351W started missing

[Bob & Sue 110]

We've put about 500 miles on it since new dizzy & spark plugs after my stock Motorcraft with Pertronix I died. I put a Spectra Premium ( RichPorter ) distributor in it till I get a MSD to go with my 6AL-2 box. Plugs are new, wires have about 1000 miles on them. We've had 80-94* temps for the last 2 months I've noticed after a long ride the carb is boiling the fuel out, I was hoping to wait till this winter to put an isolating spacer on it & rebuild the carb Holley Street Avenger. I put 8 gallons of 92 oct in it yesterday from a small station.

Yesterday coming home it developed a hicup or it feels like it might stall but doesn't it kind of feels like when you set the low idle speed screw in to far it almost dies almost feels like water in the fuel. Hard to describe the symptom hope it made sense.

I'm not sure if it's in the electrical or carb, I'm going to start by putting the spacer on it today or tomorrow & pulling the primary bowl off to check for water bad fuel. If that doesn't fix it I'll change the plugs it has Autolite AP25 in it going to change them anyway to E3's.

Any thoughts I'm kind of stumped.

86* yesterday I was picking up a converted FoMoCo r12 to r134 compressor. Anyone have the stock mounts they want to sell?

Bob

[skidmarky 50]

This might be out there, but does it have the correct gear on the distributor?

[1969_Mach1 333]

Could be a lot of things, spark plug or wire breaking down.  Although cold is when a bad spark plug or wire will first act up.  So it sounds more fuel related.  Might have got some crud in the carburetor.  For the low cost of a rebuild kit and heat insulator gasket, it might be worth rebuilding the carb now.  Is it only at idle that you notice the issue?

If you swap out the spark plugs for another brand, I suggest NGK.  I've had good luck with NGK and they are kind of popular in performance engines.

If fuel is boiling out of your carb, the insulator gasket will help or stop it.  I'd install one regardless.  Be a little cautious of the Phenolic type heat insulators, they have a tendency to crack over time and thermal cycles.  Double check the float levels.  If one or both are high and were fine before, there might be crud in a needle and seat or a float has got some gas inside of it and is partially sinking.

It sounds like you are using an aluminum intake manifold with the heat crossover passage open?  If so, aluminum conducts heat at a much faster rate that steel and cast iron.  For that reason most people install the heat crossover block off plate included with the intake manifold gaskets when using an aluminum intake manifold.

[Bob & Sue 110]

Yep correct gear.

I have an Edelbrock heat insulator like the one in the link not phenolic.

Good idea on checking float height I'm going out to work on it in a couple hours or after the Hawks whoop Oakland hoping Marshawn gets less than 20 yards.

Not sure about the heat transfer block manifold was installed by PO.

The more I think about it tend to think it's the fuel, just added a can of Seafoam with 3 gallons of gas & changing the fuel filter.

 https://www.oreillyauto.com/detail/edelbrock-3451/performance-16477/engine-16841/fuel-system-16571/carburetors-16703/carburetor-mounting-gaskets-18318/heat-insulator/9266/4288689

[1969_Mach1 333]

After starting the engine cold and it's been running for about 5 minutes, touch the intake in different locations, including the heat crossover passage.  If the PO left the heat crossover passage open there will be a noticeable temperature difference.

[Bob & Sue 110]

After heating the engine up to 160* I took some readings on manifold most areas were 135*-140* one area was 160* where the manifold (Holley Dominator) has an oval cover with 2 bolts on RH side. All the cylinders measured 155*-160* on the headers that eliminates a bad plug.

Changed the fuel filter it appeared to have a small amount of water in pretty hard to tell with that amount.

Secondary float was a little high dropped it down to halfway below center of sight glass & top of threads.

Took it for a ride no miss showed up, the original miss was at idle, cruising and going up a hill more of a surge than a miss. I'll take it out for a spin tomorrow my neighbor will be home then with a trailer if I need it.

As far as plugs I prefer E3 Diamond Fire, NGK are an excellent plug also. 

Isolator & rebuild kit is next on the list.

Thanks for the ideas

[1969_Mach1 333]

Wow, you have an old Holley Street Dominator intake manifold.  I haven't one of those on a 351W since 1982.  They are actually a very good single plane intake manifold for street use.  For a single plane, they still provide good low and mid range power. 

[barnett468 418]

i would trash the e3 plugs ad use normal plugs.

your fuel level was definitely too high.

set your timing curve to the optimum level if you haven't done so yet.

i have seen some of your posts on vmf. it is amazing to me how many self appointed "experts" over there have no idea what they are talking about. there are very knowledgeable people on this site.

 

 

[LoneWolf2U 136]

Install a 4 hole spacer plate under the holley and lower your float levels to right at the bottom of the sight holes.

The spacer plate will keep heat away and lessen fuel boil and it will add to your bottom end torque response.

[barnett468 418]

2 hours ago, Mach1Rider said:

Install a 4 hole spacer plate under the holley... The spacer plate will keep heat away and lessen fuel boil...

 

Not if it is metal.

[LoneWolf2U 136]

I beg to differ, I have a 4 hole spacer plate installed with a thick lower gasket.

The spacer is hollow inside and is cool to the touch with the engine at operating temps.

You can not hold your fingers on the intake, But the spacer is only slightly warm to your fingers.

[Bob & Sue 110]

On 8/31/2017 at 6:41 PM, 1969_Mach1 said:

Wow, you have an old Holley Street Dominator intake manifold.  I haven't one of those on a 351W since 1982.  They are actually a very good single plane intake manifold for street use.  For a single plane, they still provide good low and mid range power. 

Could you take a look at this manifold on ebay the plate I described is between the upper bolt holes in the center the plate isn't on it in the picture.

What's it for?

http://www.ebay.com/itm/Holley-Street-Dominator-intake-manifold-for-ford-351-Windsor-/282608692730?hash=item41ccca6dfa:g:DjkAAOSwRYBZj1Df&vxp=mtr

[1969_Mach1 333]

That opening is for a factory choke hot air tube or choke stove that some original carbs used.  The two small holes in the back of the intake manifold are for a factory EGR valve that were on some cars.  Those Holley Street Dominators were setup to be emission compliant.

If you were to remove the center plate you are referring to, you would be able to see if the PO installed the heat crossover block off in the intake manifold gasket.  

[Bob & Sue 110]

Thanks for looking.

The 2 back holes are plugged, I'll pull the plate off later to check the crossover gasket want to pickup some gasket material before pulling it off. It was a California car built and bought in San Jose.

[1969_Mach1 333]

Mine was also built in the San Jose plant.  That's about 30 miles north from me.  As best I can determine it was first sold in Arizona and since Arizona has been in California.  I got lucky, almost 100% free of any rust through areas.

[Bob & Sue 110]

Mine is a one family owned car the father bought it at the oldest Ford dealership in Cal he drove it till his son was in high school his son got tired of it and gave it back to him. The son moved up here in 2006 and the dad gifted it to his son who had it till I bought it. I have the original license plate, all paper work along with 2 boxes of receipts right now it has 63,000 miles on it. The engine was rebuilt 5000 miles ago in Palo Alto and FMX was changed to a C4. The son kept it garaged up here only drove and started it a couple times a month for the last 10 years he wasn't into cars his dad did all the work on it. I can't find any rust anywhere except for some surface rust in a couple places I've already taken care of. Engine bay is mostly chrome, Procar/Scat seats, engine build, etc wish it was a Mach 1 with all the history I have on it. 

I'm just finishing the interior new door panels, some plastic pieces, new carpet, all new weatherstripping & building a carpeted trunk. 

[Bob & Sue 110]

Thought I should post my findings & results.

After a lot of time spent looking & changing out all fuel filters, new plugs, dizzy, drained gas tank ( it was a new tank 2 years ago ). Found some water in 3 gallons maybe 1 pint. Put 4 gallons of 94 octane non ethanol in it added some Valvtec & Seafoam. 

Bought a Holley Trick Kit (not a refresh or rebuild kit it comes with a selection springs, jets, power valves, etc) specifically for my carb from Holley. While taking it apart I found in the primary side 2 of the 4 air bleeds were plugged. I went down to a 5.5 power valve & lighter spring on accelerator pump left the .064 primary jets in it for now.

Spoke with 2 different Holley techs they said to cut out the Edelbrock heat 4 port insulator to match the Holley single plenum gasket & always use single plenum gaskets & spacers as the dual plenum will interrupt the fuel flow of a single plenum manifolds design.

So far we've put about 100 miles on it without any problems.

Amazing how much the air bleeds affected the idle circuit, I can now tune it without any surges or bogs idles great with instant throttle response.

Thanks for all the responses.     

[RPM 1,190]

Well that certainly is good news Bob. Thanks for posting the results.

[1969_Mach1 333]

Yeah, the air bleeds allow air into the fuel passages in the metering block.  This starts to emulsify the fuel.  They have a large control on the air fuel mixture.  Glad to hear you solved the problem.