I will be installing J-heads with 2.02 valves on a 1975 318. Part of this install will include an LD-340 intake and an XE-262 cam with the goal for a nice street cruiser, not a racer.

I am curious to know if it is necessary to notch the top of the cylinders for valve clearance given the 2.02 valve size? I am planning on a set of Fel-Pro gasket set with standard ~.040 installed thickness.

Is there anything not so obvious that I should consider before I go down this road? All of this is based on the assumption that I have a standard compression ration for a 1975 318, 2bbl motor.

Not looking for specs on a fancy small block build but more of simple notes that I should not overlook before I begin the teardown on a weekend project.

thanks!

no notching needed. unshroud the chambers/bowl hog/square up port openings/ do basic home porting. 3 way t chain to adv it as needed. dial in dist when running. #1 want a freeflowing ex system. you are cube limited SCR limited & no quench. Eddy 1405 or 1406 would be a good choice

Just my opinion, but 2.02" valves are overkill for a "street cruiser". All else being equal, 1.88" intakes will help more in the rpm range you will spend most of the time in. The bigger chambers will lower compression as well. I don't know off hand how much you'd need to mill to equal the 318 chambers. Worked closed chamber 318 heads (302) would work well.

Heck J heads are overkill for an other wise stock 318 short block, unless you are going to turbo it. If you want good flowing stock based heads with decent compression on a 318 go magnums.

Tips? My tips are don't do it. Compression will litteraly be about 7 to 1 and NOT be a fun cruiser. A 302 or better yet a 920 casting head upgraded to 1.88 1.60 valves would be way more fun to drive. The chamber in a j head is on average about 72 CC vs about 60 for the heads I mentioned VS about 65 for what you have as well as higher port velocity than the J head. The factory basically did what you are doing with the bigger heads and added a 4bbl at the same time and only made like 10 more HP and I can tell you from personal experience TQ was no where near as good as the 2bbl. The head gaskets you are considering are way thicker than originals as well, you can no longer find the original sheet metal thin gaskets. The thinnest readily available head gaskets are the mr gasket 1121G and they are still thicker than the original.

That is a good cam if you do the other heads, it will only add to the suck factor if you run it with the ultra low compression. If you are set on running the J heads and want a cam that sounds a little better get one of the hughes whiplash cams, the smallest one they have, the tight LSA helps TQ and make the idle a little rougher.

Your car will be no faster with the heads then with a standard set of 1.88 360 heads but use what you have on hand. Problem is that engine has no real comp . You would be better off with standard comp 260 Hyd in fact it will run better. Get a mech advance dist and get as much total in it as you can at least 44 degree's by 2000 it will really pickup go with a 600 dbl pumper and a 4 hole 1 inch spacer on the LD DO NOT close off heat passage and run a 195 stat 180 dead of summer. If you have the money gear it to at least 3.23s as you only have 5500 rpm tops power is done in low 5k renge

When you pull the heads you will see that your pistons (1.720CH)are almost exactly 0.100" down in the block. This is about 20cc. The 1121G head gasket is maybe 7 cc. The heads are 72cc. So you're looking at 99cc above the piston.

The swept volume of a stock bore 318 is 652cc. (652 + 99) / 99 = 7.59:1 compression.

IMHO you will be building a dog. You'd be much better off with a set of stock Mag heads.

What that engine needs is a 3.51" crank to go with those J heads. That'd get you some compression and a few extra cubic inches to play with.

R.

I went through a similar situation only it was Camaro Z28 that was 305 smog motor powered. It was one of the ones that did not have an LT1 motor that was using the big valve heads. The owner overheated the motor and both heads cracked. He got a deal (??) on some big valve heads and when we compared the new heads to the old, I showed him that the big valve, big chamber heads were not compatible with the dished 305 pistons because the CR would be far less than stock and the result would be an embarrassing dog. I put the right heads for the application on the motor and never heard from the fool again.

What little squeeze the engine has will be even lower with that 262 cam.

302 heads are a bolt on as with 308s,the 308 have 1.88/1.60 valves and both will improve compression.
I had a set of 302s opened up for 1.88/1.60 valves,did some porting and put them on with a set of .022 gaskets on a 88 318 along with other goodies.
I can tell you it is surprising the differences there is.
Unless you go with an aftermarket aluminum set that is probably the easiest choice.

308 heads are not an improvement in compression, they are open chamber 360 heads, 302's are closed chambered.

308 heads http://www.forabodiesonly.com/mopar/showthread.php?t=60004

302 heads http://www.americancylinderheads.com/cyl...s-_-AC108C.html

308 heads are swirl port, medium sized valve heads, 302's are swirl port small valve heads.

Don't spend the money on either, magnums are better than both.

I put big valve 2.02 915 heads on a 318 once. Worse running motor I ever had. It lost a lot of low end torque. Follow the advice given and put 318 heads back on your 318.

my junk runs fair for a daily driver

88-318
360 heads-1.88/1.60 in a 85 stepside with NV4500 5 speed

from the factory out of a 89 police car = nothing special but does have the better 85-up 9.0 CR pistons .020 in the hole.

I have a hughes whiplash roller cam for the 318 magnum. made for the stock low comp engines and street duty.

I run a holley street dom intake with a 6210/650 DP spredbore along with headers 2.5 duels, 3.55-29x9.5x15

is it a racer? no. does it do well in daily traffic? hell yea and gets 18 mpgs.

I cruz mine 100 miles a day x5 and at least 100 on weekends.

IMHO, the right cam will make or break it.

the #302 heads did just as good. just moved the torque peak on the rpm band by a few 100 rpm.

I can live and be happy with less with my junk. I am happy to drive a mopar everyday no matter how slow or fast it is.

from a hot rodders view I can see don't do it. but from a daily driver view and the fact the Ma Mopar did it there is no reason not to do it.

the papers I have show the stock 88 #302head 318 has 150 HP and the the 88 318 #308head 4-v police engine has 177 HP. AND with a lower comp ratio rating.

not much but it is where it is needed in daily traffic.

results vary and depends on what you want to do with the 318.

Even sticking the 1.88 1.6 valves in the existing open chamber 318 head will be a better choice. No valve shrouding like the 2.02 valve will give you, no uber low compression like the big chamber will give you, no chamber over lap (or extra crevice volume) and more velocity for low end tq. I still think the 360 head is the worst idea. By the way the cop car engines had a better timing curve, 800 CFM VS 200 CFM carb and exhaust that also helped get that whopping 27 HP so a bunch of changes were needed to get that handfull of HP and off set the terrible choice of heads, the "big giant head" was only there for NOX reduction purposes. Compression was no where near 9 to 1 on a 318 in real life except for 1967 because of the 920 closed chamber (smallest CC head ever installed on a 318) head and thin head gaskets and the later magnum 318 from 92-02. Even the great 302 head with the taller pistons was less. The fact that scratchin is happy is a testament to how well the whiplash cam works, not the 360 heads.

Also to put things in more perspective the 200 CFM carb was rated with double the vacuume under it as the 800 CFM thermo-quad or later 750 q-jet.

that's what I was getting at. the whiplash works for a lopo JY throw together like my junk.

the lunati 292/292 I had first...not so much.

I like my 440whiplash once I got the dist recurved and dialed in. great street cam with a nasty idle. fun in traffic light to light and will buz 2000 rpm at 55 mph getting 12.5 mpg all day long.

I run a stock low stall with 2.76gear 29x15x15 M/Ts and is fun as a daily driver.

Appreciate all the responses. I have certainly learned quite a bit. I originally intended to use what I had available (J-heads with gasket matched LD-340, and went with an XE262 from previous advise).

Pulled the motor this weekend and found it is a numbers matching 1975 318.

After reading all this information I have chosento keep the matching numbers block on the 1975 Hang 10 Dart and, if possible, still use J-heads/intake but realize I may have to return the cam and get a better one for the combination I chose to go with.

I have decided to rebuild the bottom end on a reasonable budget. Some options are:

1) get higher compression pistons and use existing reciprocating components. I am guessing J-heads may not be the best choice and I can certainly change to some with 1.88 valves. Need advise on cam choice.
2) get a stroker kit for the 318 (any recommended kits or suppliers?) and keep the existing heads and intake. Need advise on cam choice.
3) open to other suggestions

thanks!

build a 360! & stroker cranks are dirt cheap now (Hughes has em on sale). I'm doing one & I might be able to mill the OE cast 360 pistons. just need to mockup & see where I'm at & a cometic custom thick gasket is an option around this also if it comes to that & if not, stroker pistons ain't that costly. After you feel that power the numbers matching 318 sitting in your garage will be the last thing on your mind.

How about using a set of KB167 pistons, and the j heads? I've never seen anyone say what that combo might yield as far as compression. Might be worth checking on if you'd like to keep the numbers matching block in the car. Using a 4" crank and making a 390 stroker out of it could be fun too.

The KB167 pistons are a great deal.

https://www.uempistons.com/index.php?mai...products_id=521

They're not cheap, around $300 plus shipping if you shop.

That link gives you the comp ratios for different head volumes. But my calculations show that those numbers are for a later block with deck height 9.577

On a 9.600" block, what you have, the piston is 0.012" in the hole. With a Mr Gasket thin head gasket you have the perfect 0.040" squish clearance if you use a closed chamber head.
There is no earthly reason for the first overbore to be 0.030, it could as easily be 0.020 and leave you meat for another rebuild later. 393 x 3.31 = 321 which makes 658.2 cc swept volume. Valve notches are 5cc, I'm assuming the head gasket and the volume from the 0.012 below deck as 9cc.Thus there is a total of 73 + 5 + 9 = 87cc.(658.2 + 87) / 87 = 8.57:1.

Put on a 63cc head and it turns into 9.55:1. Hello 262 cam (218/224 @ 50 lift).

Of course put a 4" crank in it, it becomes a horse of a different color and then your J heads will have some cubic inches to play with. But you have to decide.

R.