Swap - ET2 / A18 / B20A (JDM) / B20A5 / B21A : Head - A20A : Block

[Ichiban]

I talked to the local engine builder/machinist today while i was picking up my 20R head, he says not to bother filling the other side of the hole once it's drilled out. if you really wanted to, he says, you could tig in some material before you drilled it, but there would really be no point. he says he'd be more concerned about adding material to the side of the "pedestal" that the bolt tightens on that you've moved the hole towards. But even if there's lots of material anyway again there's no point.

is someone gonna measure the B20A5 crank sprocket out for me? I found a company that will make every possible sprocket configuration conceivable. i also found a company that makes custom timing belts.

So there.

[Swap_File]

I can measure everything this weekend (I am down at college for the week).

The last person I talked to thought it would be cheaper to machine a stock gear, and make a spacer, rather than having a whole new gear made.

If you want a basic idea of the size of the sprocket, look at this picture:



Both gears are the same width. Teeth are spaced the same, and shaped the same. It's just less teeth means a smaller gear. The other difference is that the B20A5 shaft is 28mm, while the A20 shaft is 25mm.

[Ichiban]

i'll try and get a price estimate for the off-the-shelf gear on Monday. I was thinking about just getting a piece of 1.5mm shimstock and welding it around the ID of the B20 gear, and using an oversize key. thoughts? what are the B20 gears made out of? steel? aluminum?

[Swap_File]

Well, it turns out the information I got from preludepower was incorrect, the A20 intake manifold does NOT bolt up to the B20A5 head. Neither does my B18 intake manifold. The B20A5 bolt pattern seems to be much wider than anything else. Check out the pictures:



A20A3 head on top, B20A5 head on bottom. I would have held the B20A5 gasket up to the A20A3 head, but it refuses to peal off the head in one piece.


Next time I am at the junkyard I will grab the B20A5 intake that I left there. If I rip out the butterfly plate, it might make it low enough to clear the Accord's hood.

I am still not too worried about the intake, that can always be delt with later. I am more worried about the head bolt problem. While I am sure the hole could be moved, I just hope it will not end up costing an arm and a leg to do.

[Swap_File]

I almost forgot, here is the information on the crankshaft cam gears.

A20A3:

Thickness: 25mm
Shaft Diameter: 25mm


B20A5:

Thickness: 25mm
Shaft Diameter: 28mm

For both gears, the keys are built into the gears themselves. The gears appear to be made of steel.

The images were scanned at 600dpi. By either tracing them in a CAD program or measuring them in a photo-editing software you should be able to get closer measurements than I could ever get with my cheap calipers. If you need more information (or better pictures), let me know.

[Legend_master]

I almost forgot, here is the information on the crankshaft cam gears.

A20A3:
Thickness: 25mm
Shaft Diameter: 25mm


B20A5:

Thickness: 25mm
Shaft Diameter: 28mm

For both gears, the keys are built into the gears themselves. The gears appear to be made of steel.

The images were scanned at 600dpi. By either tracing them in a CAD program or measuring them in a photo-editing software you should be able to get closer measurements than I could ever get with my cheap calipers. If you need more information (or better pictures), let me know.

Looks good man, the intake should be no problem. I think your biggest problem will be the timing belt. Have you looked into the 86-90 integra belts. They are Dual cam, but are not very large motors 1.6L. There might be other swappable parts from that car also, just check it out.

[A20A1]

Well I tried editing the gears in PS, the pics were taken at a bit of an angle so the measurements are off a tad. I tried to find the center of the gear then rotated it to even out the radius on all sides.

It's in 100 pixles/cm right now...

The outside diameter appears to be 62.5mm




This picture measures the radii

[A20A1]

This is as best I could do with the B20A5

Again:
The thick lines represent the Radius

[A20A1]

B20A5
- ID : Aprox. 28mm
-OD , TEETH : Aprox. 50mm ( Gear OD )
- ID , TEETH : Aprox. 44mm

A20
- ID : Aprox. 25mm
-OD , TEETH : Aprox. 62mm ( GEAR OD )
- ID , TEETH : Aprox. 56mm

Both A20 And B20 have a TOOTH Depth of 6mm



Here is a B20A5
not sure about the tooth degrees... I think they are spaced Somewhere between 21.1* - 21.25* degrees apart from eachother.

[A20A1]

That drawing is not even/exact... so dont trace it and use it to make a gear.

[smufguy]

if there are 17 teeth on the gear, then the teeth spacing deg would be 360/17 which is 21.1764 deg exact. so yes, ur right, they are a rounded 21.2 deg apart.

[A20A1]

Hehe, I need to go back to school if I forgot something as simple as that.

Thanks Praveen

[smufguy]

you are most welcome buddy. and you know i always get excited to see what you have to say, cause most of the time its something i never heard of.

PS: Your post count makes me wanna cry. lol

[A20A1]

Swapfile, if you can mike out the b20 crank gear and give me all the dimensions (width, tooth height/spacing/count) and the ID of the A20 crank gear...

(B20A Gear OD 50mm /// Gear OD W/Out Teeth 44mm /// B20A & A20A Belt Width 25mm /// B20A & A20A Tooth Height 6mm /// B20A Tooth Spacing 21.1764 Deg. /// B20A Tooth Count - 17 /// A20A ID 25mm)

A20A3 head on top, B20A5 head on bottom. I would have held the B20A5 gasket up to the A20A3 head, but it refuses to peal off the head in one piece.

Damn, looking at those pics I just realied that Carotman sent me his B20A5 Intake manifold Gasket when he sent me his old carbed A20 manifold.

[Ichiban]

thanx eh for the specs...

huh...i didn't realise the teeth had rounded troughs like they do. i'm not sure if i saw that style in the catalogue i was looking at. I'm gonna print off the specs and see what i can dig up...any word on intakes, i was really hoping to use my BT1 non-EGR intake and computer.

[A20A1]

I'n my drawings I left out the champher on the teeth...

the key And the little hole they drilled for the balancing.

[Ichiban]

im hoping a few things here, but untill my buddy gets back off of holidays next week i won't know for sure:
-the tooth design and pitch is a standard "feature"
-the gear comes balanced
-a 17 tooth gear is availiable (most seem to be even numbers....)

next week i'll find out.

Edit:was it a balance hole or is it the timing mark, i noticed the timing marks on the A20 and B20 gears are opposite in swapfile's pictures. also, the integral key is a little strange.

[A20A1]

hrm I thought it was for balancing... or maybe the gear + crank is balanced together but not apart?
I thought the flywheel was the timing mark.

[rjudgey]

Well not sure what drugs Sean was on when he first posted i was bored yesterday and i'm off work for two weeks so i thought i'll have a play with my engine bits, so pulled out my B20A head and got a A20A head gasket just to see how close they were. To my amazement they weren't that far off, the bolt holes were all the same even the locating dowels fitted. The only downside was that the two oil drains at the front of the B20A head would need to be welded up a little as they widen out over the A20 head gasket, and also the oil feed on the back of the block was a little bit out but not by much, with some work it could be made to fit an A20, ET or ET2/A18 block, now the major set back as it stands is that the cam gears overhang all the A20 and ET geras by quite a bit at least an inch and a half which means that no belt is going to be able to fit on and drive all the different pumps etc. Even if you get round that problem your then left with sorting out pulleys to drive the whole lot. So to me this is a whole load of pain that for a little bit extra power that can easily be had by just fitting a whole B20A and tranny anyway?? If you guy;s are lacking engines and tranny's U.K. market only sold manuals and theirs still a few engines and box's knocking around in yards and as secondhand cars in both Accords and Preludes although the Accords are rarer sor some reason B20A accord never really sold well over here.
Can be done but with custom pulleys, belts and a little bit of welding but is it really worth the trouble i think i'll stick to my ET1 and A20 for now and leave my B20A in my 2G Lude SI where it belongs.

[Swap_File]

If you just hold up the gasket, it looks like the B20A5 head will bolt up to the A20 block, but believe me, it does not. If you actually set the head on the block you will see that middle bolt on the intake side is offset in the block, and not offset in the head.

One of the biggest reasons I did not want to install an Accord B20A was the unavailability of parts in the USA and the cost (I won't be finding an Accord B20A at the local junkyard). Sadly, a Prelude B20A5 head swap will probably end up needing quite a bit of machine work, once again leading to a situation where it would be hard (and or expensive) to find replacement parts.

For now I have pretty much put my B20A5 head swap plans on hold. I am still looking into it, but focusing more on just getting a turbo installed in my Accord.

[A20A1]

I thought he's saying the JDM B20A is the close fit not the B20A5 right?

[Swap_File]

...i think i'll stick to my ET1 and A20 for now and leave my B20A in my 2G Lude SI where it belongs.

I thought he was refering to the B20A from the 88-91 Prelude SI (B20A5), but I may have mis-understood.

[carotman]

Damn, looking at those pics I just realied that Carotman sent me his B20A5 Intake manifold Gasket when he sent me his old carbed A20 manifold.

Really? I don't remember having a B20A5 gasket honestly

[A20A1]

hehe, well you must of, cause it's right next to me under my labarynth of DVD's
. I thoght I had asked you about it... when I first got the big box (rims) in the mail. or maybe it was someone else.

[rjudgey]

UK 2G Lude SI came with B20A as standard and it's the same as the Accord B20A, Surprised about the fit not sure what the B20A5 3G lude SI head is like not seen any of those, was just playing with the spares that i had it's a shame that the cmap pully's didn't line up otherwise could have been a fiarly easy swap a JDM B20A head onto a ET/A20 especially with the larger bore and shorter stroke could have made quite an interesting hybrid i bet you wouldn't get any probs revving that to 9K apart from valve float from the weak springs in a B20A but Cat Cams do uprated springs of the shelf so not too much of a problem. But anyhow not worth the time i don't think better off spent on modding A20 Head.