Vitos Stroker Questions

[wwholden]

I got a bottom end with a vitos stuffer +3 in it. I also have a ported cylinder laying around that I know nothing about. Im wanting to run it without the spacer plate if possible. Is there a way to check to see if my ported cylinder was ported for a +3? Like take some measurements to see? Or does that even matter? Is it the head that I should be worried about? What do I need to check for when throwing this together?

 

[sicivicdude]

hmmmmmm.... throwing this together? Bad words, very bad words.

The very best way to see if the top end was ported for a stroker crank is to install the cylinder onto the bottom end with a usable piston installed (and the base gasket thickness correct) and see if the ports line up. Basically, the top of the piston should just be at the edge of the transfer ports at BDC.

 

[wwholden]

Haha throwing this together was just a figure of speech. Im asking because I want to do this right. Right base gasket thickness? Standard gasket not good enough? Ive heard of something getting decked when going to the +3. Is that the head or cylinder?

 

[sicivicdude]

One would assume stock base gasket thickness but really, anything is possible depending on how the builder cut that cylinder. It may have been designed not to use a base gasket at all on a stock stroke engine, never know!

You want to do it right? Get out your degree wheel and drop that cylinder down onto that bottom end. Map the cylinder first and determine port timing. If the ports don't line up on that crank, that cylinder probably wasn't ported for a stroker crank.

 

[wwholden]

No base gasket? What do you use to seal it up? Im assuming this is used for race use..... more compression?

Also doesnt porting adjust port timing? So how would I know if its within tolerance?

 

[sicivicdude]

You normally wouldn't see an engine built without a base gasket but one COULD if they wanted to and use sealant to seal it.

The point is that without knowing what it was built for, it's hard to know if it will work for your application or not.

Generally, engine ported for a stock stroke will have a greater amount of port timing on a stroker crank than it is built for on the stock stroke crank. This can have one of two outcomes. Either it was fairly mild on the stock crank so it'll be just right on the stroker crank OR it was really good on the stock stroke and it will be too much on the stroker crank.

 

[scotj77]

most builders won't touch a stroker topend without the whole motor bc it is waaaaaaayyyyy too hard to get it exact without having everything in hand. probably best to send it to someone

 

[sicivicdude]

most builders won't touch a stroker topend without the whole motor bc it is waaaaaaayyyyy too hard to get it exact without having everything in hand. probably best to send it to someone

And how would we know that?! LMAO!

I had to cut two heads for Scot's motor before we got it correct. Good news was, the second one was a MONSTA.

 

[wwholden]

Ok so i just need to look at if the piston is at the bottom of the transfer ports at BDC when I have the cylinder installed with the base gasket. Or get a degree wheel. Which Ill look into getting.

Also doesn't there have to be some work done to the head. Like I said earlier if your not running the 1.5mm spacer wont something have to get decked?

 

[sicivicdude]

Ok so i just need to look at if the piston is at the bottom of the transfer ports at BDC when I have the cylinder installed with the base gasket. Or get a degree wheel. Which Ill look into getting.

Also doesn't there have to be some work done to the head. Like I said earlier if your not running the 1.5mm spacer wont something have to get decked?

You will have to have a rechambered head cut for that setup. That's what Scot is actually speaking to, most folks won't mess with a stroker head without the whole motor being there because it's very difficult to turn the measurements taken off an engine elsewhere and do the stroker head mod correctly the first time. For some reason, the measurements never seem to add up!

 

[wwholden]

most builders won't touch a stroker topend without the whole motor bc it is waaaaaaayyyyy too hard to get it exact without having everything in hand. probably best to send it to someone

Im going to try and do this on my own. Im a machinist so Id like to do the head work myself.

 

[scotj77]

yes they have to modify the head they shave the squish down and then cut a raised portion into the head for the piston to go into bc with a 3mil your piston actually leaves the cylinder just a little

 

[wwholden]

You will have to have a rechambered head cut for that setup. That's what Scot is actually speaking to, most folks won't mess with a stroker head without the whole motor being there because it's very difficult to turn the measurements taken off an engine elsewhere and do the stroker head mod correctly the first time. For some reason, the measurements never seem to add up!

Yeah I saw Joe's how to on turning a head on a lathe. Im going to try that. Im guessing you remove material until the squish is right. By doing the squish test with solder?

 

[sicivicdude]

Yeah I saw Joe's how to on turning a head on a lathe. Im going to try that. Im guessing you remove material until the squish is right. By doing the squish test with solder?

With one very important caveat, Joe's heads are for stock stroke engines so the squish area is dead flat with the head gasket mating surface. Yours will be inset approximately the amount that you want the squish gap to be set at.

If you have access to a lathe, you're golden. I'll PM you a little info

 

[wwholden]

Yeah I have a lathe and Im going to make myself an arbor here soon. Which by the way do you know how many threads per inch the spark plug threads are?

But I wont be turning the head till I check out this cylinder. I should be able to get a visual on it tomorrow. Then order a degree wheel.

Any info is greatly appreciated civic!!!

 

[slickerthanyou]

yes they have to modify the head they shave the squish down and then cut a raised portion into the head for the piston to go into bc with a 3mil your piston actually leaves the cylinder just a little

Pic of my 3mil for Mr. holden -

 

[wwholden]

Pic of my 3mil for Mr. holden -

Ahhh I see. So im assuming the side of the piston that extends from the cylinder would measure approx 1.5mm?

Also the purpose of a stroker is to add cylinder volume right? More cc's? To me with this set up (no spacer plate) you would be loosing potencial power on the top half of the stroke?

 

[slickerthanyou]

That's what i'd say Not counting the top of the dome!

 

[wwholden]

Yeah I guess you would call the indentation from the gasket surface on the head would be the added cylinder wall length needed.

 

[wwholden]

Ok so I installed my cylinder over my +3 stroker today to check the port alignments. And Im sort of confused. The piston does extend over the top of the cylinder like slicks picture above. However the piston at BDC is not below the transfer or exhaust port. They seem to line up perfect. So I thought maybe the cylinder had a port job that was built around a 3 mil so I installed stock cylinder/port over that crank. And there isn't much difference at all based on where the piston meets the ports. I do not have a stock stroke engine laying around to compare where it would normally line up. So is a stock stroke have the piston partially covering the ports roughly 1.5mm. Because to mu knowledge you want the piston at BDC to be flush with the ports and my stroker is going that in this set up so is it good? Here are some pics. By the way this is WITHOUT a spacer and using a cometic gasket measuring .4mm.