Engine buildup!!!
 

I have purchased a set of heddman headers, an Edelbrock Performer intake, and a Edelbrock performer 600cfm manual choke carb.

The truck is a 69 GMC 910 with a 350 in it. Currently, it has the stock intake, 490cfm Quadrajet, RV cam, 305 heads ( I know they suck! ) 10:1 pistons .030 over, and yes, a Powerglide tranny!

With installing my new purchased equipment, do you guy's think there will be a noticable increase in power? the truck has dual exhaust of course, but it is like, 2 inch pipe, is this REALLY bad or will it be okay?

Must the engine be lifted to install heddman headers or will they fit in with the engine on the mounts?

Any help is much appreciated, If you have any tips on the intake and carb, please share!

I need all the help I can get!!!

Bandit

you can install the headers with the motor in. The 2 inch pipe should be OK, not ideal though.

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'69 CST Short fleetside
Lowered, 400 small block, 700R4, 4 wheel disc brakes, front & rear sway bars
See my truck at: http://www.geocities.com/low69cst/
Student at the University of Kentucky.
Feel free to message me on AOL, SN- SS95ZQ8
My Dad's projects:
72 Short Fleet 4x4 Chyenne Super
72 Long Fleet 4x4 Chyenne Super
Both 350 autos restored original

I think you'll like the new carb and intake. When I slapped a new Edelbrock carb on mine, I didn't notice too much power improvement, but it sure ran a lot smoother and more reliably. You'll probably notice more improvements with the intake.

If you haven't already, a worthwhile upgrade is an HEI distributor. It's like night and day compared to the old points stuff.

Thanks for the replies guys! What would be your guess as far as horsepower gain from the header, intake, and carb installation. The Performer intake as I believe is better for torque than it is horsepower, which is good with the powerglide. Would a 40hp gain be too generous?

Thanks again!

Bandit

I went ahead and got the casting number off the block, it is 3970010 which is either a 68 327 or a 69-78 or something 350. The guy I bought the truck off said the engine was a four bolt main from a 73 z-28 and with checking the other numbers, I came to the conclusion he wasn't bullsh!ting me. The engine stock was 245 hp, mind you, the heads had been changed as earlier stated to 305's. How much power loss would there be from these heads being installed. My comression ratio is about 10.5:1 i figure because I have to run premium all the time. Does high compression mean higher hp, or just a cleaner burn?

Just a note. Having 305 heads on a 350 will cause detonation or "pinging". Get yourself some 350 heads pretty soon or start running 110 octane. Detonation will kill a engine in a heartbeat. Been there, done that and got a T-shirt.
Ben

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67 Fleetside Custom C-10
SBC 350 .030 9:1 comp.
Comp Cams Extreme Energy XE256H-10
Carter AFB 600
Edlebrock performer intake
Screw in rocker studs
Oversize valves
Scat 350 crank
Everything balanced within one gram.
Marine grade plywood bed(looks awsome)

I would get a adj fuel pressure regulator to go with the carb.

Those edelbrock carbs tend to load up if they have more than 4-6 PSI of fuel pressure.

what will happen is it will push the needle out of the seat and load up pretty bad.

Some of those carbs are worse than others but I havent seen many that run good at 6psi and over.
PS. that goes for 600-750 edelbrock carbs as well as the old carter AFB's.

Why do the 305 heads cause detonation, or pinging? Don't they just boost compression due to the smaller combustion chamber?

Anyways, I just pulled the oil pan off the engine and to my suprise I found not one, but two ends of dipsticks. They have been brocken off right around the full mark. Has ANYBODY ever seen this before????? Also there were three self locking nuts off that plate that is attached beneath the crank. Most of these nuts were loose and I'm sure glad I pulled the pan off!!

P.S. What is the best octane boost? I usually use Super 104+ and it seems alright, but all suggestions are appreciated!


Bandit

Hey all, I'm putting in a new front and rear seal and I need some assistance on installing them. What kind of silicone should I use etc.?

back to the top

Whoa! I don't get it! 305 heads on a 350? 10.5 compression? junk in the pan? I think (IMHO) you should rethink the whole thing. and a powerglide? a 2 speed? I don't think this thing will do what you want it to do, no matter how much money you throw at it. What is your goal? daily driver? drag strip special? street bruiser? Tell us what your ultimate plan is, but I think (again, IMHO) you're headed in a couple of different ways, and setting yourself up for disappointment.
Bill - Tucson

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56 Studebaker 2 dr Wagon
66 Chevelle 2 dr 4 speed
71 C30 Longhorn
86 Monte Carlo SS
96 Tahoe

It's the kind of thing that I put 12k miles on in the summer, park it for the winter. I would like it to have better torque for off the line, but I don't plan on having it see over 5000 rpm. Headers are more or less for sound and gas mileage.

305 heads have small combustion chambers..along with limited flow, also smaller valves..they are a lighter casting, which makes them crack prone, also they wont desipate heat as well...which may cause hot spots which lead to detonation...if you have 10-1 pistons..which are for a 64cc head, the C/R will be a little over 10.5-1...with the small cam thats a lot of compression. Now a 64cc head and a bigger cam, like in the 268-270 range the motor will perform better, but with the 2 speed tranny, your kinda between a rock and a hard place. maybe a stall converter and 4:10s and ...i dont know...a TH350......

One Thing I would do if I were in your case would pick up a either set of Vortec Iron Heads or even the Etec Heads from Edelbrock. Either heads will out flow your current heads and give you a little more power and then I would definitely rebuild the engine and put either a TH350 or a 4L60 Tranny and get rid of that damned powerglide !! For street use the Powerglide is crap but either a 4L60 (700R4) or TH350 will be better for the street and give you a little better gas mileage !!

Here is my Engine Setup and my gas mileage just sucks but hell this is what I get for building a 350 like this

91 350 (non roller block but can accept the OEM Roller Cam and Lifters), L79 66 Corvette Cam, 3890462 Corvette Fuelie Heads, Flat Top Piston, Carter 9635 625 CFM Electric Choke, Edelbrock Performer, accell HEI, MR Gasket Headers(Old headers but were free) and I am running around 10.5 - 11.5 somewhere around there. And I am running approximately 350 HP and I have to run nothing less then 91 Octane (had to back my timing off just to run 91 effeciantly) and I am running TH400 Tranny w/ 3.73:1 Gear Ratio. My Gas mileage blows but I will not change my heads unless I have to but if I were running 305 Heads, I would get me a set of Vortecs in a heartbeat!!

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Truck #1 68 Chev LWB Fleet w/ Wood Floor (Sucks Gas and Hauls Ass!) and in process of Body Work...

Truck #2 1994 GMC Sierra SL w/ 4.3L Vortec V6, 4L60E Auto!!

Hey DMNall, What are your RPM's at 65 mph??

The pinging comes from the higher compression, which is what higher octane prevents. That's why higher compression engines require premium gas, and why premium gas is a waste of money unless you need it.

Glad my truck doesn't need premium - $1.11 a gallon's bad enough.



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Tim Rich
Kennesaw, GA
72 Stepside
65 Must@ng

$1.35 here. The Studebaker has 10:1 flattops, roller rockers, dart heads, and needs 91 octane. Paid 189.9 per gallon outside DelMar last month. Glad the 700R and 3:55's let me get 23 MPG.

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56 Studebaker 2 dr Wagon
66 Chevelle 2 dr 4 speed
71 C30 Longhorn
86 Monte Carlo SS
96 Tahoe

The thing is, My gas mileage is great with 22-23 mpg. I rev 3100 in the 65-68 range with the two speed and what I believe are 3.23 gears. I've been told that my rpm's sound too high for them to be 3.23's. People always say it sounds more like 3.73's.

Anyway, what kind of gas mileage increase can I expect from adding the headers intake and carb. I'd like to see 25, is this outrageous??

Bandit