Any general consensus on piston to valve clearence limitations?
03-12-2009, 01:04 AM
#1
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Any general consensus on piston to valve clearence limitations?
Ok what is the general consensus as far as the biggest cam with the stock sized roller rockers on the 87 - 93's? I refuse to go with a letter cam because it seems their durations are really low to me, my car is a 89 SSP LX 5 speed. Has a Ram HDX clutch, a fender mount cold air, long tube hookers/3 inch x-pipe with flowtech 2 chambered mufflers. In the long run I plan on pretty much doing as much as I can with the stock block in the car(heads, intake, maf, throttle body/egr spacer, gears, lightweight driveshaft) then swapping in a built DSS short block.
But for right now I am looking for the biggest cam I can stuff in with the stock head/piston combo. I know the 86' have flat tops so they suggest staying at or under a .500 lift 235ish duration cam but I know that mine has valve reliefs. I know that the cam I put in will be to big for the breathing abilities of my head and intake but those are things that will come in the future(AFR 165's and a Twisted Wedge Box-R intake) so as you can tell from the exhaust setup and intake choice I want my power from 2000/2400+rpm. Lack of low end does not bother me.
But for right now I am looking for the biggest cam I can stuff in with the stock head/piston combo. I know the 86' have flat tops so they suggest staying at or under a .500 lift 235ish duration cam but I know that mine has valve reliefs. I know that the cam I put in will be to big for the breathing abilities of my head and intake but those are things that will come in the future(AFR 165's and a Twisted Wedge Box-R intake) so as you can tell from the exhaust setup and intake choice I want my power from 2000/2400+rpm. Lack of low end does not bother me.
03-12-2009, 06:51 AM
#2
D.R. THE PATHETIC DORK
Join Date: Jun 2007
Location: West Virginia
Posts: 30,863
ptv needs to be checked, there is no stuff it in and let it go, a custom cam designer can design you more than most ots cams can offer of the shelf, my friend had a .550 lift cam and mild duration on a stock bottom end with no ptv issues
03-12-2009, 01:06 PM
#4
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I find it hard to understand that with all the 5.0 efi/maf mustangs that are running around that there is not a certain line you do not cross with a stock block with cam selection. I am not looking at slapping a huge cam in it maybe like a 230 to 240 duration with around a 520 to 530 lift. I doi drive the car daily but I dont pound on it on the street so as long as my top end power and mid range tq is increased then I will be happy.
03-12-2009, 04:45 PM
#5
AFR165's + Box R intake is going to be a DOG... i know you want more of a top end motor, but that thing wont wake up until 5000+ rpm.
better bet to go with AFR 185's and something like a TFS Track heat or a RPM II manifold.
you'll grow out of the 165's pretty fast.
talk to Jay Allen and he'll get you a custom grind thats the best for your combo.
remember OTS < custom grind.
better bet to go with AFR 185's and something like a TFS Track heat or a RPM II manifold.
you'll grow out of the 165's pretty fast.
talk to Jay Allen and he'll get you a custom grind thats the best for your combo.
remember OTS < custom grind.
03-12-2009, 05:41 PM
#6
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Hate to be the bearer of bad news but 240 degrees of duration is huge with those heads. You WILL have problems. Better get down to -220. Grab an engine building book. You are headed in three differant directions and none of them are right.
Last edited by Portmaster; 03-12-2009 at 05:44 PM.
03-12-2009, 07:05 PM
#7
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there are a whole bunch of variables that the casual wrench turner would not understand... which is why you ALWAYS check PtV
.080 intake, .100 exhaust
03-13-2009, 03:57 PM
#9
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Like I said I drive it daily but street manners and wide tq ranges are a thing that does not matter to me because I will use the car twice a week at a local 1/4 mile strip and once a week at a 1/8 track for tuning purposes.
I myself think that cam selection is key and am just trying to iron out what I'm faced with.
03-13-2009, 04:50 PM
#10
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I'm new to the forum so forgive me if I come off as a dick because I am not trying to but I understand timing events, valve lift, and duration of cam lobes. I am new to Ford though, I know that I want a cam that will make power from 2000 to 6000 rpm that will work with the stock engine and will accel with aftermarket add ons like heads, intake, then a built DSS block. The E7 heads and stock intake suck I know and they are my bottle neck now but they will come at a later date.
Like I said I drive it daily but street manners and wide tq ranges are a thing that does not matter to me because I will use the car twice a week at a local 1/4 mile strip and once a week at a 1/8 track for tuning purposes.
I myself think that cam selection is key and am just trying to iron out what I'm faced with.
Like I said I drive it daily but street manners and wide tq ranges are a thing that does not matter to me because I will use the car twice a week at a local 1/4 mile strip and once a week at a 1/8 track for tuning purposes.
I myself think that cam selection is key and am just trying to iron out what I'm faced with.
you are quite right, and with the limitations you have set forth on yourself you will realistically be looking towards a custom grind camshaft... however, doing such before choosing a head and intake combo is, for lack of better terms... retarded!