MCSA on a sbc head

[Little Mouse]

I want to build an engine in the 321 range to 331 to make power to 7800 rpm. Wallace calculator at 321cu. Says i need a miniumum of 2.29 mcsa area. Heads i would like to use are either profiler 185 or afr 195 race version. Afr says the mcsa is 1.92 on there head cant find any info on profiler. So do i need to open up the push rod pinch area on these heads to get to my goal of 7800 rpm.

[Kbails]

is the plan to make it rev to 7800 and be happy or make peak power at 7800 and shift at 8500ish? i think depending on what this engine is designed for your going to be looking for a much bigger head but i could be totally wrong. whats the application?

[Little Mouse]

11.1 comp. High strung street engine 4.125 bore 3.00 stroke 321cu. Calculator in three different ways shows i need a 2.29 minimum csa. But at that small engine at 100 ve shows it only needs 243 cfm of head flow. All the smaller heads that can do that have no where near a minimum cross section of 2.29. Im leaning torwards for the cost the 185 profiler that claims around 260 cfm and opening up the push rod pinch area. Now my definition of a street driving engine is if you can regester it and still run on 93 octain pump gas all is ok and before i get blasted for just go bigger i have had up to a 454 bbc i like the small engines.

[swampbuggy]

Little mouse...get that combo correct and it'll haul the mail !!!!! Mark H.

[Little Mouse]

Well thanks swampbuggy
Always considered the sbc the poor mans ferrari high rpm screamer even ifts not making that much power lol. Im going to use a yellow terra shaft system i think for what it costs and what i want to do its plenty good enough. Never have liked stud system.

[In-Tech]

While some might balk at your 11:1 compression thinking it is too high. I applaud it and think you could go even higher. Cam events for higher rpm also alleviate cylinder pressure at lower rpm as well as the EGR factor during overlap. If you get around to it, let us know how it all works out. Thanks.

[mag2555]

Your not showing any concern for drivablity below 4000 rpm with that small a cid motor so go for the 195 cc heads.

[Carnut1]

Post up whole combo for better advice. My Dart 215's stock only flowed 265 cfm. Add carb, manifold and air cleaner and it will drop even more most likely. Flowing the all the parts on the bench is a pain but will give a good idea of system flow. Thanks, Charlie

[swampbuggy]

Shaft rocker system....GREAT move. don't skimp on rods and rod bolts, thick wrist pins/non tapered, lightweight pistons, you will be on the borderline for steel valves, esp. on the intakes, high quality valve springs and keep an eye on them. Just my opinion on a few things. Mark H.

[Little Mouse]

Im considering using a 3984 weiand single 4 tunnel ram. Valves i want to use ferra hollow stem. As far as the 195 head just not sure the engine can use anywhere near the 300 flow especialy at only 7800.

[Ericnova]

Mixture distribution on a single carb old school tunnel ram like that is just awful….and significant power will be lost because of it. Use 2 carb top or don't use it at all.

The only single carb tunnel ram stuff that actually works is custom sheetmetal stuff....the old cast stuff is just crap, total crap.

[Little Mouse]

Im reconsidering. Think i will use profilers 195 head.

[pdq67]

I don't know how much truth there is in it, but I have read years ago where the SBC wedge chambered head doesn't respond good to compression over like 11.5 to 1??

I think that back then, they had to install TALL domed pistons to get above 11.0 to 1 CR so they ran into flame travel problems due to the tall domes.

I also think that this is when piston sparkplug flame travel notches came about.

pdq67

[pdq67]

I don't know how much truth there is in it, but I have read years ago where the SBC wedge chambered head doesn't respond good to compression over like 11.5 to 1??

I think that back then, they had to install TALL domed pistons to get above 11.0 to 1 CR so they ran into flame travel problems due to the tall domes.

I also think that this is when piston sparkplug flame travel notches came about.

I won't have any of these compression problems with my ICON stepped/dished flat-top pistons and my EQ heads that have 50 cc chambers! And I am going to use Felpro's #1094 shims to tighten it up a skosh more! Shooting for like 10.25 to 1 or so for a 325" 4.155" large bore/3.00" short stroke engine.

pdq67

[Little Mouse]

Ya have considered darts 49 cc iron heads so i can stay away from a dome but i have convinced myself the profiler head flows better.