Ok I have seen the threads where the crossovers have been filled using aluminum poured into the heads when they are off the car. But I have heard that there are plugs that can be pounded into the heads. If so where can one get these? and can it be done with the heads on the engine and the engine in the car? Thanx a bunch for any help.

 

The plugs supposedley come loose more often than not. I got a pair with my intake when I ordered it from Edelbrock.

 

http://www.jegs.com/i/Edelbrock/350/2733/10002/-1

I have used them on 3 engines, so far no rattles, but I have heard others complain of a noise. Take your time and file fit them.

 

I have ground on the plug and made them fit the intake side. I ground on them until they were a tight fit and hammered them in. It take some work to make them fit until the last 1/8 inch and them pound them flush.

Gene

 

The plugs go in the intake manifold, not the heads. More importantly, the whole purpose of filling the heads is so that you can properly port the exhaust ports on the two center cylinders. Simply pounding the plugs into the heads will not help and may actually hurt flow.

 

Ok so the plugs go into the intake. Does it help? Does it help keep the engine/intake cooler? Does it let the engien run any better? I just hate to pull the heads on this engine as it is not my build an I have no info about it which means if I pull the heads everything would need to be cc'd to make sure I get the right head gasket and therefore the right compression ratio. All of which would mean pulling the engine. And if I am going to do that then everything get's re-done. Not something I want to do as the engine runs pretty good.

BTW Joe I found a good part of my problem with my carb. It didn't like the aircleaner. I switched it out and now it runs tons better. Still a big stumble off the line but if I use the trans to shift and get the revs up a bit it will go. I now have more than 3/4 throttle off the line where it was maybe a 1/3.

 

What???
Pull the engine?
No you don't.

 

One of the reasons to fill the heat riser ports is that the two middle ports are "siamesed" in the heat riser area, disrupting flow. Olds blocked off one port in the head for the late 60s W30s. So, simply blocking the heat risers at the intake only accomplishes one of the two goals. With the heads on the engine, you could carefully machine a pair of plugs to go into the heads and seal against the center head bolt boss to separate the two ports as well as block both from the intake surface.

 

18436572.
4365, those cylinders fire in progressive order, keeping those exhaust ports pressurized all the time, because of that crossover.
The port does a poor job of scavenging if under pressure. A pressure drop in the port is what you are trying to create, that is why headers work. Until you address this problem, your headers will not scavenge these ports, and your car will sound like a tuna barge.
Some have had luck with the plugs, I like filling them with aluminum.
Just putting a blocking plate on the intake surface:5-7 HP
Job done right=25 HP
Jim

 

Jim and Joe are absolutely correct. You're not only keeping heat out of the intake but increasing the scavenging ability of the port and/or headers. I did some minor changes to mine years ago and not only felt the difference but heard a difference in the exhaust note as well, plain and simple.

 

is this something i should have done to my motor while it was all taken apart? im running an edelbrock performer 350 intake on a pre '77 350, the motor when i got it came with headers, but i was forced to use stock exhaust manifolds from a '76 i think it was..

 

I suspect that now you want to go back and play with the air valve wrap spring tension.