Discussion Forum - Northstar Chevelle Club

jim larson · 2K+ Club

Can spacer cause idle rpm issues?

Enganeer · Mega Poster

Seem like you have identified that the pass side has a reaction to the carb spray. Remove the spacer, look at the gaskets and try it with out it.

I don't think your going to lose any performance by getting rid of the spacer. 305 heads don't flow that much anyways.

Derek69SS · Founding Member

If the mating surfaces to carb and intake manifold are the right design, then it should not leak.
I have seen square-bore & spread-bore combination mixed incorrectly causing a vacuum leak.

Lost in the 60s · President

Derek69SS wrote:
If the mating surfaces to carb and intake manifold are the right design, then it should not leak.
I have seen square-bore & spread-bore combination mixed incorrectly causing a vacuum leak.

Yep, on that issue. The carb is square bore and the intake could well be spread-bore. The spacer number is a square bore riser, NOT an adapter from spread to square, which is what you may need.

What is the number on the intake ? That should tell you what model it is and whether is is a spread bore design.

jim larson · 2K+ Club

Intake is. A Edelbrock performer, I think spread bore. carb is Edelbrock 1460, I think square bore. Here are some photos. I can’t find a number on the intake.

-- Edited by jim larson on Thursday 31st of October 2019 03:15:30 PM

Lost in the 60s · President

Look at the gasket on the intake side for a continuous imprint and I think you will find your vacuum leak. The back corners will run off slightly at the wide part of the intake bore.

jim larson · 2K+ Club

Lost in the 60s wrote:
Look at the gasket on the intake side for a continuous imprint and I think you will find your vacuum leak. The back corners will rlun off slightly at the wide part of the intake bore.

So what kind of spacer do I need, or gasket set? Here is a photo of the intake side of the gasket between the intake and the spacer. To me looks like it might have multiple leaks. What do you think?

-- Edited by jim larson on Thursday 31st of October 2019 09:13:04 PM

Lost in the 60s · President

Yep, typically the back corners, but you have one in the center too. What you need is an adapter, not a spacer.

https://www.summitracing.com/parts/sum-g1401/overview/

Same as a Mr Gasket, but you don't need the extra fasteners.

https://www.summitracing.com/parts/mrg-1932/overview/

jim larson · 2K+ Club

What about this plate 2732 I called Edelbrock and they said this plate should give me more sealing surface. I ordered the adapter from amazon this morning for about $24. Amazon also has the plate for about $12. Both with free shipping and free return. I wonder which product gives you the best results. I would think someone on this site may have an experience with both.

Lost in the 60s · President

I guess it would work. I like the aluminum one, as it follows the shape of the intake better. The flat plate may cause turbulance at the rear of the intake.

SShink · 3K+ Club

I won't use another Edelbrock carb without one of these:

3/8 inch heat spacer link

EDL-9265.jpg?rep=False

Edelbrock's are terrible for fuel boiling after engine shutoff and hard restarts. This seems to fix that problem and may help with the sealing issue. You use a carb gasket on both sides of this, and I think the kit comes with them.

This is the one for a square bore carb that I think is the carb you have.

Lost in the 60s · President

Good idea for heat soak, Stan. He still needs the adapter to seal at the intake, but this on the adapter would prevent the boil over, WHICH may be why the plastic riser was on there to begin with ...

jim larson · 2K+ Club

So I add both the adapter and the heat sink??? I worry about the carb post hitting the hood. I will have to figure something out to measure the clearance. I think the Moroso spacer might have been to solve that problem. I read somewhere about plugging the heat passage to the carb with that performer intake. I plugged my holly intake on my SS.

jim larson · 2K+ Club

Maybe the heat sink and the plate Edelbrock suggested?

it will sit too high with adapter and heat sink.

fine with plate and heat sink.

maybe modify the plate to solve the turbulence issue?

-- Edited by jim larson on Saturday 2nd of November 2019 09:06:23 PM

dashboard · 2K+ Club

jim larson wrote:
So I add both the adapter and the heat sink??? I worry about the carb post hitting the hood. I will have to figure something out to measure the clearance.

Loosely ball up some tinfoil and lay it on top of the air cleaner, then slowly bring the hood down to see how much clearance you have.

Lost in the 60s · President

The Mr Gasket adapter is .750 and the insulator is .375, so the combo will be about 3/16 higher than the Moroso spacer, with the additional gasket.
Dashboard has the procedure to check clearance...

jim larson · 2K+ Club

All three are due to arrive tomorrow. Adapter, plate, and heat sink. To use the adapter and heat sink I will have to change out the intake studs. Heat sink and Plate I am good to go. I will have to check to see if there are studs available to correct length that would allow me to use Adapter and Heat Sink.

jim larson · 2K+ Club

Adapter didn't work. Called edelbrock and they said this is what I need 9266.

-- Edited by jim larson on Monday 4th of November 2019 01:18:04 PM

dashboard · 2K+ Club

jim larson wrote:
Adapter didn't work. Called edelbrock and they said this is what I need 9266.

-- Edited by jim larson on Monday 4th of November 2019 01:18:04 PM

Didn't work as in didn't fix the problem or was it the wrong part?

jim larson · 2K+ Club

dashboard wrote:
jim larson wrote:
Adapter didn't work. Called edelbrock and they said this is what I need 9266.

-- Edited by jim larson on Monday 4th of November 2019 01:18:04 PM
Didn't work as in didn't fix the problem or was it the wrong part?

Wrong product. My manifold was a not a speed bore ( think its just called a dual plane square bore), carb is square bore 1406 Edelbrock. Main issue Edelbrock said was that the morso spacer bottom side design cause the vacuum leak problem.

jim larson · 2K+ Club

jim larson wrote:
dashboard wrote:
jim larson wrote:
Adapter didn't work. Called edelbrock and they said this is what I need 9266.

-- Edited by jim larson on Monday 4th of November 2019 01:18:04 PM
Didn't work as in didn't fix the problem or was it the wrong part?
Wrong product. My manifold was a not a speed bore ( think its just called a dual plane square bore), carb is square bore 1406 Edelbrock. Main issue Edelbrock said was that the morso spacer bottom side design cause the vacuum leak problem.

Boy am I having a bad day!! It is the right product, I had a gasket on the intake and I didn't think the adapter was correct; but it is. Sorry for all the confusion.

Lost in the 60s · President

I was wondering what was going on, because your pic of the intake indicates it is definitely a spread bore. No confusion on OUR part...

Git er together and take a ride, before the snow gets too deep.

jim larson · 2K+ Club

OK confused again. The adapter I got is for a 4- bbl manifold to a Quadrajet Carb which I do not have. Or for a Quadrajet manifold to a 4 bbl carb, which I think is correct for my situation which is a Edlebrock Preformer Intake (Quadrajet type) to a 4 bbl carb (Edelbrock 1406. The instructions I found online don't show that application; but I think I have figured it out.

Should I use the gasket with the big square hole on the bottom between the adapter and the intake. But should I modify the gasket so it fits the inside configuration of the intake and adapter? The gasket supplied with the kit doesn't fit the intake.

Then I will need a similar gasket to go between the Heat Sink and the adapter and between the Heat Sink and the Carb or does the heat sink act as the gasket between the adapter and the carb? I think it acts as a gasket? But the Moroso spacer I had need gaskets and I have never done this before.

Well the Heat insulator arrive tomorrow. I think it should look like this; but trying to research for the best type. Heat Does anyone know the best one to fit between the carb and the adapter? Thanks. What about this for an Insulator?

-- Edited by jim larson on Monday 4th of November 2019 04:06:37 PM

-- Edited by jim larson on Monday 4th of November 2019 04:09:22 PM

Lost in the 60s · President

Both of the adapters I posted come with the correct shaped gasket between the intake and adapter. What adapter did you get ?

dashboard · 2K+ Club

Jim, while you have the carb off take the time to rebuild it. If the car has been driven very little over the last several years the inside of the carb could be a mess. I don’t understand why the engine bogs down when you spray carb cleaner on the base.

jim larson · 2K+ Club

Lost in the 60s wrote:
Both of the adapters I posted come with the correct shaped gasket between the intake and adapter. What adapter did you get ?

I got the 1932. The gasket for the Quadraet carb the Quadrajet intake sides does not fit the spacing of the studs in the Edelbrock intake. It looks like the other one would work.

-- Edited by jim larson on Monday 4th of November 2019 06:25:39 PM

jim larson · 2K+ Club

dashboard wrote:
Jim, while you have the carb off take the time to rebuild it. If the car has been driven very little over the last several years the inside of the carb could be a mess. I don’t understand why the engine bogs down when you spray carb cleaner on the base.

I don’t understand either, I thought it was suppose to speed up. But it definitely wanted to kill. Other then on idle carb seemed to work fine. Especially cruising at 30 mph or more or on WOT.

Bobs_Place · Vice President

jim larson wrote:
dashboard wrote:
Jim, while you have the carb off take the time to rebuild it. If the car has been driven very little over the last several years the inside of the carb could be a mess. I don’t understand why the engine bogs down when you spray carb cleaner on the base.
I don’t understand either, I thought it was suppose to speed up. But it definitely wanted to kill. Other then on idle carb seemed to work fine. Especially cruising at 30 mph or more or on WOT.

Ether you sprayed enough at the leak to cause a very rich mixture or some of the fumes were sucked in the intake of the carb, or maybe both. Check it with a closed air cleaner that has a snorkel off to the side and a way from the carb cleaner fumes.

Lost in the 60s · President

jim larson wrote:
Lost in the 60s wrote:
Both of the adapters I posted come with the correct shaped gasket between the intake and adapter. What adapter did you get ?
I got the 1932. The gasket for the Quadraet carb the Quadrajet intake sides does not fit the spacing of the studs in the Edelbrock intake. It looks like the other one would work.

-- Edited by jim larson on Monday 4th of November 2019 06:25:39 PM

Your carb base is drilled for both bolt patterns. You may need to use the Q-jet pattern to get this work.

jim larson · 2K+ Club

I thought about that Mitch. To use the spread bore gasket I would have to mount adaptor to intake with 4 inside Allen wrench studs provided in the kit. then put on adaptor on the outside 4 studs then the heat insulator, then the carb mounted on the 4 outside studs With nuts.

i didn’t like the appearance or fit that way as I would have to save the ends of the spread bore gasket (unless I don’t use the heat insulator and remove the 4 outside studs). It looks like the summit kit might have a little different spread bore gasket that would work.

what would be wrong with saving the big square gasket on the inside to match the spread bore opening on the intake or just leaving it as it is?

Bobs_Place · Vice President

Try this

https://www.summitracing.com/parts/sum-g1420/applications

This should cover the spread bore manifold and fit the carb, you can the also use the heat spacer. Use the above or below the g1420 which ever looks to flow better. Shouldn't cause any more turbulence than a carb sitting on a opened plenum as long as the openings of the plate and the heat spacer get progressively bigger towards the manifold.

I use that same style heat insulator with no gasket at the carb to insulator and have removed and reinstalled the carb many many times with no leaks.

Look like the two aluminum adapters are directional, one adapts a spread manifold to square bore carb the other adapts square bore manifold to spread bore carb

Lost in the 60s · President

I have no clue why you think you would need a second adapter ???
Will the adapter you have slide on the 4 existing studs ? yes, ? the issue is the base gasket doesn't fit over or between the existing studs ? Carefully trim off enough of the base gasket with a scissors to clear the studs, but retain the bolt holes, use a very thin smear of Black Ultra sealant and attach the adapter with the 4 Allen screws.
From there, proceed with the square, open gasket, the insulator and carb, with or without another gasket, as Bob does.

jim larson · 2K+ Club

This is what I Did and it sounds like what you are suggesting Mitch. I trimmed the spread bore gasket, then trimmed another gasket to make up for the gap between the intake and adapter. After setting made up gasket on intake I dropped on adapter, used the 4 set screw studs to secure adapter. The put on the heat insulator, then set on the carb. I wasn’t implying I need both adaptors, one just looked like it might work better than the other.

SoI use a gasket between adapter & heat insulator; but may or may not use one between insulator & carb?

i wish the studs were a little longer, I may have to replace them later. But this should be enough for a good test.

-- Edited by jim larson on Tuesday 5th of November 2019 10:12:43 AM

-- Edited by jim larson on Tuesday 5th of November 2019 10:50:10 AM

Bobs_Place · Vice President

Jim

I would also suggest that you check the carb base plate for flatness, it is very possible that someone has over tightened the mounting fasteners to try to stop the leak, which can worp the base. Flip the carb, lightly run a fine flat file across the base, use a little WD to lub the file, to show the high spots. You could also use some 400 paper under the file to show any high spots. If every thing is flat you won't need much torque to seal things up. I use a nut driver/screw driver handle with just a light twist, no two handed and NO a ratchet.

Lost in the 60s · President

I don't know that the little tabs in the corners, under the adapter was necessary, but I guess they won't hurt either.

Like Bob says, that carb isn't designed to be torqued down tight enough to bend the corners of the adapter without those tabs and they aren't sealing anything.

This should get you up and running and be able to get the idle down to 700 in gear...

jim larson · 2K+ Club

Lost in the 60s wrote:
I don't know that the little tabs in the corners, under the adapter was necessary, but I guess they won't hurt either.

Like Bob says, that carb isn't designed to be torqued down tight enough to bend the corners of the adapter without those tabs and they aren't sealing anything.

This should get you up and running and be able to get the idle down to 700 in gear...

HOPE so, I have to wait for a rear axel cover gasket, then I can install the gear oil and posi additive. Who knows it might actually work, seemed to work on wet grass. Snow tomorrow, maybe drive thursday or this weekend. Surgery on the Hernia schedule for next Wednesday. Don't think I feel good enough to attend the meeting on Saturday.

Lost in the 60s · President

You haven't started it up ?? Come on, we are all waiting with baited breath.
Don't need no stinking axle cover to run the engine...

jim larson · 2K+ Club

Hopefully the problem is solved, we’ll find out tomorrow. I just checkEd the Edelbrock carb and intake with a flat ruler. When I rebuilt the holly on my other car I sanded the holly base on a plat piece of glass with 600 grit sandpaper to make sure everything was flat. Maybe I’ll have to do that in the next step if I still have a vacuum leak.

I installed the axel cover this afternoon. Will add gear lube tomorrow and then hope for the best.

-- Edited by jim larson on Tuesday 5th of November 2019 06:53:07 PM

-- Edited by jim larson on Tuesday 5th of November 2019 06:54:59 PM

jim larson · 2K+ Club

Well I started the engine up today, well I guess the show blower engine as we had about 4". Hope it melts over the next few days with no salt being spread on the roads.

SShink · 3K+ Club

jim larson wrote:
Well I started the engine up today, well I guess the show blower engine as we had about 4". Hope it melts over the next few days with no salt being spread on the roads.

Thanks for the snow and snow blower update.

Did the idle drop or not after reassembly? Inquiring minds want to know.

jim larson · 2K+ Club

SShink wrote:
jim larson wrote:
Well I started the engine up today, well I guess the show blower engine as we had about 4". Hope it melts over the next few days with no salt being spread on the roads.
Thanks for the snow and snow blower update.
Did the idle drop or not after reassembly? Inquiring minds want to know.

I may not have explained myself correctly. I could get the car to idle down to 700 rpm without any issues just sitting in Park in the driveway. The issue was when shifting into Reverse or Drive the car would Die or want to Die especially when trying to move backward or forward.

So until I can actually drive the car I will not know if the problem is solve. Looks like there might be a 40-50 degree day next week. But Wed, Thu, and Fri I am sure I will not feel like driving the car after hernia surgery next Wed.

SShink · 3K+ Club

Sounds like you've made progress Jim on the idle in neutral. Maybe the next step is to adjust the idle mixture screws?

I had a similar issue that it idled fine in park, but not in gear and we adjusted the idle mixture screws and the idle quality in gear improved a lot.

You should be able to see if you've made improvements just by going from Park to Reverse or Drive in the garage and not need to drive the car if the roads are sloppy.

jim larson · 2K+ Club

SShink wrote:
Sounds like you've made progress Jim on the idle in neutral. Maybe the next step is to adjust the idle mixture screws?
I had a similar issue that it idled fine in park, but not in gear and we adjusted the idle mixture screws and the idle quality in gear improved a lot.
You should be able to see if you've made improvements just by going from Park to Reverse or Drive in the garage and not need to drive the car if the roads are sloppy.

I already went though the idle mixture screw check and set up. I worked as shown on the Edelbrock video. I feel that that part is OK.

jim larson · 2K+ Club

Well the issue is not solved. I started and ran the car some as the streets were clear and no salt dumped after recent snow. Car runs the same as before, fine at 700 rpm while in park or neutral. When you **** into reverse or drive with foot on brake the car will kill or if your coming up to a stop sign and you brake to stop the car, it will kill when idle drops below 1000 rpm. With idle set to 1050 rpm car acts fine when shifting into reverse or drive and foot on brake. Or when braking at a stop sign car does not kill. I will have to check for a leak at the Power brakes and all around the intake again. I believe the carb was installed in 1997, would it likely need a rebuild?

67ss · 1K+ Club

Did you check base timing with vacuum advance disconnected? Try bumping it up a couple degrees and see if it helps.

jim larson · 2K+ Club

67ss wrote:
Did you check base timing with vacuum advance disconnected? Try bumping it up a couple degrees and see if it helps.

When I got the car Base timing was at 4 degrees with VC plugged. I have since bumped it up to 14 degrees with VC Plugged. VC add about 20-22 degrees approximately according to my timing light. Car seems to run fine at WOT. Even when gaining up an incline I don't hear any pinging. But that was before I messed with the whole gasket/adapter thing. Maybe I should go a little richer on the air mixture screws? But I followed the edelbrock guide line. Adjust right to highest rpm, reset throttle according to rpm, adjust left to highest rpm, then reset throttle, then repeat, and repeat.

Bobs_Place · Vice President

67ss wrote:
Did you check base timing with vacuum advance disconnected? Try bumping it up a couple degrees and see if it helps.

With the engine at idle (1050 or so) check timing and note, than back out the curb idle screw and watch the timing, if you see the timing retard disconnect the vacuum advance and rerun the test. The timing should not move at or below and not start to move until about 200 or so above the curb Idle.

Also check while checking for vacuum leaks check the secondaries to be sure they are closing properly.

Lost in the 60s · President

jim larson wrote:

I will have to check for a leak at the Power brakes and all around the intake again. I believe the carb was installed in 1997, would it likely need a rebuild?

Just pull the hose off the check valve and plug it.

There are many cases of aftermarket boosters leaking, sometimes badly.

As long as the engine runs good, other than stalling, the carb should be OK. It may have sludge in the fuel bowls and accel pump circuit, but it can't be too bad, since it doesn't hesitate or backfire.

Disassembly and cleaning of the carb could be a winter project for a day.

jim larson · 2K+ Club

Checked compression today. All plugs were kind wet. Number 7 was quite low 125. Maybe I can put some gas through it before the hernia surgery puts me on the couch for a few days. Does the compression reading tell me. The booster is an original 67- Delco.

I forgot to warm the engine up, so would it be higher on all cylinders?

-- Edited by jim larson on Saturday 9th of November 2019 05:45:41 PM

Bobs_Place · Vice President

Jim

Was the engine fully warmed up the last time the engine was run before the plugs were pulled, if not that would explain the wet plugs.

The low cylinder is not what we would like, but with the choke on and a cold engine, that doesn't help the compression numbers ether.

And I do not think the low cylinder is causing the idle problems.