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Learning how to build Lotus Seven replicas...together!
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PostPosted: June 14, 2021, 6:58 am 
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Nice welding job welding without heat affecting the banjo braze. I’d pressure test with air and soapy water like you would for a tire leak but higher pressure to check the weld for porosity that could allow fuel to escape.

The tab on the banjo prevents vibration and the weight of the arm from loosening the banjo bolt. You can add a support clamp or flip the tab to lie against the flat on the rail.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
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360LA 442E: 134.5x46x15
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PostPosted: June 15, 2021, 1:05 pm 
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Nice machining and fab work. I really wish I had a lathe when I did my Locost.


Johnsinski wrote:
I think it'll work great after I make another one with 18 TPI instead of 14, ugh. Apparently, on the mini lathe, if you accidentally install the 40T gear where the 45T goes and vice versa, you get 14 instead of 18. :oops:


#1 reason I sold my modern import lathe and got an 80 year old American machine - much more difficult to make that mistake on a quick change gearbox.

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PostPosted: June 17, 2021, 3:11 pm 
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This is my general layout for my fuel system. Only the regulator is mounted right now. Should any of the other tanks be rubber mounted? I was thinking angle iron and rubber for the big one, the surge tank has flanges with holes.

The 4 gallon (far) has 2 lower fitting and 2 upper fittings one of which has a ball check valve (it looks like). Is the ball check for a vent line?

I want to get a filler tube that ends up near the regulator in that frame triangle.

As I have it the return from the regulator goes back to the surge tank. I will have another return line from the surge tank back to the main tank. Is that right?

Where I live I can dig 2 feet down and get nice clean sand. I was thinking about making a sandblaster to maybe clean the frame for priming, there are a lot of tight corners that need cleaning.


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PostPosted: June 17, 2021, 4:08 pm 
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Johnsinski wrote:
This is my general layout for my fuel system. Only the regulator is mounted right now. Should any of the other tanks be rubber mounted? I was thinking angle iron and rubber for the big one, the surge tank has flanges with holes.

It is a good idea to isolate the aluminum tanks from the steel chassis but not required. I’d use two ½ inch straps with a one inch angle frame and tire tube or other rubber around the inside of the angle. You could fit a thin rubber gasket under the flanged tank if you want.

The 4 gallon (far) has 2 lower fitting and 2 upper fittings one of which has a ball check valve (it looks like). Is the ball check for a vent line?

Yes. That is a roll over valve. The vent pipe should loop above then come back down near the bottom of the frame. Add some window screen around the end with a zip tie to prevent insects from blocking the pipe.

I want to get a filler tube that ends up near the regulator in that frame triangle.

As I have it the return from the regulator goes back to the surge tank. I will have another return line from the surge tank back to the main tank. Is that right?

Yes. The pump tank should have a vent line at the top that overflows to the main tank for when the regulator is returning more than the engine is consuming.


Where I live I can dig 2 feet down and get nice clean sand. I was thinking about making a sandblaster to maybe clean the frame for priming, there are a lot of tight corners that need cleaning.

Home Depot sells a metal prep (phosphorus) concentrate by the gallon you mix with water in a spray bottle that works great. Spray as needed to dissolve rust, dry, scuff, paint.


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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: June 23, 2021, 2:56 pm 
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Ok, I'll try to find the rust cleaner, thanks.

Some exhaust tubes finally arrived. I've been trying to CAD it up, and I'm finding it a bit difficult. But this is what I've come up with. Each side is 2 into 1 and each will go out through the frame and then to a muffler. Seem ok?


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PostPosted: June 23, 2021, 4:41 pm 
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https://www.homedepot.com/p/Klean-Strip ... /100406369

If you must have such a short, split system, I’d pair the outers and inners so the first cylinder pressure wave isn’t high when the adjacent cyl fires.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


Last edited by Miatav8,MstrASE,A&P,F on June 23, 2021, 6:41 pm, edited 1 time in total.

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PostPosted: June 23, 2021, 5:02 pm 
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For rust remover, I did Ospho on the frame of my Locost. Available pre-diluted, by the gallon at my local Ace Hardware.
Bought one of their harsh chemical sprayers & refill as needed. Knocked off as much of the loose surface rust as I could & sprayed it down.

Left behind some black scale, that a stiff brush clears off pretty well.

Now to get it flipped over & give the underside a once-over.

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PostPosted: June 23, 2021, 10:59 pm 
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I had several criteria to meet. The stock pipes go under the engine and I didn't want that. If I ever get to doing a dry sump I want to be able to lower it a couple inches and take those 2x4 spacers out ;). I also wanted the engine forward as much as I thought I could get away with, so it's gonna be tight. I also thought it would be good to get them outside the engine area quickly. I'm still contemplating a fan or two blowing upwards (or down?) just behind the firewall (1/8" alum, crosses fingers :oops: ). I'll cover it with some silica insulation. Maybe a sheet of phenolic too?

Anyway, my design is shorter than the stock ones. Mine is about 13"-14" to the collector and the stock is about 18". My understanding is the firing order is 1-3-2-4, so I think that my grouping should be alright, not as long as the stock one though. I got a decent deal on the stock header, which I pretty much needed for the manifolds that bolt to the head. I'l probably use both of the 2 to 1s and maybe those mount sections.

I spent a fair amount of time designing them to be equal length, maybe overkill?

I'm sure i'll have to do lots of heat shielding, there are a couple coolant lines going to the oil cooler.

Jamador, I did build a rotisserie for the frame, which allows full rotation. I'm hoping that will make any finish welding easier and the final cleaning/priming/painting easier.


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PostPosted: June 24, 2021, 1:15 am 
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Oh, I think I'm wrong and you were right on the firing order, MV8. The internets seem to think the firing order is 1-2-4-3. So my pipe grouping is not optimal. Hmmm.....

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PostPosted: June 24, 2021, 9:30 am 
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I see honda didn’t bother with phasing. I don't think you will miss it by making a simpler system with easier access.

You could get more primary length by adding the 90s outside the frame then transition to a tapered collector before the muffler. The collector could be slip-on with tabs for springs or bolts. Then it would be easier to remove. On the collectors, weld between the (slip-over or primary) pipes first, then fit the collector over so you only need access to the outside to seal it up.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: June 24, 2021, 2:36 pm 
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Johnsinski wrote:
The internets seem to think the firing order is 1-2-4-3.


The 2004 service manual agrees with the internet - 1-2-4-3.

I'd guess Honda was trying to take advantage of the scavenging from the first cylinder in each set of primaries.

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PostPosted: June 24, 2021, 4:44 pm 
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Yeah, I also looked up a manual online to see the firing order before posting about the primary arrangement. It could be honda made the primaries slightly unequal. It's worth checking if you can but the angles they used at the collectors doesn't appear to favor the last fired cylinder. They look parallel then converge evenly.

Another thing about the 90s outside the frame is the bend radius can be much tighter with the smaller primary tubing.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: June 25, 2021, 2:36 am 
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Look in the manual, what a concept. :oops:

I was just looking at a Hotrod article online about primary length. At one point they were talking about a motor spinning to 10,000 RPM (which is about what this one will do) and they said the primaries might be as short as 26"! What? So are the stock Honda's primaries no where near long enough? I'm guessing it's 4 into 2 into 1 for packaging needs around the oil pan. I could find no "solid" info about pros/cons of 4 into 2 into 1 vs 4 into 1.

I forgot about the little exhaust port header and the port length, if you account for that I guess the length from the valve to the collector is more like 22"-23". Which still seems biased to high RPM.

My point though is if I'd like more midrange torque would I want even longer primaries than the suggested 26"? And then tuning the ECU? Arrrrrrgh!!!

I'm probably over thinking this as usual. I have to keep reminding myself that I'm not trying to land a man on the moon here. But I suppose there's no reason I can't make them that long. Maybe installing them would be more difficult. But I think they should still slide/rotate in from the side fairly easily.

It would probably look nice with over/under pipes coming out the side for awhile.

Ambien's kicking in, time to hit post

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PostPosted: June 25, 2021, 8:37 am 
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The more cylinders you have, the fewer the degrees between exhaust valve openings. Hotrod cams tend to have a lot of overlap so they need longer primaries to comp and also why adverts for cams tend to say “headers needed”. You can still put the big cam in with log manifolds and it will have the sound but not perform nearly as well as it could. Headers would improve the ve.

The oem header is not optimized for peak output. I found Honda bikes are about all-around performance and value over maximizing output. Hard for Honda to make next year’s bike better if they have already done their best. “Tri-Y” headers are typically mid-range torque boosting over long tubes with a single collector.

Unless you want to deal with mixture tuning, you may want to duplicate the original system as best you can. IMHO, going to a split system will reduce the back pressure, reduce low-mid torque, increase peak hp, and require some mixture adjustment to comp. This being efi, other than tweaking fuel pressure to compensate causing the mixture to be richer under all conditions (not good), you’d need an aftermarket tuner or spend a lot of time learning, building, and tweaking an MS system.

I think a good compromise would be to duplicate the lengths in a split system and fit reasonably restrictive oem bike mufflers such as Harley or other touring bike takeoffs that can also be tuned by modifying the inner baffle tube. An auto muffler will have passages far too large for dual exhaust.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: June 27, 2021, 11:41 am 
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I did similar exhaust on the A Mod version 2.
It ran like crap until I added small mufflers to create a little back pressure (and make me sound level legal). Once I put small mufflers on it, the thing was an absolute screamer.

Attachment:
IMG_0609.JPG


This was built with simple 90s on a 6" CLR die


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