home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > maintenance & nonperformance

Reply
 
Thread Tools Display Modes
Old 05-01-2021, 12:45 AM   #26
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

Quote:
Originally Posted by planetman View Post
Remove the secondary butterflies and the secondary throttle shafts and plug the holes in the manifold.

We've seen people unnecessarily drill, tap and install threaded plugs, while we have the correct size plugs that just need to be tapped in with a hammer.

If you look carefully you will see that Volvo did the exact same thing by using a tap in plug for the inner holes for each of the secondary throttle shafts.

In fact we used to re-purpose the used plugs from cracked manifolds and when that supply ran dry we bought them right from Volvo back when they were available and when that well ran dry, we sourced some from a supplier that made the right size plug.

FYI, you will need to remove the carbs to remove the secondary butterflies and if not already done, you should solder closed the decel valves that are built into the butterflies in the carburetors.

We also have carb base gaskets as they might tear when you remove the carbs.
Where can I get the plugs and gaskets? Seems like the way to fix it.
1968 volvo is offline   Reply With Quote
Old 05-01-2021, 01:37 AM   #27
planetman
Board Member
 
planetman's Avatar
 
Join Date: Apr 2012
Location: Torrance, CA
Default

We've got them. $10.00 for 2 plugs and 4 gaskets plus shipping.
__________________
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
planetman is offline   Reply With Quote
Old 05-01-2021, 11:34 AM   #28
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Default

Quote:
Originally Posted by planetman View Post
We've got them. $10.00 for 2 plugs and 4 gaskets plus shipping.
I suppose for ten dollars, its worth a shot. Is your website High Performance Automotive Service? Or is it better to buy from you?
1968 volvo is offline   Reply With Quote
Old 05-01-2021, 12:10 PM   #29
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by 1968 volvo View Post
I suppose for ten dollars, its worth a shot. Is your website High Performance Automotive Service? Or is it better to buy from you?
Planetman and his brother hiperfauto are the gurus for the OHV cars. Every time I had a problem their solutions worked the best.
__________________
1967 122s, carbed B20F, M41, the sports tractor
1998 S70, grandma-mobile
1989 240 B230F, V15 cam, chipped EZK, M47 swap (Lost a fight with a Chevy express van), the millenial falcon
2012 VW Tiguan (screw plastic water pumps), daily
spock345 is offline   Reply With Quote
Old 05-01-2021, 12:42 PM   #30
planetman
Board Member
 
planetman's Avatar
 
Join Date: Apr 2012
Location: Torrance, CA
Default

Both of those parts are on our website and you can place an order after registering, but you won't be able to pay as we have disabled the payment module.

To ensure accuracy, we found it necessary to interact with our customers. It is very easy to order the wrong parts due to the interchangeability of parts between the different Volvo models.

For example, it is not uncommon to find a B20 engine in a car that originally came with a B18 or even a B16 engine.

You can reach me through our website via our contact page below.


http://hiperformanceautoservice.com/contact_us.php



Quote:
Originally Posted by 1968 volvo View Post
I suppose for ten dollars, its worth a shot. Is your website High Performance Automotive Service? Or is it better to buy from you?
planetman is offline   Reply With Quote
Old 05-13-2021, 09:06 PM   #31
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Question

Hello again! Thanks to all who had great suggestions for me on how to fix my high rpm. It seems that the majority of people were suggesting to try to investigate either the carb/manifold gasket or the secondary butterfly valves in the intake manifold. Since then I cleaned the carb and manifold mating surfaces and I replaced all the gaskets. I also removed the old butterfly valves and threaded the holes and plugged them that way. ( I know people said that that is excessive but I had the right tap lying around my garage so i went for it anyway) My rpm is still 2000. Any suggestions?
1968 volvo is offline   Reply With Quote
Old 05-13-2021, 09:16 PM   #32
JohnMc
PV Abuser
 
JohnMc's Avatar
 
Join Date: May 2004
Location: St. Louis
Default

They look like HS6 carbs - maybe make sure the choke mechanism isn't holding the idle up? Are the throttles resting against the idle adjuster screws?
__________________
'63 PV Rat Rod
'93 245 16VT Classic #1141
JohnMc is offline   Reply With Quote
Old 05-13-2021, 09:17 PM   #33
JohnMc
PV Abuser
 
JohnMc's Avatar
 
Join Date: May 2004
Location: St. Louis
Default

Also, if the throttle shaft bushings were installed even a slight be off center in the bores, the throttle valve might hit on one side and be gapped open on the other.
JohnMc is offline   Reply With Quote
Old 05-13-2021, 09:23 PM   #34
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by JohnMc View Post
Also, if the throttle shaft bushings were installed even a slight be off center in the bores, the throttle valve might hit on one side and be gapped open on the other.
I can see this being a problem especially if the carbs have the older linear throttle springs. They seem to put a force on the shaft that worsens vacuum leaks.
spock345 is offline   Reply With Quote
Old 05-14-2021, 12:33 AM   #35
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

Quote:
Originally Posted by JohnMc View Post
They look like HS6 carbs - maybe make sure the choke mechanism isn't holding the idle up? Are the throttles resting against the idle adjuster screws?
Yes the throttles are resting flush against the idle adjustment screws.
1968 volvo is offline   Reply With Quote
Old 05-14-2021, 12:40 AM   #36
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

Quote:
Originally Posted by JohnMc View Post
Also, if the throttle shaft bushings were installed even a slight be off center in the bores, the throttle valve might hit on one side and be gapped open on the other.
I had a man by the name of Thomas Bryant rebuild my carbs... he seems to have a good reputation and to be confident in his work. Have you heard of this problem when he rebuilds carburetors? How can I check to see if they are off. Is it something I can see or is their an other way to conclude that it is off
1968 volvo is offline   Reply With Quote
Old 05-14-2021, 12:50 AM   #37
c1800
Board Member
 
Join Date: Jun 2014
Location: A small village of one.
Default

Suggest a call/email Tom Bryant and discuss with him. Maybe he has some advice.
c1800 is offline   Reply With Quote
Old 05-14-2021, 01:23 AM   #38
hiperfauto
The Librarian
 
hiperfauto's Avatar
 
Join Date: Nov 2011
Location: So Cal
Default

Quote:
Originally Posted by cwdodson88 View Post
PCV check- Pull the pcv and brake booster (if it has a booster) hoses off the intake, and plug the intake them. See if that changes anything.
Did you ever try this?
hiperfauto is offline   Reply With Quote
Old 05-14-2021, 11:03 AM   #39
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

Quote:
Originally Posted by hiperfauto View Post
Did you ever try this?
I tried plugging off the brake booster side and it changed nothing. When it is connected, it does seem to have a negative effect on the engine when I press the brake. The car nearly dies and sometimes does when I push the brakes.

Can I run the engine with the pcv disconected and the hose plugged?
1968 volvo is offline   Reply With Quote
Old 05-14-2021, 11:05 AM   #40
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

Also strangely enough, the dome light on the interior of the car suddenly decided to work.
1968 volvo is offline   Reply With Quote
Old 05-14-2021, 11:12 AM   #41
JohnMc
PV Abuser
 
JohnMc's Avatar
 
Join Date: May 2004
Location: St. Louis
Default

Yes, you can do that. The PCV system on thse is pretty simple, practically no moving parts, none of it is very essential to the way the motor runs.

One hose runs to the fitting on the intake manifold. This fitting has a very small hole in it, to sharply limit the flow. And the intake manifold only has significant vacuum in it when at or near idle, the pressure rises as the throttle goes down, to close to ambient at WOT.

So at lower throttle/idle, there's more vacuum, and the little hole will suck the small amount of crankcase vapors through into the intake manifold, pulling fresh air into the block from the air cleaner via the other hose.

Step on the gas, the vac goes away, and the draw through that tiny hole goes mostly away. Then the flow reverses, and the larger amount of crankcase fumes (blowby from the pistons, mostly) will go out the hose into the air cleaner, where it will get sucked into the carb.

So you can certainly run it with that PCV hose plugged, it will just passively vent to the air cleaner like it would under throttle while driving. See if it makes much of a difference with the hose leading tot he intake plugged or not plugged. The hole is small, it's not supposed to make much of a difference. It's possible someone replaced it with something else at some point which is letting too much air in (which would make it run lean).
JohnMc is offline   Reply With Quote
Old 05-14-2021, 11:18 AM   #42
JohnMc
PV Abuser
 
JohnMc's Avatar
 
Join Date: May 2004
Location: St. Louis
Default

Quote:
Originally Posted by 1968 volvo View Post
I had a man by the name of Thomas Bryant rebuild my carbs... he seems to have a good reputation and to be confident in his work. Have you heard of this problem when he rebuilds carburetors? How can I check to see if they are off. Is it something I can see or is their an other way to conclude that it is off
Don't know him, or his reputation. I haven't had SU's on my PV for a couple of decades (more or less). But when I had them I had the slightly worn throttle bushing issue, and occasionally the throttles would sag and hang up on the side of the bore, not closing completely. I just learned to 'tickle' the pedal a little bit to get them to 'unhang' and close properly.

Then I stuck DCOE's on it instead of trying to have the SU's rebuilt.

You might be able to see it by looking down the bores, look carefully at the top and the bottom of the throttle valve, see if one side seems to be sitting flush with the carb throat, and one is sitting even a tiny sliver away from it? But on an SU, they sit way back behind that constant vacuum regulating piston up front, you'd need to lift that all the way up and peer behind it with a light, might be hard to see.

The thing is, though, an air leak can only keep the idle speed up so much on a carbureted vehicle. Air leaks are not going through the carb, so they're not getting fuel added, they're lean air leaks. So a modest air leak can make the mixture leaner, and raise the idle. But you shuold be able to drop the idle down by closing the throttles more and more, even if the air leak is still letting air in, closing the throttles ALL the way will cut off the flow of fuel since no air will be going through the carbs.

So if you've really closed those idle adjusters all the way down, and it's still running (and running too fast), then it rally means that air is still going though the carbs, which means the throttles aren't rally closing all the way for some reason.

Last edited by JohnMc; 05-14-2021 at 11:25 AM..
JohnMc is offline   Reply With Quote
Old 05-14-2021, 06:58 PM   #43
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

I don't know why I didn't remember this earlier but I recall having a problem with the fast idle screws keeping my throttle plates open a bit. If screwed in too far they will contact the fast idle cam and cause a high idle even when the carbs aren't choked. The end result is that I could unscrew the regular idle screws all the way and the idle would hover around 1500 rpm. Also make sure the jets are fully seated when the carbs aren't choked.

Also have you tried looking at the fuel pressure? Maybe too much fuel? I know that modern aftermarket mechanical fuel pumps can be a bit overeager. My weber would just run like crap and far too rich on 5psi. The SUs would be guzzling fuel and causing all sorts of problems.

Emailing Tom is probably the right way to go. He also has a guide on how he tunes these carbs on his site.
spock345 is offline   Reply With Quote
Old 05-15-2021, 03:23 PM   #44
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

I know my car isn't choked. I had a bit of problems earlier with my choke that I had to sort out... That said and done I think I can eliminate the choke from being a factor. Ill check the idle screws and the email Tom about the fuel pressure. Someone else told me to check with him to see that the butterfly valves are seated properly.

I plan to go out to my shop today and get greasy today so Ill update you guys on my situation either tonight or tomorrow. Ive got a bit to check.
1968 volvo is offline   Reply With Quote
Old 05-15-2021, 04:28 PM   #45
alschnertz
Enough already!
 
alschnertz's Avatar
 
Join Date: Oct 2009
Location: CT
Default

Quote:
Originally Posted by 1968 volvo View Post
Since then I cleaned the carb and manifold mating surfaces and I replaced all the gaskets.
Did you check that the intake manifold was not warped?
With mine, I taped emery cloth to a known flat surface and then slid the manifold across it.
It was easy to see the imperfections (noted by the shiny surfaces) after that.
Just eyeballing it was not good enough.
__________________
Differences of opinions should be tolerated, but only if they're not too different. - Sharon Craig
alschnertz is offline   Reply With Quote
Old 05-15-2021, 06:43 PM   #46
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

Quote:
Originally Posted by alschnertz View Post
Did you check that the intake manifold was not warped?
With mine, I taped emery cloth to a known flat surface and then slid the manifold across it.
It was easy to see the imperfections (noted by the shiny surfaces) after that.
Just eyeballing it was not good enough.
I checked it by seeing if it rocked in any directions when placed against a flat surface. I also held a flashlight on the opposite side of the manifold and saw if there was light poking through. are those tests conclusive? My manifold seemed to pass the test. I suppose its also possible for the head to be warped? I didn't check that however.
1968 volvo is offline   Reply With Quote
Old 05-15-2021, 07:01 PM   #47
alschnertz
Enough already!
 
alschnertz's Avatar
 
Join Date: Oct 2009
Location: CT
Default

I doubt the head is warped.

Is it still ok on start-up but the rpms go up as it warms up?
Did you spray carb cleaner directly at the base of the shared stud where the intake and exhaust manifold meet?
alschnertz is offline   Reply With Quote
Old 05-15-2021, 07:13 PM   #48
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

A little update. I checked the choke idle speed screws and with them completely backed out there was no change in idle speed. I did notice one interesting thing about my carburetors. While the engine was running, I was able to reach into the carburetor and manually pull the round thing that has the nettle on the bottom, down. This dropped the rpm. And then when I released it the rpm rose. Is this normal behavior. I tried to replicate the effect on the other carburetor but I failed to do so. I also now realize that that was stupid to do because it could backfire on to my hand or something but nothing bad happened so what can I say.
I haven't tried to inspect the pcv yet. The sentence about the carburetor thing sounds confusing to me but I don't know what the part is called and I cant seem to explain it better. If it does not make sense let me know and Ill try to describe it better.
1968 volvo is offline   Reply With Quote
Old 05-15-2021, 07:44 PM   #49
1968 volvo
Board Member
 
Join Date: Apr 2021
Location: Santa Rosa California
Post

Quote:
Originally Posted by alschnertz View Post
I doubt the head is warped.

Is it still ok on start-up but the rpms go up as it warms up?
Did you spray carb cleaner directly at the base of the shared stud where the intake and exhaust manifold meet?
Thats a relief.

The idle is ok upon start up. And then the rpms don't go up until the car is warm. Ill double check it but I'm also pretty sure that the rpms don't go up unless the car is reved. Not like make some noise revs but just normal driving revs.

I haven't tried to spray carb cleaner directly in that location. Also my intake/ exhaust manifold are one piece... is that a factor in the test?
1968 volvo is offline   Reply With Quote
Old 05-16-2021, 03:30 PM   #50
spock345
Board Member
 
spock345's Avatar
 
Join Date: Nov 2016
Location: Santa Cruz, CA
Default

Quote:
Originally Posted by 1968 volvo View Post
A little update. I checked the choke idle speed screws and with them completely backed out there was no change in idle speed. I did notice one interesting thing about my carburetors. While the engine was running, I was able to reach into the carburetor and manually pull the round thing that has the nettle on the bottom, down. This dropped the rpm. And then when I released it the rpm rose. Is this normal behavior. I tried to replicate the effect on the other carburetor but I failed to do so. I also now realize that that was stupid to do because it could backfire on to my hand or something but nothing bad happened so what can I say.
I haven't tried to inspect the pcv yet. The sentence about the carburetor thing sounds confusing to me but I don't know what the part is called and I cant seem to explain it better. If it does not make sense let me know and Ill try to describe it better.
Have you got dashpot oil in them? The oil is supposed to provide a dampening effect on the pistons rising. The dashpot cover works as a one way valve that resists the upward movement of the pistons. The pistons rising too far due to too little or too light of an oil may cause this condition. The factory stuff is supposedly SAE 30. Tom's blog posts talk about 15w50 having similar consistency at the SU's temperature when warmed up.

I use this stuff and it works pretty well.
spock345 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -4. The time now is 06:53 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.