[Chumley360]

OK I've been going in circles on this for a while and it's starting to get old. I've got a freshly rebuilt '64 352 FE block in my '68 Jeep M715. I've gone over everything I can think of and asked everyone I know so now I'm hoping the internet might turn up some answers. I've checked fuel, timing(mechanical and distributor), ignition parts, vacuum leaks, compression, vacuum gauge readings, filters, etc. The truck has been redone from the ground up so most everything of importance is brand new. I only have about 150 miles on it.

So the problem is that after the motor hits operating temperature and is being driven I get a loss in power and the motor will cut off if I let up on the accelerator for any reason(this makes shifting interesting). It takes about 5-10 minutes after the motor hits temp for this to happen, it's not an instant thing. When it shuts off I can either pop the clutch or crank it over with the starter and she'll fire right up and run. At this point as long as I let the motor idle I get no other shutting off issues. Now sometimes, but not always, I'll get a little bit of engine "rattle" while the truck is being driven once it starts doing the shut-off thing. Now if I'm just letting the truck idle for a long period of time, like when I'm checking things out, I don't get the shutting off issue at all. Even when I goose it every so often. Operating temp seems to be 200*, the motor stays right there or a bit lower. It doesn't seem to be over heating.

Engine specs are: 1964 Ford 352FE .040 over bore, single point distributor, stock 4v valves and ports, heads milled .020", deck milled .010", TRW cast pistons(advertised to drop comp ratio from 11:1 to 9:1 for modern fuel), Clevite RV cam, Weiand aluminum intake, 1" intake spacer, 180* t-stat, Sanderson shorty headers, Holley 600cfm vacuum secondary e-choke carb with #72 primary jets, MSD coil, Autolite #45 plugs, idle set to 650RPM, base timing 10*, full advance of 30* at aprox. 3500 RPM and up, mechanical fuel pump for 4brl FE.
I think that's all of the important stuff. I'm using a NV4500 transmission, NP201 transfer case, and still have the stock 5:87 gear in the axles with 36" tires. I run right around 2k RPM at 45MPH.

Any ideas what I should check? I'm about ready to pull the darn motor and drop it in a deep hole.

 

[DoubleVision]

Have you checked it for vapour lock?

 

[old76c10]

i had an old 78 f250 4x4 that would do the same thing i also had new everything ended up being to much fuel pressure

 

[Chumley360]

What's the best way to check for vapor lock? Take the gas cap off and drive around? I've got the 1/4" vent port on the tank run to a vent valve up at a high spot under the hood. I'm using plastic emissions tubing and rubber fuel hose for a little flex. Another thing I was thinking about is should I have a fuel return? Some motors need them and others don't care. This engine was in the truck when I got it, I just rebuilt it and did a better job fitting it into the frame. There weren't any fuel lines on the truck when I got it, so I just ran new 3/8" hard line from the tank to the pump and 5/16" from the pump to the carb. Also a new stock-type 4brl fuel pump should flow enough fuel for this engine setup shouldn't it?

 

[DoubleVision]

If any line is exposed to heat it can vapour lock. after it shuts down hop out, pop the hood and get a feel of the fuel line, if it`s excessively hot you likely found the problem. The fuel line also cannot be near the exhaust or in contact with anything that gets excessively hot. The fuel pressure is something to check also as mentioned, if you don`t have a fuel pressure gauge installed it would be wise to install one.

 

[Play400]

Since you mentioned the "engine rattle", ping I assume, before it starts stalling made me think of my old Bronco where 1 of the distributor springs would "drop" and hold the mechanical weights open. Something to look at

 

[carsavvycook]

The breaker plate in the distributor, and the coil overheating come to my mind.

 

[Chumley360]

OK so I was tinkering around some more yesterday and today and here's what I've got. Yesterday I let it idle up to temp in the drive way, then I took it out for a drive. Putting around the neighborhood everything seemed fine so I decided to take it out to a road I could open it up on. Well shell pulled well at full throttle in 2nd, shifted fine into 3rd and still pulled well, but when I shifted into 4th and then floored it she backfired so violently that I had to knock the choke plate back down into the air horn. So I let it sit for a few minutes then cranked it over and everything fired up like normal. I drove back home and shut it off for later investigations. Today I only did driveway tests, mostly for info gathering. Fuel pressure is 7.5psi and steady. Dwell is 32*. Total advance of 30* hits at around 3kRPM and stays there the rest of the RPM band. I have 10* base timing. After I'd been letting it idle for the better part of an hour I've got 15psi oil pressure, but it does shoot back up with throttle increase. The truck was running at a steady 210* temp by the time I was ready to turn it off. I got no backfires of shutting off while goosing the throttle. The fuel lines aren't hot at all. I did develop and off idle knock or rattle near the end of all of this. It starts at about 1200rpm/22* of advance and stays the rest of the way up. Oil pressure stays up so I'm hoping it's not a rod bearing.

I'm starting to think that I'm running lean but I can't seem to verify it. I pulled the plugs and they all look the same. But they're dry-sooty black with grey/white electrode tips. So that seems more like it's running rich. The best intake vacuum I can get at idle is 13", it seems like I should be closer to 15-17 with this cam and engine setup. I don't think the coil is breaking down, because the engine starts up just fine after it shuts down. No long cranks or anything like that. My experience with coil and module breakdown is you have to wait for them to cool down before they'll work again. I'll see about checking the distributor out tomorrow. I rebuilt it with the motor, but something could be broken or came loose.

 

[DoubleVision]

My question is why are you still using points? The best place for points are the trash. Has the distributor ever been rebuilt? if not you can bet everything in it`s worn out. Points distributors can cause all kinds of driving woes. I`d switch it to a HEI or get a conversion kit for what you have.

 

[Chumley360]

Yes the distributor is rebuilt. I did it with the motor. And why not use points? They're only questionable when someone doesn't know how to adjust and maintenance them properly. As the dwell readings show they are adjusted correctly and I have rechecked the gap. But this is all personal opinion and sliding from the point. So I'll check out the distributor tomorrow.

 

[Chumley360]

OK so I pulled the distributor out yesterday and checked it out. Everything seems fine. The springs are in good shape, no play in the shaft, and the breaker plate loos good. The points are in good shape, no corrosion or burn out. And the ground wires checked out. This is good as everything was replaced with new only eight months ago and the motor only has about 150 miles since the break-in. Once I put everything back together I dropped the timing down to 6* BTDC, as per the original 1964 Ford specs. All the FE building guys I talked to during the setup recommended 8-12*. Well the ping showed back up a while after warm up.

So I turned to the carb. I started the metering screws at 1.5 turns, as-per Holley, and ended with them out 3 turns. Still only getting 13" of manifold vacuum at best. So I let everything cool all the way back down, then took it for a test drive. Things did a little better, not as much cutting off on deceleration( it only happened twice and not every time I let off of the accelerator), but that dang off-idle ping showed back up. I'm wondering if I'm on the right track now though? Could I not be getting the fuel I need off idle? It's a standard Holley 600 cfm #8-0457s, it should be plenty of air flow for this motor, but maybe it's not enough fuel. I have put larger jets in, #72s, but the power valve is stock as is the accelerator pump. I'll have to check what number PV in in there, but after doing the math I should have at least a 6.5. I think I'll try that next then move on to the accelerator pump.

 

[techinspector1]

Just a couple of thoughts here. First off, fuel pressure. I know Holley says you can run more fuel pressure than, for instance, a Carter AFB or Edelbrock, but I am of the opinion that no modern 4-bbl carb needs or can tolerate more than 5 psi fuel pressure at the needle and seat. Mallory makes a neat log fuel setup for the Holleys that incorporates a built-in regulator. You install the log and run a return line to the tank.
http://www.summitracing.com/parts/MAA-4302M/
It's a little pricey, but hey, all the nice stuff is pricey.
You could of course, rig up your own return line with a conventional regulator in the line. This arrangement will be easier on the pump because it no longer has to "dead head" and as a result, the fuel delivered to the bowl will be cooler.

My other thought has to do with this:
"TRW cast pistons(advertised to drop comp ratio from 11:1 to 9:1 for modern fuel)"
While a piston with a reduced compression height will lower static compression ratio, it goes the wrong way in establishing a good squish to quell detonation. You end up with more piston deck height and by the time you put the head gasket in place, squish is non-existant. Just something to consider in your statement about ping.

 

[Chumley360]

My other thought has to do with this:
"TRW cast pistons(advertised to drop comp ratio from 11:1 to 9:1 for modern fuel)"
While a piston with a reduced compression height will lower static compression ratio, it goes the wrong way in establishing a good squish to quell detonation. You end up with more piston deck height and by the time you put the head gasket in place, squish is non-existant. Just something to consider in your statement about ping.

OK sorry but I'm not sure that I follow you 100% here. I understand the terms, but just don't see what you're getting at. I've rebuilt a hand full of engines, but all were either stock or mild builds where I never really put a lot of effort into compression ratios, chamber volume, and stuff like that. And I haven't run into this sort of problem where either changing the timing or adding a bit of fuel didn't get rid of the ping.

 

[DoubleVision]

I`m curious, does this engine have a bigger than stock cam? 13 inches of vacuum for a stock engine is god awful low, pointing out there`s a problem somewhere.

 

[old76c10]

i would 7.5 is a little high...you dont have any manifold leaks?cracks?

 

[Chumley360]

Here's the specs on the only specs I could find on the cam. It's a Clevite RV Torque camshaft:

# Clevite RV Torque camshaft for Ford FE 332-352-390-410-427-428. Operating range 1500-4000 RPM with a smooth idle. Use stock valve springs and hydraulic lifters. Cam specs as follows:
#Lift 484/510
# Adv. duration 270/280
# Duration @.050" 204/214
# Lobe sep. 107/117

It's a fairly heavy truck that's meant for hauling and other work duties, although at this point it's only a lawn ornament. So I went with this cam because it's not too radical, but still would give better low end.

Since I bought a used aluminum intake I had the machine shop check it for cracks and they didn't find any. Since then I've used both soapy water and carb cleaner and found no vacuum leaks. I've even plugged off all the vacuum ports and checked to see if a component was leaking, still nothing.

 

[Chumley360]

OK, so I've been reading about how quench and dynamic compression ratio will work together or against each other. Mostly because of what techinspector1 said got me thinking. I think I've got a better understanding of the relationship now and see what he's talking about. The only way I can see to check this out though would be to take the heads off, and I think if that needs to happen I'll just pull the motor and find something else. But if it helps on this front here's all the mechanical info I have on the related parts. According to the FE engine manuals I bought while rebuilding this motor the block and head numbers matched up to a 1964 352 4V, 300hp 11:1cr 72-74cc heads. The block is .040" over, the pistons have an advertised CR of 9:1, the deck was shaved .010", the heads were shaved .020", no other work to the heads was done. Does this help give any idea if I'd be running into an issue with quench?

 

[techinspector1]

I'll take a SWAG (scientific wild-*** guess).

Let's say the pistons are Sealed Power #246NP-040.
Compression Distance: 1.816"
Head Type: Flat Head w/ 4 Valve Reliefs - 9.0:1 Compression Ratio
Minimum Piston to Wall Clearance: .0015" At 2.150" From crown of piston
Pin Diameter (Inches): .9751"
Pin Diameter (mm): 24.768 mm
Ring 1 Qty: 1
Ring 1 Width: 5/64"
Ring 2 Qty: 1
Ring 2 Width: 3/32"

Let's say the block deck height was stock at (+/-)10.170", then you cut it 0.010" for a new block deck height of 10.160".

Let's say the rods were stock length at (+/-) 6.540".

Let's say the crank was stock stroke at (+/-) 3.500", giving a radius of 1.750".

We know the compression height on the pistons is 1.816".

If we add the stack of parts, 1.816", 1.750" and 6.540", we arrive at a stack of 10.106".

If we deduct the stack (10.106") from the new block deck height of 10.160", we find a piston deck height of 0.054". Now, if we add a nominal gasket thickness of 0.041" to that, we find we have a squish of 0.095". Not quite what one would want in a motor that needs to run on pump gas with any respectable static compression ratio. HOWEVER.....

This motor does not have a respectable static compression ratio. If we figure the chambers at 75 cc's originally (they always pour larger than published data) and you took a 0.020" cut on the heads, we might guestimate 1 cc for each 0.007" cut and call the chambers 72. A bore of 4.040" with a stroke of 3.500" calculates to 735 cc's in the cylinder. The pistons are flat top with 4 valve reliefs, so we will figure 7 cc's in the eyebrows. The bore of 4.040" and piston down in the bore 0.054" at top dead center calculates to a piston deck height volume of 11 cc's. A nominal head gasket diameter of 4.400" with a thickness of 0.041" calculates to 10 cc's.

Adding up the volumes with the piston at bottom dead center and dividing that by the volumes with the piston at top dead center calculates to a 8.35:1 static compression ratio. (735+72+7+11+10) divided by (72+7+11+10).

Even with a non-existant squish, in my opinion, the motor should not be pinging on pump gas at 8.35, even with the short cam you're using.

Chumley, this is the kind of stuff you need to be figuring out when you're building a motor. :thumbup:

 

[Chumley360]

WOW! thanks for doing all the math. And no slight to the effort you just went through, but all that does is say what I already knew in my gut and what the machine shop told me back when I was building the motor.

So it comes back to the question at hand; What the heck is causing this? back to the issue of fuel. Is there some reason that the carb I'm using just isn't putting out the correct amount of fuel at off idle for this motor?

 

[orangecrushm454]

Maybe this will help, maybe not. Had an 84 f150 pickup. Had a 351 cu engine. And the thing would just die without command. No nothing. In the distributor there was a ,( below the module) a coil or some other thing (a coil below the module) that went bad. as the engine heated up it would heat up a thermister ((a thermostatic resistor) in the distributor) that was the problem. It may or may not help but it is worth a try.