Can a 4AG 16V Exhaust cam be installed into a 20V head (EX) and work?

[Futo_gt86]

CAR: KETO

ENG: ST20V, Microtech, 1J inj.

Issue: Aftermarket Camshafts.

Did a search, didn't come up with much, found something similar in 9000rpm site, but contradicts what I just physically measured.
Stock 20V exhaust cams reground to fit 16V head.
http://forum.9000rpm.co.za/viewtopic.php?id=8550&p=2

I played with Rotary's be for 4A's, Cams are new to me, so be gentle.
I'm looking at cams for my Silvertop 20V.
I got lost on the Toda site looking for exhaust cam's, I could find 4AG 5V intake np, but not the listing for 5V exhuast...might have been translation site I was using...anyway I got thinking, would a 4AG 16V exhaust cam fit into a 20V head?
*Now obviously the dizzy drive on the cam is of no use, one of SamQ 20V relocation kits would be the trick.

I have a Bigport head exhaust cam and a stripped spare Silvertop 20V head, why not physically measure it and try it.

***Just so we get this straight, depending on budget, I'm looking at 272-292 duration, 9mm-10mm lift**
I don't want to put stock 16V ex cam in 20V head, I just wanted to see in a 16V cam would fit.

So first I measured the journal/ round lobes, and they both measured 27mm on verniers.

http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545004.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/DSC_0778_zpsazc3vbov.jpg.html)

http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545005.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/DSC_0777_zpsitcfx4fw.jpg.html)

Lobes are in identical positions.
http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545006.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/DSC_0772_zpsvwbrrzlc.jpg.html)

http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545007.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/DSC_0776_zpssbtq7zla.jpg.html)

http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545008.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/DSC_0775_zpsdgwqseng.jpg.html)
The 20V ex cam base circles / lobes are meatier then the 16V.
20V ~ 32mm ish
16V ~ 28mm ish
Stock 20V exhaust cam duration is 250 deg vs 16 valve is 240 deg.
Is the extra ~4mm (2mm per side) thickness solely due to more duration on 20V ex cam?
Or is there another reason for the 20V lobes being thicker?

I placed the 16V ex cam in 20V head and it fits, no problem?
Below pictured, bigport 16V exhaust cam in 20V head.
http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545009.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/DSC_0773_zpshwmdtg6h.jpg.html)

So my question is,
Could I use a 4AG 16V Exhaust cam with desired duration in 20v head, with out any ill effects?
Or is there a reason this is not a common install?

[Matt]

Never thought about even attempting this due to the number of valves differing. I used kelford cams in my 20v.

the duration of a 20v cam is quite large from factory and quite often larger than what people use in their 16v

[phoenix]

The 16v cam won't have the dizzy drive on the back of it for the 20v dizzy/cas. The SamQ kit only shifts the cap etc to the front but still utilises the distributor body at the back of the head

[Futo_gt86]

Never thought about even attempting this due to the number of valves differing. I used kelford cams in my 20v.

the duration of a 20v cam is quite large from factory and quite often larger than what people use in their 16v
Not looking for a brand name plug Matt, but will keep that in mind thanks.
20V exhaust has 2 valves per cylinder, where as the intake has 3 valves....and as you can see from above, the exhuast cam valves are in the exact same location as 16V.
Do you mean the valves are different lengths?


The 16v cam won't have the dizzy drive on the back of it for the 20v dizzy/cas. The SamQ kit only shifts the cap etc to the front but still utilises the distributor body at the back of the head

Nick, ? Huh man ? Might want to double check that...
SQ "dizzy relocation kit", ie re-locates entire dizzy to exhaust cam gear, there is a blanking plug that bungs the rear of the head.
Edit: I am wrong, annex garage is the relocation kit.

Also note, that 16V and 20V stock exhaust cam gears are interchangeable.

[davew7]

Next Question. Does that mean that I can then use a 20V exhaust cam on the intake side of a 16V which will give me 250* duration? Dave W

[phoenix]

This kit it is a distributor cap relocation kit. The cap and rotor button are moved to the front of the engine while the original distributor base along with the wiring is kept intact at the back. This means all wiring bar the spark plug leads are left in their original position. It is suggested that the distributor blanking cover product is used to block off the electronics of the base.

That was a copy and paste off SamQ's thread on these dizzy relocation kits, so unless I'm reading something different or something has changed since this was posted the original dizzy is still used just cap and rotor relocated

[Futo_gt86]

Next Question. Does that mean that I can then use a 20V exhaust cam on the intake side of a 16V which will give me 250* duration? Dave W

Dave, read the 9000rpm link listed in first post, you can use two cut down 20v exhaust cams as intake and exhaust on 16v. It's not a straight drop in swap, but can be done. Do google search, found another post stating that ~8mm lift was obtained in with this type of set up.

http://www.toymods.org.au/forums/threads/35862-Very-silly-4AGE-question-%2820V-exh-cam-in-16V%29

gixer is correct. I have been running a ground 20v cam in my bigport for, shit yeah, about 5 years :eek:

Spec for cam are about 263deg with 8.3mm lift, cannot remember the Tighe grind number, just asked for the largest duration that can be ground on the cam up to 272. Cam was from Silvertop.

I now race the motor with the Tighe partnered with HKS 264 8.35 at modern regulaity level here in SA and have never had any issues. All shim clearances set to TRD bible spec.

I take it jazae86 means that his 16V intake cam is cut-down 20V exhuast cam to Tighe spec, and that his 16V exhuast cam is HKS 264 8.35 - as the dizzy drive is on the front of the exhuast cam, a cut down 20V cam used in place of the exhuast cam would not have the gear to drive the dizzy.
Another approach would be needed, adding a gear to it, or modified Cam gear drive style or Crank toothed wheel with hall effects sensor or something along those lines.
So, for the 16V intake cam, yes
For the 16V exhaust cam, not exactly straight forward, but could be done.
http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545016.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/DSC_0772_2_zpsnvyjbmno.jpg.html)
Depending on the cost involved, you might want to just fork out for a legit set of cams.

But, Lets not get off track, stay with my 20V question please.

[Futo_gt86]

This kit it is a distributor cap relocation kit. The cap and rotor button are moved to the front of the engine while the original distributor base along with the wiring is kept intact at the back. This means all wiring bar the spark plug leads are left in their original position. It is suggested that the distributor blanking cover product is used to block off the electronics of the base.

That was a copy and paste off SamQ's thread on these dizzy relocation kits, so unless I'm reading something different or something has changed since this was posted the original dizzy is still used just cap and rotor relocated

OK, how about that, shit sorry bro. I must have been thinking of the garage annex kit.
Anyway, all that to one side, just bung the hole left like this
http://www.ae86drivingclub.com.au/dcimages/7/7/7/6/545017.jpg (http://s1280.photobucket.com/user/alaistairb/media/Parts/Bung_zpsabuymzwz.jpg.html)
and then use Sam's sweet ass kit, not like its a major hurdle.

[Futo_gt86]

I'm starting to think that the answer lies in the different base circle thickness........ and the valve length.

So, do the base circles keep the shim/bucket in place whilst valve is closed, so it doesn't float, and the cam doesn't smack down onto the top surface, or in 16V the shim doesn't fly out ? (i'm new to cams)
Am I correct in thinking that with 20V buckets, with use on 16V cam, based on the measurements taken above, that there would be ~2mm or more difference, and no way to shim it up.
....whats the heat expansion tolerance, 2mm is bit much yeh? LOL

Below link is 20V cam in 16V head.
http://forums.club4ag.com/zerothread?id=90045
Stock 16V valves are too long, hence the grind preformed to make them work with 16V

So in the reverse, 16V exhaust cam used in 20V head would need incredibly high lift to match the stock lift.....