Could someone please explain to me what is going on here?

[garnold]

I'm watching this video and trying to better understand what this guy did to his engine and how it has improved it. It apparently has a very low ideal which is a good thing? Thank you

https://www.youtube.com/watch?v=vEw5TnZN21s

[austin8214]

All it sounds like he did was take .100 off the head and clearanced the valves. Raising the compression ratio of the engine. Then he stuck a #30 carb on it and killed his torque.

[garnold]

Originally Posted by austin8214

All it sounds like he did was take .100 off the head and clearanced the valves. Raising the compression ratio of the engine. Then he stuck a #30 carb on it and killed his torque.

I hate to sound so dumb here but what does lowering the head do for you? I'm guessing the valve clearance was needed because the head has been lowered and they would smack against the head? Is the use of a #30 carb what reduced his torque? Why would he put that carb on there if it did? Again, I'm sorry to reply to your answer with a slew of new questions but this topic is just very interesting to me and I'm trying to learn tips on how to not only rebuild these engines but push them maybe a little further then they are built stock but still keep them reliable.

[J-Mech]

Garnold, you should probably just stick to the basics. I'm not being mean or anything, (just being honest) but I'm not sure your going to understand the complex explanation of custom building if you are just "getting into" engine basics.

Shaving the head raises compression. Yes, the head is closer to the valves, thus the need to cut a relief. As far as the carb goes......lets go with bigger is not always better.

[austin8214]

Originally Posted by J-Mech

Garnold, you should probably just stick to the basics. I'm not being mean or anything, (just being honest) but I'm not sure your going to understand the complex explanation of custom building if you are just "getting into" engine basics.

Shaving the head raises compression. Yes, the head is closer to the valves, thus the need to cut a relief. As far as the carb goes......lets go with bigger is not always better.

That is it in a nutshell. The larger venturi on the carb reduces the velocity of the air rushing into the cylinder so it does not fill as efficiently. He'd make better power with the #26 carb.

[austin8214]

Originally Posted by garnold

I hate to sound so dumb here but what does lowering the head do for you? I'm guessing the valve clearance was needed because the head has been lowered and they would smack against the head? Is the use of a #30 carb what reduced his torque? Why would he put that carb on there if it did? Again, I'm sorry to reply to your answer with a slew of new questions but this topic is just very interesting to me and I'm trying to learn tips on how to not only rebuild these engines but push them maybe a little further then they are built stock but still keep them reliable.

If you want a nice reliable modded engine read Kirk engines killer Kohler writeup and follow his blueprint. Only my suggestion would be to use the Zach Kerber Gov#1 cam since Kirk does not make a cam anymore. http://www.zkbrmachine.com/item.php?product_id=285

[garnold]

I'm good with that and totally understand and appreciate the honesty on this. I'm completely cool with the crawl then walk thing and don't want to turn something that could be pretty darn fun into a nightmare because I pushed to much.

As far as the carb goes I'm glad you both said the same thing on this. Reason why is because I read the same thing that putting a larger carb is not always good so I just could not understand why what he did was so great. I don't need the details now but just wanted to at least know what I read is consistent

[garnold]

Originally Posted by austin8214

If you want a nice reliable modded engine read Kirk engines killer Kohler writeup and follow he blueprint. Only my suggestion would be to use the Zach Kerber Gov#1 cam since Kirk does not make a cam anymore. http://www.zkbrmachine.com/item.php?product_id=285

Yep, thumbs up here. This (and the great content I have gotten here) was going to be my direction for my engine once I get the hang of things. Not super tricked out but just enough that I can feel cool around the other guys and can say I mod'ed my engine some HAHAHAHA

[austin8214]

Originally Posted by garnold

I'm good with that and totally understand and appreciate the honesty on this. I'm completely cool with the crawl then walk thing and don't want to turn something that could be pretty darn fun into a nightmare because I pushed to much.

As far as the carb goes I'm glad you both said the same thing on this. Reason why is because I read the same thing that putting a larger carb is not always good so I just could not understand why what he did was so great. I don't need the details now but just wanted to at least know what I read is consistent

My understanding is the reduced air velocity kills the vacuum signal at the high speed jet. In effect reducing the amount of both fuel and air that gets sucked into the cylinder.

[J-Mech]

Originally Posted by austin8214

My understanding is the reduced air velocity kills the vacuum signal at the high speed jet. In effect reducing the amount of both fuel and air that gets sucked into the cylinder.

That's correct.
241 just doesn't have enough cubes to make that carb work.


Don't let the sound of the motor in the vid fool you. It's only idling at around 300RPM, which is incredibly low. Plus, no exhaust that makes it sound like it has a "lobe", which it really doesn't. Lots of fire out the exhaust means exhaust valve probably isn't sealing well along with too much fuel on decel (heavy vacuum situation). On acceleration it probably is running lean given the large carb, and low vac due to the venturi size. That guy is going to find it isn't the motor he thinks it is when he puts it back in.

Garnold, you want to "hop" your engine up: get a LP head, bump the timing up a couple degrees, index the plug and set the high-idle, no load to 3800RPM. The Kerber cam is a good choice (only hear good things about them, but haven't used one yet) but they do cost quite a bit. As much as the engine kit is going to cost, so I don't know how much you are looking to spend. Not really necessary, AFAIC, for the application you are after. Your just like most everyone is....... you want to "hop it up"...... but there is no reason to unless your going to take it to the pulls. If you want more power, put a bigger motor in it. It would be cheaper to do that than custom build a 10hp. Just my It's your money.