Screaming Mad - 351W Cams ??

[Broncobowsher]

What aluminum heads?
What roller rockers?
What are the specs on the valve springs as installed?

Years ago I had a shop redo a set of heads. Hung an exhaust valve in 30 minutes. That was fixed. Withen a year...
Hung another exhaust valve, had it fixed
Hung another exhaust valve on the other head, pulled both heads and had all the exhaust valves reworked.
Hung an intake valve, had it fixed and had the shop check all the intake valves. Fine after that. The initial setup was wrong and I kept chasing hung valves until I had ALL of them reworked. Stock cam and springs, never lost any lobes.

I am courious about the combonation of parts. Me thinks you have too much spring pressure. Fine for race, not so fine for street. Add in high ratio rockers and even more stress on the lobes.

Why 1.7 rockers are bad on cam lobes... (simplified math to easier follow along)
Lets say you have 200# of open spring pressure with 1.6 rockers. That is 320# on the lobe (ignoring inertia at speed).
Now try 1.7 rockers. Valve opens a little further, that raises the opened spring force a little, call it 220# (estimated). That has 1.7 times the force back on the lifter so 374# on the lobe.

Start stacking a little here and a little there and it can ballon into a failure that no single part would have caused. But as a whole it can't last.

 

[Ranchtruck]

Have you considered retrofitting a roller cam and lifters?

 

[Broncobowsher]

Have you considered retrofitting a roller cam and lifters?

I think he needs to figure out the bigger problem (stuck valves) before he throws more money at it.

 

[Timmy390]

What heads are you running and what parts did that "race" shop put in/on the top end? I worry about the springs and lifters being right for the (3 or is it 4) cams you’ve had in the block.

I don't like taking street stuff to a "race" shop. Race shops are generally of a mindset to get the most possible out of what you have but longevity is sacrificed as a result. They build stuff to run a race not go 100K miles.

With all the issue you’ve had, I would start over with those heads and find a different shop to work on them. Another option would be to get a new set of E-Brock RPM heads fully assembled and then run the E-Brock RPM cam.

Until you get those heads correctly done, you will continue to have issues.

Tim

 

[bmc69]

Sounds like valve springs more than anything..with some other effups thrown in for good measure.

When yr in the lift range of approaching 0.5" and better, valve spring setup become critical. Not only do you need the correct springs, they need to be very carefully set up and checked for specified spring height. And then checked again for coil bind at max lift (and piston clearance!) after everything is installed..especially when using aftermarket rockers that might have a different ration than the stock rockers.

 

[ft bronc]

Bottom line - this is not rocket science for an experienced engine builder. We've been building HP small block Fords in this country for almost 50 years now. Find another machine shop before you waste more time & money.

 

[73azbronco]

I'm betting coil bind at full cam lobe height. If you've been wiping cams, it might be time to pull the motor apart and totally flush the oil system passages again for debri.

 

[Idaho Slim]

Sounds like valve springs more than anything..with some other effups thrown in for good measure.

When yr in the lift range of approaching 0.5" and better, valve spring setup become critical. Not only do you need the correct springs, they need to be very carefully set up and checked for specified spring height. And then checked again for coil bind at max lift (and piston clearance!) after everything is installed..especially when using aftermarket rockers that might have a different ration than the stock rockers.

BINGO, that is what is going on right now. The complete motor is now at the machine shop, complete tear down & rebuild by them with my Service Manager buddy overseeing it. He is going to do the valve spring setup & measure spring coil bind @ max lift himself ( thanx bmc & others ! great minds think alike!).

The root issue, crap mechanic installed the heads (has been fired) & the incorrect parts installed into the heads initially by the machine shops kid.

Should get it back next week & I am starting to feel much more confident about its reliability .......... damn what ever happened to "Do it right the first time"?? grrrrrrrrr

Thanx for everones interest & help, love this forum ! (in fact - its time I bought a membershipr ..... cheks in the mail). ;D

 

[73azbronco]

make sure they pull it all aprt, vat clean it, install all new bearings everywhere including camshaft.

 

[bad 68]

I can assure you it's not a "W" problem. My 351W runs strong and has been very reliable taking a near Daily Beating. It has heads with all parts designed to work together.

Maybe the shop fired the guy, but I would probably went for a refund after 3 attempts rather than another chance. I think 3 chances to get it right were more than enough. That entire long block need completely disassembled and cleaned with new bearings, oil pump and maybe new crank and rods. A lot of metal goes through a motor with a cam failure.

 

[Idaho Slim]

I can assure you it's not a "W" problem. My 351W runs strong and has been very reliable taking a near Daily Beating. It has heads with all parts designed to work together.

Maybe the shop fired the guy, but I would probably went for a refund after 3 attempts rather than another chance. I think 3 chances to get it right were more than enough. That entire long block need completely disassembled and cleaned with new bearings, oil pump and maybe new crank and rods. A lot of metal goes through a motor with a cam failure.

Thanx for the info, Read above, thats exactly what is happening, and you will just have to take my word for it that the dealer is stellar. Like some have said, "a couple of effups" as in $hit happens. I am good with them to the highest level.;D

 

[Idaho Slim]

WOW, did not see this coming ............... the block has a lifter hole out of spec and looks like the machine shop had sleeves in all lifter ports except this one causing that lifter to work the crap out of the cam lobe and ultimate quick failure. Also took out the piston at that location. Machine shop is providing another block for $150, and performing all the machine work/boring etc. My Ford dealer is covering the rebuild install labor and parts......... I am content with that!

 

[73azbronco]

I was going to say if you are at 60 over now, might as well start with a newer block, what is the new one bored out at? Sorry, but 60 over is to much for a windsor.

 

[Idaho Slim]

I was going to say if you are at 60 over now, might as well start with a newer block, what is the new one bored out at? Sorry, but 60 over is to much for a windsor.

Ya 60 over .............. please continue ???

 

[bmc69]

the machine shop had sleeves in all lifter ports except this one -)

What?? Sleeving lifter bores is almost never done except for all-out racing blueprinted blocks. Few shops are equipped to do it. And in a block they took 60 over too??

Just wow.

Good luck with the new build..

 

[Timmy390]

Is that new block at the same machine shop that's screwed so much of this up? I don't think I would let thoes clowns near my stuff no matter who or what was monitoring them.

Who's inspecting the "new" block to verify it's good? If doesn't arive vacumn sealed in a bag from a well known operation, I would not accept it. These guys have done you SO wrong I would get the block and take it to another shop.

Prob file a case in small claims court too. Minimum I would report them to BBB

Tim

 

[707Bronk]

I have a 302 cam in my 351W. All I did was change the firing order.

They have basically the same firing order, only the companion cylinders fire differently.
This is true at least for my '74 351W.

 

[addicted]

I would make sure those clown dont bore your replacement block out to match your 60 over pistons. They should do a minimum bore to clean it up and throw in some new pistons of your choice. I cant believe they are charging you for a replacement block in the first place.

 

[73azbronco]

Ya 60 over .............. please continue ???

60 over, the motor is done.

60 over is used by shops to get a motor back together and into the hands of a driver so they can say they "fixed it", knowing that not to many miles beyond 10,000 they will be back with another worn out motor.

The lifter issue alone is reason to dump the original block.

Like others have said, get to another shop. Tell them you expect a full refund.

Go on craigslist and find a block, go get it and start over.