[Johnny406]

Starting to build a new engine for my 78 T/A. I have a 1971 400 2 bolt block out of a Catalina for the foundation. The crankshaft I will use is my new Molnar 4" stroke forged crank with factory length Molnar rods and JE flat top 421 pistons.

I want to build it to be a bracket motor with occasional heads up 1/8th mile racing with as much nitrous as reasonable (300 shot perhaps?). I've been running a 175 shot on the current 455 but don't want to push it any farther with the 2 bolt caps & bolts as well as the stock cast crank.

With that said, since this block wasn't drilled for 4-bolt caps I was thinking of going splayed and using the ductile iron Milodon 11525 caps.

Is this a wise strategy? I will also be bottom filling the block as well.

[chiefbigb]

Splayed caps would be my choice. Filling the block to the bottom of the water passages on a bracket engine is helpful. Redirecting the coolant flow from the rear of the block to the water outlet is worth the time also.

[Dragncar]

Wise, yes. Might want to get the front cap too.
I have PE billet caps on a 2 bolt 400 block. But the front cap with studs was a bit of a fitment issue. I had to make a cardboard cutout of my front cap and send it to Steffs so they could make sure the pan fit.
My Canton pan hit the studs.
Just find a shop that knows what they are doing because if they don't that is a big mess to fix.
Mine turned out sweet. Just took it out to the track to run it, break in the rings. I could not hook it up, track was not prepped, been 6 weeks since any race.
Could not hook on the line or even halfway down the track when I got back in it.
Now if you fill it let that stuff dry with a head or tq plate torqued down. The hard block changes things, bore distortion,.

[mgarblik]

My opinion on your build with heavy doses of nitrous would be to use 4 aftermarket caps. IMO, only the rear cap is rugged enough with support in the rear of the block to keep it in place. I would install long dowel pins in all 5 caps. Most of the expense will be machining the block. That being said, I would spend the extra $$ to use steel billet caps from Program Engineering vs any type of cast cap, mallable or ductile. Filling the block is too controversial for me to comment. Some people swear by it, some do not. I can only say that the block will need a refresh and re-hone once the concrete has heat cycled and taken a final set for best power as it will push the cylinders around initially. Good luck with your build. IMO, your starting with a good block casting.

[steve25]

If your 421 Pistons are indeed set up for the needed 20 degree valve inclination angle of a pre 1967 motor then the amount of lift you can run with those 14 degree heads is going to be limited, and may infact be a build issue

Do a mock up and check what you have without a head gasket in place.

[b-man]

Once you add up the parts and machine shop labor needed to upgrade your ‘71 400 block you might find you’re within a thousand dollars of a far superior aftermarket block.

Checking their websites today I saw the MR1 at $3600 and the IA2 at $4000.

Perhaps starting off with a more solid foundation is worth considering.

[AG]

Originally Posted by b-man

Once you add up the parts and machine shop labor needed to upgrade your ‘71 400 block you might find you’re within a thousand dollars of a far superior aftermarket block.

Checking their websites today I saw the MR1 at $3600 and the IA2 at $4000.

Perhaps starting off with a more solid foundation is worth considering.

That is the price of the block. It still need bore/hone, decking and maybe the mains sized so it's definitely not within a $1000 all said and done. I would still go aftermarket block over a done stock block with everything since you will have plenty of room to grow and will always be way stronger.

[chuckies76ta]

Like has been mentioned. Check out the after market blocks. Pick one and move on. Great investment in safety in my opinion.

[chiefbigb]

If he is doing heads up racing that does not have any rules about block material I would get a aluminum block. A iron block is a heavy piece where you don't want the weight. They are more expensive but repairable and light