So I got my new 308 running today and so far it's pretty cool. I found the motor, with all the below components in a junkyard for $150.00!!! I broke it down and re-ringed it as well as new bearings. I'm running it with open headers right now until I get the exhaust fabbed up. Here are the specs: 79-302 block, bored .040 over Forged Pistons Forged Rods .010 under crank 289 HiPo heads Edelbrock Torker 289 intake Long tube headers Holley 750 Crower .500 lift cam Comp Cams 1.6:1 roller rockers Points ignition C4 Auto w/2800 stall 8" rear with 3:00 gear. Anyway, it's doing a few weird things. At a certain rpm, there is a vibration. If you're above or below the rpm, it smooths out. Not sure if it's a balancer issue or what just yet. I used the HB and flexplate that was on the motor, so I'm feeling pretty good about that. It also doesn't want to idle too smoothly. It's hard to diagnose right now because it's so loud. I set the valves at 0 lash but they probably need adjusting again so it might not be running on 8. Just a few thoughts that went through my mind. I feel like the mav is gonna be pretty quick with this motor once I get it dialed in!!!
Stock points ignition?? Slap in a Perktronics to replace the points. 200% improvement over stock without the expense or learning curve of HEI electronic ignition swaps. Max
That a D8VE block ? And are the heads truly 289 Hi-po pieces ? If they are, you can sell em for lots of cash and buy better aftermarket heads. Look and see if they have cast in spring pockets. And I second the ditching the points.
Got it figured out! It was only running on 6 cylinders. I had the valves adjusted wrong. Now check this out. It runs great but at a dead stop, if I mash it, it spark knocks like a son of a bitch. If I'm driving and I mash it...no problem. I have taken timing out and taken timing out to where I'm running at about 10° btdc. Any ideas? I'm still running points ignition too. Thanks!
Did you calculate the compression ratio for your engine?? Also what is the total timing at full advance? Sorry missed the points thing. I just assume nobody had points anymore. You really need to get rid of them.
You have the smallest chambers that were ever used on a 289 bolted to a bored 302. That is a great way to get detonation because the compression is too high for the fuel you are using. Replacing the points with an electronic unit will do nothing for the detonation. It might let you rev higher (depending on the points you use) but the compression has to be below about 10.5:1 to work with todays fuel unless you go to full electronic engine controls.
10*BTDC is fine, you'll need to run a higher octane fuel though. Ditch the points ASAP. Might also try a bigger accellerator pump shot too. Lean conditions can cause spark knock sometimes.
10.5 is fine on pump gas, my 331 has that and it's fine running on 93 octane fuel. His comp ratio may not be that high, that's going to depend on what flat topped pistons he's got. The pin heights for 302 flat tops varies from 1.585 to 1.620. Only with the taller ones will his ratio add up to 10.5 to 1.
Thanks for the input guys! I did a couple of thing and it seemed to take care of it. 1. I re-checked and adjusted all my valves. All the compression is equal now. Huge difference!! 2. It actually wasn't spark knock. it was the trans line rattling!! I made some stand offs and secured them. problem solved!!! I am going to put some GT40 Irons on it soon too. I know the 289 heads kind of blow. Especially on the exhaust side. This thing gets after it already. I can't wait to drive it with better heads on it!!!
The new heads will lower your compression so you might lose power - depending on the amount of reduction in compression and the increase in breathing of the new heads.
Baddad, 289 heads had very small chambers compared to the 302 heads. There can be 10 CCs difference in the chamber size - if my memory is working. The 289 had 9.5 to 10.5:1 compression depending on pistons. Add the extra displacement of the 302 and compression might go over 11.25. It is a moot point since he found that his rattle came from unsecured metal lines but it is possible with the small chamber 289 heads and a 302 with zero deck heught - isn't it?
