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Username Post: 305 Performance Build advice/options        (Topic#373763)
Locus2298 
Newbie
Posts: 5

Reg: 09-12-23
09-12-23 01:27 PM - Post#2862502    

Hey guys, I have an 86 MC, LS, with the original 305. Heads have 14014416 casting numbers, which if I have my info right, are 1.84int/1.50exh, with 58cc heads. I was planning to install the next parts on it, all from summit:

- Comp Cams K12-600-4 kit
Cam specs:
279int/297exh
At 0.50 227int/241exh lift
.479int/.465exh valve lift
- Holley 0-4777SAE 650CFM double pumper carb
- A forged rods kit, tbd
- KB KB144.030 piston kit - advertised to have 10.5:1 CR with the heads I have
- Weiand 7547-1 Single Plane Intake

My question is, does anybody has a similar setup? What HP and TQ numbers are you pulling with a similar setup? Will this even work? I would like a nice low-end torque with hard mid-torque. I have a TH350, 300HP kit on it, stock converter and stock rear end.

Any opinion will be greatly appreciated.

I already know that a 350 will be better, however, I'm from Costa Rica and getting hands on a good junkyard block here is close to impossible, even more impossible to get a full 350 or any other SBC, so I want to squeeze all power from the 305 I have. Thanks.



 




Shepherd 
Valued Contributor
Posts: 3411

Loc: Lake George, NY
Reg: 11-11-15
09-12-23 02:56 PM - Post#2862507    
    In response to Locus2298

10.5 is too much compression with steel heads. The cam and intake will hurt normal driveability unless you have more gear or a higher stall convertor.



 
Locus2298 
Newbie
Posts: 5

Reg: 09-12-23
09-12-23 03:17 PM - Post#2862508    
    In response to Shepherd

I believe I have a 2000RPM Stall converter, per my time driving the car it starts moving on brakes at around 1800-1900 RPM.



 
Shepherd 
Valued Contributor
Posts: 3411

Loc: Lake George, NY
Reg: 11-11-15
09-12-23 03:56 PM - Post#2862511    
    In response to Locus2298

My experience tells me that will not be enough with your planned mods. What rear gear ratio are you running?



 
Locus2298 
Newbie
Posts: 5

Reg: 09-12-23
09-12-23 04:03 PM - Post#2862512    
    In response to Shepherd

Stock 7.5" 10-bolt GM



 
Shepherd 
Valued Contributor
Posts: 3411

Loc: Lake George, NY
Reg: 11-11-15
09-12-23 04:36 PM - Post#2862513    
    In response to Locus2298

Ok, but what gear ratio?



 
Locus2298 
Newbie
Posts: 5

Reg: 09-12-23
09-12-23 04:48 PM - Post#2862514    
    In response to Shepherd

3.73

Also,forget about that cam, I believe the XE256H will be a far better option. These are the specs:

256/268
0.447/0.454

RPM range from 1000 to 5500 rpm

I think that will give me the torque I want with the other components



 
Shepherd 
Valued Contributor
Posts: 3411

Loc: Lake George, NY
Reg: 11-11-15
09-12-23 04:57 PM - Post#2862515    
    In response to Locus2298

Gear ratio will get the job done, but 65mph cruising will be around 3k, depending on tire size. Better cam choice. But compression is your next issue. My 305 with 60cc chambers and the block quench decked. .042 head gaskets, flat top .030 over pistons with 4 valve reliefs is right at 9.4 on paper.



 
Locus2298 
Newbie
Posts: 5

Reg: 09-12-23
09-12-23 06:59 PM - Post#2862518    
    In response to Shepherd

I will install domed pistons, 0.30 OB. The head gasket will be an standard one. With the pistons I chose, I should get around 10.1:1 on paper. The pistons I will use are on the specs I posted.



 
bobb 
Super Senior Member
Posts: 6663

Loc: paradise
Reg: 09-05-03
09-17-23 10:52 AM - Post#2862619    
    In response to Locus2298

make sure to get the correct quench. i would do a mild head port job. practice on a junk head to get experience. look at david vizard videos. stock rods will work fine. single plane is a mistake. send us some pasteles. lol

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


Edited by bobb on 09-17-23 10:57 AM. Reason for edit: No reason given.

 
bobb 
Super Senior Member
Posts: 6663

Loc: paradise
Reg: 09-05-03
09-24-23 10:06 AM - Post#2862801    
    In response to Locus2298

another option if you have the desire and funds is a baby blower. it will add a ton of torque that would make it a blast to drive. downside is they tend to eat up tires. lol

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
Bad56Sedan 
"17th Year" Gold Supporting Member
Posts: 1854
Bad56Sedan
Loc: Pasadena, Texas
Reg: 04-29-04
10-05-23 10:34 PM - Post#2863126    
    In response to Locus2298

find this article

Attachment: 001.jpg (999.7 KB) 140 View(s)




VC56S 2 door Sedan, 44 Years


 




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