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Horsepower Gain
- Thread starter Stretch
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GregW
Yoda
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Hi Jerry,
With the cam I’m using, I had to relieve the block under the exhaust valves with the 1.55:1. Gary at Rocker Arms said that with the 1.6:1 rockers, you also had to widen the holes where the push rods go through the head. On the outboard side. I passed on that one. /ubbthreads/images/graemlins/tongue.gif
With the cam I’m using, I had to relieve the block under the exhaust valves with the 1.55:1. Gary at Rocker Arms said that with the 1.6:1 rockers, you also had to widen the holes where the push rods go through the head. On the outboard side. I passed on that one. /ubbthreads/images/graemlins/tongue.gif
Lots of great info. GregW and D Russell, thanks for plotting the estimated HP/torque diffferences between the various cams. Looks like the BJ8 cam is best for my purposes. Since the BJ7 outriggers need to be changed to use the 2in. exhaust system I think I'll try adapting headers into the existing BJ7 exhaust.
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Hi DT,
My experience is that the only down side of many DW products is that they don't fit without "some modifications". On the BJ7 exhaust to quote DW "the left front outrigger cut-out must be to the BJ8 size to suit under floor silencers". Not a really hard task, but does require some cutting & welding.
A further illustration, the DW headers on my BN2 required some hot bending & reshaping of the tubes to get things to fit into place. I also added a flex section ahead of the muffler to prevent engine torquing induced contact of exhaust parts with the body structure. The end result WAS worth the trouble though.
The DW & other headers do not incorporate the original flex sections in the down pipes. I would consider adding high quality braided/bellows flex sections to the down pipes ahead of the muffler. This reduces mechanical vibration & removes a lot of the strain on the rest of the rubber flex exhaust hangers which have a tendency to break the rubber bond. Also use high quality rubber hangers. Some hangers tend to separate/delaminate more easily. The flex sections from JC Whitney have been previously discussed.
Most modern cars have enough room around the exhaust system to prevent exhaust to body contact with very flexible hangers & don't need the flex pipe section. -- Not the healeys.
If you chose not to use the flex sections, be prepared to have spare rubber hangers or baling wire for emergency replacements. I think that high quality "Mikalor" exhaust clamps have already been discussed.
D
My experience is that the only down side of many DW products is that they don't fit without "some modifications". On the BJ7 exhaust to quote DW "the left front outrigger cut-out must be to the BJ8 size to suit under floor silencers". Not a really hard task, but does require some cutting & welding.
A further illustration, the DW headers on my BN2 required some hot bending & reshaping of the tubes to get things to fit into place. I also added a flex section ahead of the muffler to prevent engine torquing induced contact of exhaust parts with the body structure. The end result WAS worth the trouble though.
The DW & other headers do not incorporate the original flex sections in the down pipes. I would consider adding high quality braided/bellows flex sections to the down pipes ahead of the muffler. This reduces mechanical vibration & removes a lot of the strain on the rest of the rubber flex exhaust hangers which have a tendency to break the rubber bond. Also use high quality rubber hangers. Some hangers tend to separate/delaminate more easily. The flex sections from JC Whitney have been previously discussed.
Most modern cars have enough room around the exhaust system to prevent exhaust to body contact with very flexible hangers & don't need the flex pipe section. -- Not the healeys.
If you chose not to use the flex sections, be prepared to have spare rubber hangers or baling wire for emergency replacements. I think that high quality "Mikalor" exhaust clamps have already been discussed.
D
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Hey DT,
I like the JCW flex pipes just fine. I do get the high quality Mikalor clamps from Denis Welch, UK. There are lots of similar clamps around but not as good, IMO.
D
I like the JCW flex pipes just fine. I do get the high quality Mikalor clamps from Denis Welch, UK. There are lots of similar clamps around but not as good, IMO.
D
B
BUNDYRUM
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Hello Money Pit, I just found this site the other day and haven't had time to check it out and e'mail the company with questions. www.epiflex.com click on ultra flex. Regards, BUNDYRUM.
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DT,
Two inch flex would be the inside diameter of the flanges to fit over a two inch OD pipe. The main flex part is about 3/4" to 1" larger diameter than the pipe size. The flex should go in a somewhat straight section of the pipe ahead of the muffler. You will need to remove a section of the head pipe - pipes to fit the flex in. Select a length & location that fits easily. Probably something similar to the original factory flex pipe location. The flex can be welded in or in my case, I slit the flex flanges & used Mikalor clamps.
If you don't have the original, see the pic here:
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=28861
You can see JCW flex couplers here:
https://www.jcwhitney.com/autoparts/Brows...0012761/c-10101
Likely your local specialty car parts store or muffler shop will have something in stock that will work just as well. Check around a bit. What you are trying to do is duplicate the original factory setup with much higher quality flex sections.
D
Two inch flex would be the inside diameter of the flanges to fit over a two inch OD pipe. The main flex part is about 3/4" to 1" larger diameter than the pipe size. The flex should go in a somewhat straight section of the pipe ahead of the muffler. You will need to remove a section of the head pipe - pipes to fit the flex in. Select a length & location that fits easily. Probably something similar to the original factory flex pipe location. The flex can be welded in or in my case, I slit the flex flanges & used Mikalor clamps.
If you don't have the original, see the pic here:
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=28861
You can see JCW flex couplers here:
https://www.jcwhitney.com/autoparts/Brows...0012761/c-10101
Likely your local specialty car parts store or muffler shop will have something in stock that will work just as well. Check around a bit. What you are trying to do is duplicate the original factory setup with much higher quality flex sections.
D
B
BUNDYRUM
Guest
Guest
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Hello Money Pit, you may end up having to e'mail the people at epiflex to get the outside diameter dimentions of the flex area. If the diameter is too large the two flex pieces may not go side by side as per the original but may have to be staggerred. You can choose whatever length of flex you want but a good guide would be the original length or something close to it. You could actually get away with using a length of flex shorter than original based on the fact that this flex seems to be of a better quality than the original so it may not need to be the same length as the original. This may work in your favor if you have to stagger the flex pieces as per my earlier suggestion.Because it's your car the best part is deciding for yourself, "with a little help from your friends". Regards, BUNDYRUM.