Max cam lift?
- Thread starter kwiktsi
- Start date
liljoe07
5 Year Member
Total Valve lift has Zero to do with Piston to Valve clearance.
When the valve is at full lift, the piston is at the bottom of the bore, and farthest away from the valve.
When the valve is at full lift, the piston is at the bottom of the bore, and farthest away from the valve.
I understand that, but it is partially open prior and after TDC. The more max lift it has, isn't it going to put it closer to the piston as it opens? I know I have had to check and flycut pistons in the past, but don't really want to do it with this motor since it is just a beater. This cam is pretty big (for a stock bottom end and heads), though it is going to be a drag car more than a street car. Here are the specs-
Intake= Lift @ Valve: .654/ Adv Dur: .630 Lobe sep: 106
.050 Dur: 276 Valve size: 2.125 Rock ratio: 1.6
Exhaust= Lift @ valve: .630/ Adv Dur: .615
.050 Dur: 282 Valve size: 1.625 Rock ratio: 1.6
I can get it for a decent price and plan on doing more with the motor/heads down the road, so if it will work in a stock 94 351 w/o clearance issues, I'll use it, if not, I'll stick with an F or X cam and then worry about it later, though someone said they would not work w/o flycutting either
- is this true? Thanks for the help, I am admittedly not really a Ford guy, so it is a learning curve for me.
liljoe07
5 Year Member
The most critical point is the Overlap. This is when both the Exhaust and Intake valve are slightly open, and the piston it at TDC(or close to it).
Why does the cam specs have valve sizes in it?
If those are actuall .050 specs, thats Solid Roller territory.
Why does the cam specs have valve sizes in it?
If those are actuall .050 specs, thats Solid Roller territory.
Yes, it is a solid roller. I wasn't aware of that when my buddy told me he had it. Looks like this isn't going to work with stock heads (non-adjustable valvetrain) anyway. As for the valve sizes in the specs, I couldn't tell you why they're there. It is a custom ground comp cam, and those are the specs my friend sent me. He probably got them right from his build sheet or something from his engine builder.
This aside- will an F or X cam work on a stock 351 without flycutting do you know? This is just a complete budget build right now, so I am looking at whatever cheap/used parts I can find. Once the car is done (running, paint, some 1/4 mile trips, etc.), I will be tearing the motor down for a complete rebuild and such. Just trying to get it moving under it's own power and be as quick as possible for as little as possible. I will not just leave the motor stock though as I will not have my "race"/play car be slower than my daily driver (05 CTS-V) lol.
liljoe07
5 Year Member
Didn't want to yank the heads to check the PTV clearance- like I said, this is "project el cheapo" lol. I was hoping I could find someone who has used either an F or X cam in stock 351 before. I mean, it's not like they made millions of mustangs or anything- someone has to know lol
.I have enough money into my other car to buy a dozen 86 GT's, I just want this one to be bare bones cheap
. Heck, if I had my way, the car would have a single turbo LS1 going into it right now, but the wife axed the big budget ideas since I have too many toys as it is 
. I was going to do a single turbo setup on my CTS-V this winter, but decided that for the price of the Fox body, I'd rather just do that this way I can beat the snot out of it and not care if it breaks or anything .
Maryland Stang
Active Member
You don't have to yank the heads. You can use the "drop valve" method. It won't tell you how close the sideways clearance is but it will tell you how far the valve is from the face of the piston. As long as you're using the stock valves with a stock piston the sideways clearance isn't an issue anyway.
Pull all of the spark plugs out of the engine. Put a degree wheel on and bring number 1 up to 20° BTC. With the rocker arms removed measure the height of the valve stem tip or zero it out. Now remove the keepers and springs and let the valves drop down onto the top of the piston. Take that measurement and write it down. Then move the crank so the piston is 10° BTC. Take the measurement again. Then go to 0° (TDC), 10° ATDC and 20° ATDC. Now you have your clearances.
Don't turn the crank too far or you will be removing the head to get those valves out of the cylinders.
You don't have to yank the heads. You can use the "drop valve" method. It won't tell you how close the sideways clearance is but it will tell you how far the valve is from the face of the piston. As long as you're using the stock valves with a stock piston the sideways clearance isn't an issue anyway.
Pull all of the spark plugs out of the engine. Put a degree wheel on and bring number 1 up to 20° BTC. With the rocker arms removed measure the height of the valve stem tip or zero it out. Now remove the keepers and springs and let the valves drop down onto the top of the piston. Take that measurement and write it down. Then move the crank so the piston is 10° BTC. Take the measurement again. Then go to 0° (TDC), 10° ATDC and 20° ATDC. Now you have your clearances.
Don't turn the crank too far or you will be removing the head to get those valves out of the cylinders.
I've ever done it that way, that's a piece of cake! Thanks for the advice!
But if the valve falls all the way in, can't I just crank it as hard as possible until it comes back out?
Maryland Stang
Active Member
No, no, no! You want to use a 3/4" impact turned all the way up. No point in straining yourself!
No, no, no! You want to use a 3/4" impact turned all the way up. No point in straining yourself!
I was thinking of using my like 3' long 1/2" breaker bar with a jack handle on the end
. Thank you again for the info!Just off the top of your head though, are there any off the shelf cams you would recommend for this motor that are known to not have clearance issues? It is going in a gutted fox chassis with 4:10's, so I'm assuming I'm going to have to get some R's out of it, but others have said the heads don't flow worth crap up top
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Maryland Stang
Active Member
I was thinking of using my like 3' long 1/2" breaker bar with a jack handle on the end
Just off the top of your head though, are there any off the shelf cams you would recommend for this motor that are known to not have clearance issues? It is going in a gutted fox chassis with 4:10's, so I'm assuming I'm going to have to get some R's out of it, but others have said the heads don't flow worth crap up top
Send a message to [email protected] and ask him. Mike is a really good guy and has been around Ford engines forever. He really knows his way around Ford heads.
