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305 Build

 
MarkAK MarkAK
New User | Posts: 1 | Joined: 10/10
Posted: 10/02/10
10:27 AM

I built the 305 motor in the Popular Hotrodding article to add 150 HP to my 305.  After all is said and done, it does not idle and is extremley sluggish at the start (up to 2500 rpm) after that it comes on strong. The carburator is a new 650 Holly, less than 100 mile out of box. Intake is a RPM Air Gap, Cam is a XE268H grind Comp Cam with1600-58-- range Duration Intake 268 Exhaust 280, Duration @ 0.50 lift Intake 224 Exhaust 230, Valve Lift 0.477 Intake and Exhaust 0.480, Lobe lift Intake 0.318 Exhaust 0.320 The gears are 2.73, I plan to use it as a weekend driver with a little spunk if I can get it to run. The heads are 906 castings with I believe 64 cc chanbers, and steel shim gasket. It has dished pistons, compression is 135 to 145 all around. Has stock HEI distributor (no vacuum advance) ignition is set at 10 deg BTDC at 700 rpm in drive. Any help would be appreciated.  

miguelracing miguelracing
New User | Posts: 7 | Joined: 11/10
Posted: 12/02/12
08:38 AM

First: Are the heads worked for use the proper springs for the cam? Use a converter no bigger than 2000rpm stall. The heads must be cutted for 60 cc chambers to keep running on pump gas. Ignition set at 30 degrees total. Change the carburator power valve from 6.5 to 4.5. Jets lowered to 65 at front and 70 in rear. Raise the gears at least 3.08. My experience at the track with a roller factory block(1986)at the track in a 81 camaro with 3700#,3.42 gears and th350 tranny with the same cam specs but roller: 14.48 @ 97 mph. Recently, was installed a 700r4 tranny and in the highway runs better. This is the car to go anywhere and have fun during the weekends. And i have to screw some ricers who thought where running with a "slump" in the highway. I hope be helpful with this info.  

pepsi1 pepsi1
User | Posts: 81 | Joined: 10/11
Posted: 12/02/12
04:34 PM

I just looked that stick up. That is one stout cam...If you didn't put a 2000RPM torque Convertor in you trans, it won't idle. It won't start coming on until 1600RPM. It says you can use a stock torque convertor. Thats too tight a center/line to run a stock convertor. Like MiguelRacing said, you need to match the cam and valve springs.
  I hate to disagree with the writers that did this piece. But boy that really should be installed in a 350 and up CI engine. What they did is pushed the dur. numbers to get the small cylinder head to work.
  I'd hate to ask this, are you sure you got the cam straight up? Then I would just recheck all the settings. The high rear gear you have is not going to help either. You really need a 3:50 rear gear with that cam at a minimum. Install a vacuum advance HEI distributor. You can pick them up brand new for $100 on Jegs or summit. You do that and I'm sure that engine will come alive.  Grin  Cool

Bob  

pepsi1 pepsi1
User | Posts: 81 | Joined: 10/11
Posted: 12/05/12
11:59 AM

I have to ask this question as it seems the person that asked the question first never replied to any of the post answers.

If you used the 10239906 Vortec 5700 head L-31 64cc/170cc intake port volume. They have 1.94/1.50 valves already in them. You should have used the P/N 14014416,or 14014415. They have 58cc combustion chambers with a 1.84/1.5 valves. Those are the chosen heads to use. Don't believe everything you read.

Back a few months ago I had a guy that wanted to build a duplicate engine that was on the CHP magazine. When he started asking questions, and finally had the dollar figure. It was not an engine to run on the street. But he found that out before he went and spent money on parts, and machine work. He is building a smaller version of the same foundation. Grin  Cool

I don't know what the 305 is going in. I have a 1986 Monte Carlo SS. It has a 305 HO. That runs like its on fire. All I ever did was install a home made shift kit, back in 1985 when we bought it there wasn't much for a 200R4 trans. Then I installed a set of roller rockers. They had 1.6 ratio, and that will melt the tires if you don't get out of the gas. It has a posi 3:73 rear gear ratio. Thats really what you need to do to your car. With that big cam you need gear. As I said prior a 3:50-3:90 rear gear ratio will really wake that engine up.

Bob  

pepsi1 pepsi1
User | Posts: 81 | Joined: 10/11
Posted: 12/16/12
10:08 PM

miguelracing

Please don't bring up old post's.
Thanks
Bob  

kruso kruso
New User | Posts: 1 | Joined: 12/12
Posted: 12/20/12
06:47 PM

Bob...please check dates.  You can do it.

What are we going to do to get this place rolling?  

pepsi1 pepsi1
User | Posts: 81 | Joined: 10/11
Posted: 01/01/13
12:58 PM

Icon Quotekruso:
Bob...please check dates.  You can do it.

What are we going to do to get this place rolling?


Heay Kruso

I didn't pull it up. You should have said somethinbg to Miguelracing. I saw his last posted date. Its a dead horse so tell him. Go turn your rearend upside down.  

gtomustang gtomustang
Enthusiast | Posts: 457 | Joined: 06/09
Posted: 01/07/13
01:39 PM

do dead horses make dead horsepower ratings? or just dead reckoning? Smile

anyway, someone else may come around here and have that question on their mind...it won't hurt to answer and chase the tumbleweeds away from the site.  
Just because you can't do it...doesn't mean its impossible

dond1965 dond1965
New User | Posts: 48 | Joined: 12/13
Posted: 12/01/13
03:39 PM

seems all in agreement,needs lower gears,that would also require an even looser convertor,but overlooked was the need for a quick advance curve in the distributor.maybe advance the cam another 6 degees to boost the bottom end power,clean up the idle.