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MG TD TF 1500 - head mods for unleaded fuel

ok guys give your thought on
1. running unleaded in unmodified car (ie additives)
2. best mods to head to allow for the use of unleaded with no addedtives
cheers
hayden
h smith

Hayden - I have been using unleaded fuel in our TD for twenty years now, with no modifications to the head. To date, there has been no detrimental effects. I know that eventually, the valves will dig their way into the seats and at that time, I'll have hardened seats installed, but I am not sure that's going to happen in my lifetime. My philosophy on this is that Valve jobs are cheap as compared to the modification to the head, so why rush into it. Cheers - Dave
David DuBois

Hayden, this is probably one of the most asked about issues on this board. I'd suggest that you might want to search the archive under 'unleaded' and look at some of the many threads. BTW, I thoroughly support Dave's philosophy.
Bud Krueger

Hayden, I ran unleaded with no modifications for years. I switched to a lead substitute for a few years, but thought it made the valves sound noiser (probably my imagination, those things can be noisy for a lot of reason, including the way the were built!) And the last few years I went without the substitute, buying leaded fuel when I could at the little independent down the block.

When it came time to rebuild my engine I opted to have the valve seats hardened since I wouldn't have the cushion of the old lead running with new valves and reground seats. Incidently, only the number one exhaust valve was shot, the rest were useable, but I decided to replace the valves at the same time. I also went to the bronze guides, and was careful to ream them to the proper size for expansion. The cost to do all of this was included in the US$1100 I paid to have my machine work done, including balancing the crank and clutch assembly.

I hope this is helpful,

warmly,
dave
Dave Braun

another thought on this subject. i have gone through three old motors recently. two of which had ONLY been run on leaded gas and have been idle since before lead was removed. one engine had 47 thousand miles and change,the other motor had 42 thousand miles and change. BOTH had valve seat recession! the XPAG, which has been on the road continuously since built had mild valve seat recession. i can't say for sure when the recession occured on the XPAG, but ALL of the valve seat recession occured in the terraplane engines while running on LEADED fuel. as everyone knows, lead was added to raise octane number. it only became credited with being a lubricant when the government outlawed its use. i thought you might be interested in my experience. sincerely, tom
tm peterson

I got a call last summer, from a gal who has a TF.

About 4 years ago she faced the same dilemma as Hayden. At that time, I urged her to install the inserts but she chose to ignore it.

When putting the car on the road for the summer, she had a lot of trouble getting the engine to catch and so took a compression test. the highest was 75!

... removed the head and guess what?

She had to put in the inserts anyway, and considered herself lucky that she hadn't damaged it beyond repair.

Is it worth the risk?

As an aside, with today's modern fuels, its probably a good idea to advance the distributor a couple of degrees over the factory (reccommended) setting to let the engine run a little cooler, which in turn, should be of help to those that also ignore the use of valve seat inserts.

Gord Clark
Rockburn, Qué.

Gordon A. Clark

I put the hardend valves in my car when I did the engine overhaul about 5 years ago. HeadWorks in Bloomington MN did the job for about 400.00 including the guides but I bought the Moss Valves. They wanted to install thier own guides. I have had no problems and am glad I did it because running the additives seemed to result in fouling and smoke prior to that. IMHO I would go with the new valves while the engine is apart.
Tom

Sorry to bore those of you that have heard me on this "soap box" again....but for those that haven't :
Check out :
http://www.ttalk.info/picture_this.htm#JetHot%20coated%20manifold
Every car I have done this to has decreased operating temp by about 20 degrees ....
Takes about a week, about $100, and very little work, and looks better than a rusted exhaust manifold!
No, I don't work for JetHot! I just believe in it!
Cheers,
David 55 TF1500 #7427
David Sheward

I just had my TF 1500 engine overhauled at 32,000 miles after a blown freeze plug and a blown head gasket. It was rebuilt, stage 2 tuned, ported and polished in 1986. It has been run on US unleaded from then to now. Standard valves were uses and seats just ground.

Bob Wagner, who rebuilds vintage race engines, reported that in my engine no recession at all, and that he does not reccomend installing valve seats for unleaded gas. His experience has been that in the race and stock engines he has rebuilt that the stock iron heads don't need seats to run on unleaded. Any valve seat recession he has seen in many rebuilds was due to running too lean.

He says his experience has been that the "unleaded gas recession" in standard heads is a myth. He does NOT reccomend it on XPAG/ XPEG, or MGA/MGB engines. Far more harm comes to the engines from a dropped insert.

Do a proper valve job, and tune the engine right (NOT too lean), advance the timing a bit, and keep it cool!
Don Harmer

Out of curiosity, has anyone on this board ever dropped a hardened seat?
Evan Ford - TD 27621

Hayden

I have been running my TD on unleaded for 25 years. The head was just revisited when I put it on my current motor (rod bolt let go on the old one).

Mechanic said the head was perfect. Valves were fine. He also did not recommend putting in the hardened seats.
Bruce Cunha

I agree with Don Harmer. I had a 1954 TF that I rebuilt the engine with standard valves and seats. 66,000 miles later I replaced the head gasket as it was weeping a bit. I hand lapped the valves at that point and there was zero recession. I drove it as hard as Don has and it was constantly at 4400 RPM on the freeway for many hours.Grant you Don is in a hilly area and I am in Flatlander Florida, but I think that a properly cooled XPAG will not have valve recession in standard form.
Just my two cents for what it is worth.
Sandy Sanders

Hi Don. will you be at the GOF in Crystal river next month?
Sandy Sanders

This thread was discussed between 02/03/2006 and 03/03/2006

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.