Tight clearances

[nosdelacruz]

I assembled my 351c short block yesterday and noticed I had some tight bearing clearances in the con. Rod area. It is recommended to have .010 - .020 but I can't even fit a .010 in there. How do u open a clearance? I had the rods reconditioned before installation. Anyone?

 

[droptop73]

The proper way to adjust side clearance is to mill the sides of the rods equally. I have seen it done other ways. Take it apart and go back to the machine shop.

 

[Mister 4x4]

^^^ ::thumb::

(What he said )

 

[will e]

How exactly are you measuring? What does fit?

 

[nosdelacruz]

Man this cleveland really doesn't want to be put back together. This will be the 5th time it has been put together and taken apart just the short block. I am measuring by putting a ten thousands feeler gauge in between the two con rods. I have good clearance between the crank and con rods but no gap between connecting rods themselves. Am i measuring wrong? It spins pretty freely.

 

[caspianwendell]

They will move side to side if the wrist pins have proper clearance. What are the measurements from rod to crank?

 

[nosdelacruz]

Some were about 14 thousands and some were .10.

 

[marks73]

Did you accidently mix up the bearing caps?

 

[VegasFastback]

I assembled my 351c short block yesterday and noticed I had some tight bearing clearances in the con. Rod area. It is recommended to have .010 - .020 but I can't even fit a .010 in there. How do u open a clearance? I had the rods reconditioned before installation. Anyone?

It may be the picture but I cant see the number stamp on the rod cap. If its backwards it may cause problems.

 

[nosdelacruz]

I double checked and all the caps matched number to number. I double checked the one in the picture and it was just etched off some way. So all the caps are correct.

 

[Mister 4x4]

Well, it came out of there like that... and if it spins freely... I'm just sayin'. :huh:

I didn't even consider this when I put mine back together - especially, since everything spun freely just like you said - and it runs great. Maybe it's not worth worrying about, unless you have some hard information that says otherwise (I know 'Maybe' is not what you want to go with when putting something line this back together - so take it with a grain of salt, please).

I know you'll get it sorted out, but good luck just the same. ::thumb::

 

[caspianwendell]

Some were about 14 thousands and some were .10.

Your good to go as like I said the rods have movement in the wrist pins. As long as you have clearance between rod and crank they will settle in their perspective positions when rotated.

 

[Paul of MO]

You are fine - like others have said there is some "sliding" on the wrist pins and such. If these are the rods that came out of your engine then they likely did not magically get fatter at the machine shop. LOL.

This is what I have done for years for 351C and other 4 inch bore Fords.

Put the pistons on backwards.

Get the rings positioned on the pistons correctly

Make sure the ring ends don't touch when in the holes

Use ARP Rod Bolts

Lube the bearings

Put the parts together

Torque to specs

Check that it spins smoothly with a bit of resistance

Smile and drink and adult beverage.

Wait, what, put the pistons on backwards? - yet another Cleveland building trick:

Piston pins and rods on a Cleveland and on some other Ford small blocks are slightly off center. Ford did this to reduce engine noise when starting cold.

Note: A piston not only moves up and down (vertically) it also moves around or floats (laterally) in the cylinder bore.

This engineered offset basically holds the piston slightly harder against one side of the cylinder wall keeping the piston from rattling before everything gets hot and expands. It also helps to keep the engine quiet over the years as the piston skirts and cylinders wear out.

The way the cranks, rods, and the pistons, all fit together if you put the pistons on backwards it centers them in the holes as the engine rotates and frees up quite a bit of horse power.

Full blown and expensive racing piston and rod sets do not have this offset.

When not running the piston is still offset but now in the opposite direction that Ford intended. When the engine is running, especially at high RPMs, the piston will "float" laterally in the bore and actually will end up being better centered.

This might shorten the life of a street motor but I have put hundreds of thousands of miles on various Ford small blocks and had no issues.

This "trick" is good for 5 to 8 percent more HP which is pretty substantial for having no cost. Any decently built street Cleveland makes about 350 hp. Built this way we would get closer to 370 hp plus the engines seem to rev faster and run a bit cooler.

I now build 4.6 Mod Motors for others. Now that is some fun technology! I have not had a customer request for a Cleveland build in several years. I still put a few together for friends and for myself from time to time.

Paul of MO

 

[nosdelacruz]

Alright cool guys thanks for all the feedback!!! I really appreciate it. Hopefully soon she will get done and I can get some 1/4 mile passes on it!!!

 

[wwhite72]

My forged pistons rattle for first minute or 2 when cold but quiet down by the time she starts idling. Sitting in the seat wih the window open, feathering the pedal,,,,listening to the engine come up to temp and the gold race rockers ticking like a swiss watch. Watching out the mirrors for the exhaust to heat up and blow out the moisture, its another favorite thing about the mustang. My girlfriend says it takes me a 1/2 hour to get outta the garage. Whats the rush?

 

[MotoArts]

My forged pistons rattle for first minute or 2 when cold but quiet down by the time she starts idling. Sitting in the seat wih the window open, feathering the pedal,,,,listening to the engine come up to temp and the gold race rockers ticking like a swiss watch. Watching out the mirrors for the exhaust to heat up and blow out the moisture, its another favorite thing about the mustang. My girlfriend says it takes me a 1/2 hour to get outta the garage. Whats the rush?

Excellent!

This should be etched into large granite plaques, and placed above the tool box in every heartfelt Muscle Car owner's garage.

Ya either "get it", or ya don't

::beer::

 

[VegasFastback]

You are fine - like others have said there is some "sliding" on the wrist pins and such. If these are the rods that came out of your engine then they likely did not magically get fatter at the machine shop. LOL.

This is what I have done for years for 351C and other 4 inch bore Fords.

Put the pistons on backwards.

Get the rings positioned on the pistons correctly

Make sure the ring ends don't touch when in the holes

Use ARP Rod Bolts

Lube the bearings

Put the parts together

Torque to specs

Check that it spins smoothly with a bit of resistance

Smile and drink and adult beverage.

Wait, what, put the pistons on backwards? - yet another Cleveland building trick:

Piston pins and rods on a Cleveland and on some other Ford small blocks are slightly off center. Ford did this to reduce engine noise when starting cold.

Note: A piston not only moves up and down (vertically) it also moves around or floats (laterally) in the cylinder bore.

This engineered offset basically holds the piston slightly harder against one side of the cylinder wall keeping the piston from rattling before everything gets hot and expands. It also helps to keep the engine quiet over the years as the piston skirts and cylinders wear out.

The way the cranks, rods, and the pistons, all fit together if you put the pistons on backwards it centers them in the holes as the engine rotates and frees up quite a bit of horse power.

Full blown and expensive racing piston and rod sets do not have this offset.

When not running the piston is still offset but now in the opposite direction that Ford intended. When the engine is running, especially at high RPMs, the piston will "float" laterally in the bore and actually will end up being better centered.

This might shorten the life of a street motor but I have put hundreds of thousands of miles on various Ford small blocks and had no issues.

This "trick" is good for 5 to 8 percent more HP which is pretty substantial for having no cost. Any decently built street Cleveland makes about 350 hp. Built this way we would get closer to 370 hp plus the engines seem to rev faster and run a bit cooler.

I now build 4.6 Mod Motors for others. Now that is some fun technology! I have not had a customer request for a Cleveland build in several years. I still put a few together for friends and for myself from time to time.

Paul of MO

I going to have to commit this to memory. How did you figure this out? I'm just starting to get into engine rebuilding and things like this really make my day.

 

[nosdelacruz]

I was reading about pistons going in backwards and people said it really does give u some more hp! But like you said it eats up pistons and walls faster. Some people stated they were have piston to valve clearance issues, guess u gotta adjust the valve reliefs.

 

[Paul of MO]

I was reading about pistons going in backwards and people said it really does give u some more hp! But like you said it eats up pistons and walls faster. Some people stated they were have piston to valve clearance issues, guess u gotta adjust the valve reliefs.

You are correct - you have to make certian that you get pistons with mirror image valve cuts in them. All cast and most forged flat top have these. You also get more HP out of cast pistons than forged. They are a bit tighter in the bores and they weigh less. They are weaker but in a properly tuned engine this is not an issue.

Single relief pistons can not be reversed. Bad things happen.

If you go with real expensive race only sets then you do not have to worry about it because they are already centered.

Can be reversed

Can not be reversed

Insane Wiseco Stuff - does not need to be reversed.

Paul of MO



I going to have to commit this to memory. How did you figure this out? I'm just starting to get into engine rebuilding and things like this really make my day.

I seek out and trust the experience of the old timers who are willing to share what they already figured out. I couldn't figure out crap like this on my own if my life depended on it.

Back in the late 70's I bought a 302 all iron engine that had run 8.70's on pump gas in a fairly heavy car. No small feat. Lots of neat tricks inside it. The retired racer that sold it to me was nice enough to explain what and why he had done what he had done. We became friends and he helped me build a few 302/351W engines. He was a huge 351C fan and we built a Super Gas 351C that I raced for several years. 9.90's all day long without anything breaking.

I started building ford race engines for others and it turned into a nice side business for me.

Now I build 4.6 DOHC / Supercharged stuff. Our 2003 Cobra dynoed at 535 to the rear wheels.

Fun times to be playing with cars!

Paul of Mo