Hot Rod Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
First off I'm new here so take it easy on me.I'm about to build my first SBC and need some advise
My block is a 350 which needs to be line bored due to it was missing the main caps when I got it.Also I am planning on having the block bored to 0.30 over.I've been told this is about the best over bore size on a 350.
Also I will be using 58cc heads that I picked up.I was told that the were great heads to run on a 350.They also have to bee worked.
I need to know what size cam to run.I don't want stock because I want to have a bit more than stock.Can I run a roller cam without having the valve train completly roller?
Timing chain vs. gear drive?Pros and cons from those of you have delt with both.
Flat top vs. Domed vs. Dished pistons?Pro and cons.
Also I'm curious to what the compression ratio will be in this motor.
Last on the carb.Elcetric or manual choke?I'm carb retarded.
Keep in mind I need this motor to run on pump gas.
Thanks for any advise you guys can give me.
 

·
Registered
Joined
·
3,441 Posts
We really need to know what you are putting the engine in for a carb/cam/intake choice. The pistons will need to be a flat top or slight dish to keep compression ratio pump gas friendly. Let us know if you want to be able to run 87 or if 93 octane is okay. There are alot of things you have to take into account to be sure you are happy with the engine. I am also curious what the heads came off of. I am guessing they are 305HO heads maybe??? If you decide to run a roller cam, you will need matching springs and roller rockers are probably a good idea due to the more aggressive lobes on the roller cam and the resulting increase in needed spring pressure.

Chris
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #3 ·
This engine will be going into a 97 GMC Sonoma.The octane doesn't matter to me as long as I'm not having to run racing fuel. I'm not sure what they came off of but they are 305 heads that were produced from 1980 to 1986. So no roller componets for me cash flow will not allow that. Thanks for your help any additional advise will be appreciated.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #5 ·
I'm not looking for monsterous amounts of horse power just what ever I end up with will be fine since it's going to be in a Sonoma.I'm trying to get away without running a stall if possible. I think I have decied on a Lunati Bracket Master II cam with a 284 Dur. and .458 lift because if falls in the rpm range I usally run an engine in.Thanks for your input and keep it coming.
 

·
The lean mean donut machine
Joined
·
386 Posts
First of all, if you want to run a roller cam you need to make sure you have a block from 1986 or later, or you will need big $$$ for a retrofit lifter system. Roller cams must use roller lifters and properly matched valve springs. If you are not going to shoot for monster horsepower you really don't need the extra expense with a roller cam. A flat tappet cam with about 220 duration at .050 lift should be good from idle to 5000 RPM with those heads. An Edelbrock Performer or Performer RPM manifold with a 600 or 650 cfm carburetor should work great for a street motor. As for the choke, personally I just yank them off, always seem to have problems with them not working properly, but if I had to use one I would go electric. If you are OK with using 93 Octane gas you could get away with flat top pistons with valve reliefs with the 58cc chamber, just make sure your machinist mills the block deck down to no more than .005 clearance. Octane boost may be needed, but the 11.7:1 compression really pumps up the power, I know from experience. If you want to go for total reliability, I would get a 10cc dish in the pistons to put the compression near 10:1. If you want to get the most out of your engine with the heads you have, I recommend doing a port and polish job on your heads. Even for beginners, it's really easy and inexpensive, and can get you an extra 20-30 horses. Check out the guide at www.sa-motorsports.com/portdiy/diyport.pdf
 

·
Registered
Joined
·
3,441 Posts
You will want to go with a slight dish piston. If you can find something in the 10cc dish range it will land CR at about 10:1 with .040 head gasket. That is still getting close to the limit with iron heads and pump gas. I would shoot for about 9.5:1 which will make plenty of power with no problems of preignition. That would take a 15-18cc dish piston. This is assuming .010 in the hole with .040 head gasket. Cam in the 215-220 range duration at .050 would make good low end torque and work well with 9.5:1 CR.

Chris
 
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top