seat inserts, or it might only be possible to put exhaust inserts in.

Intake valves don't need inserts for unleaded purposes, but might for repair or excessive wear. So, in part, the condition of the head might dictate what changes can and cannot be made.

I'd definitely suggest using the bronze valve guides in the 4 cylinder head. These provide better self lubricating properties that's necessary without the lubricating properties of leaded fuel.

If yours is an early 4 cylinder head, CT21000 approx or earlier, it uses a .55 outside diameter exhaust guide and a .50 intake guide. As already mentioned, it's easy to convert to a 5/16" stem on all valves, with the correct exhaust guides. Or, if you wish you can retain the 3/8" exhaust valve stem.

Perhaps you've already considered these, but here are a few more things to think about regarding the rest of the valve train:

Are you doing any work elsewhere? Cam, followers, pushrods, rockers, springs?

Briefly, cams can be hardened to help reduce wear, especially during break in. Properly lubricated and broken in unhardened cams seem to last pretty well, though. If using harder cam followers, a hardened cam becomes more critical. Ken now offers GT40 followers with special shims that seem to solve many problems. In the past, various hard metal followers were tried and largely just accelerated cam lobe wear.

For my car, I've got a set of standard size, phosphated followers that will be used with a freshly re-ground and hardened, slightly-more-aggressive-than-stock cam shaft.

Also consider what pushrods you'll use. Tubular are available, are stronger than stock, plus are lighter and less prone to flexing. They can also be more easily shortened to the exact requirements of an engine that's had the head skimmed a bit to increase compression (my car's head has been trimmed .125"). Tubular pushrods are highly recommended!

The rockers themselves should be refaced. That's precision machining to put just the right shape on the end that wipes the valve stem end, to keep wear and sideways pressure to a minimum. (I plan to use roller rockers for this reason, that's another alternative.)

Check for any play in the rocker shaft and/or rocker bushings that ride on it. Replace any parts with wear, or abnormal movement can make short work of new valve guides.

I understand there are some pretty poor replacement valve springs out there right now, for 4 cylinder TRs. Apparently they are pretty "soft" and mismatched, even brand new from the box. Watch out and have any you buy tested.

Many 4 cylinder TR racers question the need for heavy duty valve springs. There seems to be little or no problem with the stock rated springs, even at high rpm. Heavier springs are used in some modified engines to prevent "valve bounce". But, that doesn't seem to be a problem with TR motors. Heavier springs seem to just increase wear on cam lobes.

It is also important to watch out for valve spring bind. That's especially important with increased lift cams and/or higher ratio rockers. Stock ratio is something like 1.45:1, although 1.5:1 is often considered stock replacement. Some are as much as 1.6:1 and might lead to problems. Generally consensus seems to be to stick close to stock with 1.5:1 and have any increase ground into the cam. Still, there is apparently only a few mm of free space in stock type springs, so they should be checked against any increased valve movement.

Hope this helps!