2b_pablo
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| posted on 24/8/07 at 12:54 PM |
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moving from 40s to 45s?
is it worth it? Ive a pinto which has the following spec:
2.1 pinto with big valve head
90thou oversize pistons
new seals top and bottom end
new oil pump
Burton BLF40.41 rally camshaft
twin 40 webbers
electronic distributer and race coil
RS2000 alloy sump
uprated clutch and lightened flywheel
performance fuel regulator and pump
And I have the opportunity to pex my 40s for 45s. Im wondering tho is it worth doing? Im quite loathe to make it too racy making town driving suffer
but on the other hand I want the best from the engine on the track.
Any input appreciated.
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nick205
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| posted on 24/8/07 at 01:25 PM |
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With that engine spec I would say yes it's worth making the change. To get the best out of it you'd need to have the carbs properly
jetted and set up using a rolling road though which may add another £150-250 to the overall cost.
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2b_pablo
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| posted on 24/8/07 at 01:33 PM |
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thanks for that, problem is the guy who does the engine work is a little large to fit int he car lol so Ill have to take it somewhere else after to
get it setup. not the end of the world tho.
Im wondering if its worth the money tho or should I sell the pinto and buy a redtop or a vtec or something?
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DarrenW
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| posted on 24/8/07 at 02:12 PM |
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i looked into VX swap.
You can buy an MOT fail car for no more than £200 and sell bits off it to make the engine free.
Ive heard the ECU can be re-mapped to make std injection run, but most seem to go aftermarket carbs or throttle bodies and ignition.
Bellhousing adaptor approx £170. Sump?? New exhaust system.
I reckoned i could do it for around £1200 all in but there was probs bits i hadnt thought of (New bonnet for example if current exhaust has a cut
out).
ill give you £100 for pinto though so it could be worth doing
To be honest id probs try carb swap (if you dont have to spend much) and see if your happy. A good 2.1 properly set up should see 170 - 180 bhp at
flywheel (ive heard of 2.0's getting this as well) which is rather a lot. Maybe just spend cash on transmission to improve acceleration and
grip.
Ive heard that the 40's can be modded to get more out of them and make them comparable to 45's. Chokes bored out????
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Ivan
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| posted on 24/8/07 at 02:17 PM |
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If I remember correctly in Bell's "Tuning Four Stroke Engines" (An excellent if dated read) he says that sidedrafts should be a lot
bigger than common wisdom suggests so you really need 50's or bigger and not 45's.
Get hold of a copy and check it out.
The newer version for EFI is also well worthwhile a read.
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2b_pablo
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| posted on 24/8/07 at 02:17 PM |
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might look into that, I think Ill try the 45s, if I dont like them he will take them back again so its no big deal that way.
a vx swap is tempting but Im trying to keep costs to a minimum really.
I need to drive the bloody thing instead of pulling bits off it, been 3 weeks now as Ive been respraying it!
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2b_pablo
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| posted on 24/8/07 at 02:19 PM |
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quote:
Originally posted by Ivan
If I remember correctly in Bell's "Tuning Four Stroke Engines" (An excellent if dated read) he says that sidedrafts should be a lot
bigger than common wisdom suggests so you really need 50's or bigger and not 45's.
Get hold of a copy and check it out.
The newer version for EFI is also well worthwhile a read.
the bigger you go the more driveability suffers tho I believe 
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02GF74
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| posted on 24/8/07 at 02:37 PM |
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the never ending quest for more power......
dunno but I would guess you have gone as far as mods go before hey become serioulsy expensive. not sure how much you will gain with the bigger carbs
- are you noticeing any problems with your current ones that they are underfuelling?
have you conisdered throttle bodies?
you have to wokr out how much you are willing to spend on current engine and what you will gain and do the same for a different engine - no easy
answer I guess.
gpoing to 45s should be failry easy to do and not too costly - and the same to undo if it does not work out - so go for it I guess 
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coozer
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| posted on 24/8/07 at 04:17 PM |
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I reckon you would be better off going for bike carbs, they should be cheaper, easier to set up and run a lot smoother.
They generally have bigger chokes than 45 webers so are well worth the money.
Steve
1972 V8 Jago
1980 Z750
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mark chandler
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| posted on 24/8/07 at 06:52 PM |
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And to throw a fly into the ointment....
you can put chokes into 45's that are smaller than the larger chokes in 40's so swapping out may even be a backward step. You need to
measure the chokes you have before proceeding.
Also the vizard school of tuning looks to velocity of air as well, small chokes have higher velocity so work better in the low to mid range as
metering is stronger, just throwing on huge carbs may give ultimate power but cost driveability and fuel economy.
Now if you have a bike carb setup it has a diaphram and plunger with needle (okay its a stromberg carb, poor mans version of an SU), these work so
well because velocity is the high at all time as the chokes vary with air pressure.
Webers tend to feel really good as you get flat spots, this is why they feel great when it actual fact things may not e all they seem. Boot it, flat
spot squirt of enrichment fuel, car leaps forward.
IHMO megasquirt and bike throttle bodies or fit injectors into your inlets, strip chokes out of your 40's and block the various holes, these are
now you throttle bodies..... with that great look.
regards Mark
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