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TR6 Rebuilding TR-6 Engine - Questions, Questions...

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davidk

davidk

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After many band aids on the stroked GT-6 engine that's in my '74 TR-6, the oil pressure has finally gone to low to put it off any longer. I picked up a '74.5 block two years ago. It's at the machine shop, and looks pretty good. The questions:

Cam bearings? - I will be using a more agressive cam, and was planning on cam bearings. The machine shop says the existing cam bores are in excellent condintion and can be used as is. The head was rebuilt last year with 9.5:1 compression ratio. Are the cam bearings worth about $400 in labor and parts?

Headers or stock exhaust? - Moss has a 6 into 2 header for about $420 plus coating plus welder for installation. I've heard this can gain up to 10 hp. It can also be done later. Is it worth it?

Cam? - I'm considering the TSI TSI275-6 or the GP2 cam. Anyone had any experience with either cam?

Timing chain? - Anyone know of a source for a heavy duty chain? The gears were in good condition.

Pistons? - Are AE worth the extra money (over County)? I'll be going .020 over.

I've got to pull the existing engine to provide the flywheel and clutch for balancing, so it will be a couple of weeks before I do anything. I'm sure more questions will be coming. Thanks for your help.
 
David,

You can start here and work your way down the left side of the home page:

https://www.74tr6.com/machiningblock.htm

Yes to cam bearings, IMHO, and the details are all in the links above.

New chain and gears on a rebuild....and tensioner.

I went with AE pistons.

Aluminum flywheel and complete balance of rotating mass, including clutch.

I went with TH5 cam from BPNW.
 
I would not buy a 6-2-1 header. Only buy a good equal length 6-3-1. You might need to look around. There is a big difference in how well they work. IMHO
Rob
 
I trusted my machinist when it came to evaluating what machine work was needed. He has been an auto machinist for 52 years. He said that he had no objection to taking my money for all kinds of work, but he was greatly impressed with the condition of my engine that had about 107k miles. His offhand remark was that at the rate of wear that he measured, I could rebuild the engine 3 more times. It's an overused expression, perhaps, but they don't build 'em like that anymore.
He did convince me to install new standard size pistons. I went with County Brand pistons and Deves rings. I'm no racer, and the machinist was perfectly happy with their balanced weight.. So, if you trust your guy and he has the experience to back up his judgement why not go along with his opinion ?
If you don't trust his ability, then the engine shouldn't even be in his shop.
A good machinist sees more engines from the inside in a week than most of us do in decades.
Now keep in mind that my wishes were to rebuild the engine as stock, no performance upgrades; so YMMV.
 
I too went with County pistons. When I had the engine bored, the machinist of course had the pistons, and also when asked, said they were built well. Before I installed them, I checked their weight. A bit heavier then what came out, but all were equally weighted.

As I have opined elsewhere, I won't comment on cam bearings... :devilgrin:
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

I'm guilty of posting in favor twice. :angel:
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

Different machinists, different ideas. My guy told me to install cam bearings only if necessary. He said that typically the casting doesn't wear out.
I'm going with an Isky Z-19 cam.
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

All I did was shave the head 100 thou (approx 9.00:1 CR), put in a TH5 cam same one as Brosky's, changed all the bearings and piston rings and it's great, no headers, no cam bearings, but a lot more power. Only downside is the idle has to be set around 1000 rpm to keep it reasonably smooth.
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

Thanks for the input guys. Spent the afternoon pulling out the radiatior and everything around it. Trying to take lots of pictures and label everything for re-assembly. Anyone have a source for .020 over Deves piston rings?
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

BPNW??

And Graham, my idle has to be at 1,000 too. No big deal.
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

Thanks Paul!
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

davidk said:
Anyone have a source for .020 over Deves piston rings?
Click to expand...

Excellent choice, IMO. Have you checked BPNorthwest ?
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

Thanks PB. Yes, their website shows they have them.
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

Paul, on your website, you used ARP rod bolts and there's a comment that you had to have the caps modified to accept the ARP bolts. Why did they have to be modified? Thanks, David K.
 
Re: Rebuilding TR-6 Engine - Questions, Questions.

David,

They had to be machined a bit to allow the larger head size to fit onto the rod caps as shown here.
 

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