Thanks to the answers and solutions for my questions.
I have chevy 400 sb engine that i want to build,(low Budget), its had dished pistons (low compression), i want to increase the compression instaling 305 heads with 58cc (iron),
i know that i need to drill the steam holes to the heads. i want to put 2.02/ 1.60 valves.
IS that possible? What kind of recomendations?

 

yes its possible,but your engine couldnt breathe for shat with that

 

Wich is your recomendation?

 

what are your plans for this engine ?

 

Actually, I've been in a car that had a 350 with 305 HO heads, and it did run for shat. My neck is still sore!!!
But have you talked to a machine shop to see if there's room to install the bigger valves? And the bore size of the 400 (1/8" larger than the 350) could be another issue. But if you're talking about the stock 305 heads, use them for a boat anchor. The intake runners are too restrictive on those, and nothing can be done to make them heavy breathers.
If you need more particulars, I have someone I can ask (the builder of the 350/305).

 

The 305 and 350 have a water jacket between the middle two cylinders. I have never checked but I think that water jacket continues into the head on both engines. That water jacket is going to be right on the compression ring of the head gasket of the 400. The 400 has a small steam hole instead of the water jacket. This must have come up before cause, guys would have run the old double hump heads on the 400's if they could. I can't say I remember what heads where used on the 400 back in the day.

 

I have a 350 block that I just looked at there isnt a water (hole) that goes between the cylinders. I also looked at several heads I have, a factory 400 head, a 1979 305 head and an 993 350 head. I believe the bore centers are the same on all smallblocks but the chambers on the 305 would be smaller which gives more room between the chambers. The steam holes in the 400 head are not in the center of the space between the cylinders there are two holes one near the water jacket hole and one near the head bolt hole other than this the heads appear very similer as far as water jacket holes go. I think the 305 heads would work but to make them flow enough it would take alot of work.

 

I went through this a little before it was cheaper for me to use vortecs but there is a guy who seems to know some about the 305 heads he is the fbird88 poster in this discussion http://www.hotrodders.com/forum/400-...=305+heads+400

 

I personally have built a 400 with TPI it was a torque monster, although I did use the stock 400 heads. and I have built a 327 TPI setup using the 305 TPI heads, (and currently building anouther for my '88 Vert) pulled like h@!! to 6k then it was like the fire went out, but lets face it 6k is enough for the street! if you need more than that get on the track. Oh the first 327 TPI was getting 24 mpg with my driving, and my user name was also my nickname in Highschool, I drive em hard!!! as long as you don't "need" high rpm git-r-done.

 

Put on my 1984 z28, street and strip ,drive on weekends around my island of PR