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Fri Dec 30, 2016 1:51 pm

Have decided on a FK41 cam and 1.25 rockers, Engle lifters, single HD springs...

hopefully the crank is in good shape and I wont need to rebuild that as well. Still keeping it under the $600. Haven't factored in any machine shop costs...hopefully none is needed and if so hopefully they wont break the bank.

Thoughts?

I'll continue to update this post with pics and current status.

Sun Jan 01, 2017 11:25 am

I've used both the 100 and C25. I really like the Engle 100 and it runs well with a stock carb.

I'd crank up the compression to 8.5:1 or so. I built a similar combo for a local Baja and it was crackin' little motor.

Mon Jan 09, 2017 4:45 pm

You need to stay really mild with the cam timing with such small heads and intake. I think the CB2280 "cheater cam" would be best. The Engle W100 would be max for that engine combo.

Tue Jan 10, 2017 4:41 pm

All parts just arrived. WOOHOO. Going to get my garage cleaned up and ready for the job!

Thu Jan 19, 2017 4:23 am

with the extra lift of the cam be careful that your spring retainers dont bottom out on the valve boss. I had this problem which caused some grieve.

I m current running 1385 with engle 100 and 1.25.1 solid rockers, but only standard 1600 springs and appears to be ok for the past 4 years.

By the way dont listen to the bone heads saying put a 1600dp in. blah blah.
Something to be said that the little 40hp 1385 is more interesting.

Tue May 09, 2017 12:23 pm

as with most projects, life got in the way....work, kids sports, etc. However some quick updates. All parts for this are in - which is good so I am not really waiting for anything. I have cleaned up and set up a dedicated space in my garage...so really its finding available time. I am finishing up a rear brake job / transmission flush and since the weather is starting to get really nice I may drive it as is for a while. Goal is to finish the engine before I go to OBX this August. Wanted to tow the Buggy down there and have some fun at the beach. I'll be sure to continue to update this thread in three parts, 1) tear down and inspection, 2) Clean up, rebuild 3) test and tune

Wed Aug 15, 2018 10:48 pm

Leave us hanging! How did it go?

Thu Sep 06, 2018 3:37 am

prkid424 wrote:

So eventually there is a 1600dp but I got to learn with what I got. I do have a budget of $600 to get this engine refreshed. $600 won't get me a running 1600dp. I absolutely enjoy the challenges and it's my passion to tinker with everything. The 40hp build is just to wet my appetite and get more pep.

I like how you're thinking! 8)

Yeah, did you finish your engine build?

Fri Feb 15, 2019 1:03 pm

Life always gets in the way......engine is still as it was. Loved driving the buggy almost daily all last summer though- smiling every single time!! Finishing up a few honey-dos then its 100% engine work. I will absolutely post up here as it goes.

Question- re-looking at all parts I have purchased and more research that I have done.....with the 1.25 rockers and the FK CAM I will most likely need to “cut to fit” push rods right?

Fri Feb 22, 2019 4:24 am

If it was me I would pull the engine and install the big bore P&C . For all the hassle of splitting the case and breaking in a new cam & lifters how much more power difference could it make? On the other hand the 1385 with a bump in compression will make a notable difference. Plus, it can be finished in a weekend of free time. You can always sell the n.o.s. parts or use later.

Fri Feb 22, 2019 7:40 am

thomas. wrote: If it was me I would pull the engine and install the big bore P&C . For all the hassle of splitting the case and breaking in a new cam & lifters how much more power difference could it make? On the other hand the 1385 with a bump in compression will make a notable difference. Plus, it can be finished in a weekend of free time. You can always sell the n.o.s. parts or use later.

Which big bore kit do you mean? I might have not caught it but didn't the O/P go with the 83mm big bore kit already to achieve 1385 (up from the original 77mm x 64mm 1192cc)?

Wed Jan 22, 2020 9:40 am

Looking back at this post I can’t believe that much time has passed since I first started contemplating this rebuild. The good news is that I drove the hell out the engine this entire time- almost daily when the weather was nice. But now....it’s most definitely time. Last couple weeks I pulled the motor and started disassembly. I work an hour so every evening. Taking my time- not rushing it so this won’t be a quick “weekend build”. Hopefully tonight or tomorrow I’ll split the case. Then this weekend the block, crank, heads will go to machine shop for line bore, polish, balance, flycut etc. Pics are worth 1000 words so....
Motor Pull:

Fan Shroud, Tins, and accessories off

Heads off:

Jugs off:

Tue Feb 11, 2020 9:27 am

Finally have all my parts back from the machine shop.....work done:

*Full Balance of complete rotational assembly
-crank, flywheel, pressure plate, pulley
*Piston and pins balance
*Rods balanced
*Align bore checked
*Head Work
-grind seats
-refresh guides
-valves
-balanced spring pressure at both static and compressed state
-fly cut
-porting
*Wash all parts

I am super excited to get started. Next up is setting up the garage as a "clean engine building room" to start the mock ups, blue printing, and final assembly. May need to take cylinders back to get turned down for the proper compression that I am going for.

BEFORE:

AFTER:

Tue Feb 11, 2020 11:57 am

With an FK-41 cam on a 40 horse I would just run 1.1 Stock VW 1600 rockers and solid rocker shaft's with elephant feet adjusters from CB or maybe Scat Ball adjusters with those single hd springs, light weight lifters, Stock Pushrods if you don't mess up the engine width much. If you do run 1.25 ratio rockers you will need racing aluminum pushrods because the stock pushrods will wear against the 1.25 rockers. I like the Stainless Steel wide mouth racing Pushrod tubes CB performance sells when running ratio rockers.
With the stock carb manifold and heads. It will idle rough but sound nice and if decked, cc-ed and balanced it will run amazing smooth at RPM. Cruze is still going to be 65mph but it will pull up to 75 or 80 with the big tires. Keep and eye on oil pressure. I would full flow the case and run a remote filter. Or perhaps a FilterPump Don't go over 26mm on the oil pump size on a single oil pressure relief case, also don't run a sump. Stick with 5W30 or maybe 10W30 VR-1 in hot weather. If you run regular motor oil ad a 1/2 bottle of ZDDP to each oil change. This will protect the cam and lifters against excessive wear. Be sure to follow the cam break-in procedures which involves 20 minute 2000 RPM or so run the first time you start the engine.

Tue Feb 11, 2020 4:37 pm

Danwvw wrote: ......It will idle rough but sound nice and if decked, cc-ed and balanced it will run amazing smooth at RPM.

....... Keep and eye on oil pressure. I would full flow the case and run a remote filter. Or perhaps a FilterPump Don't go over 26mm on the oil pump size on a single oil pressure relief case, also don't run a sump.

Stick with 5W30 or maybe 10W30 VR-1 in hot weather. If you run regular motor oil ad a 1/2 bottle of ZDDP to each oil change. This will protect the cam and lifters against excessive wear. Be sure to follow the cam break-in procedures which involves 20 minute 2000 RPM or so run the first time you start the engine.

Why would it idle rough?

Who do you not recommend a sump?

VR1 is all I e ever used and I add a zinc additive :wink:

Tue Feb 11, 2020 9:02 pm

You don't add Zinc to VR-1 it already has the right amount for a flat tappet engine.
If you run a sump on an engine like a 40 horse that has a small pick-up inlet tube to the oil pump you get intermittent loss of oil pressure. Too much restriction in the oil flow so they suck a vacuum, there can be cavitation in the oil pump especially if revved cold or hot with 20W50 oil or with big oil pumps.
As far as idle goes with a stock carburetor and manifold it doesn't take much cam to give it a cammed up sound.
Outside the 83mm bore and increasing the CR with stock 40 horse heads there isn't much you can do for them. The valves and ports are just too small. The valves are so small that lifting the intake valves much more than stock won't have much effect. 1.25 ratio rockers would lift the valve .455" or something which would be good in a 1600 but not used in the 40 horse. The stock cam only has .314" of lift but with the cam FK-41 your planing even 1.1 Ratio rockers will give over .400" of valve lift. If you increase the manifold size on a 40 horse the gas just condenses out on the inside of the manifold, If you increase the venturi size in the carb it may have more top end however it probably wouldn't idle.
I built a 1585cc single port once with a W-100 camshaft and ran a stock 40 horse carb and it was a good combination. Great MPG's good mid range torque. Your choice of the FK-41 cam is interesting it may work nicely.

Thu Feb 13, 2020 8:10 pm

All laid out ready to get started. I’m sure I’ll probably mock build this a few times to get all the right measurements.....will continue to update as the build moves along.

Thu Feb 20, 2020 11:15 am

That's a nice shop with the milling machine, etc. Is that all in your garage?

Fri Feb 21, 2020 5:37 am

hi heres my two cents on your build .why a fk41 cam ?are you building a all out race motor. or a friendly street motor. I looked this cam up on the net . it is for serious motor builds with dual carbs or a big single carb . you must run dual springs the add says. its rpm rang is from 1,000 rpm to 5,000 rpm . are you going to run a stock 28 carb ? or a 30 carb ? if you are I feal the fk41 cam is a over kill for a 40 hp motor . I don't think your going to be happy with that cam for the street your going to be in 3rd gear a lot .for get 4th gear. my self I don't like 1:2.1 rockers there a pain in the ass to set up. unless you buy a set of scat $200.00 + that has the right off set .on a deep sump. I have used a deep sump on formula vee 40 hp motors . they work just fine using the small pick up tube. don't get me wrong. I like 40 hp motors and dune buggies . I just want you to think about what your doing on your motor build . and ask your self am I doing the right thing on my build . your the one that has to live with your motor. my goal was not to put you down on your build .please think over what your doing .ask engle if your using the right cam good luck like I said just my two cents spencerfvee

Fri Feb 21, 2020 10:18 am

heimlich wrote: That's a nice shop with the milling machine, etc. Is that all in your garage?

I wish....