Today was a really bad day. I have about 400+ miles on my 350. It started smoking, just at idle and has been getting worse. I pulled the heads off this weekend and took them to the machine shop. They look really bad. The guides are so bad on two or three of the valves they are walking around and are rubbing the side of the combustion chamber, and the top of two valves are ate up where the rocker arm was hitting it a weird angle. I had these heads checked before I put them on, the guy at the machine shop replaced three guides and said the rest were good. WRONG!!!! The machine shop is under new ownership now and I know and trust the guy running it now. He looked at the heads and said wow, thats not good. I said yeah thanks.
Next, to add insult to injury I started asking him about my block. The same guy that checked the heads checked the block and said it didn't need bored. So I ordered pistons for it, some reconditioned rods and put it together. When I put the rings in the gap was .023, which was what speed pro recomended for nitrous. At the time I wanted to get the engine back together and in the car. What I didn't think about was the bore being way over spec, that part is my fault. So now I am going to have to rebuild the engine and have the heads redone. So I figure I am going to build the 400, or part the car out and get something nice this summer, I don't know which yet.

So this is my question, how much do 5.7 rods help in a 400? I have heard that its a really good thing to do. The reason I am asking is it would be cheaper if I don't because the engine kits are alot cheaper with the stock 5.56 rods. But if I am going to "build" the engine and I am only going to do it once and if the 5.7 rods will help I will do it.
Thanks for any advice.
Jason

 

I have heard that the 5.7's help alot with the side load on the cylinder walls, they are pretty thin anyway so anything will help. be aware if you go to 5.7's in a 400 you will have to buy pistons that are designed around those rods, standard 400 pistons will be too high and come out of the top of the block.

I once bought a rebuild kit from summit that had the new (5.7) pistons,rings,bearings,gaskets,oil pump,freeze plugs and lube for around $360.00 but it was about 8 months ago.

 

yeah, i saw the kit in summit, but there kits are for 76cc heads and they are 10.8 and 11.7:1 and I have 64cc heads.