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Ok, I have pulled, cleaned and reinstalled my intake manifold and was extremely careful and meticulous.

 

However, I still seem to have a vacuum leak in the same spot.

 

Background....

 

351c 2V. Engine ran great before. Carb needed a rebuild and I just decided to upgrade instead.

Installed Performer 2750 Intake and 1406 Carb.

 

Got it all together the first time and had a vacuum leak. So took it all apart and reinstalled. New gaskets. Gaskets were applied with Gasgacinch. RTV in valley's instead of cork gaskets.

 

Now I seem to have the same issue.

 

Can't get a constant engine rpm. If I use a little carb cleaner around intake idle jumps at same spot as last time. The apparent leak is in the middle of intake under choke. Right at the plate that blocks off the old Choke Heater Hose Assembly.

 

I checked torque on all bolts and all are equal at 20 ft pounds per directions. Manifold was torqued in the pattern in the intake instructions and in a two step method (10 and then 10 again).

 

I am really trying to do this project myself and not take it to a mechanic, but I am feeling a bit defeated.

 

I would have expected the leak to be near the front or back where the RTV was used.

 

Anyone had any ideas as to what is happening? Why I'm not getting a good seal?

73 H Code Convertible

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Was the intake new? I would put a straight edge on the gasket surface to see if it is flat. Since you did not do anything to heads I would still just check. Are you sure the heads are 2V. Look on the front top of the head just above the valve cover and there should be a 2 or a 4 cast into the head. The attached picture shows a 4-V head is on the left top of the head.

David

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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You mean the choke block off plate that came with manifold? That is installed where old choke heater tube was.

 

Fel-pro the first time and edelbrock 7265 gasket second time.

 

 

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For sure 2v heads. Completely stock 2v engine. Intake is new

 

 

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73 H Code Convertible

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Did you use the valley pan?

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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Did you use studs on the four middle bolts to help with the alignment? It is very easy to get one side a little lower than the other side. After you get the manifold on remove the alignment studs install all of the bolts finger tight and the use a 3-step sequence beginning with 5 ft-lbs. Some Edelbrock instructions say to tighten the center 4 bolts to 18 and the rest to 25 ft-lbs. Ford also used different torque specs for the 4 center bolts, although higher for the iron manifolds.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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I just aligned the bolt holes and gently lowered it down.

 

I followed the torqued directions from Edelbrock. I'll check them again tomorrow. If I still have a leak I think I am going to break down and take it to the shop

 

 

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73 H Code Convertible

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I just aligned the bolt holes and gently lowered it down.

 

I followed the torqued directions from Edelbrock. I'll check them again tomorrow. If I still have a leak I think I am going to break down and take it to the shop

 

 

Sent from my iPhone using Tapatalk

 

Nothing wrong with that. After ruining two sets of cam bearings trying to install them myself, I took my rebuilt block to the pros and spent far less that it would have cost in continued frustration and parts. No shame in getting the pros involved to save $$ and headache medicine.

 

My 2 cents.

Doc

Project started 8-7-10

Completed: All new suspension, rebuilt 351C H Code bored .030 over with mild cam and intake, new 3.50 TracLok, custom exhaust system

Current "mini-project": interior upgrade :-/

[button=http://www.7173mustangs.com/forum-garage?filterxt_uid=76]Doc's Garage[/button][button=http://www.7173mustangs.com/thread-1973-mustang-convertible-restoration-and-modification]Doc's Wiki[/button]

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I have always done mine this way and never had a leak. I am using the valley pan too with no issues. For the gasket I used copper coat on one side and place them on the heads overnight to let them set. Then I use RTV and put a small bead around each of the ports on the manifold and use the studs to guide it when setting the manifold on and then tighten to spec. Then I let it cure for 24hrs before starting.

 

For the valley pan, I do the same thing with the exception that I put a bead of RTV on the bottom of the pan and set it in place and then the bead on the manifold and set it in place and then torque it down.

 

I also use the urethane rubber gasket for the front and back instead of the bead of RTV and just make sure that the corners have good RTV coverage. I have not had any issues doing it this way.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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Looks like I'll be trying you method.

 

Shockingly I went by a couple of local shops and was told they don't work on old cars, only new stuff.

 

 

Sent from my iPhone using Tapatalk

73 H Code Convertible

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Looks like I'll be trying you method.

 

Shockingly I went by a couple of local shops and was told they don't work on old cars, only new stuff.

 

 

Sent from my iPhone using Tapatalk

 

Let me know how it goes.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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if the motor had to be decked heavy in the past, then it will cause a vacuum leak with the intake manifold because the cut angles will be wrong, so sometimes you have to have the intake manifold modified and cut at a new angle so it seals and sits lower.

 

something could be warped or getting hung up when you go to seat the intake.

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if the motor had to be decked heavy in the past, then it will cause a vacuum leak with the intake manifold because the cut angles will be wrong, so sometimes you have to have the intake manifold modified and cut at a new angle so it seals and sits lower.

 

something could be warped or getting hung up when you go to seat the intake.

 

Thanks for the info. It almost has to be something I am doing or missing. I am only the third owner of car. Engine was only rebuilt once in it's lifetime and nothing drastic was done. It is still very much stock.


heat cross over plates

 

Did I leave off a part or needed to add something I didn't have?

73 H Code Convertible

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If you did not use the valley pan then you are getting a different thickness on the mating surface with just intake gaskets. I agree with 72Hcode if any decking or surfacing was done in the prior rebuild. Sorry about the frustrations they do happen. Talk to some of the local car guys and see if any of them have a shop they work with regularly. It is probably off the beaten path. Good luck whatever path you take.

BKDunha

72 Mach 1 H-Code (Concourse driven restoration)

67 S-Code Factory GT with 4-Spd

68 Mercury Cyclone (Pro-Street project)

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Thanks for the help guys. I am going to try again. Third time is a charm right...[emoji106]

 

Going to order new fel-pro gasket set with new valley pan. The good news is I am going to eventually get real good at this.

 

 

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73 H Code Convertible

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I would test fit everything before you start tightening things down, beyond finger tight. You should be able to see down a few of the runners well enough to see how well the runners, gaskets and ports match up. An inspection camera is even better. With the lights turned out use a light on a flexible shaft and run it down the runners to see if any light is coming out around the gaskets and try to adjust the manifold so either there is no light or it is even. Make sure there is clearance between the manifold ends and block.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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  • 1 month later...

Wow,

 

Been a while since I updated on this project. I have been traveling and the car has been sitting.

 

However, I think I have it all worked out now. All put back together with Turkey pan installed. Idle sounds good and car drive well. No noises, surging, stalling, etc...

 

Now, I have to get a carb spacer, as My accelerator connection is dragging on the bottom of the stock air cleaner. Should be here tomorrow.

 

Thanks everyone for the help and encouragement!!!

 

Thanks for the help guys. I am going to try again. Third time is a charm right...[emoji106]

 

Going to order new fel-pro gasket set with new valley pan. The good news is I am going to eventually get real good at this.

 

 

Sent from my iPhone using Tapatalk

73 H Code Convertible

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I was going to suggest that you get four .125" dowel pins. Put clay balls on the top and bottom of all of the ports. Put the four dowels one on each corner and sit the intake down and press against the dowels between the head and intake then lift and measure the clay thickness. If they are way off from top to bottom you would need to have something re-cut to match. You can put some across the ends also to see if everything is coming down even. That stops you from having to guess what is off. If the gap between the head and intake is much greater than the ends then someone probably cut the head or the deck.

You can use long feeler gauges to check also with the dowels in place.

Gaskets are there to take up the variation in the machined parts and surfaces that is their function. We did build some engines and did not put head gaskets on just lapped the heads to the block. No gasket to blow. I had a set of angle plates that bolted to the ends of Ford heads and we ground them on a big wet surface grinder to get a much smoother surface before lapping.

You would never want to do that on a street engine to many heat cycles and would leak.

Sounds like you are good to go for now.

David

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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New Question....

 

So my throttle linkage is dragging the bottom of my air cleaner assembly. This is an issue for obvious reasons.

 

Has anyone modified their air cleaner assembly to fix this? Or am I just now in the market for a new air cleaner?

73 H Code Convertible

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just get a spacer and slip int under the air cleaner

 

something like this

 

http://www.summitracing.com/parts/mrg-9340/overview/

 

You can find them in various heights Just get the shortest one you can find that will give you clearance. You may need to replace the threaded rod too, to accommodate the additional height

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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