hey,
new to the forum, saw some good answers on here as i was browsing so hopefully you guys can help me out.

im currently building a 350 which i will probablydrop a stroker crank into. i wanna run a 2 stage direct port in it so i was looking at ways to up the compression ratio, one thing i was looking at is lowering the deck height ...., is this a good idea if so how much should i lower it ....., im using flat top pistons and 66cc heads. also would it be wise to put a bore on this engine ?? lemme know what you all think

 

The only way to know how much deck to get machined off is to do an assembly. With the crank and pistons in the block, the deck height can be measured. Typical factory assembly can have the pistons down in the cylinder around .030". Zero decking the block means machining that .030" off the deck. If you "guess" at how much to machine off, taking off too much can mean the piston will poke above the deck and will hit the head.

There's a big difference between building an engine and assembling an engine. A properly built engine is assembled and disassembled many times before it's done.

 

thank you good advice..., im then assumeing once i assemble my rotating assembly i should get it zero decked for a nitrous application..., also will putting a bore on this engine be better or worse for the compression that i need for nitrous?

 

If you care about the compression or getting to run as good as it POSSIBLY can, you should get it zero decked. PERIOD. Has nothing to do with nitrous.

Not sure about "putting a bore"? Most V8s come with 8 bores?

If you mean "have it bored", then yes, you probably should. That's the only way to be sure that all 8 cyls are perfectly round, perfectly straight, perfectly pointed at the crank, perfectly in a line, perfectly finished, and perfectly .... perfect. Did I say "perfect" enough? Again, none of that has any connection whatsoever with nitrous, or compression; that's just basic engine building if you want it to come out perfect. Oooppppss, there's that word again....

 

Block machining with start with a light decking to make sure the deck surface is square. The boring machine uses that reference to bore the cylinders. Wouldn't hurt to get the block line honed also.

After all that machining is done, the block is cleaned so first assembly can start. Clearances are all checked. Deck height is checked. If anything needs to be changed, the engine is stripped down and sent back for more machine work. Once the deck height is established, the short block is assembled and heads/cam are installed. With proper length pushrods, piston to valve clearance is checked. If not enough clearance, engine is stripped down again to get the pistons flycut.

Getting it all done properly can easily take a few months. Proper machine work can't be done all at once.

Wanting to use a lot nitrous means a lot of good parts and proper machine work. 4340 rods and crank. Forged pistons etc.

Nitrous is just a power adder the same as a blower or turbo. They artificially put more oxygen into the cylinders so that more fuel can be burnt. More fuel being burnt means more HP. A low compression engine can take more boost than a high compression engine. With any power adder, higher octane fuel is required to prevent detonation. The advantage of using NOS is that you can run a low octane fuel when you don't want to use the NOS but need to make sure a high octane fuel is in the tank before using the NOS. Turbos and blowers need high octane fuel all the time.