'70 Torino high speed miss? Help!

[John_Mc]

Hi, I love my '70 Torino GT but i'm going CRAZY with a high speed miss. I have a 66,000 mile '70 351 2-V Cleveland with single exhaust and a freshly re-built and recalibrated Autolite 2100. I have very slight miss at idle, but once I get to around 1,000 rpm and beyond there is a major non-rhythmic miss. Sort of feels like 2 plugs have been pulled. The car starts perfectly every time. I do not think anymore that I have an ignition problem since I have done the following: New cap, new wires, new plugs (gapped @ .035), new distributor with new points and condenser set at .017 and a dwell reading of 29 degrees at 500 rpm. The mechanical advance consistently and smoothly advances timing to about 20-30 degrees BTC. There is zero slop in the distributor bushings. The new vacuum advance system will pull the breaker plate and holds vacuum. I’ve changed out the coil - no change, I've adjusted the carb needles - no change, I've triple checked firing order and crossfire - all is correct. I see no vacuum leaks; hoses look good although they are original.

I discussed the issue with a mechanic of almost 50 years who can think of nothing other than a mechanical issue - perhaps worn cam or burned/stuck valves. I've yet to do a compression test, but will do so this weekend. Have I missed ANYTHING??? Thanks for all tips sent my way.

I do not want any electronic ignition set up and I want to keep the original carb. The car is not drivable like this.

Ford made a gazillion of these things and they all did not run like mine. I need to locate the problem, no matter what it is.

Help, help, help !!!

_________________

John Mc

'70 351 2-V GT Fastback

'29 Model A Roadster Pickup

'57 Thunderbird

'04 Taurus

'97 Ford F-150

(Ford Guy?)

[Dave@Moon]

This sounds very much like a common ailment of Triumph six cylinder engines when there's an intake manifold leak, especially in that the miss/stumble comes in at higher rpm. The method usually used to confirm that it's the manifold is to run the engine duplicating the miss/stumble while running an open, unlit butane lighter around the manifold. If the miss/stumble goes away with butane being sucked in at a particular place, you've found your leak. (<span style="font-style: italic"><span style="text-decoration: underline">Obviously</span> you need to be very sure that there's no timing issues or exhaust leaks before doing this due to the fire hazard, however.</span>)

I'm not sure the butane lighter method of detection would be on a V8 anyway, since 1/2 the gasket surface is under the manifold where the lighter wouldn't reach. You might try re-mounting the intake with new gaskets just to see if it works. I can't guarentee that it'll fix it, but it's a likely possibility.

[Guest Bluesky636]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: John_Mc</div><div class="ubbcode-body">Hi, I love my '70 Torino GT but i'm going CRAZY with a high speed miss. I have a 66,000 mile '70 351 2-V Cleveland with single exhaust and a freshly re-built and recalibrated Autolite 2100. I have very slight miss at idle, but once I get to around 1,000 rpm and beyond there is a major non-rhythmic miss. Sort of feels like 2 plugs have been pulled. The car starts perfectly every time. I do not think anymore that I have an ignition problem since I have done the following: New cap, new wires, new plugs (gapped @ .035), new distributor with new points and condenser set at .017 and a dwell reading of 29 degrees at 500 rpm. The mechanical advance consistently and smoothly advances timing to about 20-30 degrees BTC. There is zero slop in the distributor bushings. The new vacuum advance system will pull the breaker plate and holds vacuum. I’ve changed out the coil - no change, I've adjusted the carb needles - no change, I've triple checked firing order and crossfire - all is correct. I see no vacuum leaks; hoses look good although they are original.

I discussed the issue with a mechanic of almost 50 years who can think of nothing other than a mechanical issue - perhaps worn cam or burned/stuck valves. I've yet to do a compression test, but will do so this weekend. Have I missed ANYTHING??? Thanks for all tips sent my way.

I do not want any electronic ignition set up and I want to keep the original carb. The car is not drivable like this.

Ford made a gazillion of these things and they all did not run like mine. I need to locate the problem, no matter what it is.

Help, help, help !!!

_________________

John Mc

'70 351 2-V GT Fastback

'29 Model A Roadster Pickup

'57 Thunderbird

'04 Taurus

'97 Ford F-150

(Ford Guy?) </div></div>

I think you may still have an ignition problem.

According to http://www.torinocobra.com/specs.htm, your point gap should be 0.021 with a corresponding dwell of 27 degrees. Your initial timing should be 6 degrees BTDC. Not sure what you meant by your statement "The mechanical advance consistently and smoothly advances timing to about 20-30 degrees BTC." Are you talking TOTAL timing or just the mechanical advance? Your TOTAL timing should probably be in the range of 30 to 35 degrees. I would suggest trying these gap and dwell settings and adjusting the total timing and see if anything changes.

[critterpainter]

My memory MAY be wrong, but I do remember that some ford engines in that era could have an internal intake leak if the wrong bolts were put in the wrong holes in the intake to head. Or was it a gasket mis-match??? Its been too many years since I played with a Cleveland.

Bill