I have a new 212 Hemi never run yet. It will sit till I get all of the parts found to get what I want to put into it. It will go onto a go cart a copy of one the boys had when they were small. Now married with kids of their own. The parts list will be new billet flywheel billet rod not sure which cam and lifters and stiffer springs and push rods to use with the Hemi head. I would like to put in a 28mm and 26mm SS valves into the head. The Rod and piston might be longer rod with a mill to fit piston. That I would like to try to round off to fit into the Hemi head. If needed I might have to cut valve reliefs into the piston. I figure the bigger valves will need less lift to flow well. I have a friend who runs a sled shop so I can get a 22mm carb from him or the size I will need. And I was thinking of putting some reeds between the carb and engine to help with air flow. Ok has anyone done anything like this yet? So What is the good and bad of what I have laid out so far? I have no idea what HP it would have or RPMs it will turn I would like to keep it about 7000 RPMs or so. Lets hear what where I would be going wrong or right?
A very simple rule of thumb is look at the intake and exhaust size.
If you Carb is in between the diameter of these two your engine can probably pull on it with out much trouble.
Yes you can run more lift but if your valves ports are not large enough too suport the flow requirements again you have still have too much carb,
If your valves and ports are too lare port velocity drops and the engine looses at lower rpm.
You will see very big carbs and on some off these by expert builers ( I am not one of them ).
They have huge valves and massive work done to run that.
If you Carb is in between the diameter of these two your engine can probably pull on it with out much trouble.
Yes you can run more lift but if your valves ports are not large enough too suport the flow requirements again you have still have too much carb,
If your valves and ports are too lare port velocity drops and the engine looses at lower rpm.
You will see very big carbs and on some off these by expert builers ( I am not one of them ).
They have huge valves and massive work done to run that.
Newoldstock That is where I was thinking the reed valves would close faster than the valves. To help keep the largest charge into the cylinder before the valve can close. That way if my porting is a little off the reed valves would help keep the air fuel velocity up. Even if I do not port it at all I thought the reed valves would help the velocity going into cylinder. It will help the flow going one way instead of pulsing back out of the carb. I have build big V8s and I have help work on snowmobiles 2 cycle engines. I have yet to do a single cylinder 4 cycle for power. I am trying to use what I know works on the others. I still have no idea of what cam and spring to use. I do not think I need a real high lift cam as the for the bigger valves they should flow better any way. And I know I will need stiffer spring for the bigger valves in the Hemi head. And better push rods to open the stiffer springs.
I have 18lb springs, but I'd like to jump up to 22 or 26lb springs. Check out smallengines.com. You can email him, and he can give you some suggestions for you cam. He can custom make one for your application, or you can just run one of his. Many folks around here have been running his mamba cams, and they seem to really like them. I'm running a CM cam from DynoCams, and I'm pretty happy with it. Both of the mamba cams require a 26lb spring to really get the most out of them. I think the Mamba pulls well from 4k to 8k rpms, and that is right where you said you'd like to run. I run just under 8k with my 196cc clone, and I've got most of the mods you just mentioned, but I'm running stock valves with a 14cc head. I haven't done any porting, and I'm running the "cheater" carb from Dover powersports. Those guys helped me out a lot when I was building my motor. I'd recommend them any day of the week. 7k RPMs is not too difficult to do with a little cash. Your machining may not even be needed to get there. Good luck!
That is a good question:
I do not use a slide carb but I understand why many do.
They offer improved throttle response when set correctly.
I do not use stock carbs and prefer to build my own from completely different engines.
They are not as good as a well tuned slide carb, the only advantage my carbs have are I made them....
I do not use a slide carb but I understand why many do.
They offer improved throttle response when set correctly.
I do not use stock carbs and prefer to build my own from completely different engines.
They are not as good as a well tuned slide carb, the only advantage my carbs have are I made them....
Newoldstock you did not reply on your view of my reed valve idea. If it would increase the HP and torque of the 4 cycle like it does on a 2 cycle. I want the most torque I can get out of this engine. I guess by floating the valves it would keep you from over revving it and blowing it up. I bought the 212 Hemi for my nephews go cart it is a Cater pull tractor it had a 3HP briggs. Well the 212 was to big to fit into where the 3HP was it hit the sprockets and did not have enough adjustment to get it to work. I wanted a 340 single but I have a 212 Hemi so I might as well go with it. And I was thinking of using a Tillotson carb on it.
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I thought that question had been answered by Mr Wulf.
Reeds will not help you here ( but I do understand your logic ).
If you want the most torque you can get then follow some simple rules.
Use the 18cc Honda head...
Keep timing around 25-28 for initial setting and add more if you can tollerate it ( without killing your bottom end ).
Use a good header like robertson torque tube.
Use a good cam like the Isky Momba Jr designed for this kind of build.
Stick with a small carb small port job aproach.
Stock carbs are fine for this....
But if you must go aftermarket the PZ 19 or pZ22 are about las large as practical.
You may consider a HL 166 or 266 but stay away from the big racing carbs.
They race only.....
Also Valve float is destructive.
Its the swan song of your valve train beating itself to death
Avoid float......
Reeds will not help you here ( but I do understand your logic ).
If you want the most torque you can get then follow some simple rules.
Use the 18cc Honda head...
Keep timing around 25-28 for initial setting and add more if you can tollerate it ( without killing your bottom end ).
Use a good header like robertson torque tube.
Use a good cam like the Isky Momba Jr designed for this kind of build.
Stick with a small carb small port job aproach.
Stock carbs are fine for this....
But if you must go aftermarket the PZ 19 or pZ22 are about las large as practical.
You may consider a HL 166 or 266 but stay away from the big racing carbs.
They race only.....
Also Valve float is destructive.
Its the swan song of your valve train beating itself to death
Avoid float......
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When I was talking a few guys about this they thought the reeds might help keep more air pressure into the cylinder. And thanks for the way you gave a out line of what works for you. And not just it will not work with no real reasoning why it will not work. Even on the 4 stroke the air will pulse out of the carb as it is running. That is why the idea of the reeds to hold as much in as possible. It would be a pinch point to stop blow back. I might try it yet not sure. I do not know how many CCs there will be if I move the piston up into the head I could still mill it some. Like a real Hemi V8 pistons uses and also I want the bigger valves this engine has. I would like to go bigger valves yet like maybe 28 and 26. The fly wheel I was looking at has 28 degrees already. What I really am looking for is a cam to go with the bigger valves. That is why I started this Best Hemi cam and springs. How much compression will the stock block hold before it will blow the jug off? Thanks for any more input I can get!
I read a lot of these kids of posts and to be honest there is a lot of simmilar questions that lead to the same places.
So I give a generic sugestion.
By alll means try the reeds if you like.
But be warned they will add more restriction than any help they can offer with reversion.
If you have a reversion problem its usualy caused a bunch of factors anyways that were casued by a poor selection of parts.
So I give a generic sugestion.
By alll means try the reeds if you like.
But be warned they will add more restriction than any help they can offer with reversion.
If you have a reversion problem its usualy caused a bunch of factors anyways that were casued by a poor selection of parts.
Newoldstock That make sense because when my group was talking we were using what we saw on stock engines some not so new. Some stronger spring could have solved the problem too. I am old 60 it is hard to change to some thing I have not tried yet. I just have not kept up on this small of a engine over the years. It has been more V8s and snowmobiles for me. If I needed more power in a small engine I would put a bigger one in its place. This will be the first small single cylinder engine for me. That is why I am checking out what can work to get what I want. I know the best cam and valves can help get the best compression out of any engine. And I know if you get the piston the longest stroke and small chambered heads gets compression too. I am looking for more torque than RPMs.