BORE SHROUDING TEST: 4.03" vs 3.91" Edelbrock RPM Heads Really Fit a 318? Project Mission Impossible

[66fs]

You guys need to just build stuff. Dyno's and theoretical stuff can or can not help. A guy I know was racing dirt track with a 318 and 340 X heads, had the fastest car on the track. That test is questionable at best. My experience is the same as 318willrun, 340/360 heads with any either 1.88 or 2.02 intake valves takes a 318 to the 340 level. I always had the heads milled .040 and .038 intake side to keep the compression the same or better. Of course you also need the cam, valve springs, intake, carb, and distributor.

 

[rumblefish360]

You guys need to just build stuff. Dyno's and theoretical stuff can or can not help.

You hit the nail on the head right there buddy. Just build something. Get out and do it. Throw some caution to the wind.
Pre internet and before I knew of the MP books, and after as well, if you wanted to know something, you built it and tried it. Dyno time was way to expensive but the track was fun, cheap by compare and has an accurate timing system to track your results.

I had so many carbs, intakes, camshafts, cylinder heads, 8-3/4 gear sets, it was stupid. Still do today to a lesser degree.

That test is questionable at best. My experience is the same as 318willrun,

I wasn’t to keen on the tape used to reduce the bore size, but, it did seem to work. Having an entire sleeve for a closer to actual real life scenario would have been perfect. Sounds pricey to me to do.

The real honest key here is where and how the fuel flows past the valve into the cylinder.

I also echo the 318WR actions and results. It’s amazing how the 318 gets the hard hitting disrespect hammer so often. I do prefer to build one in the future with as much over bore as I can get out of it but it’s not the end of the world if I don’t. I would just prefer it.

I’m looking forward to this 318 experiment.

 

[66fs]

... I also echo the 318WR actions and results. It’s amazing how the 318 gets the hard hitting disrespect hammer so often. I do prefer to build one in the future with as much over bore as I can get out of it but it’s not the end of the world if I don’t. I would just prefer it...

I prefer the smallest bore to keep the cylinder walls as thick as possible. Maybe grind a notch and radius the area of the intake valve (staying out of the ring travel). But to tell the truth, I've run 1.88 intake "J" heads on a 273 with a 3.665 bore. Guess what? It ran like a 340, no notches or special tricks except centering the chambers on the bores. The most important thing to making power with a short block is to seal the bores at wide open throttle, WOT.

 

[rumblefish360]

I prefer the smallest bore to keep the cylinder walls as thick as possible. Maybe grind a notch and radius the area of the intake valve (staying out of the ring travel). But to tell the truth, I've run 1.88 intake "J" heads on a 273 with a 3.665 bore. Guess what? It ran like a 340, no notches or special tricks except centering the chambers on the bores. The most important thing to making power with a short block is to seal the bores at wide open throttle, WOT.

While I agree a thicker cylinder wall is better, over boring an engine, it’s not something I shy away from depending on the sonic check report.

I have had 340 blocks that are thin at a .020 overbore. They still work and run fine. Just a darn shame they were thin walled to begin with.

The valve shrouding is something to avoid though everyone gets out of control when there is some. It’s great to avoid but over rated in its effects. As soon as it’s seen or heard about, the nay sayers dog pile on top like your the stupidest man to walk the earth.

Attention has to be paid to the air flow down the port, past the valve into the cylinder. When you know how that path is traveled, porting can help, not solve the issue.

As you said and we have experienced, more power is made even with valve shrouding occurring. It’s still more airflow in.

Improving the air/fuel quality is the area to look at. Redirecting the A/F path a little bit helps in big ways. Only so much can be done. After that, I just simply ignore it.

 

[273]

You guys need to just build stuff. Dyno's and theoretical stuff can or can not help. A guy I know was racing dirt track with a 318 and 340 X heads, had the fastest car on the track. That test is questionable at best. My experience is the same as 318willrun, 340/360 heads with any either 1.88 or 2.02 intake valves takes a 318 to the 340 level. I always had the heads milled .040 and .038 intake side to keep the compression the same or better. Of course you also need the cam, valve springs, intake, carb, and distributor.

All it is, is a piece of information, outside of the 15-25 cfm loss across most the lift range it tells us little in itself, how an engine will respond from this loss ? To me 400 hp and under probably very little looking at how sub 400 hp 318 perform. But at some point it probably does have an effect. But since most aren't building 500/600+ hp 318 most will probably never be overly effected.

 

[273]

This topic reminded me of this build, the ported EQ results I all ways found a little disappointing.

The shrouding might be/part the cause of this 400 hp 318 recipe, when they upgraded the 1.92 EQ's (402 hp) to ported 2.03 EQ's (227 VS 273 cfm @ .500" lift) and got 425 hp both at 6,200 rpm.

For a gain of 45 cfm the 23 hp gain is a little disappointing, might of been better porting but keeping the 1.92 valve.



Chrysler 318 Engine - A Powerplant To Brag About

LIFT:	INT:	EXH:	INT:	EXH:
. 100	68	57	69	60
. 200	124	114	138	124
. 300	179	155	200	169
.400	213
.500	227
.600	233

 

[360notch]

Depends on exactly how much cr vs how much overall airflow gain (VE%), Airflow generally has way more potential.

1000%

 

[273]

 

[MOPAROFFICIAL]

Anything DV is in ...is garbage.

This was a nothing burger aimed at novice armchair builder/racers for clicks.

 

[273]

Looks like it to me, for anyone thinking or doing a 318 it could be useful information to them.

 

[rumblefish360]

DV doesn’t point blank much information. But it’s there.
Brilliant man.

 

[MOPAROFFICIAL]

Looks like it to me, for anyone thinking or doing a 318 it could be useful information to them.

I have to disagree about it being of much use.

How much horsepower potential do you think there is with roughly 320 cubic inches and a flat tap at camshaft around 232° duration at .050 with off the shelf parts and a some country bumkins putting it together? You can have a head that flows 250 CFM and put an intake the at also flows 250 CFM on it and watch the flow be less than 250 CFM when bolted together on a flow bench.

 

[rumblefish360]

Looks like it to me, for anyone thinking or doing a 318 it could be useful information to them.

I agree.

 

[rumblefish360]

I have to disagree about it being of much use.

How much horsepower potential do you think there is with roughly 320 cubic inches and a flat tap at camshaft around 232° duration at .050 with off the shelf parts and a some country bumkins putting it together?

More potential than not following the little tricks they show. It’s a case of every little thing that can help adding up.

This is when you see a car perform better than expected. You end up saying to yourself, man that thing runs good for what it is.

All those little tricks people do add up after a while and amount to a win over an otherwise, same engine and part build as the other car.

While Andy may have the “Country” accent, so not be fooled by it. It would be equal to others seeing that, you are from California and interjecting stereotypes of Cali’s worst onto you.

 

[273]

I have to disagree.

How much horsepower potential do you think there is with roughly 320 cubic inches and a flat tap at camshaft around 232° duration at .050 with off the shelf parts and a some country bumkins putting it together? You can have a head that flows 250 CFM and put an intake that also flows 250 CFM on it and watch the flow be less than 250 CFM whem bolted together on th4 bench.

I understand that, like I said earlier under 400 or so hp probably no big deal but seeing the results it probably would still be worth blending the bore and probably offset dowels. But there are a few out there building crazier builds especially 4" strokers versions that need all the air you can get.

Steve Dulcich got 440 hp out of a 340 ootb AFR xe268h imagine a unmodded 318 bore would kill those results.

 

[dibbons]

This 318 "project" has run completely off the rails.

On the other hand, I prefer my currect project which is a Mopar 305 build. With the stock 340 bore of 4.04 (plus and overbore of .030") I won't have an issue with the 2.02" factory intake valves being "shrouded" using the factory 340 cylinder head. However, in order to accommodate the old school TRW forged/domed pistons (L2322F) I needed to have fabricated custom rods (Cunningham Rods: 6.298" vs factory 6.123") to work in tandem with the custom 2.96" billet crankshaft (Bryant Racing Crankshaft). A very expensive endeavor for me I might add.

 

[rumblefish360]

Boring the cylinder offset is an unusual step. It makes me think what that charge would be onto the bill.
I’ve always said here that the 318 is a perfectly fine engine to hot rod with of course lesser power results due to what I have also always said, my like for and to do for sure is bore that cylinder out! I’ve stated a lot that a .060 or better bore is the min I would do.

I suppose if you wanted to go nuts on modifying stock parts, regrinding the crank for more stroke and custom pistons would yield very good results but at a cost that I’d consider a bit nutty to do. But these tricks do exist!

If the 318 can be bored to a 4.00, safely, I’d do it.

 

[Illahe]

This 318 "project" has run completely off the rails.

On the other hand, I prefer my currect project which is a Mopar 305 build. With the stock 340 bore of 4.04 (plus and overbore of .030") I won't have an issue with the 2.02" factory intake valves being "shrouded" using the factory 340 cylinder head. However, in order to accommodate the old school TRW forged/domed pistons (L2322F) I needed to have fabricated custom rods (Cunningham Rods) (6.298" vs factory 6.123") to work in tandem with the custom 2.96" billet crankshaft (Bryant Racing Crankshaft). A very expensive endeavor for me I might add.

In 1970 the Winged cars ran a 305 as an experiment and they were very competitive against the field in NASCAR on the superspeedways.

Keep us posted on your progress.

 

[Illahe]

Boring the cylinder offset is an unusual step. It makes me think what that charge would be onto the bill.
I’ve always said here that the 318 is a perfectly fine engine to hot rod with of course lesser power results due to what I have also always said, my like for and to do for sure is bore that cylinder out! I’ve stated a lot that a .060 or better bore is the min I would do.

I suppose if you wanted to go nuts on modifying stock parts, regrinding the crank for more stroke and custom pistons would yield very good results but at a cost that I’d consider a bit nutty to do. But these tricks do exist!

If the 318 can be bored to a 4.00, safely, I’d do it.

There are GT/ class racers running mid 10 second ET's with Iron headed 318's at the divisional with 1.88 valves...Velocity plays a big part in the combination.

 

[273]

Boring the cylinder offset is an unusual step. It makes me think what that charge would be onto the bill.
I’ve always said here that the 318 is a perfectly fine engine to hot rod with of course lesser power results due to what I have also always said, my like for and to do for sure is bore that cylinder out! I’ve stated a lot that a .060 or better bore is the min I would do.

I suppose if you wanted to go nuts on modifying stock parts, regrinding the crank for more stroke and custom pistons would yield very good results but at a cost that I’d consider a bit nutty to do. But these tricks do exist!

If the 318 can be bored to a 4.00, safely, I’d do it.

Instead of offsetting the bore, couldn't you do offset dowel pins? pretty sure 66fs did that with his 1.88 valved 273.

 

[273]

There are GT/ class racers running mid 10 second ET's with Iron headed 318's at the divisional with 1.88 valves...Velocity plays a big part in the combination.

If you were running factory heads smaller valve probably make more sense but if you want to buy aftermarket kind of stuck with 2.02".

 

[273]

Not like people don't expect for a 318 bore to kill some power especially compared to a 340 + bore but if there's a few minor things to do to help seems worth it.

 

[MOPAROFFICIAL]

More potential than not following the little tricks they show. It’s a case of every little thing that can help adding up.

This is when you see a car perform better than expected. You end up saying to yourself, man that thing runs good for what it is.

All those little tricks people do add up after a while and amount to a win over an otherwise, same engine and part build as the other car.

While Andy may have the “Country” accent, so not be fooled by it. It would be equal to others seeing that, you are from California and interjecting stereotypes of Cali’s worst onto you.

I didn't notice any little tricks.

 

[MOPAROFFICIAL]

I understand that, like I said earlier under 400 or so hp probably no big deal but seeing the results it probably would still be worth blending the bore and probably offset dowels. But there are a few out there building crazier builds especially 4" strokers versions that need all the air you can get.

Steve Dulcich got 440 hp out of a 340 ootb AFR xe268h imagine a unmodded 318 bore would kill those results.

Moving the bores around for 3 or 4 CFM? Maybe if theres a world record on the line.
Bore notching is "old hat" stuff.
This is going backwards.. lol
I'd use 1.94, or even 1.89 and 8mm guides take .040 of the spring seats and ad a .050 pop up lock, or just order the right length valves to begin with before id offset the bores or dowels. The chambers aren't even massaged out either.
To me.. this is the same old spam but in a oval can.

 

[rumblefish360]

There are GT/ class racers running mid 10 second ET's with Iron headed 318's at the divisional with 1.88 valves...Velocity plays a big part in the combination.

ABSOLUTELY!!!!!

Instead of offsetting the bore, couldn't you do offset dowel pins? pretty sure 66fs did that with his 1.88 valved 273.

Yes. How much can you offset?
IDK the answer.

I didn't notice any little tricks.

As a side question, do you smoke pot?