GM Inside News Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter · #1 · (Edited)
I have been looking into rebuilding a 2 bolt 350 I have in my garage so far I am looking into the following setup. Bore .030 and utilize a 400 crank. rpm performer intake and camshaft, holley 750 double feed and a set of rebuilt 416 chevy heads which were from 305 H.O. blocks. The heads I was thinking of some decent z28 replacement springs since cam is mild and oversizing intake valve to 1.94. Do you think this would get me good enough flow and compression and would it cause any issues being the two bolt main. I dont think it will be rough enough to end up with any crank walk. I have been thinking of a 200 shot of nos but think it would be a little extreme on the block being it is 2 bolt and might wanna invest in a 4 bolt on that one. Any how I am not quite sure of the potential of a 2 vs 4 bolt main and any help would be appreciated. Also as far as trannys go which is recommended for a good racing combination 5-speed manny or th350 and what gearing would go good. I have been thinking of a 350 with 411 posi or the 5 with 511 posi.
 

·
Premium Member
Joined
·
2,431 Posts
When looking into a 383 it is best to know what you want HP or TQ and what it is going into. A 2-bolt main would be fine with a 400 crank and 400 rods 5.565" and oversized 350 pistons. This combination is a low rpm combo that is budget friendly and will produce big torque. With 5.7 rods custom pistons are required and the RPM range will move up. With a better crank and 6.0 rods get a 4-bolt block. Use ARP studs, 2-bolt or 4, for extra security.

The heads and Performer RPM cam/intake are mismatched. Use a performer cam and intake, or much better heads. A 383 puts greater airflow demands on the heads especially with the Performer RPM cam. Also the 750 double pumper is a bad choice. Unless you have a light car, a high-stall converter, a manual trans, or all three you'll want vacuum secondaries. A 200 nitrous shot is overkill. You will break stuff. For that you'll need forged pistons and really good heads. Nitrous works to a point, but too much nitrous with too much cam and too little head flow simply doesn't work and at best the air flow will stall at worst a fire in the intake will result and blow back through the carb (aka nitrous backfire).

I have been looking into rebuilding a 2 bolt 350 I have in my garage so far I am looking into the following setup. Bore .030 and utilize a 400 crank. rpm performer intake and camshaft, holley 750 double feed and a set of rebuilt 416 chevy heads which were from 305 H.O. blocks. The heads I was thinking of some decent z28 replacement springs since cam is mild and oversizing intake valve to 1.94. Do you think this would get me good enough flow and compression and would it cause any issues being the two bolt main. I dont think it will be rough enough to end up with any crank walk. I have been thinking of a 200 shot of nos but think it would be a little extreme on the block being it is 2 bolt and might wanna invest in a 4 bolt on that one. Any how I am not quite sure of the potential of a 2 vs 4 bolt main and any help would be appreciated. Also as far as trannys go which is recommended for a good racing combination 5-speed manny or th350 and what gearing would go good. I have been thinking of a 350 with 411 posi or the 5 with 511 posi.
 

·
Registered
Joined
·
65 Posts
It depends on what you want out of you engine. From what I've read is that a good two-bolt will support around 500HP. I don't know what it will cost to machean a standard four-bolt or splayed out of your two-bolt nowadays. But a good four bolt would be good measure some are cast with better "materials" than the two-bolts were.
 

·
Registered
Joined
·
7,316 Posts
Yeah I know you don't want to hear it, but the 750 does seem like a stretch in the real world. Then again, you do mention racing. If that's the case I would defintely invest in some decent heads. You could always change the heads down the road, but... Anyhow, I don't know how much it would cost you (I suspect somewhere around $700) but you might think about converting that block to a 4 bolt w/ splayed caps--especially if you've got racing in mind :)
 

·
Registered
Joined
·
336 Posts
I would not use the 305 H.O. heads, they have extremely small chamber causing a insanily high compression ratio unless you use piston with huge dish in them. The 305 head and very small valve and poor port design. I would look at using Vortec 5.7 heads, they way out flow most of the "high performance camel hump" heads, and they are very reasonable in price (cheaper than rebuilding those crappy 305 heads). Check with GM Performance Parts.
 

·
Premium Member
Joined
·
2,431 Posts
I would not use the 305 H.O. heads, they have extremely small chamber causing a insanily high compression ratio.
Yeah with flat-top 2vr pistons in a 0.30 over (383) about 11:1 with a thin FelPro gasket. Good for torque, but those 305 heads won't flow enough air to support more than 300hp. The port velocity would be awesome, I bet it would go turbulent around 4500rpm!
 

·
Registered
Joined
·
65 Posts
I would not use the 305 H.O. heads, they have extremely small chamber causing a insanily high compression ratio unless you use piston with huge dish in them. The 305 head and very small valve and poor port design. I would look at using Vortec 5.7 heads, they way out flow most of the "high performance camel hump" heads, and they are very reasonable in price (cheaper than rebuilding those crappy 305 heads). Check with GM Performance Parts.
He speaks the truth.
I debated using 305 heads when I was young and on a buget. I was building a 355 to replace my L69/305 HO in my T/A. Until I looked at the head spec and saw that the heads had a 58cc and a 1.85 intake and a 1.55 exhaust valves(I think, its been so long). Insted of putting work into the heads, and using a thicker gasket and buying dished pistons, I just did some work on the original 350's "smog heads".
 
1 - 7 of 7 Posts
Top