Leaded>Unleaded Conversion

[Webb Sledge]

How costly (with and without labor)/hard/time consuming is the unleaded conversion on TR3/4/5/6s? You have to replace the head gasket right? Or is it the valve seats too?

Also, wouldn't most cars that are driven in these days have to had a conversion, since it's very rare to find leaded fuel?

[ 04-07-2004: Message edited by: Webb Sledge ]</p>

 

[waltesefalcon]

Webb,

You might get some controversy over this topic as a similar one awhile back brought quite a few opinions out of people. Anyway to make the conversion just do a vavle job and make sure you put hardended seats in and use stainless steel exhaust valves then everything should be fine.

Cheers,

Walter

 

[Steven]

or save yourself the effort and use lead additive in unleaded fuel,according to instructions. STP makes a good one.

 

[Eric]

Practical Classics had a long running series of articles over the past 3 years or so on lead replacement additives, as the UK was losing leaded fuel. They commissioned testing of many products, and found the majority of them were worthless in preventing valve seat recession.

If the car is driven gently a few thousand miles a year, you can probably get away without hardened seats. If the car is driven hard, you'll definitely need them.

On any of the TR's in North America, I'd suspect they would have been done by now if they have been driven at all since the early 80's. If you're concerned, keep an eye on your valve clearances. If you are getting seat recession, your clearances should be tightening up. If they are staying the same (you wish...) or opening up, your seats are fine.

To fit new seats, the head will have to come off and be taken to a machine shop to have the seats put in. A good time to add new valves, guides and seals.

 

[Webb Sledge]

So how much money would that set me back? If it's not an extreme amount, then I think doing that once would be easier than buying a lead additive everytime I get gas.

 

[Eric]

Depends on labour, etc. I had the seats done on my GT6 - new exhaust guides, new seats, new exhaust valves - about $300 Canadian (maybe $225 American). That was me doing the re & re on the head and delivering it to the machine shop. A 4 would cost you less. You'll burn through that much octane booster in fairly short order.

 

[Steven]

6pak a TR6 group recommended the use of lead additives back in the mid to late 80's. It's not that big of a deal to add a portion of a container everytime you fill up. I've driven about 25,000 miles on a rebuilt engine using STP lead additive, and my 75 TR6 has never run better. I think its pretty cheap insurance if one doesn't want to do the valve thing. I realize there's a sizeable portion of people out there who disagree, not only with lead additives, but with any additives. I really don't care about studies of this or that....I'll stick with what works for me, and that's STP lead additive every fillup,and STP fuel/carb cleaner every time I change the oil.

 

[piman]

Hello Webb,
one point if you decide to go the modified head route, just drive the car until the car needs to have the valves done. You might be surprised how many miles you can do before you have to spend any money.
Personally, I'm running on additive (manganese based) in the UK which is also an octane booster (About 2 points) as my engine is at 10:1 compression. To date, about 16,000 miles I have had no seat recession and my car is driven hard.

Alec

 

[Geo Hahn]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by piman:
...just drive the car until the car needs to have the valves done...<hr></blockquote>

I'd have to second that -- makes $ense to do the seats when the head is already on the bench, but I've logged many miles on 2 TRs without the conversion. FWIW - I use the widely available additive CD-2: no idea if it helps but I doubt that it hurts and a pint bottle lasts 4000 miles.

My valves seem to require almost no adjustment -- maybe the seats are receding and cams are wearing at the same rate? :^)

 

[MDCanaday]

webb, one articale I read some time back by a metalurgist stated that the length of time the car was run on leaded fuel,would be roughly equal to the time it could run on unleaded fuel. He stated that the lead slowly worked its self into the matrix of the iron and took as long to work its way out before valve resession set in. I am in aggreement that there is no need, in the short term, to fix anything that aint broke. Ression doesnt ruin the head(unless severe in the extreme).So my thought is to drive and enjoy till it gets weak, then do the valves/seats.
MD(mad dog)