Big port cams in a small port motor

[Evan]

Hey i am about to swap a 96kw rwd bigport motor out of an ae86 to a ae92 small port one.
I was wondering if there is a gain in performance if u swap to the big port cams?
I couldn't find any info on it.

cheers

[Hen]

Just quoting internet "knowledge" here, but it seems that they do improve things (as you'd expect from the specs) but wouldn't be worth paying someone to fit and reshim.

So if you can do it yourself go for it. If you are paying for the work anyway, save up a little more for some bigger aftermarket cams.

Hen

[Ben Wilson]

FWIW, I compared the cams from a smallport ZE to a bigport AE82 and are as far as I could tell, they were idnetical. The old AE86 cams may have been bigger, I haven't had a chance to check them.

[oldeskewltoy]

the differences are there(when new) but are not substantial. From memory they provide a marginal lift increase with no duration change. All and all, I agree with Hen

Just quoting internet "knowledge" here, but it seems that they do improve things (as you'd expect from the specs) but wouldn't be worth paying someone to fit and reshim.

So if you can do it yourself go for it. If you are paying for the work anyway, save up a little more for some bigger aftermarket cams.

Hen

[Mr Revhead]

they seem to help with 4agzes. but i have seen dyno results that loose power on n/a

[ivan]

From memory they are 30thou lift difference.
As mentioned before its not worth paying someone to do it.
Ivan

[Ben Wilson]

According to my digital calipers (accurate to 0.01mm), there was zero difference in lift.

[Hen]

I've heard that the change in cams wasn't bigport vs smallport. The change occured earlier than the port change. So some bigports have the "smallport" cams from factory.

Unsure of exact details of the change though.

Also the exact cam specs are around, search if interested.

Hen

[Mr Revhead]

the bluetop has one cam, all other 16vs have another type. which is the same
ie theres the bluetop cam
then theres the cam for all other 16v engines.

[Cuzzo]

As Hen suggests, smallport cams where used in some late bigports and also some bigport cams are different.(internet knowledge not actual venier checked by myself)

It has been done and dynoed creating a few kw's more, however id doubt its worth doing. Better off doing a major clean and service. To know when you flog her she should handle it alright.

[ivan]

16v 4AGE heads specifications

• Valve included angle (angle between the inlet and exhaust valves) - 45°
• Minimum valve spring seat pressure to allow for 7,700rpm - 35lbs, or 16kgs
• Inlet valve diameter - 29.5mm
• Exhaust valve diameter - 25.5mm
• Both valves have 6mm diameter stems.
• Cam bucket diameter 28mm, shim diameter 25mm

Cam Specs
Big Port
Inlet Cam
IVO BTDC - 9°
IVC ABDC - 51°
Duration - 240°
Lift (mm) - 7.56
Exhaust Cam
IVO BTDC - 51°
IVC ABDC - 9 °
Duration - 240°
Lift (mm) - 7.56

Small Port
Inlet Cam
IVO BTDC - 8°
IVC ABDC - 44°
Duration - 232°
Lift (mm) - 7.1
Exhaust Cam
IVO BTDC - 44°
IVC ABDC - 8°
Duration - 232°
Lift (mm) - 7.1

4AGZE
Inlet Cam
IVO BTDC - 8°
IVC ABDC - 44°
Duration - 232°
Lift (mm) - 7.1
Exhaust Cam
IVO BTDC - 44°
IVC ABDC - 8°
Duration - 232°
Lift (mm) - 7.1

20v 4AGE head specifications

• Valve included angle (angle between the inlet and exhaust valves) - 35° (I think ...)
• Inlet valve diameter - 26.5mm
• Exhaust valve diameter - 26mm
• Both valves have 5mm diameter stems
• Cam bucket diameter 23mm, with very small shims between the valve stem top & bucket

Cam Timings - (AE101) VVT <4400rpm & >~7000rpm
Inlet Cam
IVO BTDC - 0°
IVC ABDC - 70°
Duration - 250°
Lift (mm) - 7.97
Exhaust Cam
IVO BTDC - 54°
IVC ABDC - 16°
Duration - 250°
Lift (mm) - 7.6

Cam Timings - (AE101) VVT >4400rpm
Inlet Cam
IVO BTDC - 30°
IVC ABDC - 40°
Duration - 250°
Lift (mm) - 7.97
Exhaust Cam
IVO BTDC - 54°
IVC ABDC - 16°
Duration - 250°
Lift (mm) - 7.6

Cam Timings - (AE111) VVT <4400rpm & > ~7000rpm
Inlet Cam
IVO BTDC - 5°
IVC ABDC - 65°
Duration - 250°
Lift (mm) - 8.2
Exhaust Cam
IVO BTDC - 54°
IVC ABDC - 16°
Duration - 250°
Lift (mm) - 7.6

Cam Timings - (AE111) VVT >4400rpm
Inlet Cam
IVO BTDC - 35°
IVC ABDC - 35°
Duration - 250°
Lift (mm) - 8.2
Exhaust Cam
IVO BTDC - 54°
IVC ABDC - 16°
Duration - 250°
Lift (mm) - 7.6

Information found here.
Accuracy is unknown but it looks about right.

Hope it helps,
Ivan

[Mr Revhead]

As Hen suggests, smallport cams where used in some late bigports and also some bigport cams are different.(internet knowledge not actual venier checked by myself) .

by late bigport you must mean redtops, ie all 4ages with the 42mm crank.

there is 2 types of cam..... the bluetop ones.. then the rest. EPC p/ns

[Ben Wilson]

16v 4AGE heads specifications
Big Port
Inlet Cam
IVO BTDC - 9°
IVC ABDC - 51°
Duration - 240°
Lift (mm) - 7.56
Exhaust Cam
IVO BTDC - 51°
IVC ABDC - 9 °
Duration - 240°
Lift (mm) - 7.56

Perhaps somebody had stuck some big port cams in the ZE head I bought, just looked at the data I recorded and I measured around 300though (7.5mm) on all of them..

[c2888]

According to the EPC, the change over period was during 1987, it doesn't seem to be ruled by any sort of logic.
AW11 NA got both sets of cams, changeover being Sept 1987, BUT 4AGZE got the updated smaller cams from the start of their production in Aug 1986

The confusion lies in that australia was behind when corolla production started, so our ae82s got bigsnorts with small cams, where in japan, the cam change coincided with the model change to ae92.

Probably why the 88 build date AE82s don't feel like they go as hard as the earlier cars, smaller cams, combined with the fatter 42mm crankshafts.

The only way to know for sure what you have is to pull it apart and measure them.

Dan

it made sense when i was typing, sorry if i confuse

[Mr Revhead]

42mm crank in an ae82?
are you sure?

aw11 got both cams, cause they also got the first 42mm crank engines