90 over 318 Head Gasket info needed !!

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I may be mistaken but I believe the early 318's (67-69) have thicker walls and forged cranks . Don't throw away those old 318's folks .
318's started production with cast cranks for the autos (most of the production numbers) and had a forged version available for some applications like heavy trucks.

Perhaps the machinists/builders who have measured a lot of blocks for cylinder wall thickness will share their observations on older vs later.

My '68 273 block has very little in the way of core shift vs. a much later 360 block. The front and rear walls (non-thrust walls) on the 273 are generally the same thickness as the inner and outer walls (thrust walls) while the 360 has the non-thrust walls thinned out compared to the thrust walls. So perhaps the non-thrust walls were thinned out on later blocks. But that is just a data set of 2 blocks so it not in any way conclusive.
 
Older the block normally the better this engine is going in a 66 Dart which will be run in the Super Stock division and with a Jerico.

View attachment 1715286660
Mmmmm!!! Jeweled finish on top cover... Transmission ****! Check out summit because they show bore sizes and volumes. Being race application I would go with head studs and MLS gasket construction... Expensive but reusable. Oh, never mind, that link to Cometic will give you what you want.
 
I've always heard heavy duty truck 318's are optimum for thick cylinders and steel cranks. I'll double check with my truck connection on what years, I've read up to '78-'79 but I would more believe '74-75. Still lamenting the '72 360 W-200 block I had but had gotten away from me.
 
Is .090" over on a 318 even doable? Just curious, as I have only done big blocks. We usually go .020, .040 or at the most .060, but 60 is pushin it! How much overbore will a 318 take? Is 90 the max? Thanks.
I've bored a 1971 La .130 over to 4.040.
It's only .065 material removed. The bores are .250 in some cases on the early stuff...

To the reader, I do not promise or guarantee that your 318 block will safely bore to 4.040.
 
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Just wondering how the webbing and main caps in those 318s stack up against 340 blocks, being that 340s have larger caps. I imagine that you can get some lightweight pistons and aftermarket rods that would come in at stock bobweight for the steel 318 crank to help keep the rotating mass down, but how well do those blocks live at 340 power levels? I am completely in love with this destroker 318, I imagine if the block could stand it that it could run insane rpm levels... Perfect for the class it is going to be running in!
 
Just wondering how the webbing and main caps in those 318s stack up against 340 blocks, being that 340s have larger caps. I imagine that you can get some lightweight pistons and aftermarket rods that would come in at stock bobweight for the steel 318 crank to help keep the rotating mass down, but how well do those blocks live at 340 power levels? I am completely in love with this destroker 318, I imagine if the block could stand it that it could run insane rpm levels... Perfect for the class it is going to be running in!
I heard friends say they cracked the no.1 main caps of the mp 318 blocks , they were turning them 8500 ish rpm.

If it's the main cap, find a tired 340 block, maybe one windowed from a rod 'not too many of those' ..but you get the point, take the caps and find one close enough for a line hone and adjustment to work.
 
I know it’s a lot to sink into a 318, but I was thinking along the lines of a Milodon aftermarket two bolt ductile cap and studs. Some builders “strap” the caps by milling the tops smooth and cutting them down 3/16 of an inch to put a piece of 3/16 steel under the bolts across the caps, but I don’t think the caps absorb shock as well. This may be an instance where a girdle and studs are more mandatory that optional.
 
I've always heard heavy duty truck 318's are optimum for thick cylinders and steel cranks. I'll double check with my truck connection on what years, I've read up to '78-'79 but I would more believe '74-75. Still lamenting the '72 360 W-200 block I had but had gotten away from me.
U right 75 and older SEEMS to be the more desirable ones for sure.
 
I'd like to see that bolted up in the car. How's it fit? What bellhousing?
Lakewood is out of business I was told
I'd like to see that bolted up in the car. How's it fit? What bellhousing?[/QUOtoldI
I was told Lakewood is out of business so looks like I will be.buying the Quick Time unit which is complete with all hardware.
 
Mmmmm!!! Jeweled finish on top cover... Transmission ****! Check out summit because they show bore sizes and volumes. Being race application I would go with head studs and MLS gasket construction... Expensive but reusable. Oh, never mind, that link to Cometic will give you what you want.
Thank you Sir
Yes do it right the first time.
 
I've bored a 1971 La .130 over to 4.040.
It's only .065 material removed. The bores are .250 in some cases on the early stuff...

To the reader, I do not promise or guarantee that your 318 block will safely bore to 4.040.
Do you know it a car or truck engine?
In my.caseI haven't a clue
I dont know how to tell the difference in car and truck blocks.
 
Like Mopar Official said, three bolts around the mounts in car and four in trucks, and like he had also stated, it doesn't matter in the '68 to early Seventies if car or truck. IMHO, Chry-Co probably kept the cylinder walls thick in the first gen LA castings to strengthen the deck and increase torsional rigidity were it was most needed with the new lightweight casting design until it was mandatory to reduce the volume of iron used in production. Same reason first two years of 360 blocks were cored with super thick T/A castings. Most were used in trucks, motor homes, and C-Bodies.
 
Good point on the Mopar cast cranks as well. I once had a gouged out 400 B crank that I used as a "hammer' to reduce other pieces of bad or unwanted cast iron from the Ford and GM foundries to make it easier to load for scrap. That crank never did break, no matter how hard or high it was dropped from, but the stuff it was hitting sure did!
 
Like Mopar Official said, three bolts around the mounts in car and four in trucks, and like he had also stated, it doesn't matter in the '68 to early Seventies if car or truck. IMHO, Chry-Co probably kept the cylinder walls thick in the first gen LA castings to strengthen the deck and increase torsional rigidity were it was most needed with the new lightweight casting design until it was mandatory to reduce the volume of iron used in production. Same reason first two years of 360 blocks were cored with super thick T/A castings. Most were used in trucks, motor homes, and C-Bodies.
Good info thank you
 
Good point on the Mopar cast cranks as well. I once had a gouged out 400 B crank that I used as a "hammer' to reduce other pieces of bad or unwanted cast iron from the Ford and GM foundries to make it easier to load for scrap. That crank never did break, no matter how hard or high it was dropped from, but the stuff it was hitting sure did!
Direct Connection book has foot notes saying cast casts were used in Competition etc.
 
I have been meaning to ask what's going on top of that build. Looks like a good foundation for a W2 econo setup.
 
I have been meaning to ask what's going on top of that build. Looks like a good foundation for a W2 econo setup.
Good assumption but we are not allowed any off set rockers so to be legal I cant run them - and must be stock valve angle !!!
I have some new rpm 340 heads and had them ported in middle GA @ Killians and we are also not allowed any air gap intakes so kinda limited ### Of course I had to order a new port o sonic from OFFY last week
It was one of the best if not the best single plane single 4 set ups of its time / once its in I will take it down and have it ported etc.
 
That's going to be a fun class to run, I think your combination definitely has potential to be very competitive. Is the weight limit with the driver? It reminds me a lot of the super stock Gene Fulton small blocks that ran IHRA at Bristol, back in the good ole days, 10 grand through the big end.
 
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