Hey there. I'm building another slant six engine. I decided to leave mine as is and go with another one so I can do things really slow and counting on me and after I finish I do a swap.

The thing is I'm going with 198 rods and newer pistons (zero offset wrist pin, floating wrist pin, higher rings pack with thinner rings) and I want to know how much can I take from the top of the block safely. I'm using a custom cast /6 block produced in argentina called the 906 wich was intended for light and heavy truck operation. The block itself is more than 30 pounds heavier than the "regular" slant 6 block and withstands greater overbores (say in the .120 to .140 ballpark) W/O pricey block testings.

So my recipe is kinda the nonstroker stroker /6 from dougs article

89mm metric piston and rings
198 rods
erson 270º/270º .465" lift cam
mopar performance small block 340 springs with damper
Mopar performance 1.7 in 1.44ex valves w/ brass valve guides, combustion chambers matched to the overvore to unshroud the valves, ported and polished on the ex side, ported on the intake side.
head, mains and rods ARP studs kit
that would yield a 3910 cc slant six
maybe if the core's good I can push 89,5 mm and get a 3954cc or 90mm and get a 3999 (4 liters) slant 6

If I can mill enough from the block and .100 from the head, I can use domed pistons and close to zero deck height to create some quench in the combustion chamber... if I can't take enough I'd have to go with flat top pistons...

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I wish I could get my hands on one of these blocks, it sounds interesting.
Don't forget the oversize valve head with some porting work, this "big inch" engine will need it.
Do your compression ratio calculations, the long stroke SL6 is hard to get to zero deck and still have a reasonable compression ratio. (under 12 to 1)

I would try not to cut the block more then .125 and even less off the head if possible. Thick decks hold the head gasket better.
DD[/quote]

I would say 0.100-0.150 would be fine to cut off the block. With that big of a bore, you might want to go with bigger valves still - like 1.76/1.50. That's what Mike Jeffrey did on my head that is optimized for 0.100 over block.

Lou

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Home of Slant6-powered fun machines since 1988

I have 3 of them. Wanna get a shipping quote? I assume is going to be pricey but can be arranged. Also I'd like to take one bare block to a scale and send you the exact weight. I understand that you also had heavier blocks (maybe I got it wrong??) from one of your articles. If it's heavier than yours it might be worth trying. If not,
yeah, I wrote that but after the valves thing, my bad.
"heavy" slants have about 4mm to 5mm or even more negative deck height. I assume it's ALL reinforced... that's why I asked. Maybe I can take more than .125 if that's correct. What's the worse thing that can happen? hitting the water passages?
OK, I'll have to check after I get pistons (or after measure carefully and get specs for a set of custom pistons) how much can I take off the block and how much can I take from the upper half of the piston. My idea was to go as far as I can taking space from the wrist pin to the piston head to reduce side stress
Darn it! I already got them valves!

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

You might be thinking of one of the articles that have been floating around for a few decades claiming there was a 240 CID slant-6 used in trucks. Which isn't true, there wasn't (sad to say).

We didn't get any of these what you are talking about (extra-heavy/extra-meaty blocks).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Wasn't there a heavy duty truck slant produced in the 60's used in Power Wagons? They were painted yellow, had shot peened rods and from what I remember, the block was beefier? Some other upgraded components were installed as well. Or am I wrong?

You're not wrong about there being heavy-duty slant-6s produced in the '60s and '70s. There were two levels of "heavy duty", depending on the application and severity of intended service. The changes were to internal components (e.g. chrome rings, bimetal bearings, double-roller timing chain, shot-peened crankshaft, HV oil pump, polyacrylic valve stem seals, upgraded valve material, positive exhaust valve rotators) and to the calibration of carburetion and ignition timing curves. The blocks were not different or heavier than the passenger car blocks of the same years, but the HD blocks were "select" items (more rigourously tested on the assembly line).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

ACK! Does that mean those 150 and 250 Slant 6's on eBay every now and then aren't correctly described??????

Thanks

See? I got it wrong. IIRC one article from DD said to take in account the weight of the block if you're going to build a hi-output application and choose the heavier. Maybe that's what combined with the fact that we had those beefier blocks mislead me to believe you had those beefier blocks too. Specialty item? maybe like the RT crankshaft with less crankshaft throw (.77mm less but from thicker rod journals according to my measurements on those crankshafts) All of our crankshafts were shot peened, also most of the connecting rods were shot peened. (Truck, RT and light truck connecting rods are shot peened, coronados and polaras weren't). Light trucks and heavy trucks always had double roller timing chain and heavy duty double sprockets (cast steel I believe) Sadly, our cyl heads never got updated to the smiley face post '68 ( ? ) unit (with tubes and not the cast park plug well one) and we never got hydro cam slant sixes, since chrysler fevre argentina s.a. went out of operation in late '79.
In exchange, the ACTC (Asociación de corredores de Turismo Carretera or turismo road racing asociation, turismo is taken from the italian word application to describe good road cars) did cast some very few cyl heads with heart shaped combustion chambers and very well enlarged ports and valve seats, 1.7 & 1.44 or even larger. I'm after one of these... those have ACTC casted right below the thermostat housing location on the head on the top ridge... (easy to check out even if the head's dirty and installed on a car)

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

It is true that a 68 thru 76 block weighs a few lbs more then some of the other years but the cylinder walls and deck thickness is appx. the same through all the years.

To find a "better" SL6 block is more of a inspection & selection process instead of finding a certain year and casting number.
DD

Gee, for us is just as easy as finding a 906 ending casting #'s block. guess I got the good end at SOMETHING!

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Please apply some stamps and mail me one of those special thick wall SL6 blocks so I can get a look at it. Don't spend more then $5.00 on postage!
DD

Oohgeeze, Doug, if that's your limit on postage spending, then you should've asked Juan to mail you one of the special Magnesium thick-wall heavy-duty spicy-hot Louisiana-BBQ-flavoured big-inch slant-6s!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.