You could remove the Thermactor bumps without taking the heads off, but you'll need a good vacuum and a magnet to get the metal filings out afterwards. To bowl blend the ports, the heads have to be disassembled. The exhaust ports are the real restriction on these heads. The Thermactor bumps are half of that.

 

Hmmm well I could always pull the rockers off it will allow the valves to close then do my porting then use a small magnet or compressed air to get the metal shavings out. I really hate the thought of pulling reman heads apart to do port work. Head gasket would be no good and I don't even know what kind they used. I don't know if they used stock or if they used something else to hit the desired compression ratio if changes were made inside the engine.

 

Yea, you'd need to loosen the rockers to close the valves first. The best gasket's I've found are FelPro's 9333. They work well to seal aluminum heads to an iron block. I spray them both sides with copper kote to insure the best seal.

 

 

 

Good to hear. I would make sure to get coolant in asap once you get everything squared away. Customer at work didn't as he kept fighting the stroker engine he bought out of town not making power to spin the back tires. was pulled so many times he ran straight water and the block was pure rust inside when we pulled it out and got it right.

 

 

In your situation with performance parts you want to experiment a little, are you running vac advance off of manifold vacuum? This will result in lots of advance at idle, maybe around 30° BTDC, this is no problem. Engine will run cooler, too.

Of course what you're really concerned about is where the mechanical advance tops out at. The initial timing is not critical, but as much as she'll stand without starter kickback is probably what you want.

 

I agree, advance the ignition till the starter drags or kicks back when the engine is hot then back it down a couple degrees.

As far as total advance I cant remember I want to say engine builder I know says fords don't like much more than 32 to 34* of total advance. He recommends pinning the dist with a roll pin to limit max advance on the vacuum side to maintain a max of what ever figure he said. I will be asking him again when I go to do my 302 so I can pin my dist and give it a try.

 

 

I'm gonna disagree with everyone else. Set the initial as high as you can and not have it pinging under load. Typically this is 10-16* BTC no matter what mods you've done. Every Ford I've had runs best in this range. This is ported vacuum not full manifold.

 

My truck I had that 302 running at 12* btdc initial with manifold vacuum on timing. I tried running ported vacuum but I couldn't get the engine to idle smooth was forced to run manifold. I hope this new engine I get I can get the thing to idle dead smooth off of the timed vacuum port on the summit carb and I am going to try and push 14* btdc timing. Not sure with 9:1 compression if my stock 82 starter can spin with 14* initial timing but I sure am going to try.

 

If t wouldn't idle at 12*BTC then there was something wrong with the balancer. I've run that carbed Explorer cammed 5.0 with 16* BTC and it had no trouble starting, it would ping though running regular gas (87 Octane) I had to run 89 octane to quell the pinging in summertime. But I usually backed off the timing 2-4* to run 87 then. How did you set the carb and timing ? With the engine warm, you should first set the initial timing, then adjust the idle (throttle screw) to where it'll idle in gear (if an automatic trans) manual trans I set it to idle as low as possible and not stall when letting out on the clutch. Then set the mixture screws to fine tune it. Also need to remove the slack from the accelerator pump linkage to avoid stalling from excessive slack.

 

In general terms the recommendations are a stock engine should use a ported source of distributor vacuum. A modified, performance engine on the street may benefit from connecting to a manifold source. Experiment.

See what YOUR engine likes. Different engines, manifolds, camshaft, compression ratio, altitude, gearing, fuel quality, and more, all play a role in how much ignition advance an engine will tolerate.

Disconnect and plug the vacuum advance while setting up the mechanical advance.

Take test drives, bring a 1/2" wrench with you. Forget vacuum advance for now, till you get the mechanical setup how you like. Spool the engine up in neutral first with a timing light and see where the mechanical advance tops out, that's the number you're really concerned with, not the initial. Set the distributor wherever the initial needs to be to get that number. Most V8 like 34° to 36° BTDC, low compression engines maybe a little more, high compression engines maybe slightly less. Try 34° first, say.

For better acceleration install lighter springs so it all comes in at an earlier RPM. Stock distributor curves are usually very slow, sometimes it's not all done advancing till well over 4000 RPM. Lighter springs will bring it back to 3000 or a little less. Experiment. Keep advancing the distributor slightly until it starts to rattle on hard acceleration and back off slightly. It doesn't take much, about the width of a pencil line equals 2° timing at the damper. Record this number for future reference.

When you get the mechanical advance setup the way you like, then re-connect the vacuum advance. Experiment with manifold and ported vacuum if you like. Adjust the vacuum can for as much advance as it will stand without rattle or ping, this time on part throttle acceleration and steady cruise. Keep in mind though you're done tuning the mechanical advance; if it starts to ping with the vacuum advance re-connected then you'll have to back off on the vacuum advance, not the initial timing. Some distributors have too much mechanical advance built into them. That's why you have to check. Reducing or limiting the amount of mechanical advance the distributor can pull in allows you to experiment with higher initial timing. The stock Y Block has low compression, so it can tolerate pretty high initial timing without starter kickback, and lots of timing with cheap gas too. It won't win any races but it sounds fantastic. I like about 17° initial, limit the distributor to about 20°, the total mechanical is still somewhere around 36° or 38°, but the initial timing isn't 3° anymore. It gets this nice deceleration rumble through dual exhaust. So again, experiment with your engine and application and find out what works best for you.

Vacuum advance is only in play when engine vacuum is high, and load is low, you could put a timing light on the damper cruising down level highway and it would show somewhere around 50° BTDC. It's true.

Yes it's a pain in the *** to do all this stuff but if you want it to run right it's the only way, unless you know somebody with a distributor machine. You'll thank yourself every time you drive it.

 

I would agree with that, but people in general seem to obsess over this initial timing number for some reason, without ever bothering to check the number on the high side. That's what counts, initial timing isn't all that critical.

Manifold or ported connection makes no difference, it will not pull any additional advance above and beyond what it will at cruise or part throttle or under load. It will pull more advance at idle obviously, since there is no engine load at idle.

Sometimes achieving a steady idle is a problem with a direct connection, this is why a ported connection was utilized in the first place. This is described in the early automotive manuals. Then in the smog era everyone went to ported vacuum source, because high levels of ignition advance (most efficient combustion) at idle increase NOX emissions, the big smog contributor.

Then the engineers traded off high NOX levels, by reducing compression, retarding ignition timing, buggering valve timing, etc, the reduction in NOX was better, but this spiked HC, killed fuel economy (such as it was) and so then they had to burn the excess fuel waste out the exhaust, in a catalyst. That's right boys and girls, right in the middle of the "gas crisis" the government forced manufacturers to nuke the fuel economy of their product.