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All you need for a 4 barrel conversion

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M1kem3 Avatar
M1kem3 Michael Rawlins
San Antonio, TX, USA   USA
I've been reading about the crankcase ventilation and the EGR valve when doing the conversion. What in total do you need to route? (crankcase vent, brake booster, etc) How do you keep the EGR valve for example, if you want to install headers? Can anyone provide some pictures of the install? I am still confused about the crankcase ventilation. Does anybody have pictures of their 4 barrel setups with the PCV system modified? I'd also like better instructions to do the job than The Wedge Shop offers

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TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
I'd guess 75% of the TR8s on the road are sporting a 4 barrel. Google images will provide you with every picture you need. No rocket science here. Remove everything. Put set screw plugs in the air injection holes. Bolt on 4 barrel intake, carb, and air cleaner with a new valley pan. Run a vapor hose from the flame trap to the base of the air cleaner. You can try one of those K@N breathers in place of the flame trap, but that isn't always sufficient. Run your fuel lines with an inline filter. I like those see thru glass ones because you know whats going on and can clean them on the road if there is an issue. Sleeve the steel fuel line that runs down near the headers. Modify your throttle cable and make a mounting bracket with a return spring. If you want an electric choke, run switched power to the choke. Where you live, you don't need a choke. Take it off, and use your right foot as the choke for the first minute or so it takes to warm up. You reuse the front and rear water outlets on the manifold. You need to hookup the brake vacuum line. There should be a hole drilled inside the water housing in the front next to the tstat. Edelbrock forgot the fact that there needs to be some water flow before the tstat open. You could also drill a hole in the center of the tstat. If you don't provide for this, you will get a huge temperature spike before the stat opens. You will need to tap a hole in the top of the water jacket and install a nipple for the line that goes back to the coolant expansion tank. FWIW, you can buy just the intake from Summit for $262.35 and pick up a carb and air cleaner locally. The Holley 390 is the way to go, but those are more expensive than the 600. The 600 will work, but not as well. Because its cheaper, and there is more profit to be made, that is what comes in the "kit". Buy the parts yourself and keep a couple hundred bucks in your pocket, or more if you buy used stuff. I might even have a used Edelbrock intake I'd part with for 75 cents on the dollar.

ww.summitracing.com/search/department/air-fuel-delivery/section/intake-manifolds?N=4294951509%2B4294943595&SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=rover%20v8

M1kem3 Avatar
M1kem3 Michael Rawlins
San Antonio, TX, USA   USA
Thanks a lot. Woody states that he modifies the edelbrock manifolds he sells. Is his manifold's water housing drilled and does his conversion kit have every little thing included?

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TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Yep, modification is drill a hole and add a nipple for the expansion tank line. Thats probably where the $200 markup gets justified. Manifolds might even come with that tapping on the top now. Its been a long time since I bought one new. Last 2 TR8s I parted out had 4 barrels, plus I got one in a trade from one of the members of this board. That one is still sitting in the box it came in along with the virtually new carburetor and K@N filter. The nipple on the stock manifold unscrews and you can use it on the Edelbrock. There is also a bracket that holds an emission valve that can be repurposed for the throttle cable bracket. I can post pictures of exactly what you need to do, but only if you want to save the money and do it yourself. If your going to buy the "kit", then let him earn all that extra money he's charging and have him walk you thru it.

M1kem3 Avatar
M1kem3 Michael Rawlins
San Antonio, TX, USA   USA
Thanks. I would love to find some way to save money, but I really like the fact that everything comes with the kit. And the reason I started this thread is to get some more info on the routing of all the hoses and brackets.

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1301145 by M1kem3 I've been reading about the crankcase ventilation and the EGR valve when doing the conversion. What in total do you need to route? (crankcase vent, brake booster, etc) How do you keep the EGR valve for example, if you want to install headers? Can anyone provide some pictures of the install? I am still confused about the crankcase ventilation. Does anybody have pictures of their 4 barrel setups with the PCV system modified? I'd also like better instructions to do the job than The Wedge Shop offers

Michael:

Keeping the EGR with headers takes some work, so most people toss the EGR setup for the sake of simplicity, despite the fact that mileage goes down when you do.

If you really want to keep it, then any decent exhaust shop should be able to weld a bung onto the top of the number 7 exhaust tube. You would just need to do a trial fit of the header to determine the location and mark the tube. You might need to fab up a new tube to connect to the intake manifold as well, depending on the intake setup you choose.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Real world experience is such that when you ditch the stock carbs, stock exhaust, EGR, air pump, charcoal canisters, and every other so called well engineered piece of clutter stuck to the engine on a TR8 and replace it with headers, a 4 barrel carb, and even a performance camshaft, you end up with more power, and better fuel economy. Plus there is also the added benefit of being able to see the engine and work on it. Years of racing saddled with having to use the stock intake and carbs, plus having many street cars with 4 barrels at the same time, has proven to me that there is nothing you can do to the stock system to match the gains of a basic untuned 4 barrel system. There is a reason why these things came from the factory rated at 14 miles per gallon and modified ones routinely see 20 plus.

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tirebiter Jeff Garber
Dighton, MA, USA   USA
One of the very few TR-8s I worked on a bunch, many years ago, (unless my memory is totally off) usually returned about 28 MPG at it's worse and much better when driven gently. All stock ! Very tall rear axle gears does a good job for fuel economy.

The owner did not like my way of saying a 4-barrel will not add much unless a lot more work is done to the engine and it will take a while to get-it-right. He decided to take the car to another shop for the conversion. The other shop that did the conversion somehow convinced the TR-8 owner that a 650 Holley would provide MUCH more power due to increased airflow. Unless my math is wrong, the stock pair of Strombergs equal about the same amount of throttle plate area as a 650. Go figure. After about a year went by, the owner of this TR-8 called me back and asked if I'd sort out the Holley ... that had been plagued from day one since the conversion ... with very pronounced stumbling and hessitation, overall poor driveability and terrible fuel economy.

It took a while, numerous jets changes, venturies and accelerator pump linkages and nozzles but mostly a LOT of time spent on the primary/secondary linkage and power valve setting. Not to mention reworking the distributor advance cahracteristics. I was able to eventually get the stumble and hessitation 100% GONE. The expense for my time would have bought a full compliment of side drafts and a camshaft and high compression pistons. It was a little faster then stock but not readily apparent. Had to use a stopwatch to measure the difference.

I attributed the slight increase in power to the deletion of emissions controls and the now - performance oriented jetting and ignition curve. Fuel economy was marginally better when driven gently but fell off a lot more when booted all around town as fast as possible. Holleys can certainly dump a LOT of fuel into the airstream.

This TR-8 owner was not the only one I worked with, to help them understand the V-8 was small and not very highly tuned. Smooth and "always there" torque was the name of the game. Not ultimate power and speed. I always promoted the idea that if you wanted to go fast in a wedge at the least expense, all you need to do is rework a 7 engine.

All the carb "coin"versions I see I always ask, "how much hesitation and stumble does your car experience now ?" I always get an answer that has everything to do with all the ways you can use the gas pedal in order to alleviate the poor driveability. Occasionally someone will eventually admit that it's really bad after the conversion and there have been a couple of 8 owenrs who actually saved all the stuff and put it back to stock after being disheartened by all the promises of how good a 4-barrel will make the car run.

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1301347 by tirebiter
All the carb "coin"versions I see I always ask, "how much hesitation and stumble does your car experience now ?" I always get an answer that has everything to do with all the ways you can use the gas pedal in order to alleviate the poor driveability. Occasionally someone will eventually admit that it's really bad after the conversion and there have been a couple of 8 owenrs who actually saved all the stuff and put it back to stock after being disheartened by all the promises of how good a 4-barrel will make the car run.

Jeff:

My previous TR8 owner had done an Edelbrock performer/four barrel conversion and added headers. When I bought it from him, he complained that it never ran right after the conversion. I didn't ask him what he meant, since my intention was to go back to the Zeniths he included with the car.

I concur that it is difficult (but not impossible) to improve on the factory setup by simply bolting things on the engine. There is much tuning, fiddling, and in some cases totally replacing the new parts with other new parts before it all plays together nicely. Many (most?) people are not prepared to sweat all the details and re-engineering needed.

I raised the compression and put a very mild cam in my TR6, then spent a year messing with different needles and carb settings to get it to idle nicely, not foul spark plugs, and have good hot starts. I learned a lot about Zenith carbs along the way.

The casual shade tree mechanic overestimates the benefits and underestimates the work needed to get a power pop out of their motor. It is all worth it in my opinion, but it is more difficult than the hot rod magazines lead you to believe.

Cheers,

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

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M1kem3 Avatar
M1kem3 Michael Rawlins
San Antonio, TX, USA   USA
Thanks for your help. When you remove the charcoal canisters, how do you take care of the return line/vent, etc. I heard that once you remove the canisters the car starts smelling bad. Is that true?

vagt6 Avatar
vagt6 Mark K. Brown
Charlottesville, VA, USA   USA
FWIW, I purchasedg. Bone stock TR8 about a month ago that had been in storage for 30 years, driven just enough, with 39,000 original miles. Stromberg said, EGR, even has the heat shields still on it! All I've done is put Rota 15" wheels and low profile tires on it. Of course I rebuilt the Strombergs and fine-tuned the engine, got it just right, spot-on.

I've driven it about 1,000 miles. This car is fast, handles very well, and is very reliable. I've deCided to leave it alone. The stock setup is great.

Sure, more power would be nice, but the car is faster than many modern cars as it is. I also have an MGB and just sold a TR6 with a Rover V/8 conversion, and I've had many other LBCs. My TR8 is in many ways better, and faster, than most.

Before you start throwing new parts and money at your TR8, be sure you've got it tuned to perfection first. It might just be good enough!

TeeR8 Avatar
TeeR8 Gold Member Henri Lefebvre
Calgary, AB, Canada   CAN
In reply to # 1301747 by M1kem3 Thanks for your help. When you remove the charcoal canisters, how do you take care of the return line/vent, etc. I heard that once you remove the canisters the car starts smelling bad. Is that true?


There is no real advantage in removing the charcoal canister, it does not rob any power and the weight is minimal. My TR8 has a Holley 390 with the charcoal canister properly installed and vented which helps keep gasoline fumes at a minimum.



Henri
1980 TR8, Platinum
1971 MGB GT, Midnight Blue

M1kem3 Avatar
M1kem3 Michael Rawlins
San Antonio, TX, USA   USA
I want the 4 barrel for the extra power, as well as reliability and being able to see the engine and not all the clutter from "emissions effective" carbs

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1301747 by M1kem3 Thanks for your help. When you remove the charcoal canisters, how do you take care of the return line/vent, etc. I heard that once you remove the canisters the car starts smelling bad. Is that true?
Mike:

YMMV. If you leave the carbs open and the vapor line from the tank open, those fumes have to go somewhere, and if you store your car in a closed garage as I do, you will certainly notice the gasoline smell, or your spouse will. They don't cost you any power, and do something useful, so there is little reason to remove them, I feel.

Of course lots of people remove them anyway. The carbon canisters are easy to remove, and you can leave the fuel tank vapor line unconnected. The biggest concern is the crankcase ventilation line. If you leave it disconnected you will eventually have an oily mess on your hands, so you should plan on venting that back to the carb for burning. How you do that depends on the carb and air cleaner. Don't think you can just cap it off, as that will create oil leaks and/or oil backing out of the dipstick tube - so you must re-engineer it when you switch to a 4-barrel.

Likewise for the EGR valve. It can be successfully capped with little drama by getting the appropriate pipe plug. It will decrease your mileage slightly to remove it, so I recommend leaving it in and rerouting the EGR line to the appropriate port on your carb or intake manifold.

As to the power gain from a 4 barrel conversion, well, once again YMMV. The factory setup uses cold air, which most 4 barrel conversions do not have. The factory carbs flow around 440 CFM, and most people go with a 400CFM Holley or a 500 CFM Edlebrock, so getting a pop in air flow is questionable. The Edelbrock performer 3.5 manifold is superb, and you will get something there in the power department. Getting an air filter that fits is a bit of a chore, not too bad though. Choose carefully. Getting real power improvement will require some fiddling, perhaps some rejetting to get everything just right.

Converting to a 4 barrel will ultimately decrease the resale value. Stock setups are always worth the most money.

I purchased my car with a 4 barrel and headers, and went back to stock because I get tested for emissions where I live and I prefer orginality in my rides. My point here is keep all the old parts in a box, so that when you sell the next owner will be able to get the car through the emissions testing.

Cheers,

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

M1kem3 Avatar
M1kem3 Michael Rawlins
San Antonio, TX, USA   USA
Thanks a lot. I have decided to leave the charcoal canisters. What is I buy the setup as a kit from Woody? His carbs are not pre-jetted, but how do I route the crankcase vent on the carb that he offers?

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