MonsterBilly

Right on!

Diputado

Thanks guys, for all the great info. This is what forums like this are for! I did NOT realize that the crank throws,etc. were the same, and that I could use that other cam by just rerouting spark plug wires. Also good to hear that the TFS heads might be an option, after all. I haven't yet decided if I'm going to go with a full-blown overhaul, or just heads/cam. If I go all out, then I could also use TFS pistons AND heads and have less worries. All depends on the budget (as always!) and how the engine is behaving in a year. The engine was built by a PO a few years back, and I really have no idea of how he put the bottom end together. He told me he used a stock 289 crank and rods, and forged 10.5 comp flat-top pistons (he can't remember the brand). I have no idea of how many miles have been put on since that build, but the engine is very clean overall, and last year when I changed the intake and valve covers, there was no crud or buildup of any kind on the block or head surfaces. It doesn't smoke or use oil, and oil pressure at hot idle (190 deg., 800 rpm) is 40 lbs. Intake manifold pressure holds steady at 12-13 lbs at idle. One weird thing the PO did when he built it was to have it dynamically balanced with a 50-oz 5.0 HO balancer and a 28-os 1969 Boss 302 flywheel. I asked him why he used the 50-oz balancer, and he said that was just "what he had laying around". It works, and runs smooth. I'll let y'all know what I finally end up doing.

groho

Hey Dipu, check this out! been doing some digging, and didn't read the latest on your thread. Been looking at hyd tappet cams until my brother texted me with this...Compcams roller lifter install kit, #31-1000, and cam 35-561-44 or 35-562-44. He ran a 70 Mach1 for years at the track. I'm probably going with the latter with a 25 stall T/C, unless I find something better.

Diputado

Hey Groho....yeah...I saw those new 4-pattern cams from Comp. Pretty cool idea, actually. Then I noticed the lift...over .600...!!! Talk about beating the crap out of a 289 valvetrain! To me, this seems a bit much for a street rod. This much lift would make it tricky on head selection, and REALLY tricky on piston-valve clearance (especially on exhaust). If they made this type cam with, say, a lift of around .510-.530 then I might seriously consider it. But hey...guess that's what those custom cam grinds are for, huh?

67mustang302

Lift doesn't hurt the valvetrain. Rates of duration do....how fast does the valve have to open and close, not how much.

That's why mot custom cams have seemingly quite large lifts, yet the valvetrains are generally much MUCH more stable than many OTS grinds.

barnett468

its impossible to balance it with a 50 oz damper and a 28 oz flywheel.


the afr heads are the best choice imo. some of the trick flows have had some probs. keep it simple.

buy scorpion "race" rockers from summitt.

around 3.43 - 350 gears with that cam.

Diputado

Thanks, guys, for the comments. One thing I don't get though is 67mustang302's logic on higher lifts not increasign valvetrain stress. It seems to me that for any given duration, the higher the lift, the more (and faster) the valves and springs have to move in going from fully closed to fully open. But like he suggested, I am going to consult with a custom cam grinder before a final decision.

Regarding Barnett468's comments on the balancing. My engine does indeed have this combo. I have checked..and double-checked...and the balancer definitely has a Ford part # of E4TE-A3A (5.0 HO), and the 164-tooth flywheel has a casting number of C9ZE-6380-B ('69 Boss 302). The engine runs pretty smooth...BUT....come to think of it...I do have some unexplained drivetrain vibration starting at about 50 mph. The more I think about it, the more I think maybe I'd be better off with a complete overhaul instead of just a heads/cam swap. That's probably the ONLY way I'll know exactly what I've got. Given some of the other crazy-*** stuff the PO did (like welding Olsmobile calipers to the spindles to "convert" it to FDB..!!) that I later had to fix, there's really no telling what he did inside the motor.

As always..all opinions and suggestions are welcome..that's what this forum is for!

67mustang302

It depends on the cam lobe design, whether the valve is opened and closed gently or violently. You can have low lift with a very aggressive lobe or high lift with a gentle lobe. It's pretty subtle, but can have a huge impact on valvetrain stress.

And your flywheel was probably rebalanced to the 50oz style, easy enough to do. If they were mismatched, chances are your crankshaft would have broken long ago.

barnett468

ITS SIMPLE, THE HIGHER THE LIFT THE GREATER THE SPRING PRESSURE.

THE STEEPER THE RAMPS THE MORE STRESS ON THE VALVE AS IT SLAMS SHUT.

HIGH LIFT STEEP RAMP CAMS LIKE COMPS EX SERIES IS THE HARDEST ON THE VALVE TRAIN.

67mustang302

And one of the biggest areas of stress is the initial and ending portion of the ramp, where the valve is lifted off the seat from a stationary position, or set down onto the seat back to a stationary position. That's where inertia tends to be the highest (other than peak lift when the valve changes direction).

Most OTS grinds like the Comp XE series can be pretty hard on the valvetrain, the opening and closing portion of the ramps tend to be needlessly aggressive (the valve is flowing almost nothing at that point, so opening or closing the valve rapidly at that time is pointless). The custom grinders these days are VERY savvy in regards to this, and the profiles for the valve coming off and back on the seat tend to be quite gentle. Most OTS cams yank the valve off the seat pretty hard, which stresses the entire valvetrain pretty heavily; custom cams lift the valve off the seat gently. Most OTS cams drop the valve back on the seat pretty hard, to the point where they get bounce and erode the valve/seat; custom cams set the valve back down gently, with no bounce (and thus virtually no erosion).

Cams like the XE series are good cams, they provide tons of power and are quite reliable for the aggressiveness of the profile. However, they are still hard on the valvetrain. Custom cams cost more, but have substantially different profiles in the areas of highest stress. They're worth the money imo if for no other reason that the increased valvetrain stability.

When I ran a Crane OTS grind years ago, it was a somewhat mild CARB approved cam, and it actually beat the valvetrain up a bit over the years (last time I changed things around had to get some valves/seats/guides replaced, and the rockers were beat up pretty good). It was also noisy as hell. The current custom grind "by the numbers" is significantly more aggressive in terms of lift and duration. But the valvetrain makes 0 noise (the noise comes from the valve slapping around on the seat and from the valvetrain loading and unloading to the point where parts start to get knocked around). Talk to people that have actually run custom grinds for street cars, you'll never find anyone who had issues with valvetrain wear.

A modern custom cam profile actually has 7 separate portions, and they're all different. Opening ramp, transition to the main profile, the main opening profile, peak, main closing profile, transition to the closing ramp, and the closing ramp. It's the opening, closing and 2 transitions where custom cams have a huge advantage. It lets them run more aggressive main profiles with a gentler peak profile (so more total flow with less instability at peak), because the opening, closing and transitions reduce valvetrain stress by a ton (by gently and consistently lifting the valve up and setting it back down).