Heads and manifolds

[UKSquarebody]

Quick updates - swapped out the Holley Street Dominator manifold for the Edelbrock Performer manifold - night and day!
Runs and drives mint now.

 

[xm20k]

Probably had to do more with a leak that was fixed when it was swapped than the manifold itself. Those 76cc chamber heads are defiantly not helping no idea who would even consider those for a "race" engine build. Most guys I know won't even use them on a stock bottom end they almost always end up in the scrap pile.

Good to hear you got it running better.

 

[75gmck25]

Keith,

I just took a closer look at your last message and noticed you list the engine size as 327. Is that correct? The 327 was a great engine in its day, but never a factory option for the squarebody trucks.

The reason is ask is that the 327 came in multiple versions, and some are quite a bit different than a typical SBC 350. Small journal crankshaft was one difference in some 327 engines, and the short water pump was also a common variation in the 60’s. Those types of differences will be important if you start to buy performance parts or external accessories.

 

[UKSquarebody]

I was told lots about this build, but much of it has not been true!
Turns out is a stock crate Mexican built 350, with roller rockers on it. That’s about it!

 

[bucket]

Probably had to do more with a leak that was fixed when it was swapped than the manifold itself. Those 76cc chamber heads are defiantly not helping no idea who would even consider those for a "race" engine build. Most guys I know won't even use them on a stock bottom end they almost always end up in the scrap pile.

Good to hear you got it running better.

You seem to really know your stuff, but I would certainly disagree about a vacuum leak getting fixed by accident with the manifold swap.

A single plane manifold on a very basic and stock 350 will turn a decent running engine into an absolute turd. Even going back to a stock Quadrajet intake would make a drastic improvement in drivability, especially a truck.

 

[Ricko1966]

I had to laugh,not at what you said,but at the dyno numbers. The street dominator is just a crappy manifold,it made me laugh. I still think he had an intake leak,and probably not enough initial timing as well as a crappy manifold. But look at these numbers OE manifold is in parenthesis. Torker single plain,a 650 Holley and headers was everybody's first mod 1980ish. Not saying it was the smartest combination but we all made them idle and drive.

 

[xm20k]

I had to laugh,not at what you said,but at the dyno numbers. The street dominator is just a crappy manifold,it made me laugh. I still think he had an intake leak,and probably not enough initial timing as well as a crappy manifold. But look at these numbers OE manifold is in parenthesis. Torker single plain,a 650 Holley and headers was everybody's first mod 1980ish. Not saying it was the smartest combination but we all made them idle and drive.

You seem to really know your stuff, but I would certainly disagree about a vacuum leak getting fixed by accident with the manifold swap.

A single plane manifold on a very basic and stock 350 will turn a decent running engine into an absolute turd. Even going back to a stock Quadrajet intake would make a drastic improvement in drivability, especially a truck.

We ran single planes with nothing more than a carb and headers on stock small blocks. It would be a bit lazy just off idle but a cheap stall converter even a small one would help it not be as mushy on the bottom end because it'd allow the engine to rev up into 2000+rpm range bypassing the off idle issue.

The cheap mods we ran were intake, carb, stall converter, shift kit, and sometimes a mini spool if we didn't just weld the gears up. If you had the money later on it was cam and small chamber cast heads. We were doing this in high school with our first or second ever cars/trucks.

 

[UKSquarebody]

It was running 14 degree before and after. We also smoke tested it and found no leaks anywhere. The only parts changed was the manifold, and the manifold & carb gaskets

 

[Ricko1966]

It was running 14 degree before and after. We also smoke tested it and found no leaks anywhere. The only parts changed was the manifold, and the manifold & carb gaskets

For anyone reading this,V engine. Suspected intake leak that you can't find with a can of carbureator cleaner. Plug the pcv and breather port on the valve covers. Put a vacuum gauge on the dipstick tube and check for vacuum. It is common for them to leak at the bottom into the crankcase. There is equal surface area and potential for leaks topside or bottom side.