Big Block Options 2021

[slonomo]

Modifications

For those of us that want a "stock repower option", keeping the engine stock will be the best option for fuel economy, sound, and durability/reliability.

For those of us that want "more power"....well, modification is the only way.... You might want more power to carry more passengers, pull deer out of the woods, climb hills, tow a small trailer, or anything in between. The following are some common modifications that you may see on these engines.

Disclaimer: Modifying a small engine can void manufacturer's warranties and/or cause internal damage and should only be done by a qualified mechanic. Golf cart speeds in excess of factory limits can exceed the design capabilities of the vehicle and can cause the vehicle to lose control resulting in accidents and potential injury. Modifying a golf cart for more speed is not recommended and you do so at your own risk.

Common Mods:

1. Rev Kit - will allow your engine to rev up to 5000 rpm without valvetrain damage

2. Governor By-Pass - removes or disables the engines governor to allow it to rev past the stock 3600 rpm level.

3. Carb Jetting - installing larger jets may be needed to run at higher rpm

4. Carb Upgrade - installing a different/larger carb will allow the engine to have better power, throttle response, and more rpm

5. Header/Exhaust - larger exhaust promotes more flow and more power

6. Timing Key - advances the timing for better throttle response

These mods do not address any internal engine parts and engine rpm should be kept below 5000 rpm to reduce the risk of internal engine damage.

High performance engine building will not be covered in this thread.

[slonomo]

Primary Clutches (drive)

When using a big block engine, one might be tempted to save a few dollars and use the stock golf cart clutch with a tapered adapter. While this is technically possible, it's not the best way to transfer power.

Stock golf cart clutches are designed and engineered to work with a 9-13 hp engine on a golf course. Some clutches have been rumored to come apart at higher rpms, so there is a hazard there. Performance will not be ideal since the stock clutch is designed for low engine speeds and lower torque levels. Sometimes the tapered adapter can slip and cause damage to the crank and clutch, or even allow it to vibrate and come loose.

There are several options for primary (drive) clutches that are designed to be used with big block engine swaps in golf carts. Below are the 3 most common primary clutches. Please visit the BGW site sponsors page and order your clutch from a sponsor!

1. Comet 780 - Using a 1 3/16" belt they are rated up to 23hp and 6000 rpm, very smooth engagement at around 1700 rpm and full shift at 3100 rpm and designed for a golf cart

2. CVTech Series 06 - Using a 1 3/16" belt they are rated up to 40hp and 6000 rpm, 1600 rpm engagement and 3100 rpm full shift, very heavy duty but larger in size than the Comet 780

3. Comet Duster 94c - These clutches use pucks and springs to adjust and fine tune engagement and shift rpm, not usually ready to go out of the box, and are not typically as smooth as the 780 or 06, but are very heavy duty and durable and have been used in racing applications for years

Secondary Clutch (driven)

Most big block swaps work very well with a good condition stock secondary clutch. Power springs (stiffer springs) are not usually recommended and often times make for a poor shifting and performing clutch. Condition is extremely important here, and also high quality parts like factory Yamaha, Ezgo, and Club Car, for example. Cheap China made clutches should be avoided.

[slonomo]

Engine and Transaxle Rotation

Most gas golf carts use a "CCW" Rotation, or Counter Clockwise, when looking at the engine PTO/crankshaft. Most aftermarket engines are set up to run this way, as well as most clutches.

With that said, some engines/transaxles are the opposite and are "CW" or Clockwise rotation. Please be advised, these carts will not allow the standard big block engines to be used. Please do your homework and research on this. Make sure the engine you want to use is compatible with your golf cart and transaxle. Lots of info here on BGW.

When in doubt....start your own thread and ask lots of questions.

[slonomo]

Electric to Gas Conversion

This type of project, though not impossible, is a tough one. Electric golf cart transaxles are different from gas units in that they don't have an input shaft that will support mounting a secondary/driven clutch.

Many will attempt to use a gear and chain drive system to use the electric transaxle. I've seen some really good examples, so I know it's possible. The idea is to install a gear on the input shaft of the transaxle. Then, use a go kart style "torque converter" cvt setup on the engine to transfer torque from the engine to the trans. Gearing, strength of clutching, engine size, and parasitic power loss are all big factors here and must be considered.

The correct way:
Find a donor cart that is rusted out, has a blown engine, no body, etc....that has a functioning transaxle and transfer the corresponding parts over. This sounds expensive and difficult, but it can be done very inexpensively if you have patience and time. Entire donor carts can be had for as little as $200 with a bad or no engine. Yes it's a crap shoot as to the quality of the parts you're getting. But, most parts are available in the aftermarket, you just need the transaxle and wiring. And if you are using a big block engine you can always do without the cart wiring and start from scratch and use the key start.

Choosing The Right Cart
Some golf carts are better suited than others to accept a big block swap. Here are some examples of popular older golf carts. Generally, the newer the cart, the easier parts will be to find. But older carts often were built extremely well and can be found at a low cost compared to new. Keep in mind that some restoration and parts replacement will be needed.

Good Example: EZGO TXT Gas - lots of room, simple design, easy to work on, lots of parts available from the factory and aftermarket

Bad Example: Yamaha G1 Gas - originally a 2 cycle engine that runs backwards for reverse (no reverse in transaxle), smaller overall so larger engines are a tighter fit, parts are harder to find, great carts to keep stock.

Good Example: Yamaha G2/G9/G16 Gas - known to be extremely durable, good parts availability, full tube frame, Japanese engineering and quality

Bad Example: Early EZGO Gas 2 cycle - like the Yamaha G1, this 2 cycle runs backwards to create reverse (no reverse in trans), engines were mounted sideways in this model, limited parts availability

These are not the only "examples" just some of the more common carts.

[mgray70]

I'm looking a drive belt for a vanguard big block conversion on a TXT. What is a good belt and what size?

Sent from my SM-G991U using Tapatalk

[slonomo]

Originally Posted by mgray70

I'm looking a drive belt for a vanguard big block conversion on a TXT. What is a good belt and what size?

Sent from my SM-G991U using Tapatalk

Go ahead and start a new thread so we can keep this one clean. Glad to help, I'll look for your thread.

[slonomo]

Starting & Charging Systems:

One of the items you'll want to consider is how you will start your engine. Here are your options:

1. Factory golf cart Starter/Generator
This requires using your stock golf cart starter/generator which uses a thin v belt and tensioner. Often times these can be modified to use with a big block engine with the use of a pulley behind an aftermarket primary clutch, like the Comet 780. You also have the option of cutting the 1" crank and using a tapered adapter in order to use your stock golf cart clutch, which has the pulley on it already. Cutting and tapping the crank is not considered to be an easy job and requires some fabrication skills. If you do use the golf cart starter/gen you will also be able to use the "charging" function to keep your battery topped of and/or to power accessories.

One source for the clutch and V pulley is Vegas Carts (as shown).

2. Engine mounted Starter
This is the starter that comes on the engine, so make sure you find an engine that is equipped and not just a "pull start". Usually this type engine is fully self contained and also come with an air filter, muffler, and fuel tank. It is possible to use these engine as they come, provided you have the room in the engine compartment. This option requires you to use an ignition switch from a lawn tractor or equivalent. Basically the engine will start and run like a car with a key switch. Wiring is basic and not considered a difficult job if you understand the basics of wiring and 12v power systems.

With these engines you will want to make sure the engine has a built in alternator that has enough power to keep your battery charged. There are several engines like this on the market.

If the engine you select doesn't have a charging system, you can adapt a one wire alternator from a tractor to do the job. This will require you to fabricate a bracket, and also to use a V belt pulley. You could also use an automotive alternator.

One example of an engine with an electric starter is the Predator 420 (as shown)

[mgray70]

I did, but then found this thread and thought it might would target some of the experts in the big block arena. I got no response in either till now. I found a belt. Contacted Carts Parts Plus today, and they hooked me up! I'm a sparky and know very little about gasers.

Sent from my SM-G991U using Tapatalk

[slonomo]

PTO Flywheel Adapters

I so see some pto adapters that bolt onto the flywheel side of the engine so a clutch or alternator can be mounted on that side. I suppose if the cart I had needed a clockwise rotation setup, that's what I'd use if I couldn't get a different rear transaxle or a different cart, like for some of the club car's.

I have not used them but I have heard that the flywheel side bearing might not be suited for such a load. Anyone have any experience with this? I did, however, have a Vanguard 23 engine that came with one brand new. I believe that engine was for a repower of a piece of equipment. I ended up removing the pto adapter, looked to be for running a hydraulic pump or fan. So I'm assuming the Vanguard 23 flywheel bearing is heavy enough for that kind of load.

I'm also assuming the manufacturers of these pto clutch adapters have used and tested them without issue.

If you have used one, can you post your opinions and results?

[KentMoreno]

Hi!

I recently bought a modified golf cart (Clubman Cadet) with a Predator 670 engine for my son who is developmentally disabled.

We really like the cart but it is loud.

The current muffler is approximately 9”x3”.

I need an option that will make the noise level more acceptable to us and especially to our neighbors.

Help!!!

Take Care,



Kent