I'm in the process of building a 302. Ordered the pistons today and came across some 289 heads for around 100. they have have 1.94/1.60 valves and have been ported. With the heads I have now I will have a 9.67:1 with the 289 heads it puts it some where around 10.09:1. Is this to high for a street ap.? Has anyone tried this comination and what was the out come? The other question is, how much lift can I use with out the piston hitting a valve (how far over .500 is too far) Heads now are 58.2 cc and the 289 are around 54.4 68 block 8.206 deck ordered flat top pistons with 1.615 comp. hieght with 2 valve, can except up to a 1.94 without further machining standard stroke and std rod. And yes I plan on getting 165 afr heads just can't afford um yet
The only way to be sure about valve to piston clearance is to check it. Bolt the head on with a gasket and check the clearance using play-dough or clay.
I ran a set of those only with smaller valves and they were great! And i had crappy compression like 8.2:1 . Im sure youll love them. Like paul said the only way to know is to check it with clay.
AFR makes two different chamber sizes. One is considerably larger than the other. You must have had the large chamber heads. The small chamber heads raise compression in most cases.
what cam did you run and what was the lift? I'm trying to narrow down the cam choices. I know they're are not the best for perfomance, but I really like the "thumpr cams" sound. And about the clay, how exactly does that work. And if I use the cam I have now how do I get a measuement on how much higher I can go?
I used cranes 363901 its a really mild cam 260/272 .456/.484, and sounds stockish at idle. I have a video on it on youtube under acmav289. To check it with the clay method is to place some clay on the valve reliefs. Then install the head gasket, and the head. Now you install dummy springs, the rocker and a dial indicator. Set it up on the retainer. Know you can depress the rocker down to say .500 then remove the head and check the clay to see if it has enough clearance. Google "piston to valve clay" you will find tons of pics, threads, videos.
Valves are shrouded unless the chamber walls have been moved back away from the valves. Largest valves you can run in the early "pinched chamber" 289 heads without shrouding the valves (and untouched chambers) is 1.85"/1.55".
If those heads have 1.94/1.60 valves, the chambers are no longer 53 cc's. Price isn't bad, but check to see if they've had screw in rocker studs installed too, that's a MUST for a performance cam. The final ratio will depend on the actual numbers with all the parts combined.
No they don't have screw in rockers. I just talked to him a little while ago. They where home ported mostly on the exhaust side and they are opened up alot! He said he ran um on a mustang years ago with a 268 cam. He also said that the car was a dog coming off the line and didn't go until around 3800 rpms.(his motor was a 289) no grove for the val. springs to set in either. I don't think the are a good option for me. ^Shadow, wicked turbo set up on that mustang, Very cool^
