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TR6 TR6 Engine Questions

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bigbadbluetr6

bigbadbluetr6

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Now that I've came to the concusion that my head gasket is causing my false heating problem I have figured it is time to take the head off and replace the headgasket and do some head work. I'm planning on plaining the head to get some compression back into the engine and put my tri carb set up on the car. So my question is what can I do to besides plaining the head? Can I put bigger values in the head? Keep in mind I will just be doing the head and leaving the stock cam and crank in. What is everyones experience and opinion on doing this work? Thanks
 
Hey Eric,

There's lots to do with the head. First measure the height of the head to determine if it has been milled to raise compression. Since your car is a 73 model year, the compression stock is 7.75:1. The head should be 3.550" thick. Plenty of material to remove to raise it to 8.5:1 (3.460" thick) or up to 9.5:1 and still be very streetable.

I would suggest bronze valve guides, larger SS exhaust valves ( BPNW has a good price but try wishbone classics too) , tubular headers, a good valve job (three angle) and some mild porting/polishing. You can spend very big money on head work but the idea for a street car is to get your money's worth in reliablilty as well as performance. These changes will definitly be felt in the seat of your pants with out affecting engine life ( unless you drive like me /ubbthreads/images/graemlins/nonono.gif .)

I'm not a fan of replacing the valve seats unless they show absolute wear or recession. Most of the later models came with hardened valve seats anyway. I know many owners like to install valve seals but I have never found the need to starve the valve stem of oil. If the guides are done right there's no reason for the seal.

If you need to have the rocker arm assembly rebuilt I am a big fan of Rocker Arm Specialist. Great work. They rebuild the rocker arms and install bronze bushings along with a new hardened shaft.

Have fun
 
While I pretty much agree 100% with Mitch about the upgrades, honestly if you are leaving the stock cam in I wouldn't bother with any of them except perhaps the head skim, and that only because it's off and it is a cheap job.

The power gains are going to be pretty small with the stock cam, compared to what you can get by changing that out too. You shouldnt need to touch the bottom end if the car is solid. The best you'll get on triples is going to be about 175hp, that's going to take extensive mods and a cam change, and the stock pistons/rods/crank are still fine for that.
 
Thanks guys. The plan is to do this job as cheap as possible. I'm in college and would like to get a little bit more power out of the engine. I need to keep up with old dad. He is building a supercharged motor for his bugeye.
 
Eric,
If you are on a budget and want to have a nice TR6 to cruise around in, I would suggest going back to stock and not shaving the head. This said, you stated that you will put on your triple carb setup. Is this something that you already possess? My reasoning is: simply shaving the head without adding a cam, new pushrods, roller rockers, port-polish-flow....I say save the monies and enjoy a spirited TR6 which normally has plenty of power for fun. I just hate to see a performance engine that is only partially done and the owner tending to be disappointed.

My thoughts.


Bill
 
I already have the manifold for the tri carb and an extra carb to go on the car. I know if I plain the head I will need to get new pushrods. Would I also have to get new rockers? I might do some port polishing but nothing extreme. I'm going to be going through Kent Prather with all this. Even though he doesn't know much about TRs he knows about engines. I know a guy that has a pretty stock engine except has shaved the head and put on the tri carb set up. I haven't really talked to him about this yet either. I was just wondering what other people think. My thinking is that while the head is off I do something of these changes and make the engine a little closer to the overseas version and a tr6 that should have had 3 carbs to begin with.
 
Assuming you have good compression and no problems with a leakdown test, you can put in a cam - say for the sake of argument a GP2, add new or reground lifters - and do nothing else.

Thats going to give you the best bang for the buck with the carbs. By far.
 
hello Eric\Alan,

I agree with what Alan says above except that if the compression is 7.5 then I would go for getting that increased, and yes it does need the shorter pushrods. The rest of the rocker gear is fine.
I'm a little surprised at the 175 hp estimate, that takes quite radical changes I believe. One other thing not mentioned is the exhaust manifold, as a six-three-one or two makes a difference but they are not cheap.

Alec
 
It does - that's pretty much the max you can get out of it and still have it streetable. I was looking at a TR6 last week that the guy has 8k into the engine, running on triple SUs and only gets 165hp on an engine dyno.

I threw out the # to point out that the bottom end is fine even at that sort of power level (at least below about 6k rpm).
 
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