Does this make sense? My stock '68 289 (8.7:1 due to 63cc heads in 68) has 60,000 miles on it and is healthy. I'd like to bump the power band up as it loses steam by 4500rpm. It has a 500cfm Edel w/ Performer intake, dual exhaust from stock headers. Would an inexpensive, easy, upgrade be 1.7 rockers to get more lift without changing out the cam? TIA.
1.7 Rocker option?
- Thread starter 68conv4sp
- Start date
You would get more lift but:
1. Your heads suck
2. Exhaust manifolds suck
3. 500cfm and Edelbrock Performer don't exactly light up the night
4. You redline at 4500 because of your valvesprings.
In short, you will see slight gain, but probably not enough to spend the money.
1. Your heads suck
2. Exhaust manifolds suck
3. 500cfm and Edelbrock Performer don't exactly light up the night
4. You redline at 4500 because of your valvesprings.
In short, you will see slight gain, but probably not enough to spend the money.
Hard to say where to start. It's best to build engines as a package. Exhaust, cam, heads, carb and intake.
It's like a garden hose. If there is a restriction anywhere in the flow, all the mods you have made are only as good as the restriction.
It's like a garden hose. If there is a restriction anywhere in the flow, all the mods you have made are only as good as the restriction.
First off, your application. You've got rail rockers on your heads. Good luck finding rail type 1.7 ratio rockers.68conv4sp said:
I'm pretty certain you won't find such an animal. Only way for you to install 1.7's would be to pull the heads and have screw in studs and guide plates installed, then you could have your choice of rockers. Don't bother with the roller tipped rockers. The real gain would be with full roller rockers ( roller tipped & roller trunions) the gain there is mostly from the frictional loss's and a slight gain from the increased lift. Now if you do decide to pull the heads, have the exhaust sides ported out and the bowls under the valves blended (both intake and exhaust) and then have screw in studs & guide plates installed. Just these two things will give you a pretty decent gain over what you have now. Just the full roller 1.7 rockers will net you about 15 hp. The ported exhaust and blended bowls? I can't give you numbers there, but those two will help a lot.
68RustBucket
New Member
I'm rebuilding the exact same engine as you right now. The difference with my rebuild is that I'm replacing everything except the rods, block, and main caps.
289's are some fantastic engines, in my opinion. Not big by any standards, but they can rev the hell out of most other pushrod V8's of the time, and they're still relatively light.
The pistons in that motor are a bit dished. That, combined with the 63cc heads, are what cause the low compression. You may want to look into tearing down your bottom end so you can guage whether or not its worth just replacing the rockers. Most likely, you'll want to do a full rebuild with more new parts than rockers. Pistons aren't too expensive, reconditioning the rotating assembly and getting a new cam kit isn't a bad idea either. Really, there are tons of options.
Here is the path I've planned for my 68 289, incase you were curious ...
1) Stripped block, bored .30 over, cleaned and prepped
2) Keith Black hypereutectic pistons (KB281)
3) ARP everything
4) Shot-peen original rods
5) Edelbrock Air-Gap intake
6) CompCams 282S cam (with appropriate lifters, etc.)
7) AFR 165cc heads
8) 650cfm carb (Holley, most likely)
Built up, balanced, and put in front of a nice stout T-5 with some good gearing in the rear, I would love if this combo can give me 350hp and some decent reliability. There are lots of write-ups for 289 builds. Just search and read, my friend.
289's are some fantastic engines, in my opinion. Not big by any standards, but they can rev the hell out of most other pushrod V8's of the time, and they're still relatively light.
The pistons in that motor are a bit dished. That, combined with the 63cc heads, are what cause the low compression. You may want to look into tearing down your bottom end so you can guage whether or not its worth just replacing the rockers. Most likely, you'll want to do a full rebuild with more new parts than rockers. Pistons aren't too expensive, reconditioning the rotating assembly and getting a new cam kit isn't a bad idea either. Really, there are tons of options.
Here is the path I've planned for my 68 289, incase you were curious ...
1) Stripped block, bored .30 over, cleaned and prepped
2) Keith Black hypereutectic pistons (KB281)
3) ARP everything
4) Shot-peen original rods
5) Edelbrock Air-Gap intake
6) CompCams 282S cam (with appropriate lifters, etc.)
7) AFR 165cc heads
8) 650cfm carb (Holley, most likely)
Built up, balanced, and put in front of a nice stout T-5 with some good gearing in the rear, I would love if this combo can give me 350hp and some decent reliability. There are lots of write-ups for 289 builds. Just search and read, my friend.
A67StangMaster
New Member
ok I found these on summit you can use your Pedestal-mount rockers to an adjustiable rocker arm setup. I am leaning to this setup.
http://store.summitracing.com/partdetail.asp?part=CRN-36655-16&N=0&autoview=sku
http://store.summitracing.com/partdetail.asp?part=CRN-36655-16&N=0&autoview=sku
He doesn't have pedestal mount rockers on 68 heads. His heads have pressed in studs, with no guide plates. The only thing keeping the rockers aligned ont he valve tips are the rail type rockers. The valve end of the rocker has an inverted U shape, the valve tip sits up inside the U.A67StangMaster said:
A67StangMaster
New Member
You don't "need" different heads. That's not a "need", that's a "want". You also don't "need" a different cam, that too is a "want". Sure a bigger cam will be nice, but you don't need it. Ditto for the heads, just have the work I out lined earlier done to the heads and install something like a 270 degree (advertised not at .050) cam with around a .500-.550 lift, & springs to match, roller rockers (you won't need 1.7's then, 1.6's will do) and the screw in studs and guide plates. The guide plates & studs will allow you to do both stiffer springs and roller rockers. Sure you'd gain more with better heads, but the stock ones will do fine with a bigger cam in the specs I listed above, especially if you have the exhaust ports opened up and blended to the bowls. And actually a cam like Comp Cams 268H or 270H will be better with your compression ratio. The cam, lifters, springs will run you about $300, the heads? I'm not sure, you'd have to check that out where you're at. A good high rise dual plane intake like a Performer RPM, or a Ford A321 topped with a Holley 600-650 Carb will work here too, in any case the intake and carb will work without the head and cam work. You don't "need" to spend $3500 to get good results.68conv4sp said:
