Corvair DiagramCorvair Photo
Corvair Center
home forum corvairs calendar links Corvair Podcast
California Corvairs
Clarks Corvair
Clarks Corvair
“CORSA"



Chevy Corvair License Plate
Chevy Corvair Chrome Wheel
Corvair Center Forum :  Corvair Center Phorum The fastest message board... ever.
Corvair Center 
Pages: 12Next
Current Page: 1 of 2
140hp heads question, left or right?
Posted by: aorange ()
Date: March 18, 2021 12:46AM

Hi everyone, I have a question about something that has been bugging me and I cannot for the life of me find the answer anywhere.

I am finally assembling my engine that I have sourced rebuilt 140hp heads for and as far as I can see these are almost identical (left from right) except from what I guess is vacuum ports on the base of the carbs. One head has one port on each base but the other has only one.
Now before I torque these onto the engine, can someone kindly explain what these ports are for and why one head has one blocked off?
Have I installed the heads correctly on my engine or should I swap them over?

Many thanks in advance smiling smiley



Edited 1 time(s). Last edit at 03/18/2021 08:17AM by MattNall.

Attachments:
Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: RobertC ()
Date: March 18, 2021 01:44AM

Looks like you need the 1965 Shop Manual. ASAP.

Do not know where you got the instructions to assemble the engine so far?

The "ports" are to connect to the balance tube. The balance tube runs across the "back" of the engine (front of the car).

Never seen two "ports" on one 140 head - an indication? that the person doing the heads does not know what he is doing?

Yes, you need to swap the heads - and remove the second "port" facing the back of the car and plug it. Or, you could remove the second "port" on the right hand head and plugthe hole and could remove the "port" on the left head; plug the hole; drill a hole in the other carb base and install a "port" - a lot more work IMO.

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: aorange ()
Date: March 18, 2021 01:52AM

Thanks, I have been using the 1965 shop manual to assemble this engine but as I said, I haven't been able to find any information about these tubes/ports.

Now that you mention that they are there to balance the left and right intakes, it makes sense to me. I had just assumed they were vacuum ports based on their location.

I'll swap the heads over and block one of them.

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: RobertC ()
Date: March 18, 2021 01:59AM

There should be a picture somewhere in the manual that shows the balance tube.

Probably should find it before you do anything - just so you know what it should look like.

The port for the vacuum advance is "off" the passenger side primary carb - usually (shortest route to the distributor).

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: vairmech ()
Date: March 18, 2021 05:11AM

First off you do NOT need to swap the heads! You did just what someone else did and didn't think about the balance tube or had to replace a head and got one that was set up for the other side.

The easiest thing to do is to remove the tubes facing rearward.

BTW, there is NO different front or rear on the engine! The front is the front and the rear is the rear! Where is the front of the car? Where is the rear of the car? How is the engine placed in the car? Working on a Corvair engine you are looking FORWARD!

Now all you need to do is get a small freeze plug that goes in the hole for the one head on the right side then tap it in where you removed the tube. I'll give you one for the postage!
On the left side use a small flat punch and push the plug all the way through and catch it as it comes through into the port, put it in the hole on the REAR side.

Now cut yourself 2 pieces of 3/8 steel tube as long as the ones you pulled out, bevel one end then gently tap in the holes, now you have the heads on the correct sides!

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: dryenko ()
Date: March 18, 2021 05:13AM

No need to disassemble, the tube can be swapped to the other end of the head.
That end without a tube should have a tiny freeze plug.
Drive it into the carb hole.
Just don't drop it down the intake.
Block, temporarily, with a rag.
Reinstall in the other end with Red locktite.
The tube itself can be carefully removed with a tight fitting metal rod inserted into the tube, and worked out with a little heat and some circular jaw Visegrips.
The tap it into the other end with a soft mallet and Red locktite.
Lots less time than taking the heads off. On that note, it looks like the heads might be contacting the cylinders.
Thick enough head gaskets ??

Bob C aka Dryenko
Dobson, NC 27017

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: azdave ()
Date: March 18, 2021 05:23AM

RobertC Wrote:
-------------------------------------------------------
>Never seen two "ports" on one 140 head - an indication? that the person doing the heads does not know what he is doing?


On A.I.R. (smog) engines that used Air Diverter Valves on top of the intake runners there was a vacuum line that ran from the valve to the base of the carbs. Below is an image from an assembly manual showing a diagram from a 110 head. I don't know if any 4-carb engines used this diverter valve arrangement but some 2-carb engines did.

Regardless, cap it off for your use or better yet, pull it and plug it so no one points to it and tells you your head is on the wrong side. smiling smiley

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Attachments:
Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: aorange ()
Date: March 18, 2021 07:00AM

Thanks a million for all the good advice guys. I'll take another look at it ASAP and plug the port that doesn't need a tube in it.

I am just curious about one thing, I am guessing (correct me here) that the vacuum balance ports are there to prevent pulses on the intake air flow at low air speed. If that is the case, then it shouldn't make any difference whether the balance line is run at the rear, front or diagonally across the engine right? theoretically that is.

My experience building engines is mainly with VW aircooled engines and they differ on many interesting aspects. This is highly educational imo smiling smiley

I will also take another look to ensure that the heads aren't contacting the cylinders although I don't believe this is the case.

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: gnvair ()
Date: March 18, 2021 07:33AM

azdave Wrote:
-------------------------------------------------------
> RobertC Wrote:
> -------------------------------------------------------
> >Never seen two "ports" on one 140 head - an indication? that the person doing the heads does not know what he is doing?
>
>
> On A.I.R. (smog) engines that used Air Diverter Valves on top of the intake runners there was a vacuum line that ran from the valve to the base of the carbs. Below is an image from an assembly manual showing a diagram from a 110 head. I don't know if any 4-carb engines used this diverter valve arrangement but some 2-carb engines did.
>
> Regardless, cap it off for your use or better yet, pull it and plug it so no one points to it and tells you your head is on the wrong side. smiling smiley

That diagram is for 66-67 cars. The 68-69 cars do not have those connections at the base of the carburetors for the smog.

Lee J

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: Wagon Master ()
Date: March 18, 2021 07:33AM

[ssl.corvair.com]

[ssl.corvair.com]

If you've got the time......Do it right.

Do you plan on running chokes on your primary carburetors?

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: aorange ()
Date: March 18, 2021 07:45AM

I should add that I will be running a center mount Holley on this engine

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: 66vairman ()
Date: March 18, 2021 08:09AM

I've swapped the manifold tubes when I replaced heads.

Clark's has the tubes and plugs. See [ssl.corvair.com]

DON'T damage the head removing the tube.

Use a high temperature epoxy to seal new parts.

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: MattNall ()
Date: March 18, 2021 08:20AM

Welcome to the CCF. Tell us where you are and which shops you are using.

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
...............110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: jamesolefjensen ()
Date: March 18, 2021 08:48AM

Like Mr Goodman said, since you are running a center mount Holley, there is no reason to swap the heads or remove the tubes. All you'll need to do is cap the tubes somehow.

When I rebuilt my 140 (using the factory manual), I made the same mistake. But since I'm running a Holley, I didn't need to correct it. I capped both tubes with a plastic caps anyway.

The only downside is if you go back to a 4 carb setup with a balance tube, you'll have some extra work to do.

On the plus side, the tube closest to cylinder 1 makes for a very short vacuum advance line.

James
65 Corsa
SF Bay Area

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: aorange ()
Date: March 18, 2021 08:52AM

Thanks again, the response to this question has been great. I wish I had asked it earlier =D

I am based in Sweden unfortunately, so getting parts usually takes quite some time. I have bought parts from Clarks and the heads came from Starr Cooke in CA.

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: MattNall ()
Date: March 18, 2021 09:08AM

Yes it does!! You've been building for 7 years. Remind us of what type of car you are building?

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
...............110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: aorange ()
Date: March 18, 2021 09:10AM

I am building this reverse rotation 140hp engine, which was originally a 110 for my VW Baja Bug. It was never meant to take so long to finish the engine, but I didn't have a car to put it in and I moved countries in the meantime so has taken a while spinning smiley sticking its tongue out

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: steve c goodman ()
Date: March 18, 2021 09:37AM

Well I feel pretty dumb, I went back to look for the 'other' owner in Sweden and it is you. Sorry guys for wasting space and time. Maybe if Matt reads this he will show me mercy and delete both posts.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC/V8 Registry

Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: azdave ()
Date: March 18, 2021 11:13AM

azdave Wrote:
-------------------------------------------------------
> On A.I.R. (smog) engines that used Air Diverter Valves...see diagram.


gnvair Wrote:
-------------------------------------------------------
> That diagram is for 66-67 cars. The 68-69 cars do not have those connections at the base of the carburetors for the smog.


Yes. That is why I said those extra tubes were only found on A.I.R. engines that used diverter valves. I was not sure when those valves were deleted so thanks for the clarification.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Options: ReplyQuote
Re: 140hp heads question, left or right?
Posted by: RexJohnson ()
Date: March 18, 2021 12:06PM

Those heads look like they would have come off of a '66 or 1st design '67 AIR system. That system used mixture control valves that plugged into the air cleaner cross over tube. Under high manifold vacuum they would send clean air to the extra port on the head as in Dave's picture. That was easy on the 2 carb heads but on the 140's the RH head could not have the tube facing the rear because the smog pump was in the way. So on the passenger side the balance tube had an extra fitting right where it left the cylinder head and that is where the mixture control valve attached. The heads on the poster's picture are on the opposite side but sense he is installing a center mount 4bbl all that needs to happen is to plug the ports.

RJ tools
Salem,Oregon

Options: ReplyQuote
Pages: 12Next
Current Page: 1 of 2


Sorry, only registered users may post in this forum.
This forum powered by Phorum.