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MG TD TF 1500 - Shave the head, Pros, Cons...?

I'm sending the head to Del's for hardened seats, guides, etc.

He recommended a clean-up shave on the surface. Should I consider a bit more to raise the compression a tad?

Worth doing it? Any benefits?

How much... what is factory spec on the casting's height?
MAndrus

Mitchell. Del's in "Sacramento"? I would have them take the minimum to true the surface. Unless your building a purpose built engine i.e. Fast Road in which this would be the beginning of other mods I would leave it as close to stock specs as possible. Remember as the bore size enlarges your CR will increase without the mods. There are plenty of shaved heads out there if you want to up compression. I chose to buy forged pop up pistons instead. See the other site for a shaved head that would likely be available. Fresh work but wasnt what the customer asked for. Did you come up with a crank? I thought you had decided to do the 1500 B Series swap

Cheers

Bill Chasser
TD-4834
W. A. Chasser

It all depends on which head you have. A round-hole head came, I believe, at 75.16mm.

My feeling is that IF the head is warped, have it lightly kissed to flatten it, which will raise the compression slightly. But if it is flat, don't - that is metal you can never return to the head.

Time was, when these parts were readily available, you could do anything you wanted for no big investment; I used to buy heads all the time for less than $50, and I experimented with all different sorts of valve sizes, combustion chamber shapes, intakes, etc. If the experiment didn't work, I threw the head away.

But now they are pricier and no longer available so easily, and I err on the side of caution, and leave as much meat as possible.

Tom Lange
MGT Repair
t lange

Vale seat inserts are only needed if the valve is recessed too deeply into the head. Inserts can and do loosen up and fall out. You need to read Hal Kramers article on Tuning the t type head.
Len Fanelli

The thickness of a stock TD or TF1500 head is 3.022 in. A stock TD MkII and TF1250 is 2.962 in.

Hal Kramer's excellent article, that Len refers to, was published in the June, 2001, issue of the the NEMGTR's Sacred Octagon. Obtain, or borrow, a copy of the NEMGTR's CD-ROM.

Shaving the head down to 2.922 in. (.100" from stock TD) raises the compression to about 9:1. Personally, I can think of no practical reason to want to keep a car at the 7.25:1 level. Bud
Bud Krueger

Yes, Dels Sacramento.

Bill, I did find a magnafluxed tested crank dressed to .030/.030. About a grand shipped.

Except that the cylinders and pistons are .040 and absolutely perfect and don't need to be touched, the 'valves and rings' job has turned into the full crank and cam rebuild, budget will be about $2,600.00.

Ouch.

I'm just going to be very careful to set the con rods to avoid the problems with the bearings (other posts).

Thanks, but for now, I don't need the B engine.
MAndrus

I got 3.006, 2.994 and 2.998 in 3 places. I blame dirt for the variance. It looks like it's already been cleaned up one.

If 3.022 is stock, I'll have him leaving it alone, thickness wise.

I found a number 7 stamped into the mating surface (valve side) of the head, off to the side near the front. Maybe a marker by a previous machinist?
MAndrus

Well, if the thing isn't much out of true, a skim will take very little off, and properly done by milling will leave a surface which will grip the gasket well. If it is more seriously warped it needs the work, regardless of how much comes off.

The thing to avoid at all costs is surface grinding - that gives you a beautiful surface with no real grip on the gasket.

I've got a 4/44 head on mine and a maximum shave gave only 8.5:1 compression with flat top pistons, which is pretty much a road compression, and suits the blower nicely.

Other opinions awaited....

David
DavePro

I agree with Bill, don't shave the head unless you have to. It's easy to find heads that are already shaved quite a bit if that's what you want. I, too, went with raised pistons to achieve approximately 9.1:1 using a head at stock thickness.
Steve Simmons

I'll send it instructions to do the bare minimum. We'll see what comes back and go from there.

I like the idea of adjusting with the pistons. Mine are .040. Who sells these?
MAndrus

Mine were NOS Covmo. Not sure who makes them now but you may have to get something custom if you want to go that route.
Steve Simmons

This thread was discussed between 02/12/2016 and 05/12/2016

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