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need advice on building a hot 6 

 

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 Post subject: need advice on building a hot 6
Posted: Tue Aug 30, 2011 11:35 pm 
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Ride: 1975 TD Cortina

Location: Perth
WA, Australia

Hey Im currently lookin at building a hot 6 for my TD Cortina and need some help, firstly i know nothing about engines except for very basic parts, so far my plans are a rebuilt 250 pre-xflow with a 2v head, triple carbs(im thinking a redline manifold), extractors, 2.5"Exhaust, roller rockers(not sure kind to put in, a good allround cam and a shot of nos.

My questions are What sought of power will get, will it be reliable as it will need to be a daily for a while, what cam and roller rockers to use and most importantly how much will it cost me.

Cheers Adam
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 Post subject: Re: need advice on building a hot 6
Posted: Wed Aug 31, 2011 12:14 am 
Getting Side Ways
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OK, a couple of considerations for you. First off, 2V heads...I had one for years and to be quite honest I don't think they are as good a thing as you might reckon...Consider this - the pre x flow 2V isn't a bad motor, but revving is not a thing it likes to do. The best thing about these engines is the low down torque. There is no point trying to build a 250 aiming at high revs (by high I'm talking as low as 4-5,000 rpm..) - they have a very low in the rev range torque curve and because of the bore to stroke relationship just don't rev, and don't make any more power if you DO rev them.

How's this relate to 2v heads? They have very large ports and cross section of the manifold runners - which is great if you're looking for high rev type gas flow - but it kills low end torque. So, you end up with an engine that doesn't work very well down low - and doesn't work very well up top either. From just above idle until about 2,500 / 3,000 a standard 2v makes LESS torque than a 1 bbl 250 - above that rev range the thing is struggling to rev (1bbl or 2v) much so you may as well have the 1 bbl. If you are desperate to go 250 you may as well stick with the 1 bbl - what does work well is a very mild turbo setup using the standard exhaust and intake manifolds, or what about a little Toyota supercharger or a commodore V6 jobby?
In summary, while it may not look too racy, a 1 bbl 250 does a pretty good job moving a cortina around - I'd suggest sticking with a stock or extremely mild cam. You're not going to improve driveability OR make much more power throwing an aggressive cam in it. Finally, cost / economy - a near stock motor will obviously be cheaper to doand will get better economy - maybe look at upgrading ignition too for economy and power reasons, but mainly to avoid having to endlessly be fiddling with points - and if you DO stick with points, search out Echlin ventilated points - they'll last ten times as long as Bosch points (at least in a 250)

 

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 Post subject: Re: need advice on building a hot 6
Posted: Sun Sep 04, 2011 7:19 pm 
Getting Side Ways
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tearlejc wrote:
OK, a couple of considerations for you. First off, 2V heads...I had one for years and to be quite honest I don't think they are as good a thing as you might reckon...Consider this - the pre x flow 2V isn't a bad motor, but revving is not a thing it likes to do. The best thing about these engines is the low down torque. There is no point trying to build a 250 aiming at high revs (by high I'm talking as low as 4-5,000 rpm..) - they have a very low in the rev range torque curve and because of the bore to stroke relationship just don't rev, and don't make any more power if you DO rev them.

How's this relate to 2v heads? They have very large ports and cross section of the manifold runners - which is great if you're looking for high rev type gas flow - but it kills low end torque. So, you end up with an engine that doesn't work very well down low - and doesn't work very well up top either. From just above idle until about 2,500 / 3,000 a standard 2v makes LESS torque than a 1 bbl 250 - above that rev range the thing is struggling to rev (1bbl or 2v) much so you may as well have the 1 bbl. If you are desperate to go 250 you may as well stick with the 1 bbl - what does work well is a very mild turbo setup using the standard exhaust and intake manifolds, or what about a little Toyota supercharger or a commodore V6 jobby?
In summary, while it may not look too racy, a 1 bbl 250 does a pretty good job moving a cortina around - I'd suggest sticking with a stock or extremely mild cam. You're not going to improve driveability OR make much more power throwing an aggressive cam in it. Finally, cost / economy - a near stock motor will obviously be cheaper to doand will get better economy - maybe look at upgrading ignition too for economy and power reasons, but mainly to avoid having to endlessly be fiddling with points - and if you DO stick with points, search out Echlin ventilated points - they'll last ten times as long as Bosch points (at least in a 250)



You know the stroke of the 250 is the same as the SOHC and DOHC engines. but the later stuff has a smaller bore and according to your logic no one should modify a falcon 6.

About the only smart thing you said was(and you have to read between the lines to find it) is that the cost of building a good 2V engine is going to be way up there.

My advice for the OP is go find a smashed EB to EL falcon and fit the engine and management system from that.
The power those things make will really wake up an old cortina and it'll be a friendly car to drive.

If you want to stay away from EFI and you really want to build something different. Build your self a late crossflow with an EF crank and some spool H-beams in the 200 engine length. It'll rev as high as the crossflow valvetrain will allow and do it all day long.

 

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 Post subject: Re: need advice on building a hot 6
Posted: Sun Sep 04, 2011 9:08 pm 
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could always drop a 13b turbo in it

 

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 Post subject: Re: need advice on building a hot 6
Posted: Sun Sep 04, 2011 9:30 pm 
Getting Side Ways
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There are some fast 250's around, but you don't need tipple carbies to get them to haul a***.

If you would like a later OHC engine & don't want to go EFI you can get manifolds from Aussie speed that will let you fit a 4bbl or 2bbl carby to a SOHC engine from a EA thru EL. Fit up a XE electronic dizzy & coil setup, some extractors & a mild cam & you would have some fun in a corty.

http://www.aussiespeed.com/index.php?pa ... &Itemid=23

Cheers

ToranaGuy

 

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 Post subject: Re: need advice on building a hot 6
Posted: Mon Sep 12, 2011 11:38 am 
Getting Side Ways
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tickford_6 wrote:
tearlejc wrote:
OK, a couple of considerations for you. First off, 2V heads...I had one for years and to be quite honest I don't think they are as good a thing as you might reckon...Consider this - the pre x flow 2V isn't a bad motor, but revving is not a thing it likes to do. The best thing about these engines is the low down torque. There is no point trying to build a 250 aiming at high revs (by high I'm talking as low as 4-5,000 rpm..) - they have a very low in the rev range torque curve and because of the bore to stroke relationship just don't rev, and don't make any more power if you DO rev them.

How's this relate to 2v heads? They have very large ports and cross section of the manifold runners - which is great if you're looking for high rev type gas flow - but it kills low end torque. So, you end up with an engine that doesn't work very well down low - and doesn't work very well up top either. From just above idle until about 2,500 / 3,000 a standard 2v makes LESS torque than a 1 bbl 250 - above that rev range the thing is struggling to rev (1bbl or 2v) much so you may as well have the 1 bbl. If you are desperate to go 250 you may as well stick with the 1 bbl - what does work well is a very mild turbo setup using the standard exhaust and intake manifolds, or what about a little Toyota supercharger or a commodore V6 jobby?
In summary, while it may not look too racy, a 1 bbl 250 does a pretty good job moving a cortina around - I'd suggest sticking with a stock or extremely mild cam. You're not going to improve driveability OR make much more power throwing an aggressive cam in it. Finally, cost / economy - a near stock motor will obviously be cheaper to doand will get better economy - maybe look at upgrading ignition too for economy and power reasons, but mainly to avoid having to endlessly be fiddling with points - and if you DO stick with points, search out Echlin ventilated points - they'll last ten times as long as Bosch points (at least in a 250)



You know the stroke of the 250 is the same as the SOHC and DOHC engines. but the later stuff has a smaller bore and according to your logic no one should modify a falcon 6.

About the only smart thing you said was(and you have to read between the lines to find it) is that the cost of building a good 2V engine is going to be way up there.

My advice for the OP is go find a smashed EB to EL falcon and fit the engine and management system from that.
The power those things make will really wake up an old cortina and it'll be a friendly car to drive.

If you want to stay away from EFI and you really want to build something different. Build your self a late crossflow with an EF crank and some spool H-beams in the 200 engine length. It'll rev as high as the crossflow valvetrain will allow and do it all day long.


Everything I said is strictly restricted to pre x flow 250's. Many sources say the same about the 2V's low end torque deficit. I agree, fit a later model engine by all means - but in a comparison between a 1V pre x flow and a 2V , the 1 V is better low down torque wise, and neither rev particularly well.

 

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