FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: 427Fastback on October 23, 2012, 12:14:53 AM
-
Hey guys...I bought a set of the edelbrock 427 Heads for the 427 in the Mustang with the plans of putting the stock size 427 MR valves in it..I have converted them to the 16 bolt exhaust flanges and done some port and bowl work..(clean up).Recent reading is making me think I dont need valves that big and it may actually hurt me.
Engine is a 9.8 to one 4.25 bore 427.Comp 270S cam.I have roller rockers,headers etc etc.Intake will hopefully be one of Jays 2pc ones otherwise it will be a Perf rpm...
Car will be around 3000lbs and 100% street driven.It would easily pull 6400rpm with the CJ valves in C8-H heads and CJ manifolds..
Looking for opinions on valve sizes...The cam is staying in..I dont want solid rollers on the street and Hyd is not a option.(C5AE C/O block)
Share your opinions please on the valve sizes..
Cory
-
What is your horsepower target? My guess is with that cam, you don't need the bigger valves. The CJ sized valves should be fine...
-
Not to hi-jack but would the MR valves hurt him on the 4.25 bore at all? I am not shooting holes or anything just wondering if it would hurt at all. Sometimes it may be a case of lets do it now with the option of going with a larger cam later option. this way he would be set up for it and not have to do a full teardown.
-
Well, that's a good point, and no, I don't think going to, for example, 2.19 and 1.71 valve sizes would hurt. I just don't think they'll help the engine any, because that is a pretty mild cam. If the engine is slated for an upgrade later, then maybe it would make sense to go with the bigger valves now.
-
I have had the 270 in there for over 20 years..I know there are better cams available now but i really dont want to go through the flat tappet break in horror..My HP target is obviously limited by my cam.The short block(20,000 miles on it) is still assembled so i really dont want to strip it and have the block drilled for juice lifters.It is what it is and I am ok with it..Its a good eng (bottom end is still std,std) and its always been a "happy" engine...
The new heads,headers and intake should add some noticeable power to it..
I just dont want to defeat the purpose by installing too big a valve.
MR valves would be the absolute largest I would go..
Cory
-
Cory,
you can make that cam "bigger" by advancing it and tightening up the lash. also getting your quench to about .40 is a big factor. I have built a few street 427's with compartively small cams and made good power with street manners. JMO
-
So the the C8 heads had Compression of 9.8?
The ED 427 chamber is bigger like 5 or 6 cc's bigger.
You may even see a net loss of power with the new heads because of the the lower compression.
-
OK, lots of assumptions here, but if you can keep open up the valve bowl and still keep a consistent taper from intake surface to valve seat, I'd go 2.19
Not that it's a huge amount, but assuming a valve size of 2.19 vs 2.09 and a lift of .530, you are going to get about 5% more curtain area at any given lift.
Seeing you have a big bore, and assuming you port the bowls, I'd go big, it sure wont hurt anything and you have a LONG way to go on a 427 bore before there are any intake issues..
-
I had around 10-1 with the C8-H heads...I have CC'd everything and will need to mill the edelbrock heads .030 to get it back up to around 9.8 to one.The edelbrock 427 heads CC'd @ 76CC which is what they are advertised as...
I have long been running my valve lash between .015 and .018 cold...
Most of my porting effort is on the bowls and exhaust..The intake port size on the heads appears to be fine.Certainly larger than the unported RPM manifold..
Cory
-
Another cam option would be a solid roller, they make some really nice street grinds now. But I would go with the larger valves even with the small cam you have now. As said you have more area to move more air with, at any given lift. What do you have to loose. :o And if it were me I would port back into that RPM intake a few inches, again whats to loose, and its free power to gain all you put in is your time there. ;)
-
I have no objection going to a solid roller but how long is it going to last sitting at a traffic light running at 800rpm.....Cory
-
A roller is going to live longer than a flat tappet all things the same, here are some cams that are close, some are a bit wicked but dont get hung up on the lift numbers. The crower has 10 degrees more duration and would be real close to what you have now as far as duration and character. The roller will come "on" harder and hang on longer. I would not be surprised to see you hit another 40 hp with that cam. The MR valves the crower roller cam would certainly work very well together with that RPM intake and ED heads. You would have a steller package working together.
http://www.summitracing.com/search/Department/Engines-Components/Section/Camshafts-Valvetrain/Part-Type/Camshafts/Make/FORD/Cam-Style/Mechanical-roller-tappet/Engine-Size/7-0L-427/Camshaft-Usage/Street/?Ns=Rank%7cAsc
http://www.network54.com/Forum/76346/message/1351037238/Some+unshrouding+pics
-
Not sure I'd agree that a roller will live longer than a flat tappet in an FE. Most rollers have much more aggressive valve action than a flat tappet, including higher lift as you mentioned. That's tough on the lifters, and there are plenty of people who've lost roller lifters on the street, but never had problems with flat tappets. Durability is probably not the reason to go with roller lifters.
-
The lack of oil to the roller lifters at a idle is my main concern..The resulting carnage is not worth the risk to me..I chose the 270S in 1988.Cam selection was very limited,Also aftermarket blocks and heads were not available so I built the engine for torque and to last...I chose to be conservitive as 427's were expensive then and good blocks were hard to come by...
Cory
-
Yes, they are so much cheaper and easier too find these days. ::)
-
OK...poor choice of words...
-
So your saying Jay that with 10 degrees more duration and .050 more lift the roller lifter is not going to live as long as a solid lobe? I do not think that cam I pointed out was that much of a radical lobe from what he is running now that it would fail under the same conditions. But I must have missed something. My solid 690/700 lift 240 /250 @.050 has no issue in a center oiler configuration on the street.
-
Hotrodfeguy......How many miles have you put on it....????
I have pondered the idea of building a spray bar system in the valley to spray the lifters (as much as possible)It would be fairly easy to do and there is oil pressure there to be tapped into...I just havent sat down and figured it all out...
Cory
-
I am not comfortable with solid rollers on the street. Although modern lifters are bit better with oiling, I saw some carnage in the early 2000s, no warning, and parts coming apart. I also agree its from idling and low rpm
When I called Comp back then, they said "300 passes then rebuild the lifters"
Oiled stuff is certainly better and there have been great improvements, but I dont think even the cam manufacturers would recommend a solid roller on the street.
I'd run what you have, port the heck out of the heads if the budget allows, or if you want more RPM go with a 282 or 294 or equiv from another company. I run an Erson grind in my 489, solif flat tappet, and haven't had to adjust the rockers since 2006. I was checking them each year, but this year I didn't even pull the valve covers LOL
-
So your saying Jay that with 10 degrees more duration and .050 more lift the roller lifter is not going to live as long as a solid lobe? I do not think that cam I pointed out was that much of a radical lobe from what he is running now that it would fail under the same conditions. But I must have missed something. My solid 690/700 lift 240 /250 @.050 has no issue in a center oiler configuration on the street.
Going just by the lift and duration numbers is misleading. Most roller cam profiles have more aggressive ramps, because the roller lifters can use them. That certainly has an effect. And the other guys are correct, low speed oiling is a big issue. I always run the roller lifters with the pin oiling feature (e.g. Crower HIPPO lifters), but that is not the same as running a factory roller lifter where the combination of the lifter and the oiling system in the block is designed to be run for 200,000 miles.
I've run roller lifters on the street since the 1980s, and used to experience a lot of lifter failures even after a couple thousand miles. Since the pin oiling feature has become available I have not had any trouble, but I don't keep the lifters in for longer than 10,000 miles before I replace them. You could certainly go longer with milder cams than the ones I'm using, but I wouldn't go so far as to say that aftermarket roller lifters are more durable than a flat tappet lifter. Despite all the problems with flat tappet cams and lifters over the last several years, they are still a very durable combination once they are in and working properly.
-
I do 50/50 street strip and have a year under the engine but have not done a teardown yet. maybe thats some worth checking now. as I do not have the pin oiling lifter.
-
I'm going to stick with my little 270 flat tappet.It was broken in 1988 and has been good for 20,000 miles.I only ever set my valves out of curiousity to see how they are...I do my own porting so I will pour some hours into the heads..
As for the valves...I will look into some sizes...I dont want to notch the chambers to much to un-shroud them as I am trying to raise the compression not lower it...
Cory
-
427 fastback if this is a street engine I would just stay with the cam you have and valve sizes also .If you were going to the dragstrip I would do a cam swap then larger valves .I have a 66 comet with a 427 I have std. edel. heads about the same compression as you 10.1 .My cam is a lunati 237-247@50 mid 500 lift .I have more than enough power for playing around on the street .If I went drag racing with this on a regular basis I would go to larger valves out of curosity.Just to see what the results are .Your ported heads will give you more air flow than what they originally had .In your case maybe bigger isnt better . Nothing wrong with your comp cam either street engines are more fun when they are torguey .My 427 does have a 428 crank so it has the torque but I imagine your car has more than enough power .Maybe think about a bit more cam after you see how your ported heads run until then enjoy your car .Doug 8)
-
I have had the car since 1977 and the 427 has been in it since 1988.I was happy with the torque as it was (we always want more) This was with the C8-H heads ported with CJ valves,C7-F intake,stock rockers and CJ manifolds..I figure a substantial gain with the ported 427 E-bok heads,roller rockers,FPA headers and either Jays new 2pc intake or a performer RPM..
It has never been on the track.I built the car for the street and to have fun on our never ending mountain roads.
As I have very little in the way of shock towers any more I may re-think the headers and build my own to make use of the extra room.As Jays book points out that sharp turn could use a inch or two of straight pipe...
Cory