Project: TR7 part 10 — The big bill comes due

Jack Maurer at Automotive Machine inspects Project TR7s cylinder head.

Project: TR7’s cylinder head needed quite a bit of work after all. And, not surprisingly, it will be the most expensive part of returning the car to the road.

I use Automotive Machine — — a local Detroit-area shop that is just as comfortable working on a Chevrolet LS1 as it is a TR7. Two of the exhaust guides were worn out of spec. I had them all replaced with bronze guides, which are supposed to reduce friction and help the valves run a little cooler. The TR7 head needs all the help it can get, so even a minor upgrade could pay dividends. The bronze guides were twice as much as the stock ones but should never again need replacing.

Bronze valve guides about to go in

Three helicoils were installed in the exhaust port flanges, the valves were given a three-angle grind and the head needed to be milled 0.007 of an inch to be made completely flat. The machinist also milled the exhaust ports. The head came back looking like new, but there was still work to do.

The TR7s head is reconditioned and ready to go another 40 years.

Installing the new cam and adjusting the valves was a time suck.

On my workbench, I installed Project: TR7’s mild performance cam, which is supposed to deliver a little extra kick at around 3,000 rpm. That job took a fair bit of time and effort. Underneath each tappet resides a dime-sized shim. The valves are adjusted by changing the thickness of these pallet shims — thinner to increase the gap, thicker to decrease the gap. Sounds easy enough, right?

But it took me at least eight go-rounds of installing the cam, measuring the gap between the cam lobe and the tappet face, removing the cam, changing the shims and reinstalling the cam and measuring again — wash, rinse, repeat — to get all the valves set properly.

The oil pan looked pretty beat. …

But it cleaned up well …

and looked pretty good after painting.

Other engine-related projects included cleaning and painting the oil pan, cleaning the front cover and installing a new timing chain, tensioner and guides. A German company, Iwis, makes a premium nonstretch 106-link chain for a Mercedes that also fits the TR7. It’s expensive, but I bought one.

Dirty timing cover

Timing cover is clean and a new seal installed

One of the best upgrades for a TR7 engine is a set of ARP cylinder head studs and bolts. They won’t seize. They won’t rust. They won’t break. And they take more torque than the stock studs, so the head can be mated tighter to the engine. So, 40 years from now when the next idiot takes apart Project: TR7, he’ll thank me.

Upgraded studs should improve the TR7s weak cylinder head sealing problems.

New old stock gaskets are the best you can buy today.

Although eBay has lost a lot of its luster in recent years as it tries to compete with Amazon, every now and then you can still find great stuff. I picked off an NOS Unipart cylinder head gasket set and an NOS set of Vandervell rod bearings, the exact same ones installed at the factory. These are good parts, too. Toward the end of the TR7’s production run, British Leyland realized it was going to have to spend money for quality parts from top-tier suppliers if it was going to make the TR7 more reliable.

NOS Vandervell bearings are a perfect fit.

The bill to recondition the cylinder head — the weakest part of the car — and replace the timing chain, install the new high compression pistons and a new set of rod bearings, and related parts, totaled $1,172 and looks like this:

Machine work: $390
Performance camshaft: $145
ARP head stud set: $89
NOS gasket set: $39
Bronze valve guides: $60
Timing chain and parts: $56
9.35:1 pistons: $281
Vandervell bearings: $20
Piston rings: $70
Two new motor mounts: $22

One minor snag drove up that price: I broke a piston ring. And because no one sells just one ring, you have to buy a new set. While the cylinder head and engine work left a sizable dent in my checking account, the radiator rehab didn’t inflict much further damage. Mel, the Ferndale Radiator King of Cooling, cleaned Project: TR7’s radiator, pressure tested it and declared it good.

The radiator looks good as new thanks to Mel.

He didn’t charge me for it. Believe it or not, that’s one way he stays in business. He often doesn’t charge for the small jobs because he knows customers will come back for the big ones.

Project: TR7’s engine went back together fairly easily and without major drama, if a little slower than I planned.

High compression pistons look good in their bores.

NOS cylinder head gasket hopefully will seal tight.

The German timing chain should be the last one the engine ever needs

Remember the missing ball bearing from the Head Honcho? Well, it wasn’t in the engine. I discovered it wedged in the left-side engine mount bracket when I was installing a pair of new motor mounts. That’s a huge relief. With that concern off the table, I began getting ready for the last big job: pulling the transmission to replace the rear main seal and clutch.

The missing bearing is finally found.

Engine reassembly went smoothly.

And that’s when a funny thing happened that set me right back to where Project: TR7 began, but we’ll have to save that for next week.

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