New engine - runs but wont idle

Tim65GT · Jan 25, 2008

New Ford Racing crate engine with aluminum GT-40 cylinder heads Pt# M-6049-X303

For now, I bolted on my old Edelbrock Performer Intake with a 600 cfm carb. (I plan on going EFI sometime in the future)

I have the idle screw cranked way up and it still sputters and dies. When I spray carb fluid around the intake manifold gasket at the heads, the idle goes up indicating a leak. I tried to re-torque the intake gaskets, but no difference. When I put them on, I noticed they didn't line up as good as I would have liked.

The oil looks a tad milky too, indicating the coolant/water is making its way into the crankcase.

I'm not sure what gaskets they were, I threw away the box and can't find the receipt. I know they were Fel-Pro.
What gaskets should I be using? The carb intake type or the EFI intake type?

fvike · Jan 25, 2008

I'd get new manifold gaskets, and try again. Also, did you use cork gaskets at the manifold front and rear? If you did, don't do that next time, but use plenty of RTV.

D.Hearne · Jan 26, 2008

Fepro makes several different intake gasket sets. Sounds like you went with the cheapest std stock head set. You need the 1262 gaskets at a minimum for the GT40X heads. As for the end gaskets, test fit the intake without sealer and the end gaskets first, before deciding whether or not to use the end gaskets. Set the head-side gaskets in place, then set the intake down on them, then check to see how the sides and ends look. Measure the end gaps and see how that measures up to the end gasket thickness. If the gaps are thicker than the end gaskets, I doubt using RTV alone will seal that.

starchiefus · Jan 26, 2008

I just went through this on my engine, the intake gaskets i got with my generic rebuild set were like paper compared to the Felpro 1250 set i ordered to go with my new manifold.
If you decide to use the 1250's (supposedly universal fit on ford 260 thru 351 including Ford motorsport AR aluminium heads) go ahead and use the cork end gaskets they come with adhesive on one side so they will not slip, rermember to put a bead of RTV on the end/side gasket junction, I also put three 1/8" beads of RTV along the manifold ends as well, 1 on the inner and outer edges and 1 in the middle, and then the hardest part, waiting for the RTV to cure before installing, I gave mine the full day they recommended. This fixed my vacuum leak into crankcase problem i was having.
Hope this helps,

Steve.

Tim65GT · Jan 26, 2008

Thanks for the replies. I pulled the intake this morning and I just got back from running around with the old gaskets. The local parts store didn't have anything other than stock replacements. I went to Yearwood Speed shop here in town and the guy sold me the Fel-Pro #1262. Comparing them with the old ones and my port measurements, they look good. They say for "Ford Motorsport AR aluminum heads". I'll install and then wait at least a half a day before filling the coolant and giving it another shot.

D.Hearne · Jan 26, 2008

I use the 1262's on my 331's Canfield heads. The stock O.E. style Felpro sets don't match the larger intake ports.

Tim65GT · Jan 26, 2008

IT RUNS! Woo Hoo

I topped off the coolant and gave it a crank and wala! It RUNS and sounds badass with the Flowmaster system. I checked the oil pressure, adjusted the timing, let it warm up, checked for leaks, ran through the gears, kept adding trans fluid, adjusted the fan thermostat.

Tim65GT · Apr 3, 2010

I think have an issue with the compatibility of my setup. It has gone back to not idling correctly, just like before.

The #1262 intake gaskets I installed worked, but it took a while, and they have developed a crack/opening almost a 1/4" wide at the top of the 2nd ports from the front on both sides (#2 and #6 cylinders). It looks like they may have expanded out. When I spray carb cleaner in the area it increases rpms, so it definetly is leaking vacuum there.

The 1262's fit the head ports great, but not so great on the Performer intakes shorter port height. Anyone else run across an issue like this?

I didn't upgrade the intake when I swapped in the crate motor, because I am holding off for an EFI (maybe the FAST EZ-EFI). I was thinking about getting the Performer RPM with it. If I swap now, I can still use my carb and my EFI upgrade will later bolt right on. How about hood clearance with the Performer RPM compared to the Performer?

D.Hearne · Apr 3, 2010

Did you try retorquing the intake ? That may fix it.

Tim65GT · Apr 4, 2010

Yes, I checked the torque of the intake bolts.

Here is a picture of one side. You can see the blue Printoseal area of the gasket and the gap of where it separated and is allowing the vacuum leak, so the only real fix is to replace the gaskets. I was looking at the port dimensions of the Edelbrock Performer vs the Performer RPM and there isn't too much difference.
Felpro Gasket: 1.28" x 2.10"
Performer Port: 1.09" x 1.84"
Perf RPM Port: 1.05 x 1.86"
I couldn't find any port dimension data on the Ford Racing GT-40 Heads.

I was also thinking the Ford Racing Gaskets would be better at .070" compared to the Felpro at .060".

horseballz · Apr 4, 2010

Are you making sure that the bolts are lubricated before they are installed and torqued? Especially with steel bolts into aluminum, this is a huge issue, because of friction and possible galling. A lubricated bolt provides up to 17 times more clamping force for a given torque than dry threads!
Gene

D.Hearne · Apr 4, 2010

Tim65GT said:
Yes, I checked the torque of the intake bolts.

Here is a picture of one side. You can see the blue Printoseal area of the gasket and the gap of where it separated and is allowing the vacuum leak, so the only real fix is to replace the gaskets. I was looking at the port dimensions of the Edelbrock Performer vs the Performer RPM and there isn't too much difference.
Felpro Gasket: 1.28" x 2.10"
Performer Port: 1.09" x 1.84"
Perf RPM Port: 1.05 x 1.86"
I couldn't find any port dimension data on the Ford Racing GT-40 Heads.

I was also thinking the Ford Racing Gaskets would be better at .070" compared to the Felpro at .060".

RPM ports are usually undersized, but the intake itself should have more "meat" around it to seal against heads with larger than stock ports. I can't find info on port sizes either, but I'm using a Felpro 1262 gasket on my Canfield heads with a repop Ford 3x2 intake and it seals fine

MitchGT · Apr 4, 2010

Are you torquing the bolts from the center out, like the manual says to? I've never had the center squish up like that...

blown65 · Apr 4, 2010

Has that intake been milled for some reason. How much of a gap is under the ends of the manifold when you set it on?

Looks like your gluing the gaskets on first so I'm assuming they aren't shifting, just looks like the intake is sitting too low or something. Really hard to tell by the pictures.

Tim65GT · Apr 5, 2010

Yes, I followed all the correct installation procedures. As you can see from my original post date, the 1262 gaskets worked since Jan '08. The Performer Intake has not been milled.

RPM ports are usually undersized, but the intake itself should have more "meat" around it to seal against heads with larger than stock ports. I can't find info on port sizes either, but I'm using a Felpro 1262 gasket on my Canfield heads with a repop Ford 3x2 intake and it seals fine

That what I was hoping that the RPM had more "meat" around the ports. Can any one verify this?

D.Hearne · Apr 5, 2010

blown65 said:
Has that intake been milled for some reason. How much of a gap is under the ends of the manifold when you set it on?

That's a good question that needs to be answered. If he's got too big of a gap under the ends, and used a bead of sealer in place of a gasket, that would be the reason the intake sat down so low and uncovered the ports.

Tim65GT · Apr 6, 2010

Thanks for the replies

Originally Posted by D.Hearne:

That's a good question that needs to be answered. If he's got too big of a gap under the ends, and used a bead of sealer in place of a gasket, that would be the reason the intake sat down so low and uncovered the ports.

I did. (above -

The Performer Intake has not been milled

.)
I bought it new in 2000 and had it on my old 302 for 8 years.

The primary sealing is the manifold intake ports to the heads. The intake ends are important too, but the geometry of the manifold and the heads are what determines what this gap will be. If I use thicker Intake gaskets, that should raise the manifold and the lining up of the ports, right? Anyone have any experience with the Ford Racing gaskets?
What I'm wondering is If I buy the RPM Intake, am I looking at the same issue down the road? Is this possibly an issue with the GT-40 heads?

D.Hearne · Apr 6, 2010

Tim65GT said:
Thanks for the replies

I did. (above - .)
I bought it new in 2000 and had it on my old 302 for 8 years.

The primary sealing is the manifold intake ports to the heads. The intake ends are important too, but the geometry of the manifold and the heads are what determines what this gap will be. If I use thicker Intake gaskets, that should raise the manifold and the lining up of the ports, right? Anyone have any experience with the Ford Racing gaskets?
What I'm wondering is If I buy the RPM Intake, am I looking at the same issue down the road? Is this possibly an issue with the GT-40 heads?

Did or did not use the end gaskets ? Thicker gaskets will help raise the intake, I've seen SBF gaskets that are up to .090 thick, and possibly some thicker than that. Felpro makes Ford's gaskets, may as well buy Felpros, if they're cheaper. No two intakes are going to fit any one engine the same. I had my Canfields milled .060 for a previous build and had to mill the Vic Jr I used on that build to get it to fit. Now I've got the same set of heads on my 331 and the 3x2 intake fit with only a little opening up of the bolt holes. No milling was neccessary. I've seen the same thing happen on a 400 Ford. I milled that motor's heads .030, the block's deck .020 and never had to mill the intake (Performer 400)

Tim65GT · Apr 8, 2010

Lol, I got ya confused when I quoted myself. When I said "I did" I was referring to your question that needed to be answer about the milling. I meant I did answer it.

Anyway, Yes I did use the cork end gaskets. And I have also put intakes on (Chevy) with milled blocks with no issues.

I think I'm going to order the Performer RPM, since it is actually recommended by Ford Racing for my crate motor. Edelbrock recommends the #7220 gaskets with that manifold (1.20" x 2.00") Also a fresh can of Gasgacinch since the one I have is pretty old - maybe that was the problem all along. I've had good luck with the Permatex Ultra Black RTV for the water ports and end seals.

Thanks for your input.

By the way, I won best engine at the last car show I was at.

Tim65GT · Apr 14, 2010

CSI on the vacuum leak...

It's a lot worse once I got the intake off. There were several small gaps where the gasket separated.

I have the hardware and fittings transfered to the new RPM manifold and will be installing it tomorrow.

New engine - runs but wont idle

Tim65GT

Active Member

fvike

Member

D.Hearne

New Member

starchiefus

Member

Tim65GT

Active Member

D.Hearne

New Member

Tim65GT

Active Member

Tim65GT

Active Member

D.Hearne

New Member

Tim65GT

Active Member

horseballz

D.Hearne

New Member

MitchGT

Member

blown65

Tim65GT

Active Member

D.Hearne

New Member

Tim65GT

Active Member

D.Hearne

New Member

Tim65GT

Active Member

Tim65GT

Active Member

Similar threads

New engine - runs but wont idle

Active Member

Member

New Member

Member

Active Member

New Member

Active Member

Active Member

New Member

Active Member

New Member

Member

Active Member

New Member

Active Member

New Member

Active Member

Active Member

Similar threads

Privacy & Transparency

Privacy & Transparency