Joined
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3,216 Posts
Major Update:
Okay everybody, due to unforeseen complications in obtaining a suitable head gasket for the ET overbore, and difficulty in finding a proper A18, I have made the decision to go with an A20. This decision is more involved but will sooner realise my ultimate goal: A larger than 2 litre engine with weber carbs. I wasn't planning on converting to webers until after the rebuild due to cost, but due to availability of FI A20s, I'll go for webers as part of the rebuild. This will be a bit more expensive than originally anticipated, but I'm sure the additional time will be more than worth it! :twisted:
So the plan now is to buy an 2.0SI A20 and do the rebuild on this. Overbore by 0.3mm, and take 1mm off the head and 0.5mm off the deck. Use 0.3mm oversize pistons. I am atking more off the block and deck to try and squeez a bit more compression out of it. This is because in converting from the ET to 82.7mm bore, and taking off the head and deck I would have respectively been squeezing more out of the ET than I would be by doing the same to the A20. So I want to go a bit further and get as much as possible from the A20 straight up! So .3mm oversize bore, and 1.5mm collectively off head and deck.
The other point of interest about doing the A20, is that I will be using an A20 head. Which has different input ports to the ET but the same exhaust ports. So I can keep my curernt exhaust system (hurricane extractors to 2.25 inch all the way, no cat). But I can't carry over my carbs, so I will need to go webers. This is fortunate because there are weber manifolds made cheaply by Rowland manifolds and by Redline too I think. Whereas there is nil availability for the ET or A18. So I would have been looking at a custom job down the line if I were to stick with the ET.
I am still looking at doign custom larger valves all around, with brass valve guides. And most likely use aftermarket A18 exhaust springs all around. Or maybe see how many OEM springs I can salvage...
There is also a financial benefit to doing the A20, albeit a trade off. It allows me to transfer engines (ET) between my silver (good) and red (spare) ludes, then sell the red lude with the ET that is burning oil. This will get me some funding straight away to buy my parts. It will probably cover almost all the parts cost except for the webers. Then I'll have a good ET in my silver lude while I rebuild the A20. And after I finish the rebuild, I'll have a good ET left over for a potential stock resotration down the line... or for sale, or to do up another lude to sell. I probably would have got more money for the red lude if I had off continued the ET build and held off to sell it with its current good ET engine - but that is besides the point.
I will edit the following parts and labour list, and keep the superseeded items in parenthesis and blue color for reference purposes. Overall pretty much all of the information in this thread will apply to either ET/A18 or A20, as the blocks are identical apart from bore size. Headwork has been discussed generally for either head.
**************************************************************************************************
Green parts have now been sourced.
PARTS:
OEM pistons A20A4 83mm oversize 0.3mm from Honda, (13103-PJ0-307 ) for AU$128.10 each *4 = AU$512.40
[[ OEM pistons A20A4 82.7mm (not oversize) from Honda, (13103-PJ0-308 ) for AU$122.05 each *4 = AU$488.20 ]]
OEM Rockers from A20A1/2/3/4 and A18 from Honda, A: 14621PC6600
B: 14622PC6600 AU$22.41 each *12 = AU$268.92
Total AU$781.32
Honda Australia Victoria national Spare parts division:
T: 03 9579 1811
Honda Australia Victoria Upper Ferntree Gully Spare parts division:
T: 03 9758 9888
ACL Conrod Bearing Set (racing high performance version) from Nasons Dandenong East; ;(4B1946H) AU$70.60 std. or oversize
ACL Thrust Washer Set from Nasons Dandenong East; (1T1952) AU$10.00 std. or oversize
ACL Main Bearing Set from Nasons Dandenong East; (5M1947) AU$71.50 std. or oversize
Total AU$152.10
Toga HV oil pump (OPH15-HV) US$100.84
Total AU$125.15
Clutch kit from Clutchnet.com:
Yellow fibre carbon clutch disc with sprung hub for Honda Prelude SKU: 4822Y30 US$135
From Rockauto.com :
Water pump (GATES Part # 41039 cast aluminium) US$20.79
Gates Timing belt and tensioner (TCK160) US$32.79
Subtotal US$53.58
Total AU$65.59
From Rockauto.com:
Felpro upper kit (for A20A4) (HS9429PT) US$101.99
Felpro conversion kit (CS9429) US$52.79
Felpro head gasket (spare) (9242PT) US$37.79
*check with Rich after purchase*
Total AU$235.87
Cam Regrind (see machine work)
Flywheel lightened OEM (see machine work)
Running total: AU$1612.25
(plus shipping)
Grand total: :crazy:
Budget: AU$2000 including all of the shipping costs.
Items to re-use:
conservatively including extra parts. (Not including additional tools).
*Miscellaneous info for posterity*
Rich's guide to headwork (including custom larger valves):
http://www.preludepower.com/forums/showthread.php?t=240061&highlight=port
QUOTE Cygnus:
""Are there particular piston rings to go with the A20A3/4 pistons in particular, or will it just be a matter of finding ones to fit."
I don't think so. Obviously you could just get the rings from Honda and leave it at that. If you want to get fancy you can get oversized rings and hand file the gap for a perfect fit. One thing I discovered about that is that I ended up buying 2 sets of rings; one standard and one oversize. I did this because the oversized oil control rings didn't seem to fit right. So I used standard sized oil rings and oversized for the compression and middle rings.
Also, I would use the standard Honda piston size (82.7mm) instead of the 0.3mm oversize (83.0mm). The only reason is if you ever want to rebuild the engine again in the future you'll have that much more material to work with. In the end it's unlikely to make a difference either way, but there is no real reason to use the oversize instead of the standard size."
QUOTE Rjudgey:
"check with rockers you have, on the ET the original ones were very weak and wore out quickly with high revs e.g. constant revving to above 4krpm. So first thing i would do is check these and see what you got. The best ones to use are from the later A18/A20 from the Accord and Prelude they have a hardened pad that wears much less at hi rpm."
"Plenty thanks! lol!
For your ET engine you would need to make sure you buy a Felpro headgasket the racing blue version commonly used on all there head kits. For some reason Felpro made sure the combustion chamber seals on the head were big enough for large bore pistons. 82.7mm works fine and you'd probably just about get away with 83mm with carefull head gasket placement, but any bigger will be an issue. stock ET CR ratio for your engine is 9.4:1 so you would indeed need pistons from A20A4 which are 9.4:1 CR ratio as well, these can only be bought in oversize .3mm form PN:13103-PJ0-308. With your ET head and these pistons you'd be able to bump your CR ratio up to something a lot higher 10.5:1 maybe 11:1 depends how much you take out your chambers when flowing your head and also when you remove the sharp edge protruding into the bores when you do the rebore. Personally i still think it's worth opting for some uprated rods and custom forged pistons cause you get better reliability less weight and higher CR ratio as you can remove the need of having the useless 4th valve pocket dish and have a completely flat piston crown and you can have it bored to a slightly safer 82mm or 82.7mm instead of the stock honda 2.0l size.
And Yes an ET block will happily bore to 83mm i have one that has been. only thing that might prevent this if the block has extensive corrosion on the inside from poor maintenance then it will be fubar!
I reckon a 2.0 high CR block with stock ET head with bigger valves and modded carbs would be good for an easy reliable 170-180bhp with a cam thats not too aggressive say something like a 262 degree with 10mm lift, but would still need to look at a custom profile with offset lobes to match the funny ET head inlet ports. would give you absolute killer torque probably something like 140-150lbft maybe more!! Would make your ride very quick off the line combined with weight savings etc. would make for a damn quick car nearly as quick as mine. Would still be pretty smooth and reliable too, if you start pushing a cam with more duration on stock internals etc. engine reliability and smoothness goes out the window lucky to last 20k miles maybe 30k miles and then will idle and drive like a bird on the time of the month!!!"
Quote cygnus:
"With some rough calculations I figure that just increasing the bore from 80mm to 82.7mm will get you to about 9.6:1 CR. Then milling the head 1mm will bump it up to around 10.3:1. I don't know what the limit is on head milling but I don't think it's more than 1mm.
Decking the block will get you more but there may be other complications like clearance with the head gasket. As I recall the piston tops are almost exactly flush with the deck surface at TDC.
With head milling and/or block decking you will also need an adjustable cam gear to correct the cam timing. They aren't "off the shelf" available but there have been some group buys over the years so they pop up occasionally."
"Well, you wouldn't *have* to have an adjustable cam gear but if you don't the cam timing will be a little off. It works out to about 1.8 degrees per millimeter taken off the head (or block). I wouldn't get too worried about it. You can always put a cam gear on later too if you happen to find one."
Quote mikes87lude:
"You shouldn't need to run premium untill you get right up next to 10.1:1 and over, until you get up to about 11.5:1 or 12.0:1, then it's methanol time."
Quote Rjudgey:
"Hello I'm awake! Right you can safely take off 1.5mm off the head wouldn't recommend though as if you need a skim again you'll have some issues. AS you have a spare head I'd say safely take off .75mm And then .25mm off the deck that will get you the 1mm with a bit of safety and margin available for future work. Or you could just go all out and chop 1mm off the head and .5mm off the block.
Pistons wise you could try and use the 83mm A20A4 pistons but would need to be really well positioned on the gasket to avoid pistons contacting the gasket. Order the Gasket kits first and then have it all measured up, then get the block stripped then start ordering the parts up once you know the state of the engine and what you need exactly.
One thing i know for sure unless your head has had the newer rockers fitted you'll be wanting to change those out for A20 ones with the harder pads that are welded on rather than just hardened rockers.
If you are using honda pistons you should be able to get enough clearance in the pistons for the valves you may need to have someone machine the pockets diameters a bit more to fit the valves but at least there in the right place in teh first place which helps. Only really an issue if you were using high lift and duration cams to be honest so avoid machining the pistons as much as possible. You can play around with them once you have the valves installed and then match the pistons to them after and check the clearance as well."
Quote Rjudgey:
"
engine mods
If you were to do a basic head job, combustion chamber flowing and polishing, matched manifolds, 2"-2.25" system, cat by pass, no emssion rubbish, 2.0l re-bore, mod the stock carbs a little to get more fuel and improve air flow, i reckon 135-140 tops maybe a little more if you up the fuel pressure a little but the stock carbs are a real restriction even if you did a A20 engine swap and ran a single Weber 38/38 downdraught that would be a lot better than stock carbs, be looking at 150-160bhp, but 150bhp would be really easy to get with two Weber DCOE's or a set of Bike carbs even with a 1.8l bottom end and stock exhaust system a minimal tidy head job and a mild cam, anymore than that you'll be looking at header, exhaust, 2.0l bottom, bigger valves etc.
If you really want to hit the 200bhp mark theirs gonna be a couple of things you need for sure, Twin Webers or Bike carbs, header, 2.25-2.5" system, bigger inlet valves. If you did go with new carbs but kept stock valve sizes you'd be looking at around 170-180bhp without the exhaust system or header you'd be looking at aroujnd 150-160bhp max with a 2.0l bottom.
When i had my original engine which was very tired, with a really basic head job, mild cam, the two webers, matched manifolds, ported exhaust manifold i got nearly 150bhp but U.K cars have no emission equipment and no cat, before the webers had stock carbs was putting down around 125bhp so their was a huge difference between the two BTW U.K ET was 115bhp so a cam and basic headwork only made about 10bhp difference althought the engine powerband was better at the top end revved nicely upto 7K."
Okay everybody, due to unforeseen complications in obtaining a suitable head gasket for the ET overbore, and difficulty in finding a proper A18, I have made the decision to go with an A20. This decision is more involved but will sooner realise my ultimate goal: A larger than 2 litre engine with weber carbs. I wasn't planning on converting to webers until after the rebuild due to cost, but due to availability of FI A20s, I'll go for webers as part of the rebuild. This will be a bit more expensive than originally anticipated, but I'm sure the additional time will be more than worth it! :twisted:
So the plan now is to buy an 2.0SI A20 and do the rebuild on this. Overbore by 0.3mm, and take 1mm off the head and 0.5mm off the deck. Use 0.3mm oversize pistons. I am atking more off the block and deck to try and squeez a bit more compression out of it. This is because in converting from the ET to 82.7mm bore, and taking off the head and deck I would have respectively been squeezing more out of the ET than I would be by doing the same to the A20. So I want to go a bit further and get as much as possible from the A20 straight up! So .3mm oversize bore, and 1.5mm collectively off head and deck.
The other point of interest about doing the A20, is that I will be using an A20 head. Which has different input ports to the ET but the same exhaust ports. So I can keep my curernt exhaust system (hurricane extractors to 2.25 inch all the way, no cat). But I can't carry over my carbs, so I will need to go webers. This is fortunate because there are weber manifolds made cheaply by Rowland manifolds and by Redline too I think. Whereas there is nil availability for the ET or A18. So I would have been looking at a custom job down the line if I were to stick with the ET.
I am still looking at doign custom larger valves all around, with brass valve guides. And most likely use aftermarket A18 exhaust springs all around. Or maybe see how many OEM springs I can salvage...
There is also a financial benefit to doing the A20, albeit a trade off. It allows me to transfer engines (ET) between my silver (good) and red (spare) ludes, then sell the red lude with the ET that is burning oil. This will get me some funding straight away to buy my parts. It will probably cover almost all the parts cost except for the webers. Then I'll have a good ET in my silver lude while I rebuild the A20. And after I finish the rebuild, I'll have a good ET left over for a potential stock resotration down the line... or for sale, or to do up another lude to sell. I probably would have got more money for the red lude if I had off continued the ET build and held off to sell it with its current good ET engine - but that is besides the point.
I will edit the following parts and labour list, and keep the superseeded items in parenthesis and blue color for reference purposes. Overall pretty much all of the information in this thread will apply to either ET/A18 or A20, as the blocks are identical apart from bore size. Headwork has been discussed generally for either head.
**************************************************************************************************
Green parts have now been sourced.
PARTS:
OEM pistons A20A4 83mm oversize 0.3mm from Honda, (13103-PJ0-307 ) for AU$128.10 each *4 = AU$512.40
[[ OEM pistons A20A4 82.7mm (not oversize) from Honda, (13103-PJ0-308 ) for AU$122.05 each *4 = AU$488.20 ]]
B: 14622PC6600 AU$22.41 each *12 = AU$268.92
Total AU$781.32
Honda Australia Victoria national Spare parts division:
T: 03 9579 1811
Honda Australia Victoria Upper Ferntree Gully Spare parts division:
T: 03 9758 9888
ACL Thrust Washer Set from Nasons Dandenong East; (1T1952) AU$10.00 std. or oversize
ACL Main Bearing Set from Nasons Dandenong East; (5M1947) AU$71.50 std. or oversize
Total AU$152.10
Nasons Dandenong East
T: 03 9797 1115
ACL Bearing Company
T: +61 (3) 6324 4600
From Horsepowerfreaks.com :T: 03 9797 1115
ACL Bearing Company
T: +61 (3) 6324 4600
Toga HV oil pump (OPH15-HV) US$100.84
Total AU$125.15
Clutch kit from Clutchnet.com:
Consider using Red Pressure plate.
Yellow performance level pressure plate for Honda Prelude SKU: 47615XY58 US$128.00
Yellow fibre carbon clutch disc with sprung hub for Honda Prelude SKU: 4822Y30 US$135
From Rockauto.com :
Water pump (GATES Part # 41039 cast aluminium) US$20.79
Gates Timing belt and tensioner (TCK160) US$32.79
Subtotal US$53.58
Total AU$65.59
From Rockauto.com:
Felpro upper kit (for A20A4) (HS9429PT) US$101.99
Felpro conversion kit (CS9429) US$52.79
Felpro head gasket (spare) (9242PT) US$37.79
*check with Rich after purchase*
[[From Cygnus x-1:
Felpro upper kit (for ET2) (HS9289PT) $?
Felpro conversion kit (CS9289) $?
Felpro head gasket (spare) (9289PT) $?
*check with Rich after purchase* (racing blue teflon - 82.804mm bore size)]]
Subtotal US$192.57Felpro conversion kit (CS9289) $?
Felpro head gasket (spare) (9289PT) $?
*check with Rich after purchase* (racing blue teflon - 82.804mm bore size)]]
Total AU$235.87
Federal Mogul victoria: 03 9753 4400
RockAuto Estimated shipping US$121.13
Cam Regrind (see machine work)
Flywheel lightened OEM (see machine work)
Running total: AU$1612.25
(plus shipping)
Grand total: :crazy:
Budget: AU$2000 including all of the shipping costs.
Conrods
Crank Shaft etc.
Keep 3rd gen distributer ignition
Cam will be re-ground.
Extras:Crank Shaft etc.
Keep 3rd gen distributer ignition
Cam will be re-ground.
Spark plugs
Leads |
Hoses | > all light blue
light blue crank case breather
Oil Filter
Fuel Filter (front and back)
Fuel Pump ?? Walbro?
Engine Paint light blue and clear coat
Budget: AU$500
Machine work:Leads |
Hoses | > all light blue
light blue crank case breather
Oil Filter
Fuel Filter (front and back)
Fuel Pump ?? Walbro?
Engine Paint light blue and clear coat
Budget: AU$500
*Speak to Hans, get quote.*
degrease and inspect block and head
Bore and hone cylinders to 83mm
Blueprint engine (hand gap piston rings etc.)
fit pistons to rods
fit rocker arms
fit bearings, washers etc.
fit head gasket and head (after I've assembled and painted the block)
Machine flywheel for sprung clutch disk *get photos off of Rich*
lighten flywheel
resurface flywheel
balance flywheel
DIY - clean up (basic port/polish) intake manifold and ports $FREE
Camshaft regrind from webcamshafts.com grind number: 148i/158US$209
Total AU$259.40
Running total: AU$259.40
Grand total: :crazy:
Budget: AU$2000 including all of the shipping costs.
Overall Budget: No more than $4500Bore and hone cylinders to 83mm
[Bore and hone cylinders to 82.7mm]
Machine 0.5mm off the block deck
[Machine 0.25mm off the block deck]
Machine 1.0mm off the cylinder head
[Machine 0.75mm off the cylinder head]
Custom fit bigger valve, 5 angle seats, brass guides, bigger valves etc.
[Custom fit bigger valve, 3 angle seats, brass guides, bigger valves etc.]
Final Clean block and head
Blueprint engine (hand gap piston rings etc.)
fit pistons to rods
fit rocker arms
fit bearings, washers etc.
fit head gasket and head (after I've assembled and painted the block)
Machine flywheel for sprung clutch disk *get photos off of Rich*
lighten flywheel
resurface flywheel
balance flywheel
DIY - clean up (basic port/polish) intake manifold and ports $FREE
Camshaft regrind from webcamshafts.com grind number: 148i/158US$209
Total AU$259.40
Running total: AU$259.40
Grand total: :crazy:
Budget: AU$2000 including all of the shipping costs.
conservatively including extra parts. (Not including additional tools). Miscellaneous:
Purge fuel tank and lines -- new lines?
Flush Radiator -- new hoses.
Will paint block, head, and extractors in bright, light blue.
Maybe paint some other miscellaneous parts.
Tuck and neaten wires, hoses etc. as much as possible while engine is out.
Purge fuel tank and lines -- new lines?
Flush Radiator -- new hoses.
Will paint block, head, and extractors in bright, light blue.
Maybe paint some other miscellaneous parts.
Tuck and neaten wires, hoses etc. as much as possible while engine is out.
*Miscellaneous info for posterity*
Rich's guide to headwork (including custom larger valves):
http://www.preludepower.com/forums/showthread.php?t=240061&highlight=port
QUOTE Cygnus:
""Are there particular piston rings to go with the A20A3/4 pistons in particular, or will it just be a matter of finding ones to fit."
I don't think so. Obviously you could just get the rings from Honda and leave it at that. If you want to get fancy you can get oversized rings and hand file the gap for a perfect fit. One thing I discovered about that is that I ended up buying 2 sets of rings; one standard and one oversize. I did this because the oversized oil control rings didn't seem to fit right. So I used standard sized oil rings and oversized for the compression and middle rings.
Also, I would use the standard Honda piston size (82.7mm) instead of the 0.3mm oversize (83.0mm). The only reason is if you ever want to rebuild the engine again in the future you'll have that much more material to work with. In the end it's unlikely to make a difference either way, but there is no real reason to use the oversize instead of the standard size."
QUOTE Rjudgey:
"check with rockers you have, on the ET the original ones were very weak and wore out quickly with high revs e.g. constant revving to above 4krpm. So first thing i would do is check these and see what you got. The best ones to use are from the later A18/A20 from the Accord and Prelude they have a hardened pad that wears much less at hi rpm."
"Plenty thanks! lol!
For your ET engine you would need to make sure you buy a Felpro headgasket the racing blue version commonly used on all there head kits. For some reason Felpro made sure the combustion chamber seals on the head were big enough for large bore pistons. 82.7mm works fine and you'd probably just about get away with 83mm with carefull head gasket placement, but any bigger will be an issue. stock ET CR ratio for your engine is 9.4:1 so you would indeed need pistons from A20A4 which are 9.4:1 CR ratio as well, these can only be bought in oversize .3mm form PN:13103-PJ0-308. With your ET head and these pistons you'd be able to bump your CR ratio up to something a lot higher 10.5:1 maybe 11:1 depends how much you take out your chambers when flowing your head and also when you remove the sharp edge protruding into the bores when you do the rebore. Personally i still think it's worth opting for some uprated rods and custom forged pistons cause you get better reliability less weight and higher CR ratio as you can remove the need of having the useless 4th valve pocket dish and have a completely flat piston crown and you can have it bored to a slightly safer 82mm or 82.7mm instead of the stock honda 2.0l size.
And Yes an ET block will happily bore to 83mm i have one that has been. only thing that might prevent this if the block has extensive corrosion on the inside from poor maintenance then it will be fubar!
I reckon a 2.0 high CR block with stock ET head with bigger valves and modded carbs would be good for an easy reliable 170-180bhp with a cam thats not too aggressive say something like a 262 degree with 10mm lift, but would still need to look at a custom profile with offset lobes to match the funny ET head inlet ports. would give you absolute killer torque probably something like 140-150lbft maybe more!! Would make your ride very quick off the line combined with weight savings etc. would make for a damn quick car nearly as quick as mine. Would still be pretty smooth and reliable too, if you start pushing a cam with more duration on stock internals etc. engine reliability and smoothness goes out the window lucky to last 20k miles maybe 30k miles and then will idle and drive like a bird on the time of the month!!!"
Quote cygnus:
"With some rough calculations I figure that just increasing the bore from 80mm to 82.7mm will get you to about 9.6:1 CR. Then milling the head 1mm will bump it up to around 10.3:1. I don't know what the limit is on head milling but I don't think it's more than 1mm.
Decking the block will get you more but there may be other complications like clearance with the head gasket. As I recall the piston tops are almost exactly flush with the deck surface at TDC.
With head milling and/or block decking you will also need an adjustable cam gear to correct the cam timing. They aren't "off the shelf" available but there have been some group buys over the years so they pop up occasionally."
"Well, you wouldn't *have* to have an adjustable cam gear but if you don't the cam timing will be a little off. It works out to about 1.8 degrees per millimeter taken off the head (or block). I wouldn't get too worried about it. You can always put a cam gear on later too if you happen to find one."
Quote mikes87lude:
"You shouldn't need to run premium untill you get right up next to 10.1:1 and over, until you get up to about 11.5:1 or 12.0:1, then it's methanol time."
Quote Rjudgey:
"Hello I'm awake! Right you can safely take off 1.5mm off the head wouldn't recommend though as if you need a skim again you'll have some issues. AS you have a spare head I'd say safely take off .75mm And then .25mm off the deck that will get you the 1mm with a bit of safety and margin available for future work. Or you could just go all out and chop 1mm off the head and .5mm off the block.
Pistons wise you could try and use the 83mm A20A4 pistons but would need to be really well positioned on the gasket to avoid pistons contacting the gasket. Order the Gasket kits first and then have it all measured up, then get the block stripped then start ordering the parts up once you know the state of the engine and what you need exactly.
One thing i know for sure unless your head has had the newer rockers fitted you'll be wanting to change those out for A20 ones with the harder pads that are welded on rather than just hardened rockers.
If you are using honda pistons you should be able to get enough clearance in the pistons for the valves you may need to have someone machine the pockets diameters a bit more to fit the valves but at least there in the right place in teh first place which helps. Only really an issue if you were using high lift and duration cams to be honest so avoid machining the pistons as much as possible. You can play around with them once you have the valves installed and then match the pistons to them after and check the clearance as well."
Quote Rjudgey:
"
engine mods
If you were to do a basic head job, combustion chamber flowing and polishing, matched manifolds, 2"-2.25" system, cat by pass, no emssion rubbish, 2.0l re-bore, mod the stock carbs a little to get more fuel and improve air flow, i reckon 135-140 tops maybe a little more if you up the fuel pressure a little but the stock carbs are a real restriction even if you did a A20 engine swap and ran a single Weber 38/38 downdraught that would be a lot better than stock carbs, be looking at 150-160bhp, but 150bhp would be really easy to get with two Weber DCOE's or a set of Bike carbs even with a 1.8l bottom end and stock exhaust system a minimal tidy head job and a mild cam, anymore than that you'll be looking at header, exhaust, 2.0l bottom, bigger valves etc.
If you really want to hit the 200bhp mark theirs gonna be a couple of things you need for sure, Twin Webers or Bike carbs, header, 2.25-2.5" system, bigger inlet valves. If you did go with new carbs but kept stock valve sizes you'd be looking at around 170-180bhp without the exhaust system or header you'd be looking at aroujnd 150-160bhp max with a 2.0l bottom.
When i had my original engine which was very tired, with a really basic head job, mild cam, the two webers, matched manifolds, ported exhaust manifold i got nearly 150bhp but U.K cars have no emission equipment and no cat, before the webers had stock carbs was putting down around 125bhp so their was a huge difference between the two BTW U.K ET was 115bhp so a cam and basic headwork only made about 10bhp difference althought the engine powerband was better at the top end revved nicely upto 7K."
