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TR4/4A TR4a Head

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Alex_McMillin

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Hello,

I have a spare (TR4A) engine and was wondering if the head from the TR4A is interchangeable with a TR4 block. Has anyone ever just had the head rebuilt? Or should I be rebuilding the whole engine? I was hoping to spread out the cost somewhat. So, along those lines, what's the cost of rebuilding the TR4A head vs a complete (stock) engine rebuild? The engine currently in my TR4 runs pretty well and has good compression in all cylinders. I just thought I'd like to freshen things up a little. What's the general concensus? I'd appreciate any and all advice.

...........Cheers, Alex
 
Yes, it will fit and work fine; in fact the 4A head is sometimes used as a performance upgrade for the earlier TRs.

I did a rebuilt head without doing the short block; nothing particularly wrong with that. I went kind of overboard with the head rebuild, with oversize valves, hardened exhaust seats and so on. ISTR it came to around $1000 including the rocker shaft (but that was quite a few years ago, it probably would cost more today).

However, that's not where I would start to just "freshen" things a little; unless you have a specific problem (like a burned valve), then IMO a worn head has relatively little effect on performance. New rings & rod bearings provide much more "bang for the buck" IMO.

Watch out that you get components that match. For example, the later TR4 and 4A took different exhaust valves and guides than the earlier TR4 did. There are also different valve spring sets, some of which need different pedestals under the springs.
 
I just refurbed a 4A head for the 3A engine I'm building. As a guess, it was about $300 machine shop work for new guides and hardened seats plus skimming the head. That and about $150-$200 to have the rocker arm assembly rebuilt so all in about $500.
 
Thanks for the advice and info. I would prefer to rebuild the whole TR4A engine and plunk that in and know exactly what I'm starting with. I am also curious about taking advantage of some modern day technology, particularly ignition. I know a lot use pertronix, but what other options are there? Please keep the opinions coming. I appreciate it.

......Alex
 
Alex
I have an Excel spread sheet that has all of my specs and aftermarket stuff for the race car with build budgets, racing clearances and a lot of helpful stuff.
I'll send a copy if you like.
Jim G
RMVR # 102
 
I went with pertronix and a high performanc coil as well as having the head rebuilt. my engine guy (bruce begley) felt the pistons, rings cam and crank were fine. so just my two cents.
 
Jim, I would be very interested in seeing your info sheet.
With regards to the pertronix unit, how much fiddling with timing is involved?
 
Alex_McMillin said:
Thanks for the advice and info. I would prefer to rebuild the whole TR4A engine and plunk that in and know exactly what I'm starting with. I am also curious about taking advantage of some modern day technology, particularly ignition. I know a lot use pertronix, but what other options are there? Please keep the opinions coming. I appreciate it.

......Alex
Click to expand...

I run points (no condensor) and an MSD6 unit w/blaster coil. You get the hot mult spark. I've always liked the MSD box's.
The points last forever as pitting is a result of low spark. I usually change them out every other year and they still look great. No need to worry about dwell/gap much either. As long as they open/close it'll run fine. I hide the box in my glove compartment.
 
Modern Day Technology ? I have some of that
I use the 1-2-3 programmable distributor and it works great.
I can dial in a timing curve for any track or altitude.
( I live at 5200') We run 36 - 38 degrees advance up here.
I also use the Mikuni HSR 45 carbs which were designed as a direct replacement for the SU's. They flow the same as Weber 45 DCOE's but you can dial in the jetting in an afternoon.
After that just forget about em. They never screw up.
Also, 1/2 the price of webers.
Another bonus is I can have a carb off the car and in my hand in just over one minute.
I use the MSD 7AL-2 ignition with the 1-2-3 distributor.

Jim G
 
jimg said:
Modern Day Technology ? I have some of that
I use the 1-2-3 programmable distributor and it works great.
I can dial in a timing curve for any track or altitude.
( I live at 5200') We run 36 - 38 degrees advance up here.
I also use the Mikuni HSR 45 carbs which were designed as a direct replacement for the SU's. They flow the same as Weber 45 DCOE's but you can dial in the jetting in an afternoon.
After that just forget about em. They never screw up.
Also, 1/2 the price of webers.
Another bonus is I can have a carb off the car and in my hand in just over one minute.
I use the MSD 7AL-2 ignition with the 1-2-3 distributor.

Jim G
Click to expand...

Can you post a pic of your set up, sounds interesting
 
Alex, if fitting a TR4A head to your TR4 block, you should also fit a matching TR4A curved branch inlet manifold, and preferably the HS6 SU carbs. Early TR4A's had Stromberg carbies which some find harder to tune than SU's.

TR4A heads and inlet manifolds have smaller diameter inlet ports than the TR4.

In reconditioning the TR4A head the main things to look for are surface cracks, a flat deck and no burnt exhaust valves. Sometimes all that's needed is a valve grind.

When swapping heads make sure the liners aren't disturbed. They must be clamped down (see workshop manual) before turning over the engine with the head off.

Regards,

Viv.
 
prb51 said:
jimg said:
Modern Day Technology ? I have some of that
I use the 1-2-3 programmable distributor and it works great.
I can dial in a timing curve for any track or altitude.
( I live at 5200') We run 36 - 38 degrees advance up here.
I also use the Mikuni HSR 45 carbs which were designed as a direct replacement for the SU's. They flow the same as Weber 45 DCOE's but you can dial in the jetting in an afternoon.
After that just forget about em. They never screw up.
Also, 1/2 the price of webers.
Another bonus is I can have a carb off the car and in my hand in just over one minute.
I use the MSD 7AL-2 ignition with the 1-2-3 distributor.

Jim G
Click to expand...

Can you post a pic of your set up, sounds interesting
Click to expand...


I have some up my face book page.

Jim G

https://www.facebook.com/home.php?

try this
 

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What's a Face book?


We are kind of technology backwards here :jester:
 
DNK said:
What's a Face book?


We are kind of technology backwards here :jester:
Click to expand...

It's when you fall asleep on the couch reading and the book falls across your face.
 
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