I am starting to gather parts for building an engine around a set of W5 heads and matching small port intake. End use will be street and auto-X use with some occasional drag racing thrown in the mix once or twice per year. This is all going into a '65 Valiant hardtop with a 4-speed.

I have a 1974 360 block, but I'm starting to rethink using it, thinking the power potential of the heads and my intended use might kill this block pretty quick (I have milodon splayed bolt caps and gear drive I was going to use, and was planning to half fill with block cement, but maybe that's not the most durable setup?).

Any tips on which block to select? I'm considering an MP siamese bore 340 block. There seems to be a few various blocks to choose from these days. I'm leaning to build a large displacement stroker using rotator parts similar to the hughes 426 rotating assembly.

i'll say take a close look at the x block....on the other hand r3 blocks are all over, at good prices, but they will carry an extra weight at your valiant nose...not good for your car, that's the reazon i sold my two r3 block...

Lots of guys have had good luck with a stock block with your intended use... On the other hand I broke my 360 stock block with my drag only w5 motor. Cracked 2 and 4 mains, I had billet splayed pro gram caps on mine also. I am doing now what I should have done yrs ago and bought a new R block. Problem solved BTW mine was a 14.5 comp, injected on alky motor. Pushed it to far.

The X-block looks like it would be a good option, IF I can find one.

Doing a little research and it seems I can't easily use roller lifters in a R3 or an XR block that's setup for 59* lifters... unless I mod my heads to use 48*?

I'd rather not go the super big buck high-end route if possible. I'm probably not going to exceed 12:1 compression (I'd like to keep it around 10.5 or so).

go to t the engines parts for sale there is one ...

I have a 59 degree R3 block here at the house and also have the lifters that IMM/OU812 sells and they drop right in once you do some MINOR clearancing of what is left of the valley bolt hole boss. Its really quite simple.
In your case with W5s and more than likely a stroker deal, you better look into a X or R block. Prefferably a siamesed bore deal. These days, if your gonna spend the dough on a good block, spend a little extra and get it siamesed bore. You will be money ahead in the future. I personally wouldnt spend my dough on a non-siamesed bore block. Definitely no stock block for stroker/W5 combo.

If you go looking for an R block , make sure to get the tall deck unless you want to fight rod length and ring pack issues.
Lots of folks selling R blocks and but few with tall decks.
Then , there are folks who advertise tall deck blocks and ship 9" deck.
Thanks Rick ........ by the time I got the parts , I was happy to just have something for my money.
And you can do some cool stuff with a short deck , but with anything over a 3.79 arm in it , you will soon find how to spend money like a drunken sailor , and remaining stone cold sober the whole time.
Also , most short deck blocks are dry sump only , some have the motor mounts removed and all are 48 degree..........as a rule.
But I am finding out that the " rules " are pretty fast and loose.
They are a sturdy piece though.

The Mopar race blocks are super heavy, my 340 resto block weighs 211 lbs bare. That is about 60 lbs more than a factory 340 block.

Good luck getting a set of roller lifters to fit in a 340 resto block. You'll need to do a lot of grinding and machine work in the valley and you still might not get it to work. Just be prepared for a lot of mocking up and re-work. I spent a lot of time machining and grinding in the valley of my block for hyd roller lifters and finally gave up. I'm now trying to see if solid roller lifters will fit. I've tried a couple of sets so far and they don't work so we'll see what happens. I have a new set from Comp on the way that they say will work.

The Magnum race block from Mopar might work but I haven't tried one. They have the valley machined for hyd roller lifters which probably means that solid roller lifters will clear but Mopar doesn't publish any pictures or provide any detailed info on the block so you basically have to do the R&D yourself.

i ran a stroked 340 for years 3.79 stroke and lots of leaking head gaskets and cracked cylinder walls...bought a r3 back in 2003 and no problems cents then.......i should of bought one years earlier...would have been lots cheaper in the long run...

I've got a new r3,59>,9.2 deck block with a new timming cover for sale,$1700 + freight,jg309 or call 618-806-1564, thanks

I looked over a R1 block at the machine shop the other day and the roller lifters dropped right in. Of course that block didn't have 4 bolt mains which is a draw back.

If you have the money you can have Ryan CNC mill a R3 block into shape. That will save a bunch of weight and he can do the machine work so roller lifters will drop in. In hindsight that is what I should've done with this 427 that I'm building.

Curious on your lifter fitment issues Andy. Have you tried the lifters that Brian ( IMM ) has that I often see mentioned that "fit"?

FWIW our W5's are on a stock 340 block, filled, BRC 2 bolt main caps.....so far so good. Not sure of the HP, but has a best of 9.87 @ 136 in my dads Duster.

My R1A block doesn't have the tall lifter bores like a R3 block, but it does have 4 bolt mains... Of course the the 4 bolt mains could have been added later, i picked this block up used from RyanJ.

I'm freshening my 408 W-5.The 360 block has 2 bolt mains w/studs.Its filled and average wall thickness before boring was about .200 on the thrust side.The caps didnt show much fretting.The bores arent perfect(left over rust pits)but are basically the same as 300 passes ago. Best of 6.09 @110 Now changing to alcohol

Yes, it's going to be a stroker. The conclusion I was coming up with too was: 59* tall deck siamese bore R3 block. Any advantages to just run a 48* block right off the hop? I have to get my heads built up anyhow, so adding clearance for 48* lifter angle probably won't be a huge add-on. Other than the cam being different, what else would I have to get that's special?

If you already own a cylinder head designed for 59 degree tappet angle, I would suggest sticking with that. I have seen guys use 59 degree heads on 48 degree blocks but its a pain in the rear and not worth it for most street/strip setups. Usually just all out race deals that are high 7500+ RPM. Nothing wrong with the 59 degree stuff worth complicating matters. W5 are 59 degree stuff.

Here is a pic of W-5's converted to 48deg. So you can see how close the PR comes to the manifold face and see how much you will have to elongate the PR holes.

The only thing you would gain going to 48 is you could run your tappets dry if you chose to. Not somthing the average Guy wants or needs. You do not gain much by straightening out the pushrod until 8500+ RPM. Plus I hear it may be a problem getting a 48 deg cam core for a while.

I'll patiently wait to see what AndyF finds out when his new lifters show up.

Looks like one of the following blocks should work for me:

P5153478AB
P5153743
P5153579
P5153452