Cheapish stroker build

So I know about the 5horse crank in an animal but that's all I know. Kinda wanting to build one on the cheap and was really wondering what it's gonna take to put something like this together. I know it'll need a different rod for sure but another thing I'm curious about is a block extension to make more of a stroker. How much of the block would need to be clearanced to run something like that? Never built one of these but looking to make a little more power without sending it off and having a lot tied up in it.
 

flattop1

Dawg 89
Block extension can do two things . Allow more stroke or a longer rod or both .
It is also not a simple operation .
The 5 hp crank is way simpler .
Crank , rod , piston , bearings and cam gear.
 

CarlsonMotorsports

Premium User
Yea, there's a little more to it than just dropping the parts in, but you do not have to do a block extension to increase stroke and cubic inches.
Parts are all readily available as well.

The block extension (welding the deck plate on then resleeving and align boring) is pretty involved, even for the experienced.

-----
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Carlson Racing Engines
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Jimbo

A trial w/o witnesses is like racin w/o tech
I build engines with extended decks all the time.
There is more than one option for the rod length for the extended deck blocks.
One of the advantages of the extended deck is that the longer rod gives you a better rod ratio.
Another advantage is that it gives you a more stable deck than the die cast block. You get something better to bolt the head to and get a more stable head gasket surface. That's nice if you want to have a higher compression ratio.
Here's a picture of my deck extension plates:
1568913102192.png

$49.95
If you want to do it cheap you'll get out of it what you put into it.
The flat head crank was made for 5HP and a low compression flat head.
A good OHV stroker motor can make 4 to 5 times the HP of a flat head.
There are no new Briggs Flat head cranks being made anymore.
Are you sure you want to put a used one in it??
 

CarlsonMotorsports

Premium User
I'm now imagining someone purchasing the deck plate from Jimbo, bolting it on and wondering why it didn't run. :LOL:
PS...Don't forget the sleeve, the welder, the align boring machine, the mill, and the hone.
 
Well I seen someone else's post asking about the crank and you supplied an arc # number and it got the rubber burning on what else I could do with an animal and a buddy had an extension on his that sat for years. I'm not a person to put sketchy things together so putting a used crank in it wasn't really a plan and Brian I could see that happening as well. Even not being an engine builder I knew that just bolting all of it together wouldn't work you'd destroy the rings and possibly the Piston as Soon as it turns over lol. Thanks everyone for the input I really do appreciate all the knowledge you guys share.
 

Jimbo

A trial w/o witnesses is like racin w/o tech
If you use a model 15 block with an aluminum bore, weld the deck extension on the inside of the cylinder and uses a piston and rings made for an aluminum bore or plate the cylinder with Nikasil you don't have to sleeve it.
I'd suggest welding the deck extension on the outside also.
 

delray

Member
hey guys I been doing little research on this stroker setup for the briggs animal block. I was also wondering if you could verify when installing the 5hp stroker crank in the block without the block extension. would the piston be a .640 height with a .490 pin and the rod would be a 3.625(arc) 4908
or correct me if I am wrong.
any info would be greatly appreciated. thanks again
 

delray

Member
oop's my bad . 4908 was a measurement. not the part number.

yes cam gear I know and bearing ..thanks and a correct seal too.
i'm assuming you just run the flathead billet flywheel then,so the keyway is correct and taper end
 

flattop1

Dawg 89
No key its in wrong place .
You have the pvl coil ?
Flywheel choices can vary .
Might want too see what Jimbo or Carlson have to say on that .
The jr race car flywheel fit the flatty , animal flywheel should as well .
 

delray

Member
yes,pvl coil would be the choice.
so the animal pvl/coil arc billet flywheel would work then? taper still the same too?
 

flattop1

Dawg 89
Carlson or Jimbo should confirm or deny .
I believe it too be true .
The balance factor could be differnt also .
Or an arc flathead flywheel with pvl magnets .
 

delray

Member
ok thanks for your input, hopefully the guys will chem in. also without them or calling arc racing. I am assuming this is the correct flywheel.


also this maybe a option too. engine would be use for strickly drag racing only, but on the lite flywheel I would have to know if I can still mount the cooling fins on it. bike does have sit and idle between drags.
 

Jimbo

A trial w/o witnesses is like racin w/o tech
Flat head crank with the 6240 ARC stroker rod and a Wiseco piston with .640 compression height will give you about .100" of piston pop up. You will need to machine the top of the piston to get an acceptable pop up that won't crash into the head.
FWIW I don't like the 6600 SA flywheel. I prefer the 6606 SAP wheel..
You can not attach fins to the 6600 SA flywheel. However, it does move some air because of it's design.
 

flattop1

Dawg 89
yes,pvl coil would be the choice.
so the animal pvl/coil arc billet flywheel would work then? taper still the same too?

If you talk the talk you should walk the walk
Oct 13, 2015
Yes it fits the flat head crank.
The taper is the same but the key way is in the wrong place.
Some people say they can just lap the flywheel to the crank and torque the starter nut tight enough to keep it from slipping.
I have never found this to work consistently and always cut a new keyway in the proper position.

B FASTER
 

delray

Member
thanks jimbo, that was one other thing I was also hoping hear that the wiseco piston had extra material so I can machine it to my deck height...etc..
in the pass i have had good and bad with light flywheels. for example trying to use a 20 or 30 series torque converter can really cause havoc. units are just stamp steel with 4 pcs of casted aluminum/magnesium material with two springs wrap around trying to expand between to unbalance stamp steel round plates. when i installed a 340 jr dragster that part of it is machine out billet aluminum pulley that works on three rollers and installed a third bearing support the engine was very smooth right to 8000 rpm's. this was tested on two different engines that both had light flywheels and got the same results.
jimbo i am curious what kind problems you have encountered with the light flywheel. i'm too still leaning towards the heavier flywheel .
 
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delray

Member
jimbo I was just looking at that model 15 block. does that block have a lot more casting ALL around the cylinder bore area then a animal block. assuming it does because of the big sleeve installed. something that can't be done in a animal block,only 15 model block.

I hate to ask all this questions or list new postings on them. all still tied in with stroking an animal. you or anybody else would you happen to know off hand the stock cc's on a animal head and the cc's on a formula head.
thanks.
 
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Jimbo

A trial w/o witnesses is like racin w/o tech
Personal preference. Others may disagree. It does not have a steel hub in the center. To adjust the timing you must use offset keys to rotate it on the crank. Recommended torque of the flywheel nut is 60# and i have had them come loose at that torque. If you tighten it tighter than that you run the risk of cracking it. It if explodes you or someone else could get hurt. I see very little performance gain with it and to me it's not worth it.
Yes the mod 15 has more material around the cylinder area.
 
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