Corvair Forum

Anyone got seat of the pants experience with 3 barrel weber conversion? What hp is it worth on a 140?


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the 3 barrel weber conversion is worth a bunch of hp on a 140. but you got to do a bunch of work to put them on the engine. its not a simple bolt on thing.

if you got like $3k & want to spend it on a 3 barrel weber conversion - go for it!

-Scott V.

Yup. The magic is the individual intake runners that allow you to run a 310-duration cam and retain good idle quality (this is impossible with a shared manifold) I had one back in the '70s and it would run right with my friends 351 manual trans mustang. That Corvair was amazing.

Picking one up tomorrow with this setup. Stock cam tho and idles almost dead smooth. Much smoother than stock 140. Havent punched it hard but didnt feel that extra strong.


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Can I get 200 out of it without going radical? Want to put on an AC unit so it cant get too stupid.


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Technical data from the 140HP shows the stock 4 HV carburetors have adequate CFM.

As learned as a kid - a bigger carburetors than what the engine was designed for is a waste of money.

As others said - you'll have to spend a bunch of money on head work and a big cam to take advantage of the Webers (if not done already).

Hmmmm - never had an issue with a properly tuned 140HP having a rough idle. They typically idle fine.

I havent either. Just commenting that it doesn't have the lope of a stock 140. Has 34 venturis in it and is silky smooth. So i dont think it is over carbed. Has headers too. Doesn't seem much stronger than stock 140. Wamt 180 to 200 without tpo much work. Heads are from Starr cook and are per invoice port matches with staked seats, new valves and guides as well as springs. Felt it should have morenlivk in thenass than it does. No drivability issues at all. What can I do to make it stronger is my rel question without making it too radical.


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180 to 200HP is in the "Stinger" category. You can read up on those mods in books published.

Regarding more -oomph compared to a 140HP engine. There's an old saying - you advertise HP, but you drive torque. Generally speaking a naturally aspirated engine has to move the torque peak higher up the RPM range to make more HP.

Axle ratios and tire size impacts "ooomph". I have a 140HP with a 3:55 rear end, and one with a 3:27 - same tires. The 3:55 is quicker off the line, but I really like the 3:27 axle at highway speeds.

Today things like variable cam timing and modern turbocharging can produce lots of torque though out the entire RPM range with good throttle response.

Performance can be ruined if the heads were ported by someone who doesn't know what they are doing. Mismatching of camshaft, compression and ignition curve can also ruin performance. Running too rich of an air fuel can also degrade the performance.
Just adding Webers and headers is not a guarantee for a power increase.
200 naturally aspirated at the flywheel requires a very well matched combo, but is doable.
Kevin Wilson who used to post on here had a late model with a 3.1 liter, with Webers, angle port exhaust, professionally ported heads, matched camshaft, etc ran high 14's pretty consistently at about 95 mph. Doing that math with this http://wallaceracing.com/et-hp-mph.php
At 2500lbs he would have been making 152 horse power to run those times.
Paul Fox has a similar set up in a lightened (read gutted) auto cross car that runs high 13's.

Thanks. Heads were done by Starr Cooke. I am not sure they were ported.


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You will get mixed reviews on Starr Cooke by a lot of the racers. He is known for staking stock seats which will still fall out.

I got 150k miles out of my last ones before a seat dropped


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Just because the last ones lasted 150k does not mean the current set will. Some dropped seats when they were still relatively new or lower miles. Most 140 heads are now 48-53 years. You don't know the history such as whether they were overheated. I have lost several seats over the years. Any Corvair engines I build that will be driven long distances get new high press deep seats done by someone reputable. Just saying....

Notched

Who does your seats staking?

Thanks

Mike


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MtnVairMike wrote: ↑Fri May 05, 2017 8:36 am Notched

Who does your seats staking?

Thanks

Mike


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I don't have my seats staked. It doesn't work. I have had seats replaced on a pair by Michael Leveque and on another pair by Tom Knoblauch. The heads that are on my stock turbo engine were done by a shop out in LA that the name is slipping my memory. The heads on my new turbo engine that I am putting together were done by Tom along with some custom welding of the chambers to adjust the quench without having the issues you have when milling them down to the step.