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Old 08-07-2010, 08:08 PM   #1 (permalink)
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hi everyone i have a 87 sammy that i have redone the 1.3 on it.i put 10.2 high compression pistons on it . with a rv2 cam thorley headers , and magna flow exhuast. what carb would be best i am thinking of a 34/34 webber. any sugg..
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Old 08-08-2010, 02:55 PM   #2 (permalink)
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Not to Hijack, but did you find the high compression pistons you used stuck up above your block at TDC? I recently did the same rebuild you did, with HC pistons, and measured from the wrist pin to the top of the piston, the HC ones were 0.038" taller.

BTW, I ended up re-using the original Sammy carb on my engine due to visual and emission checks where I live, and it runs fine. Perhaps drilling the main justs a few 'thou would help, but I'm not sure how much you will gain with a bigger bore carb, though it may be a couple HP.

I put a 32/36 Weber on a modified 1600 engine w/ headers and vs. stock I can't say I gained enough HP to actually notice anything dramatic, or worth the money spent on the carb.

Plus the Webers have a reputation of starving for fuel at moderate angles you may encounter if you off-road your Sammy. This is from a guy that builds and races Sammys, so I don't have personal experience with that.

Bob
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Old 08-13-2010, 09:46 PM   #3 (permalink)
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i actually still am building the motor but it is almost done , i was thinking of using the stock carb.i really dont plan on 4x4 the sammy to much un less i have to.i am building it for speed,highway speed is what want to get out of the build.as for the hc pistons being to high i dont know a machinest have my motor . he builds racing motors for aliving,to fund his drag racing.so i think iam fine. did you build a 1.3 or a 1.6
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Old 08-13-2010, 11:23 PM   #4 (permalink)
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Quote:
Originally Posted by SAMMYJAMMY View Post
i actually still am building the motor but it is almost done , i was thinking of using the stock carb.i really dont plan on 4x4 the sammy to much un less i have to.i am building it for speed,highway speed is what want to get out of the build.as for the hc pistons being to high i dont know a machinest have my motor . he builds racing motors for aliving,to fund his drag racing.so i think iam fine. did you build a 1.3 or a 1.6
The HC pistons may make a very slight difference in power, but to be honest, I didn't notice a difference between the tired engine w/ STD pistons in my Sammy vs. my newly rebuilt engine with HC pistons except oil usage (more then, less now). The rebuild was for longevity and reliability, not power. I think if you are staying 1.3 and expect more HP you may be disappointed, depending upon your expectations.

I was speaking of two engines in my posting. The 1.3 is what I rebuilt and replaced in my Sammy. The 1.6 I mentioned was another situation-it is a 1.6 liter English Ford pushrod engine in another vehicle which I mentioned only because the 32/36 Weber was not a night/day situation power wise.

There is no substitution for displacement when you want power. If you want power increase displacement, or go with a supercharger or turbocharger, both of which have the same effect as increasing the displacement (by compressing the charge).

As for the HC pistons, you might ask the machine shop to take a wrist pin and share it between one piston of each type (norm and HC), and see it the top of the HC piston is significantly above the std piston. Then let them determine if it will be a problem. Pistons can be machined BEFORE mounted on the connecting rod, but after, your only recourse is by using head gasket shims or the like. Unless the shop has done these engines before, they will probably not do this check-I know this because the machine-shop who did mine were shocked that the new pistons were taller (measured from wrist pin to the top deck).

Bob
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Old 08-13-2010, 11:29 PM   #5 (permalink)
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If you needed more "kick in the pants" power then a higher output carb would give you a better throttle response and more pull at the cost of efficiency. The stock carb will give you a decent top end while maintaining good fuel efficency and mixture control.
There isn't a whole lot of extra power for passing at freeway speeds, but it's a good carburettor to break in a new or rebuilt engine on. I wouldn't upgrade to a higher output carb untill you've gone through the break-in period on the rebuilt engine.
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Old 08-14-2010, 12:08 AM   #6 (permalink)
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My experience is that carbs can only provide what an engine asks for.

By that I mean if you look at the engine as a pump, only if you increase the amount of air an engine can suck in, process, and exhaust, will a bigger carb will give more power.

But replacing a properly sized carb (matched to the engine) with a larger one won't give more power, especially at low rpm, where venturi velocity is marginal.

In fact, a larger carb may HURT low end torque and throttle response (since a larger bore results in lower air velocity through the venturi, reducing efficiency), while it may help high rpm use (since at high rpm the engine is moving so much more air, and can get decent air velocity through the bigger bore).

The fact that you are improving the breathing of the engine (making it a more efficient pump) may make it a reasonable candidate for a larger carb for high rpm use.

I rebuilt my 1300cc engine (rather than replaced it w/ a 1600cc) only because time was a factor, and I didn't have access to a larger Vitara engine, or time to fabricate mounts to install a 1.6 Toyota engine. Either of those would have been my preference based on my Samurai Guru.

The fellow I used as my Sammy "guru" (he's from Puerto Rico where Sammys are popular) has a Mazda rotary (5.13 gears) in one Sammy* and a turbo Toyota 3TC in the other.

Bob
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Old 08-14-2010, 05:57 AM   #7 (permalink)
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that's my experience too. It's also my experience that the samurai's carburetor is built for fuel efficiency and emmision control rather than power. You can step up the carb quite a bit without overcarbureting the 1.3L engine. I ran dual twin 40mm mikunis and it was a beast. It would mash me back in my seat on take offs. I could lay rubber, but when I saw what Gekkocycles did to his drivetrain doing burnouts on his samurai I decided that wasn't a good idea. My top end wasn't much higher than the stock carb could net, but I could sure get there a lot faster with the Mikunis.

With the cam and the headders though, SammyJammy should be just fine with a stock carb for normal street driving. Like I said, the stock carb will have pretty close to the same top end as a higher flow carb, they all top out at the same CFM under natural aspiration. A higher flow carb will kick you up there more quickly but it will wear on your newly rebuilt engine and your 20 year old drive train.
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Old 08-14-2010, 09:40 AM   #8 (permalink)
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what mileage or hours should i put on the new motor before it broken in. as far as the carb goes i like the sound of getting put back in the seat . remember this is not a daily driver,weekends when the kids are gone or if another car goes down , is when it would get driven.it would need to pass a e-test. i live in albuquerque new mexico were there not to strict on the emissions.I see ads stating webber carbs on a sammy can pass emissions except in californa.So is that true or not,we dont have to have cars inspected here , just pass emission and your good.34 webber is what i am instrested in , but i have heard some rumors of some engines being damage form the webber carbs on high compression pistons . any truth to this, and is the 34 webber a good choice .should i just stick with the stock carb . my stock carb is a hitachi never had a problem with it . the only problem i had with the engine besides stacking bearings jacking up the crankshaft, the sammy would stall out when i would stop, after it was warmed up all they way up.but that was before the bearing problem.Well maybe the stalling issue will be solve aleast i hope so thanks for your help guys

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Old 08-14-2010, 02:07 PM   #9 (permalink)
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Something I ran into when I built the Stalker project. It was built specifically for the street with an emphasis on performance... I got tired of having to stay in the slow lane on the highway.

I built the 1.3 with the high-Po kit from John's Foreign Engines (flat tops, rv cam, etc.). I then replaced the 38mm DGAS Weber with a 44mm Screamin Eagle Harley carb and custom intake. I used a Thorley header and a 2" exhaust. This more than doubled the HP from a stock motor.

Here is the problem... I have sheared the woodruf key from the added torque not once, but twice. Ths is because of the stock 1.3 components that are still used in the build. If you are going to really push this block to the edge, you need to think about strengthening that key.
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Old 08-15-2010, 08:32 PM   #10 (permalink)
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billjohn all my stuff is from sammypro A.K.A. johns forein engines.the stalker project was were i got the idea to do all this.but anyway i am not sure what a wooddruf key is or what it does.i am not trying to break the speed record on sammys but like i said before i want to do highwayspeed with no problems.if it can maxout the speedo that would work for me.another thing is that the rest of the sammy will stay stock i might bump the tire size up alitte 275/70/15 and thats it for me.thanks for all the input guys
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