2.15 int. Valve too big for 318 @30 over?

I read before that a 318 can have valve interference with the cylinder wall if the valve is too large? My 318 has been bored 30 over and I wanted to know if a 2.15 intake valve would be too big. Also, is a 300 cfm flow too much for a street engine? The engine has the kb167s in plus a 274 retro roller cam. I want a nice street engine so I want some low end power, not the top end.

What heads are you putting a 2.15" intake valve in?

The right foot controls how much air goes into the motor unless it is at WOT, correct
My message is you control what the motor drives like on the street, not the valve sizes, correct

your about 323 CID, a 5.7 hemi is 345 so not a big difference in CID, there are bone stock 5.7s with well over 300 CFM from the factory so no that is not too much flow. It will however be hard to get that big of valve and flow in a 318 wedge head configuration, the valve will need shifted towards the bore centerline to get that big of a valve in there, a 2.02 barely works on a stock bore 318, a .030 over bore gives you an extra .015 clearance meaning a .030 bigger valve for a grand total of 2.05 valve size... to fit a 2.15 you would need to move the valve about .050. If you do that you will have to put a very small exhaust valve in or move it over also further shrouding that one. I don't think ex flow is all that important but you do eventually get to a point where you just got to much coming in and not enough out. Also if you got to moving valves around and that big of a valve your KB167 has a valve releif that will not clear the valves anymore. Bottom line is that in order to get that big a valve in it you will have to spend a mountain of money for little to no gain, so possible? Yes. Reasonable? No. If you really want that much flow a mild W2 rework will easily do that with a 2.02 valve. If you want it to drive similar to the 5.7 hemi get as high of a rocker ratio as you can to straighten out the PR angle as much as possible and run a short duration fast lifting cam and proper timing events and it should be very streetable. Those new hemis have giant sewer pipe size ports and crazy flow numbers but can be super tame fun to drive every day engines.

Nowhere near enough velocity & rpm on the street to even consider a valve that big with heads that flow that much.

I ran 2.14 intakes on a 4.030 408cid... you are still under 4 in with a 318 I would measure twice to be sure

Then you don’t want 2.15 intake valves, or any heads that size valve would be suitable for.

Heads for good low end street power on a 318 would be like EQ magnum heads, and use the 1.92 intake valve.

The heads are a pair of Edelbrock race heads, should be 58cc chambers. I don’t own them and there is a pair for sale. I wanted to get some opinions before buying them and finding out they are too much for my intentions. My cam should be good for them but the question is it too much for a warmed up street cruiser. Trans is a 42rh and I got about a 2500 stall converter. Car is an ebony, probably use 3.55 rear gear.

They ARE too much for your intentions. ( the heads)With very little convertor( a big key to a “ racy” 318) and 3.55 gears sounds like you are just kinda looking for a street cruiser with some punch.
The kind of heads Fast68 above mentioned are a good way to go
I say all this as a guy who raced a 3400 pound pump gas 30 over 318 that ran mid 11’s with iron heads. Pretty trick little piece .That took a 5,000 convertor

The heads are a pair of Edelbrock race heads, should be 58cc chambers.



Victor heads or race prepped standard Edelbrock heads. Just wondering because it sure as heck doesn't take a 2.15 valve to flow 300 cfm. A 2.05 valve is plenty.

Pits, they are the edelbrock race heads.

Looking at the specs from the Summit page, it looks like the intake valve is mover .150 as it talks about having to use big block rocker arms:

Notes: These heads are designed to accommodate stock big block Mopar rocker arms or similar aftermarket brands with a minimum of 0.150 in. intake offset. Ductile iron adjustable arms can be used but will require special clearancing of the rocker arm body in order to clear the valve spring retainers. Arms that are not built to stock specifications may require special modifications.

I want to get a set of aluminum heads, but don't want the regular edelbrocks. The Trick flows are taking forever to release. I am trying to get a set of Promax from Marsh Performance, but he cannot get the heads in stock.

Man you are going WAY over-kill with the Edelbrock Victor heads. Don't get me wrong I want a set BAD but I gotta wait till I need new pistons because those heads require them. My Friend got his small block ProMax heads from Jegs so it may be worth calling them. I also talked to the owner of ProMaxx a couple of years ago but I have to many Edelbrock heads on my shelf now. Not sure I would run that Victor head on a 318 but that choice is yours.

https://www.jegs.com/p/ProMaxx-Performan...451148/10002/-1

How about the big mouth Hughes head or get Pittsburgh to do a set like that?

Lol. Come on now in never even finished a set for myself yet. One of these days I’ll get back on that project

Not to hijack the thread, but on the subject of after market heads. what are guys doing for pre 72 340s with positive deck pistons? Most of the heads I see have closed chambers and the pistons would not clear. I thought a nice aluminum head that flows well would be better than working over one of my sets of X heads.

Doesn't Edelbrock offer a specific head for those 340's? Seems like I've seen one on Summitt.

Yes they do. That's what is on my Son's 360 that runs low 10's. I picked up a damaged set on Moparts years ago for 450.00 and fixed them and then ported them.

I'm pretty sure that is the difference on the ProMAXX 63 and 65 CC heads. The 65 have a little more room for the positive height pistons. I think the Edelbrock do the same, hence the 340 version?

I'm pretty sure that is the difference on the ProMAXX 63 and 65 CC heads. The 65 have a little more room for the positive height pistons. I think the Edelbrock do the same, hence the 340 version? [/quote]

So the 65cc heads are an open chamber design to clear the piston. The only pics i could find of them looked like closed chambers but maybe that was a generic pic?

So the 65cc heads are an open chamber design to clear the piston. The only pics i could find of them looked like closed chambers but maybe that was a generic pic?
[/quote]



One phone call will give you better answers than any of us can give you. He kindly answered every question I had for him and if I was still in the head porting business I would have grabbed a few sets.

If you scroll through the pics at the top of the page it shows two chamber designs. I'm not smart enough to know if the one is big enough to clear a 340 piston with the right head gasket thickness. However, it seems silly to go through all the work of having two designs with 2cc difference if not. Maybe I'm all wet so call first as suggested.

https://promaxxperformance.com/product/shocker-185-mopar-cnc/

Seems that the 340 piston was .018 or so above the deck, why not just run a .054 fel pro and have .036 quench distance? If that nu number is not exactly right you can order different thickness gaskets from different places but I am sure that .018 is close.