I know they can vary all over the place and there’s a ton of variables but has anyone done a flow bench on ported iron heads? Just trying to get a ballpark. I’m going to be porting my B heads but have no plans on getting them flow tested unless I make my own flow bench. I am curious what numbers others have come up with if anyone had theirs flow benched?

 

My B heads with light porting flow 240/170 ish at .500 lift for about .70 flow ratio which for that engine put me at a 224-230 comp cam.
Stepping up to ported edelbrocks puts that flow ratio at .74 which is where I switched to a single pattern cam in the 244-244 range.

 

Your reasoning on the cam choice vs head flow isn’t totally correct. There are other factors involved. Just saying.
Op- Ported irons can range from about 270@.600 to as much as 290@.600 on the intake side. But again, other factors come into play.
And if you’re not going to have them flowed then don’t bother. You could actually be making them worse, I’ve seen it happen.

 

It seems like no matter what you do to these heads, flow seems to level out at .500 lift.

 

Not true.

 

I haven't found that to be the case with any of the A,B,C,E,F heads I have had over the years. I have seen many sets of stock castings flow far (relative statement) beyond .600

 

OP. You might contact "cutlass EFI" here. If you want to build your engine, he is a wealth of information/experience and talent. He has helped many (including myself) realize their goals or at least provide sound insight to allow you to have a semi-educated conversation with the machine shop you end up chooosing.

For example. I had a 425 build. I purchased my pistons from cutlassefi. I purchased my rods straight from Molar. The crank is stock (steel). The original machine shop completely tried to baffle me with BS. They didn't have a clue about the 425. In my 'free' conversations with cutlassefi I was given enough information to know that the machine shop didn't have a clue. With this information I was able to canvas machine shops for my build (local and some not so local) given the information that cutlassefi gave me (for free by the way) to find a shop that knew at least a minimal amount about oldsmobiles and knew why cutlassefi was giving the advice he gave me.

This allowed me to build a quite stout 425 (431 actually) that has far exceeded my expectations.

You might reach out to cutlassefi. I was not lucky enough to be able to have him build my motor, but if I had been - there would be no question.
When someone gives you their knowledge for free when they don't need too - that's the mark of a man.
my humble opinion and recommendation (even though you didn't ask for it).

mike.

 

Sounds like OP is "crowdsourcing" opinions and there is lots of BS out there. Chances are those people that "ported" their own heads never had them on a flow bench or the engine on a "dyno". Cutlassefi "knows" Oldsmobiles. .

 

Thank you!!

 

^^^ resident expert. Wise to follow Mark’s advice.

 

I’m only asking for other people’s experiences because I plan on running a .556” lift and don’t want to overcam if these heads can’t flow past .500”. I don’t have access to a flow bench but had some luck porting my small block 6’s. If I get it close for a good street engine than I’m happy. No all fhe ports are not going to flow even and no the bowls won’t be perfect, but I’ll be satisfied. The first set of heads I tried to port when I was 19 I used a summit at home pos kit and when I brought the to the machine shop they said “did you port these with a rock?”. My 6’s that I filled the crossovers and spent a lot of time, reshaping and m cleaning up the bowls and ports with a quality die grinder the machine said I did a pretty decent job and that 350 will run circles around most small block chevys around here.

Ive got 20 years under my belt as a master tech mechanic and have built quite a few engines and I do as much work myself as I can not just to save money but also because I don’t trust anyone to do anything anymore. If I could figure out a way to accurately cut a crank in my garage I would. I have one machine shop that I trust to do my machine work but I also tell them what I want done and that’s it. Ive walked out of machine shops who’ve told me “why don’t you just save the money and build a Chevy?
I do my own research and come to my own conclusions, right or wrong and that research includes taking everyone else’s opinions and experiences into account but at the same time with a grain of salt. I’m not knocking anyone on here and I’m sure that there are plenty of people who have a wealth of knowledge light years beyond my own and who over the 20 years that I’ve owned my cutlass have helped me along the way whether they know it or not because I’ve read all these posts over and over and over again, just behind the scenes. Now if I could figure out a cheap way to build a flow bench than I’d be happy to flow test them.

 

Crankshaft grinders
https://search.yahoo.com/yhs/search?...inder+for+sale

I am pretty sure there was an article that may have been linked to a post on here that may have told about building your own flow bench. Depending on what you feel is cheap, building your own happen.