65 convertible

All Models and Years
monzadon
Posts: 188
Joined: Fri Aug 11, 2017 3:35 am

65 convertible

Post by monzadon »

I am getting ready to put the heads back on my 140 motor and from.i have read of people rebuilding these motors They say to.not go over 27 lbs torque for the heads is this right ?
61SuperMonza
Posts: 310
Joined: Mon Apr 29, 2019 1:51 pm

Re: 65 convertible

Post by 61SuperMonza »

That is a bit of a loaded question. 30lbs. Is what I use but if you have time sert/helio coils in the case that you are concerned about 27lbs may be a good bet. I have heard of some using as low as 25lbs with good results. If the studs feel right while torquing l would try for 30lbs. What head gaskets are you using?
First corvair in 1985
Have owned 4 corvairs since
65 Corsa coupe 180 turbo
66 Monza coupe 110 PG
66 Monza coupe 140 PG
61 Monza club coupe w/ 150 turbo
Anchorage,AK
User avatar
terribleted
Posts: 4588
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: 65 convertible

Post by terribleted »

I set 30 foot pounds as well. Never add it all at once. I go through the sequence in the manual starting at 15lbs then 20 then 25 then 27.5 then finally 30 going through the entire tightening sequence each time..
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia
monzadon
Posts: 188
Joined: Fri Aug 11, 2017 3:35 am

Re: 65 convertible

Post by monzadon »

I am using big bore copper head gaskets 74 thousands thickness , the original.owner had 74 thousands under the cylinders and i changed the spacing to th heads instead of the cylinders , i had to use that thickness because the valves were.hitting the pistons with any less than that
User avatar
terribleted
Posts: 4588
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: 65 convertible

Post by terribleted »

monzadon wrote: Mon Sep 28, 2020 7:36 am I am using big bore copper head gaskets 74 thousands thickness , the original.owner had 74 thousands under the cylinders and i changed the spacing to th heads instead of the cylinders , i had to use that thickness because the valves were.hitting the pistons with any less than that
how did you get 74 thousandths head gaskets? Stacking head gaskets is not advised. Much better to go thick on the head gaskets and thick on the base gaskets to get the clearance needed and if any stacking is needed stack on the base gaskets not the head.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia
monzadon
Posts: 188
Joined: Fri Aug 11, 2017 3:35 am

Re: 65 convertible

Post by monzadon »

In the corvair books and Clarks corvair they advise not to stack the base gaskets but if you need to do.spacing do it at.the heads, when i tore the motor down the spacing was under the cylinders and i was told that was the wrong way to do it and Clarks corvair says you can go up.to.two head gaskets so.now i am confused
User avatar
terribleted
Posts: 4588
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: 65 convertible

Post by terribleted »

This is exactly the opposite of what I have always heard. Perhaps recommendations have changed, but, it would seem to me that stacked head gaskets would by likely to leak compression where stacked base gaskets would likely leak nothing or maybe a hair of oil. Fact of the matter is if you really need over 84 thousandths total stack (32 cylinder and 52 head) something is severely wrong and you should replace or repair the offending parts to fix the problem. Why do you need such a large stack? Over machined heads? Get different heads or have them welded and remachined. I see where Clark’s says you can a stack 2 head gaskets. They supply them so if need be do it that way. I have never built an engine that needed over the 37 thousandths above stock that a single thicker base and single thicker head gasket can provide. I trash heads that are milled that far as replacements have always been available for less than welding and remachining.

You say the original owner had 74 thousandths under the cylinders and you moved that 74 thousandths to the heads. What were the head gaskets you took out? Did you put more stack than that under the cylinders? If the total stack is the same as was there regardless of the position of the gaskets the engine will be the same as it was clearance wise. If valves were hitting before they will hit again unless you increased the total stack. I assume that valves hit in all cylinders if not gasket stack is not the issue. If they did hit in all cylinders something is wrong like maybe cam gear not referenced properly to the crank so valves were open when they should not be, or heavily over machined heads, or some other Issue caused by non stock parts (cylinders shortened, longer rods, something odd).
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia
monzadon
Posts: 188
Joined: Fri Aug 11, 2017 3:35 am

Re: 65 convertible

Post by monzadon »

The gasket thickness is the.same as it was before i tore it down i just moved the extra spacing to the heads instead of having it at the.cylinder base, i had to replace the heads because of dropped valve.seats, i originally used standard spacers but i couldn't turn the motor over because the valves were hitting the pistons so i replaced the same thickness.that was originally in the motor
User avatar
terribleted
Posts: 4588
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: 65 convertible

Post by terribleted »

Well what you need to do is measure and see what thickness is needed. A good set of heads with correct pistons and proper length cylinders should not need the total stack you have put in. Since you changed heads, unless they were machined to be identical to the old heads you likely gained clearance.

Sounds like you are just trying stuff and guessing. Engine building is not about guessing, it is about measuring and selecting proper clearances to arrive at a desired performance. If these steps have not been taken I would recommend stopping and finding someone who knows what they are doing to help you properly measure, fix and set up what you have (or change some parts to get a proper setup maybe), so you end up with something that operates properly for a long time, rather than an unknown guesswork that may or may not work properly. Too much money involved to not make it right the first time.

Measure the total length of the cylinders from where they contact the case to where they seat in the head and compare to a stock cylinder to make sure they are not milled shorter (topped cylinders could be the cause of clearances being so tight too need really thick head gaskets).

How much head gasket step (the raised ring around the outside of the head opening should not be flat but raised some where the head gaskets sit)is left in the heads? Any? I forget what the total new height of this was right now. When head gasket seats are trued and machined the only extra gasket thickness that should be needed is enough to compensate for the few thousandths of material removed flattening this step. The last 140 I built required 15 thousandths cut to remove the groove from the old head gasket. I put in 53 thousandths head gaskets and stock base gaskets to end up at 5 thousandths extra. IMO you should spend a little more time And maybe money now, rather than put this engine in service and have to take it back out and start over again. If I had topped cylinders I would replace them with new cylinders that were not topped rather than stack head gaskets. if everything is measured out properly and you indeed need over 80 thousandths total gasket stack to be back at stock it might be ok, but, without verifying by proper measuring it is a crap shoot what you will get and it could well be snake eyes.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia
Post Reply

Return to “Ask your Mechanical Questions here”