Wow. Those look damn good from where i'm sitting. Too good to be true you think? Or legit. I'd still have only 9:1 CR... but thats only about a 4-6% loss from 10-10.5:1...

 

4% a point from 7 to 9. 3% 9 to 10. less than that a point from there on up. try to find 60cc heads. bare heads. buy ferrea or manley valves and PAC beehive springs. cheap heads come with cheap moving parts. the castings-mostly the same procomp casting are pretty good these days. the valves, etc? not so much. skip white's heads are reasonable and valve heads do not pop off and destroy your engine.

 

I dont see much of the procomp heads anymore but these are what those look like... completely different casting.
https://www.ebay.com/itm/31312130991...pid=4027623388 Boot77 did a comparision of those vs these on youtube and found these to be much better.

and this head porter did a good series on these heads. hes also done some nice comparisions of brodix heads vs others. he doesnt appear bias and points out the flaws/ weaknesses he has found
The thing I mentioned in another thread is I see people are quick to warn against the cheap heads saying they will destroy an engine yet I dont see any actual reviews or reports where thats happened and I spent a lot of time reading reviews on everything from yellow bullet to amazon. Ive seen some reviews that were so far fetched they were clearly fake but thats common it seems on amazon. I just dont think its as likely as people warn.. Places like speedway wouldnt still be selling them if they were really that bad. (Although they still sell procomp too but ive been told even those are improved now) I could totally get that one size is not a fits all application with heads and someone using these with a stock flat tappet would want lighter springs likewise someone using a big roller cam would want stronger springs. You would think due to cheap price alone more inexperienced mistakes would happen through mismatched application with these though.

Ive read and seen plenty of valve spring failures on this forum but I dont recall ever seeing a thread about valve failure honestly.

 

Skip uses Erson stuff last time I checked. Ok middle of the road pieces.
maybe for a small flat tappet a cheaper valve might live but a decent valve isnt much I cant see the sense in cheaping out there.
Same with valvesprings those are so crucial. Most feedback are from guys who just bought them, maybe had it running for a few mos "revs to 7k and goes 8 sec in the 1/8) type stuff.
I have yet to see someone tear down theri heads after 20k miles and see what kind of wear has occured. Not thrilled with the guide quality.
If those go away so does the valve job, cyl pressure etc.

on the typical 200cc Chinese head getting 300 cfm isnt too difficult at all.
Yeah cheap valves and springs causing failures lol

 

I don't think it's easy to make 300 CFM on ANY streetable head on a 350 CI engine.
Even in the video Eric had to lift the valve to .800" to get 300 CFM, When's the last time a flat tappet street car lifted the valve that far?
More interesting is that he lost flow @ .300 and .400 started to gain @ .500. In a flat tappet street car your done by .500" usually before. So him porting that head for street use, It lost flow, not gained. Notice also that the exhaust lost flow everywhere @ and below .500".

High lift flow by augering out the port is certainly achievable. What is it going to do to the port volume and velocity of the intake charge when you take a 200cc port and make it 220 cc's by doing so? I think he alludes to those facts early in the video.
High flow below .500" with a 180cc port volume or maybe 195cc port volume is what I would look at If I want to make comparisons. AFR 180cc port volumes flow better than most 195cc port volumes on other heads. That's worth noting.

 

Proheaders done back in 2019. Saw so much conflicting info thought Id try a pair. Make nice dust collectors lol
2.02 intake, stock valve job Erson valves

Lotta companies post peak #s to sell heads it doesnt tell the whole story

 

Curious... whats 15cfm worth in HP at around .500"? Assuming everything is matched. Seems about the average flow number for these newer heads is around 15/10cfm higher than the old Performers. Interestingly enough, all the .300" numbers are pretty much equal.

 

The rule of thumb for max power from a head is to double the max flow. That's only with a very efficient VE, race engine really. In an average build it might only be around 80-85% of two times the max flow or so, could be less, could be more.

If I had to guess with a standard build I'd guess 15CFM is maybe worth 20-24ish HP. Less if the build is not very optimal.

15x2=30
30x.8=24

https://www.motortrend.com/how-to/ai...ylinder-power/

 

fair enough.
In my case, its going to take me about 15 years to get 20k on my car with as much as I drive it every summer and im likely to make more changes by then anyway honestly.

 

this procomp head looks like it is using the same pics as the speedmaster ad. and valve flow at .900 lift? why? it's not like any cam can produce that much lift. https://shanonsengineering.com/produ...cylinder-heads a guy in the philly area was trying to sell his 496. recent complete engine package he paid around 5k for with procomp heads. intake valve head dropped off at idle in his driveway. he was asking 3500. ended up getting 500. that is what cheap bulk chinese valves will do for you. or to you.

 

Whew...that guy is expensive!! ^^^^^

 

I am TOTALLY getting a .900" lift cam now. That'll sound SAVAGE in my old truck 350...

 

Cause a head carries air that far doesnt mean you gotta have that big of a cam lol
Like heads that come in early, with strong # then carry a little farther. So tempted to put the ones I posted about on mine I bet they outperform the Dart 230s I have now.
Too lazy, will sell instead.
procomps have gotten better over the yrs but would never use them personally

 

Heh... i was just joking obviously... but it brings to mind a guy i used to know. Local blower guy, built roots blowers and engines for people all over the area. Really smart guy, knew his ****. He built a T-bucket for himself, and put in a little 6-71 327. Said he barely modified the engine, stockish heads, etc. But he put in the most massive cam that he could make physically fit. It was something absurd (for a stock engine), like 260-or 270 at .050". I asked why he'd hamstring his engine so bad with a horrifically mismatched cam. He said 'Man... this thing weighs just over 1500lbs, and its got a god damn 6-71 on it. Do you honestly think i need every last 50HP...???' He said i just want this sucker to CACKLE... like a top fuel Harley. I never did hear it, but he said when he pulls into a show, or a lot, EVERYONE turns around... Besides, he said you really dont want to go over 100mph in a T-bucket...

 

I bet there are as many if not more cars with cams in them based on sound over performance than the other way around... Especially in a classic hot rod where its more often typically its about the looks and sound. Thats literally why the Thumpr series and the like exist. nothing really wrong with it.. Ive seen some fast junk and some sharp looking hot rods that couldnt get out of their own way based on owners priorities. I myself just want it to be fun to drive on the street and could care less about high speeds honestly.

 

Heh... 'overcamming' is a trend that wont die for good reason! I dont believe in overcamming. But you certain can 'under-engine' a cam....

With what i'm building, a fast, reliable, 'attitude' car... i wholly admit i intend to be guilty ov this too. However... if there is one thing i cant stand, its cars that look faster than they are. Mine will be so goddamn light that i'll be able to lose 10-20HP over my optimal build and still will races. I want a modern engine, and there is just something profane about a sick chop coming from a computer car... Another saving grace, beyond the light weight, is that it is harder to under-engine a computer car...

I LOVE the sleepers... but i've taken that to extremes too... and its REALLY fun when you get beside a hot car... and no fun at all 95% ov the rest ov the time. Had a 73 smog-era, big-bumper 4-dr Dart, beige on white vinyl with plaid seats and steel rims with 70 series tires. No scoop or bump, no big pipes, no tach, no nothing... just a hot 440 Magnum and 727, and 3.91 posi. Thing idled like an electric motor, and somehow hooked HARD. VERY fun car... 5% ov the time. The other 95%, i felt like a teenager on his way to pick gramma up from the bingo in her car. Yeah... i like the attitude. The BEST part is... you can have a hot car, and still be a sleeper. You've just gotta be REALLY good...