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Discussion Starter · #1 ·
I am taking the 393 one step below in power.Last summer I had AFR 205 heads, solid roller and Super Victor.I am restoring the runnability and good street manners of the engine with 185 heads, RPM AirGap manifold and a hydraulic roller cam.
I have replaced the valve springs in AFR 185 heads with springs which have 140 lbs closed and 400 lbs at full lift ( these are the springs which AFR delivers their 205 with)
The cam is a retro-fit hydraulic roller with 232/240 degrees and .560 lift. This engine will rev to 6500 rpm.
I have a set of Comp Cams 7823-16 Hi-Energy 3-piece 5/16" 7.700" pushrods( $ 47.95 at Summit) but I am hesitant to use them with these stiff springs. Are the pushrods strong enough or should I step up to stronger quality( Comp 7963-16 are $ 127.95) ?
Also, is there any issues running hydraulic roller lifters these pressures? The lifters are Comp Cams ( around $ 350) ones.
 

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ville; I used Smith Brothers Pushrods in my 418w. They make many of the aftermarket pushrods. You can buy direct from them, their website is http://www.pushrods.net/. I use 5/16 x .083 single piece 4130 pushrods for durability. They have swaged ends , so there is nothing to fall apart.
 

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You should call comp cams on this one concerning the spring pressure.
400 sounds like it will collapse the lifter and therby lowering your lift by a bunch and also wearing out the lifter.
302 roller hydraulics dont like more than 320 if I remember correctly.
Good luck.
 

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I think you should be ok on spring pressure with those lifters. I ran my hyd roller lifters (Ford Racing stock 5.0 replacements) with Crower springs that had 173# on the seat and 470# open at my 0.640" lift. I revved mine up to about 7100 rpms. It made peak hp @ 6500. The dyno operator was questioning if my lifters were collapsing some due the spring pressures but he wasn't so sure after it made peak power that high. But, I did end up swapping those lifters out for Sherman hyd roller lifters that use the 5.0 factory body, but he makes them so they only have between 0.025" of travel, so setting them at 0.015" preload, it gives the same power as a solid roller. I haven't dynoed it yet to see if there was a difference in top end. Btw, Sherman told me that spring pressures over 500# will start to split the lifters. Just thought I'd add that little tid-bit.

As for pushrods, I have the 3/8" Comp hi-tech pushrods at 7.700". They are the thick walled pushrods that are made for high spring pressures. Let me know if you would be interested in them.
 

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Springs should be OK, at least I would think so. It really doesn't make that much difference anyway until you get to a certain point....even at 140 lbs seat pressure, the valves will probalby start to bounce off the seat by 6200-6500.

No need for 3/8 pushrods. If you really plan on spinning it up that high, you'll want the lightest possible combination....5/16 pushrods, ti retainers, etc. Then you can get away with lighter than normal spring pressures and still keep the valves from floating. Besides, 3/8 pushrods really aren't needed...even on 600 lb springs. As long as they're straight and fairly strong, they won't bend. That's all I use (5/16"...and my springs are 250/610). Tried 3/8, no change in anything but my pocketbook was lighter. Had to change pushrods, guideplates, rockers, and lifters. All said, it was close to $500 wasted...but that is the name of the game with race cars. BTW, mine are 5/16" comp hi-tech pushrods at 8.25" long. Never had a failure...knock on wood. I spin it up to about 7400.

Seriously, I would call someone who is more in the know than I am....I ain't an engineer, just an everyday run-of-the-mill bracket racer.
 

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A well respected custom cam designer said 140# closed and 400- 425# open pressure was the best for a similiar roller cam with the heavy bar link lifters. I run a similiar spring pressure and it seems perfect.
 

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Discussion Starter · #7 ·
Thanks for the input guys. I think the lifters are ok with the setup but I am not sure yet about the pushrods.I need to do some more thinking here.
 

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Had a set of thinwall push rods. think is like .040 ? not sure.
Have about the spring pressure you state. I bent them. Went with trick flow thick wall. think is .060 .. have yet to bend these. turn my 351 to 7k


_________________
1966 Stang Coupe Org. 6 cyl. 351w,Sealed Power Hypers, ARP bolts,Total Seal rings,Eagle H-beams rods,Balanced,Hedman long tubes, TMD 2.05/1.60 Vic Jr Knockoffs, 1.6 Stainless steel Roller Rockers, Victor Jr intake, Holley 750 DP, Ed Nix Custom .600/.600 254/258 @.050 Solid Cam, Crane solid roller lifters,Richmond 4.11, Strange mini spool, Modified C4, 3500 stall, ******* Transbrake, B&M Hammer shifter, Shelby lowered, Pro-Comp 6Al system. Mickey Thompson 275/50 Et Street Drag radials.

<font size=-1>[ This Message was edited by: forthman on 5/22/06 3:18pm ]</font>
 

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I have had no luck with the 3 piece pushrods, the ends like to break off. Summit stocks a good selection of 1 piece Trickflow pushrods. They have worked well for me.
 

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Discussion Starter · #11 ·
Thanks again. I believe I need to get a set of better pushrods.Better to get them now than later when they´ve broken.
Yeah, there are some spring options with AFR heads. The spring pockets in my heads have been enlarged to accommondate larger springs/springcups.
 
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