318 head flow

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eestatic

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Ok, I finally was able to take my 318 block to machine shop and get the rebuild process underway!

Looking at the heads, they appear (to the best of my eyesight), to have a number of "2843675" stamped on both heads. I cc'd the heads and come up with 68-69 cc. Does that sound about right?

Thinking of options, does anybody have any flow number comparisons in [stock-unported form] with the 1.78/1.50 valves compared to a 1.88/1.60 upgrade?

How much more flow can I expect If I do nothing but upgrade the valves?

Not going over .500 lift on the cam.

Thanks to all!
 
I cant answer your question but I have some 302 casting heads if your interested...
 
I have those exact same castings from a previous 318 they are nothing special and not worth the money to put in them.. I would def look at those 302's. I'd either sell those or use them to learn how to port and polish. Also they should have been 58cc not 68cc..
 
I used a small medicine dispenser that was a 'needle-less' syringe.
The scale on it was 3 milliliters.
According to a google calculator, 1 cubic centimeter (cc) is equal to 1 milliliter (ml).
I pulled and injected (22) "full" syringes, to the 3 milliliter mark and then managed to squeeze in (two) more "milliliters" of fluid with No air bubbles under the plexiglass. [22 x 3 = 66 + 2 = 68]
After repeating this process 3 times for each cavity, my error was never more than 1-1.5 cc/milliliter.

What am I doing wrong here to be off 10 cc/milliliter?
 
that sounds about accurate to me. My 100% stock never before removed from the 318 heads came up at 66.5CC exactly.
 
Installing larger valves will decrease the combustion chamber size slightly.

A good 3 angle valve job with the larger valves will increase flow approx 10 CFM at all lift values. So my guess is perhaps 12-20hp gain if you have a mild cam and a good 4bbl intake.
 
I have never cc'd the heads I have I was in the same spot as you and I got the cc info off of here and moparts. IIRC they only have like a 100 cfm intake.

Turned out my block was junk for that 318 build so when I got another it came with 302 heads.
 
Larger valves will help, but unless you open up the bowls under the seats, gains will be minimal. As some have suggested, "302" casting heads are a better core if you want to use 318 heads. They have a smaller more efficient chamber, and a better exhaust port. They of course respond to larger valves and bowl work as well or better than the other heads
 
Sleeper Scamp

I'm interested in those 302 casting if you still have them. Shoot me a PM if your want to talk about it.

Thanks
 
What the Chief said. When you do up your 302's, run the 360 valves (1.88-1.60) a d do some porting under the valves in the bowl area as to take advantage of the increased valve size.
 
I have a cracked one of those castings, that I was going to scrap. If I get time this upcoming weekend, I might throw it on my flow bench to see what they do. Im thinking stock, then 1.88 valve, maybe stock with pocket port, and 1.88 pocket port?
 
ok93zj said:
I have those exact same castings from a previous 318 they are nothing special and not worth the money to put in them.. I would def look at those 302's. I'd either sell those or use them to learn how to port and polish. Also they should have been 58cc not 68cc..
Click to expand...

Sir you have no knowledge of 675 heads what so ever.

They come 68cc's, all the talk and printed literature of 675 heads is complete and utter Bullshit.

Hey also have more flow potential than the 302 head because the closed chamber of the 302 head shrouds flow.

If you want quench, then sacrifice some flow and run the 302 head...or just buy some quench dome pistons and run 675 heads...and in reality some can argue that the quench head piston can disrupt a lil bit of the flow too.
But...is quench really all that makes power?? No.

Btw 302 heads have the same damn exhaust ports as the 675's, why in the Hell are people coming on this site spewing bs???

You all might want to read my 318 porting thread...
 
Mopar Casting #2843675

Combustion Chamber will run between 66.5 to 68.0 CC {as per 1 Wild and Crazy Guy}

The 'open chamber' design allows for better flow, and with less shrouding of the valves.

We have used them, even by milling them {.045"} down to 60.6 CC on several Street Engines
and by popping in 1.88" Intakes only.

We've maintained the 1.50" Exhaust instead of the 1.60", as we like the added gap between
the Intake and Exhaust Valve.

With some 'bowl blending' and 'minor port work' they perform very well.

Mr. E - If you are 'not' planning to do any port work, I would only upgrade to 1.88" Intakes, and have
the Machine Shop open up the bowl area in the Intake Throat from 1.53" to 1.61" to increase flow.

Stock #2843675 Cylinder Head

attachment.php
 
69 Cuda 440 said:
Mopar Casting #2843675

Combustion Chamber will run between 66.5 to 68.0 CC {as per 1 Wild and Crazy Guy}

The 'open chamber' design allows for better flow, and with less shrouding of the valves.

We have used them, even by milling them {.045"} down to 60.6 CC on several Street Engines
and by popping in 1.88" Intakes only.

We've maintained the 1.50" Exhaust instead of the 1.60", as we like the added gap between
the Intake and Exhaust Valve.

With some 'bowl blending' and 'minor port work' they perform very well.

Mr. E - If you are 'not' planning to do any port work, I would only upgrade to 1.88" Intakes, and have
the Machine Shop open up the bowl area in the Intake Throat from 1.53" to 1.61" to increase flow.

Stock #2843675 Cylinder Head

attachment.php
Click to expand...


What is advantageous about...
as we like the added gap between[/I]
the Intake and Exhaust Valve.
Click to expand...
?

Also, the machine shop should know what is meant by [/i]open up the bowl area in the Intake Throat from 1.53" to 1.61" to increase flow?[/i],if I tell them just that??

I really appreciate all the help y'all posters contribute!!

*Anybody have a set of 1.88 valves I could use?
P.M. me for particular$..

Thanks
Dennis
 
So what numbers can a 675 with a 1.88 flow?
Justin's shown us that a 1.78 can flow 210 with the right "encouragement". I'd love to know what they're capable of with the larger valve???
 
With due respect to 1Wild&CrazyGuy, the 675 casting has 60cc whereas the 302 has 62.6. This comes from the How to Rebuild Your Small Block Mopar book by Don Taylor and Larry Hofer, ISBN 0-86586-128-3. It can be found in chapter 3 on interchangeability.

If 1W&CG has something different, let him state his numbers and his source. I'm not trying to start an argument here, I'm only looking for validity and consistency in the method. I've used this book for some time and have found it to be accurate, though they do seem to omit helpful details at times.

If someone publishes, they have stuck their neck out for critical review as opposed to unpublished sources. IMHO and experience cc a chamber is not an exact science. I've seen the same head return different numbers from two different shops. Even if one does not accept the absolute value of the data I've presented, I believe it is instructive for comparative purposes between the two heads discussed.

IIRC, the 302 recommendation comes out of an old Mopar Performance catalog where they make recommendations on engine build and vehicle outfitting. Larry Shepard was interviewed about the recommendation and stood by it. The 302 heads were recommended for a 13.5-14.0 sec. ¼ mile time. This recommendation seems to have taken on a life of its own as I don't see it in the 2000 catalog.

I agree with 1W&CG that the exhaust ports in the two heads are about the same. You, sir, are correct, IMHO, in focusing on head flow. I was told back in the day to think of the engine as an air pump. The engine that is going to pump the most through it is going to produce the most power.
 
Valvebounce said:
So what numbers can a 675 with a 1.88 flow?
Justin's shown us that a 1.78 can flow 210 with the right "encouragement". I'd love to know what they're capable of with the larger valve???
Click to expand...

Don't have anything that I know for sure is with a 1.88, so let's call these flows from almost 8 years ago a 2.02 intake in a 675.

lift..................stock.................ported

.100"................51......................63
.200"...............109....................124
.300"...............161....................177
.400"...............172....................218
.500"...............172....................255
.600"........................................272
.650"........................................277

I'm sure we could do better with what we have learned since that time, but these numbers will work for now.

Unlikely it is, that the 675 is 60cc, as it is an open combustion chamber, I'm just too lazy to cc it right now.
 
I for one will attest to the fact that Don Taylor & Larry Hofer's book is full of bad or incorrect "facts"... My copy has lot of little notes that I've penned in it.
Not slamming the book in any way (well, maybe I am), but I'd put my money on 1wild&crazyguy over it any day of the week.
As for the book, let's leave it to bad proof-reading and editing (which really sucks considering what it would take to fix it)...
 
Those are some crazy ow numbers for the head.
 
They are indeed.
I would ask though if you'd see those numbers in the real world on a 318, given the large valve being shrouded by the bore wall on a teen?
 
The minimum CC's allowed for a #2846375 Cylinder Head by NHRA
is 60.6 CC.

That should tell you, that from the 'Factory' they came through at a minimum of
least 5 CC's larger.
 
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