Carburator position and engine compatibility

[Chris47]

Hello, i’m Christophe and starting an RV8 built.
Just complete the empennage and received my QB wings.
I would like to know if the O360 A4k with an horizontal carburator at the rear of the engine could fit into the engine cover like the M1B?
Does any body did it ?
For a new unexperimented builder is it a good idea?
Thank you very much for your advises

 

[drill_and_buck]

Hello, i’m Christophe and starting an RV8 built.
Just complete the empennage and received my QB wings.
I would like to know if the O360 A4k with an horizontal carburator at the rear of the engine could fit into the engine cover like the M1B?
Does any body did it ?
For a new unexperimented builder is it a good idea?
Thank you very much for your advises

Too many changes to consider. Highly unlikely this will fit. There is very little room between the firewall and the aft portion of the engine. Exhaust pipe routing would also be an issue.

I would suggest exploring what changes you would need to make to the engine to place the carburetor and induction system on the bottom so you could use the traditional firewall forward kit from Vans.

 

[Chris47]

Too many changes to consider. Highly unlikely this will fit. There is very little room between the firewall and the aft portion of the engine. Exhaust pipe routing would also be an issue.

I would suggest exploring what changes you would need to make to the engine to place the carburetor and induction system on the bottom so you could use the traditional firewall forward kit from Vans.

Thank you !

 

[2theskyy]

Hello, i’m Christophe and starting an RV8 built.
Just complete the empennage and received my QB wings.
I would like to know if the O360 A4k with an horizontal carburator at the rear of the engine could fit into the engine cover like the M1B?
Does any body did it ?
For a new unexperimented builder is it a good idea?
Thank you very much for your advises

Or, if you do have the engine already. Get the superior cai and convert it to a horizontal fuel injection. Essentially a M1B.

 

[Chris47]

Or, if you do have the engine already. Get the superior cai and convert it to a horizontal fuel injection. Essentially a M1B.

It could be a good solution !
I Don’t have the engine, but one is for sale to be fully overhauled. And not easy to find a core here in Europe.
Any idea for this conversion kit Price ?
Thank you.

 

[climberrn]

Superior Cold Air Sump. $2700 USD at the first place I looked. Did that to my engine when building to convert from vertical to horizontal induction. Comes with intake tubes. The sump is an easy install for a builder. Beware, the Vans snorkel for horizontal intake will take some extra work.

 

[Chris47]

Superior Cold Air Sump. $2700 USD at the first place I looked. Did that to my engine when building to convert from vertical to horizontal induction. Comes with intake tubes. The sump is an easy install for a builder. Beware, the Vans snorkel for horizontal intake will take some extra work.

Thank you.

 

[IO390]

Agree with the above regarding the sump, you may as well get the Superior cold air sump. Bear in mind that this engine is an A4K so won't be able to accept a constant speed propeller unless you change the crankshaft and modify the case.

 

[Jonnyb]

It could be a good solution !
I Don’t have the engine, but one is for sale to be fully overhauled. And not easy to find a core here in Europe.
Any idea for this conversion kit Price ?
Thank you.

Just price up what you expect an overhaul to cost and compare it to a new engine.
You may find there’s not a lot in it. That’s certainly the case here in the UK.

 

[IO390]

Just price up what you expect an overhaul to cost and compare it to a new engine.
You may find there’s not a lot in it. That’s certainly the case here in the UK.

Agreed, but you can save a lot by stripping down a core yourself and sending items off for inspection/overhaul yourself. It only cost me about £4k to get the case done by Divco, and the crank and rods done by Aircraft Specialties. Everything else on the engine was brand new and total outlay was £17k - I found a D licenced engineer to do the build with me so it could get signed off, but there’s a few engine builders who you can ship a box of new and yellow tagged parts to and it won’t cost absurd money. It only takes a couple of days to bolt a Lycoming together. Engine shop prices over here are way off the charts absurd. And Lycomings are very simple engines, there’s no magic to them, if you can build an RV I’d suggest you can build the engine too.

 

[MidwestMan]

You can easily download the lycoming parts manual yourself and look at part numbers to see all the differences. The A4K has a solid crankshaft so you won't be able to run a hydraulic constant speed prop unless you're rebuilding the whole engine and swapping the crank to an experimental config.

The sump and carb can be swapped for around $2000 with a used sump and a new or remanufactured carb. It's a very easy job, I did it with an O-320 of a different config for the same reason. If I did it again, I would buy a superior cold air sump and convert to SDS EFI, but that would cost more like $10k. You might also need an angled oil filter adapter. You can also resell the old parts and recoup some money.

 

[Jonnyb]

Agreed, but you can save a lot by stripping down a core yourself and sending items off for inspection/overhaul yourself. It only cost me about £4k to get the case done by Divco, and the crank and rods done by Aircraft Specialties. Everything else on the engine was brand new and total outlay was £17k - I found a D licenced engineer to do the build with me so it could get signed off, but there’s a few engine builders who you can ship a box of new and yellow tagged parts to and it won’t cost absurd money. It only takes a couple of days to bolt a Lycoming together. Engine shop prices over here are way off the charts absurd. And Lycomings are very simple engines, there’s no magic to them, if you can build an RV I’d suggest you can build the engine too.

They are very simple machines.

However, when you’re quoted £14k for a new crank, and having spent £10k to get a core, and that’s without any cylinders or anything else £30k on a brand new engine from the factory starts to look very reasonable.

When I priced it up I found, if everything went well, I could save around £10k. If it went badly I could lose a lot more.

In the end, for me, it wasn’t worth the gamble.

 

[Dan 57]

a brand new engine from the factory starts to look very reasonable

plenty of good posts above already.

I replaced my kinda old O-360 last year with a YO TB O-360 last year. I had a look at all the options available, as in EI, EFII, etc systems, and came back (expense made no difference in my choice) to my proven config of carb and dual LSE III system.
EFII would be slightly more efficient, but the difference is very small, and even though I fly upwards of 300h a year (my "new" engine clocked 335h today but was started July 1st last year) it sure wasn't worth the lower reliability, more risky, and more complicated starting procedures (shields are up for advocates of opposing thoughts).
Now I ordered this TB YO 360 thru Vans (my previous one was a non-OEM) before chapter 11, and finally paid just short of 40K$. This for a naked, no fuel system, no ignition, motor.
Prices have gone up (small parts such as fittings or even bolts) and are ridiculous as it is.

Good luck in your decisions

 

[IO390]

They are very simple machines.

However, when you’re quoted £14k for a new crank, and having spent £10k to get a core, and that’s without any cylinders or anything else £30k on a brand new engine from the factory starts to look very reasonable.

When I priced it up I found, if everything went well, I could save around £10k. If it went badly I could lose a lot more.

In the end, for me, it wasn’t worth the gamble.

OK that's also all true - if a core is costing 10K then thats way over valued (IMO) to start with, but I know that they are in very short supply and so sellers often way over price them.

Going through the numbers with another UK RV8 builder recently it was clear that a new Lyc was the best option if you aren't keen on scrounging/DIYing.

One thing I can say is that starting off with the wrong engine (such as the A4K) as your core is a recipe for disappointment.

 

[MidwestMan]

OK that's also all true - if a core is costing 10K then thats way over valued (IMO) to start with, but I know that they are in very short supply and so sellers often way over price them.

Going through the numbers with another UK RV8 builder recently it was clear that a new Lyc was the best option if you aren't keen on scrounging/DIYing.

One thing I can say is that starting off with the wrong engine (such as the A4K) as your core is a recipe for disappointment.

Sounds like there's a big difference in parts availability depending on your location. In the US, like I said earlier you can convert the A4K to the sump and carb you want for around $2000. The only thing you can't easily change from the A4k is the solid crank, which some people prefer to have and some don't.

 

[jrs14855]

Sounds like there's a big difference in parts availability depending on your location. In the US, like I said earlier you can convert the A4K to the sump and carb you want for around $2000. The only thing you can't easily change from the A4k is the solid crank, which some people prefer to have and some don't.

The A4K sump can be modified to front mount for the horizontal carb. A custom engine shop can provide details. Much cheaper than a new sump.

 

[MidwestMan]

The A4K sump can be modified to front mount for the horizontal carb. A custom engine shop can provide details. Much cheaper than a new sump.

A new sump is a few thousand. A used sump can be had for $500 from ebay or barnstormers if you're careful. If you can find a machine shop who can modify one for less than $500 let me know where please!

 

[IO390]

Sounds like there's a big difference in parts availability depending on your location. In the US, like I said earlier you can convert the A4K to the sump and carb you want for around $2000. The only thing you can't easily change from the A4k is the solid crank, which some people prefer to have and some don't.

If you’re starting with a core, it’s presumably to save cost over a new engine. Once you start having to replace major components, the cost savings reduce rapidly. My main point here was the solid crank -A4K since most people these days want constant speed and even if the builder opts for FP, being able to convert to CS will pay for itself at resale.

 

[Mikeyb]

Hello, i’m Christophe and starting an RV8 built.
Just complete the empennage and received my QB wings.
I would like to know if the O360 A4k with an horizontal carburator at the rear of the engine could fit into the engine cover like the M1B?
Does any body did it ?
For a new unexperimented builder is it a good idea?
Thank you very much for your advises

When you get a new engine from Lycoming you get a new engine with all new accessories, lines, mags, etc that have been run at full power and designed to fit in your nice new quick build. That engine looks like ass. As a new inexperienced builder-pilot in 2021 I didn’t think the 25% cost savings was worth it.