63 Hot Engine Problem

[Harry S.]

This is my 250hp 63. All engine components are correct.

Anyway, I went for a120 mile drive yesterday. The car performed just fine for the drive down ( 60 miles ). I let the car sit for a bit, had some lunch then started up to drive home. As soon as I got on the highway and hit the gas the car started to stutter as if it was missing or was not getting enough gas. After about 30 miles the problem went away. I was driving at 70 - 75 most of the way.

All I can think of is the gas I'm using was boiling in the carb or had a vapor lock that needed to clear. Or it took 30 miles for the carb temp to cool down.

Any suggestions/thoughts?

[Duke W.]

Re: 63 Hot Engine Problem

...probably percolation or vapor lock, which affects a lot of cars, particularly in hot weather and from heat soak. There are many threads on the subject. If the problem is severe, insulating sleeves can be applied to the fuel pipes, and this can reduce carb temperature by up to 30 degrees.

If you have an IR gun take it with you and take temperatures immediately after shutdown and after 5, 10, and 15 minutes.

Duke

[Bob W.]

Re: 63 Hot Engine Problem

Harry, Take a look at Heat shield products their hot rod sleeve for your gas line and coolcarb for under your carb.

[Frank D.]

Re: 63 Hot Engine Problem

This is my 250hp 63. All engine components are correct.

Anyway, I went for a120 mile drive yesterday. The car performed just fine for the drive down ( 60 miles ). I let the car sit for a bit, had some lunch then started up to drive home. As soon as I got on the highway and hit the gas the car started to stutter as if it was missing or was not getting enough gas. After about 30 miles the problem went away. I was driving at 70 - 75 most of the way.

All I can think of is the gas I'm using was boiling in the carb or had a vapor lock that needed to clear. Or it took 30 miles for the carb temp to cool down.

Any suggestions/thoughts?

Almost surely vapor lock as opposed to "heat soak" resulting in percolation... The former is like the car is fuel starved and the latter has symptoms of a flooded engine.... Sometimes popping the hood while underway will get enough air flowing to help but I don't like doing it..

My bone stock 250 hp 63 does the same thing on rare, exceptionally hot Orlando days. To wit, the fuel pump is trying to pump vapor instead of fuel. Make sure the fuel pump-to-carb hard line has a nice air gap from the PS cylinder head. Insulating the fuel lines might help but I've had mixed luck with that.

Do not, do NOT use the coolcarb product....the insulating material is known to melt in some cases and can wind up in your intake!
See picture - and do some internet research. You can try a 1/4" WCFB phenolic spacer for percolation issues and here is a source (but I think you have vapor lock):

https://www.dashman.net/search.html?q=wcfb+spacer&submit=Search

You'll need to check hood clearance though...especially on the PS air cleaner snorkel...

It has gotten so bad with some owners they've added a "booster" pump at the fuel tank or converted completely to an electric pump...

[Duke W.]

Re: 63 Hot Engine Problem

First line of defense is to wire open the heat riser valve.

Duke

[Bill M.]

Re: 63 Hot Engine Problem

I was having a similar problem with my 67 I had the local speed shop take a look. the car always felt like it was starving for fuel. The shop made me a new fuel line that is away from the manifold and block. She's been running great for the last month.

[Guest]

Re: 63 Hot Engine Problem

I would check the main fuel line close to any heat or radiator hoses that could cause a vapor lock or check the rubber fuel line at the fuel pump see if the rubber fuel line didnt collapsed or getting soft would cause restrictions

[Timothy B.]

Re: 63 Hot Engine Problem

Harry,

Gotta start with the simple things first, post #5 is that starting point. I wired the heat riser open on my 67 one time and it made a huge difference in the plenum temperature.

[Frank D.]

Re: 63 Hot Engine Problem

A properly operating heat riser should be open under the conditions cited anyway; mine stay wired open with stainless steel aircraft safety wire in Florida however.... The biggest factor (and some don't want to do it) is blocking the exhaust intake manifold runners under the carb or blocking them at the carbs base. The runners are usually visible on the low HP cars by their burnt paint (tell you anything ?) The other approach is to drill, tap and plug the carb "hot" holes, circled in second picture (but not as effective)..

I've done both - which solved my percolation problem but not my vapor lock problem..

[Harry S.]

Re: 63 Hot Engine Problem

Thanks everyone. Here is the plan:

1) Check timing
2) Wire Heat riser open
3) Take a test Drive
4) Av Gas
5) Think about the intake manifold

Cheers

[Don H.]

Re: 63 Hot Engine Problem

Harry,
This probably is not the problem but worth checking. I lost the pivot pin in the fuel pump coming home from the Hershey Convention. It continued to work but would sometimes be erratic (same symptoms as yours). I have no idea how it worked, but the car ran all the way home.
Good luck, Don H.

[Duke W.]

Re: 63 Hot Engine Problem

Thanks everyone. Here is the plan:

1) Check timing
2) Wire Heat riser open
3) Take a test Drive
4) Av Gas
5) Think about the intake manifold

Cheers

All '63 engines used the same centrifugal and vacuum advance, but the 250 HP initial timing recomlmendation was 4 vs. 8 for the 300 HP and 10 for the 340/360 HP engines. All yield less than the ideal 36-40 total WOT advance because most OE spark advance map are set up VERY CONSERVATIVE for reasons I described in my 2012 San Diego National Convention Tuning seminar, which is an easy Web search.

So advance the initial timing to, say ten, wire open the heat riser valve and TEST the VAC to make sure it meets spec. Use an IR gun to measure temperatures along the engine compartment fuel pipes and carb bowls. Note how close the fuel pipe is to the exhaust manifold.

Having a proper spark advance map including a properly functioning VAC that meets the Two-Inch Rule with full time vacuum advance is very important to maintaining minimum EGT. After idling for several minutes coming back from a drive that fully warms everything up, the manifolds should be no more than 500F, and hold the gun close to the manifold so it doesn't pick up cooler background radiation that can reduce the indicated temperature.

From '62 to '66 the 250/300 HP spark advance map went through a number of changes, some of which were ill- conceived like a 24 degree VAC. They finally got it right in '66, with 30 degrees centrifugal although it was very lazy due to not coming all in until about 5100 revs. If you want to optimize earlier base cam engines (250 and 300 HP) grind out the slot to increase centrifugal to 30 degrees, use a B22 15"/16 deg. VAC, set initial advance in the 6 to 10 range, then install lighter springs to bring the centrifugal all in by about 3000 revs.

Because many of these engines have been rebuilt with less compression than OE, they should tolerate a more aggressive spark advance map, which will yield better performance and fuel economy. One easy way to get a handle on actual compression is measure head gasket thickness. OE was a .018" steel shim type. Typical rebuilds use a composition gasket, about double the OE thickness, which drops compression about half a point from OE, which with OE pistons was actually in the range of 10-10.25 depending on head chamber volume, which was about 1-2 cc less with 461x/461s compared to the later 462s.

Duke

[Harry S.]

Re: 63 Hot Engine Problem

A properly operating heat riser should be open under the conditions cited anyway; mine stay wired open with stainless steel aircraft safety wire in Florida however.... The biggest factor (and some don't want to do it) is blocking the exhaust intake manifold runners under the carb or blocking them at the carbs base. The runners are usually visible on the low HP cars by their burnt paint (tell you anything ?) The other approach is to drill, tap and plug the carb "hot" holes, circled in second picture (but not as effective)..

I've done both - which solved my percolation problem but not my vapor lock problem..

Frank, still fighting the problem. I'm thinking of adding a second thin baffle. The sequence would be manifold, baffle, gasket, spacer, baffle then the carb. That will cover the crossover holes.

Thoughts?

[Frank D.]

Re: 63 Hot Engine Problem

As to Duke's comment; Lars rebuilt my distributor and advised running the car at 16* initial which I now do which has not prevented the vapor lock on the hottest days....

You can certainly try the gasket sandwich Harry - there is also a commercially made WCFB 1/4" phenolic spacer available now (I made my own previously)....hood clearance with the dual snorkel arrangement can be an issue though...

Again - this would help address the percolation issue; but if its truly vapor lock; then its an issue at the fuel pump.

You may want to 'shoot' the fuel bowls with an I/R temp gun when you have the problem and check the result -- anything north of about 140* is a problem. At least it can give you a baseline to do a before and after assessment of your baffle approach.

I've already done ALL the percolation remedies and will experiment with an electric 'booster pump' in a week or so.
You can read through this car owner's treatise on the topic and his booster pump solution at the end...

https://49fordcoupe.smugmug.com/Fighting-Vapor-Lock/

I know of several other instances where this approach resolved a vapor lock issue....(BTW clothespins on the fuel line is a myth -- that don't help)

Other's have run a return line to the fuel tank from a modified carb fuel filter so that the gas gets cooled as it circulates....
No silver bullet.

[Frank D.]

Re: 63 Hot Engine Problem

I have one of those phenolic spacers laying around you are welcome to borrow to experiment with for as long as you care to BTW -- again you may have to deal with longer carb mounting studs and potentially hood clearance though. If it helps then you're welcome to keep it.