4AGE 16-20v Mods/Interchangeable parts

[celicaJZ]

Good day!

Guys, here are some questions and needed some more elaboration/clarification for some interchangeable and modification stuff. to give you an outline:

-> 4AGE 16V EFI to Twin weber45 carburetors
-> 20V silvertop pistons to 16v block
-> Blacktop 20v Flywheel to 16v crank


-> 4age 16V EFI to Twin Weber 45 carburetors

My friend offered me to swap his 1 pair of twin weber 45 from his small port 4age with my complete EFI set of big port TVIS AFM, the thing is there any other cheaper way of modification rather than re fabrication of both manifold adaptors?

the small port/big port head comparison:


weber carbs installed on my friends 4age smallport:


and will there be much gain switching to twin carbs from efi? aside from increased fuel consumption which is common on twin carb setups, will i gain power, torque and acceleration with twin carburetor? will a modified cam make a good combination with twin carburetors?


-> 20V silvertop pistons to 16v block

Also he offered me a set of 4 20v Silvertop pistons, will it still firmly fit with the 16v bigport connecting rods? 10.5:1 compression ratio for the st pistons, and i think 9.0:1 for the 16v bigport.

here's the connecting rod comparison:


to assume that my stock connecting rod is from 2nd generation big port versions it would be a lot hell of sturdier rod compared with the rest.

here's the actual pic:


the rods from the image are from the blacktop engine..


-> 20v BT flywheel to 16v

Checked that both flywheels are the same 8 bolter, problem is im not sure if its sure fit with 20v and 16v crankshaft bolt holes? another thing is will there be effect if it will still be used with my stock 4AC 5-speed manual tranny.?


Hoping for your kind suggestions and much more advice regarding cheap mods for 4age 16v.. already heard of 7age conversion but i'd rather not stick to that dream, crank bolt is different and is weaker...

thanks in advance.. cheers

[Sam_Q]

flywheel fit's straight on if you have the matching clutch.

You will probably not gain that much of a compression ratio raise with the 20V pistons due to the fact that the silvertop chamber is smaller.

Besides if you have a bigport none of this stuff would fit as it has a different crank

[fixeruperer]

in that pic, the two middle conrods look smaller ?
the carbs will have more grunt in the mid and top end. but youll need an adapter or new manifold made.
if you have a early bigport, the wrist pin will be an 18mm when the 20v is a 20mm.

[Sam_Q]

why would the carbs have more power?

[Harreh]

flywheel fit's straight on if you have the matching clutch.

You will probably not gain that much of a compression ratio raise with the 20V pistons due to the fact that the silvertop chamber is smaller.

Besides if you have a bigport none of this stuff would fit as it has a different crank

Incorrect, there was two revisions of the bigport, 7 rib and 3 rib. 7 Rib is the same crank as all overs, only the 3 rib had smaller journals

[trdee]

3 rib had a 40mm crank and the rods had 18mm piston pins. 7 rib onwards all cranks are 42mm with all rods having 20mm pins. same part number from 7 rib bigport all the way to blacktop.

[Sam_Q]

well let me be more specific, you have the overwealingly more common bigport atmo engine then it won't fit.

[Harreh]

Let me be more specific as you seem to once again be spreading misinformation.

If in the event you have a 3 rib block (bluetop) found in AE82 corolla or an AE86 corolla or some MK1 AW11 it will have smaller journals. However if you have a redtop bigport found in MK2 AW11's and possible late model twinky's (red top) irrespective of it's induction type it will be the same internals as whats found in all other versions of the engine.

Before being facetious when making a point it's generally an idea to ensure your facts are correct

[Sam_Q]

this is getting a bit out of hand,

how was my statement incorrect, in this country isn't the amount of 3 rib big port engines disproportionatly greater than 7 rib big port engines? If I am wrong then I want to know.

[trdee]

considering every SX corolla ever sold in australia had a smallport, and only early model AE82s had the 3 rib bigport, yes you are wrong.

[Sam_Q]

I just realised I made a typo, I editted it. Let me put it another way, if you where to look at any bigport in this country wouldn't it be highly likely that it would have a 3 rib block

[trdee]

probably not. once again you only got the 3 rib bigport in early model AE82 twincams here. whereas the 7 rib bigport was found in both the later model AE82 as well as all AW11 mr2s.

[Sam_Q]

really? I didn't realise that there where many 7 rib blocks in ae82's, I have never seen one but that's probably just circimstances

[oldeskewltoy]

well.... just to be a PITA...... and to prove that information accuracy isn't always what we are told......

My 1987 AE86 came with a 7 rib block, and 40mm internals....

Oh and it was the original engine... you see it had the VIN tag riveted to the block




Oh... silvertop pistons are pretty crappy overall, pop a set of smallport pistons in, do a bit of porting, cut the head about .020"(1/2mm) and you are good to go....

[Hiro]

really? I didn't realise that there where many 7 rib blocks in ae82's, I have never seen one but that's probably just circimstances

I've seen plenty, and even owned one. Not standard (and most of them aren't, it was only the Series 3 end-of-production AE82s that had them due to Japan switching over to the AE92), but still they aren't exactly rare.