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Old 05-04-2010, 09:36 AM
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Budget SBC build

Hello

My SBC needs a rebuild, but while rebuilding it, I'm going to put in a spare SBC which I plan to build from parts I have laying around (and get some experience out of the old parts).

I'm not after huge HP numbers but would like to get as much as possible out of it.

List of parts

- set of 71' 3986336X heads, lightly ported (1.94/1.50 valves, 76cc)
- 65' 327 cui shortblock with flattop pistons
- 750 cfm quadrajet carb
- 68' GM 'smiley face' intake manifold

I can maybe get the heads milled very cheap to bump up the compression, would that be a good idea? How much can be removed safely?

Cam suggestions?

Its going in a 68' vette (3200 lbs) with a th-400 (stock stall) and 3.08 rearend

Thanks

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Old 05-04-2010, 09:42 AM
How fast is fast enough?
 
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Quote:
Originally Posted by Roald
Hello

My SBC needs a rebuild, but while rebuilding it, I'm going to put in a spare SBC which I plan to build from parts I have laying around (and get some experience out of the old parts).

I'm not after huge HP numbers but would like to get as much as possible out of it.

List of parts

- set of 71' 3986336X heads, lightly ported (1.94/1.50 valves, 76cc)
- 65' 327 cui shortblock with flattop pistons
- 750 cfm quadrajet carb
- 68' GM 'smiley face' intake manifold

I can maybe get the heads milled very cheap to bump up the compression, would that be a good idea? How much can be removed safely?

Cam suggestions?

Its going in a 68' vette (3200 lbs) with a th-400 (stock stall and 3.08 rearend

Thanks
Since this is a spare enigne using left over parts just go with a cheap RV cam. SOmething aorund 210/214 duration on a 110LSA will be adequate. No point in milling the heads for the power level/use your going to see. I would get an Edelbrock carb if you can find one cheap- they're idiot proof and if that quadrajet has some age on it chances are it'll need rebuilding anyway. Don't spend too much time worrying about this engine though, its just spare parts, should serve as a temporary engine just fine though.
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Old 05-04-2010, 10:10 AM
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Quote:
Originally Posted by ap72
Since this is a spare enigne using left over parts just go with a cheap RV cam. SOmething aorund 210/214 duration on a 110LSA will be adequate. No point in milling the heads for the power level/use your going to see. I would get an Edelbrock carb if you can find one cheap- they're idiot proof and if that quadrajet has some age on it chances are it'll need rebuilding anyway. Don't spend too much time worrying about this engine though, its just spare parts, should serve as a temporary engine just fine though.
Thanks for the answer.

My qjet was rebuilt a few weeks ago so no problem there.

The shortblock is also disassembled and will get a hone/new rings and bearings.

I might be using the engine for a year or more and just for the fun of it I would like to see how much I can get out of it

The RV cam will give me the low end torque needed for my 3.08 rearend, right?
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Old 05-04-2010, 10:24 AM
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Quote:
Originally Posted by Roald
Thanks for the answer.

My qjet was rebuilt a few weeks ago so no problem there.

The shortblock is also disassembled and will get a hone/new rings and bearings.

I might be using the engine for a year or more and just for the fun of it I would like to see how much I can get out of it

The RV cam will give me the low end torque needed for my 3.08 rearend, right?
Correct. YOu can work on the heads and intake too if you want to spend some time on it. Porting supplies are cheap so that only requires time, but in this case anything more than some bowl work is just wasting time IMO.
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Old 05-04-2010, 10:26 AM
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I agree, I wouldnt put money into milling the heads for a temporary motor unless you plan on using the heads for a future build. Depending on your deck height id put a fel pro 1094 .015 SHIM gasket on it to bump compression a little. I believe that a 750 cfm carb is way too much for a 327. Id slap a 600cfm either q jet for a little better mileage or like previously stated an edelbrock for ease of use.
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Old 05-04-2010, 10:48 AM
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Quote:
Originally Posted by Cunferferth
I agree, I wouldnt put money into milling the heads for a temporary motor unless you plan on using the heads for a future build. Depending on your deck height id put a fel pro 1094 .015 SHIM gasket on it to bump compression a little. I believe that a 750 cfm carb is way too much for a 327. Id slap a 600cfm either q jet for a little better mileage or like previously stated an edelbrock for ease of use.
I can get them milled nearly for free, so I wouldnt use a lot of money on it.

I have not measured the deck height yet but will do

The 750 cfm qjet came stock on a 327 cui, 300 HP SBC from GM?

I know its maybe a lot of work to put into a spare engine, I take as an opportunity to get a little experience before I build my primary engine (which I will spend a bit more money on )
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Old 05-04-2010, 10:53 AM
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Well if you can get it done for free id go for it. I guess im just used to 600 and 650 cfm carbs standard to a sbc unless youre making a lot of power and have a lot of displacement
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Old 05-04-2010, 10:57 AM
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im in the same boat as far as getting experience as well, im just dumping all my time and money into one engine. I just couldnt imagine having to do it a year from now! Thats why i was saying not to get too carried away
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Old 05-04-2010, 11:43 AM
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The older intake you have, I`m thinking it has the the trough in front of the primary`s? If so make sure you use the correct gasket that blocks these holes off which is a gasket, metal plate then another gasket. If you use a regular gasket then exhaust gas will be plumbed directly into the intake and you`ll never get it to run correctly. A stock Quadrajet will run fine on your 327. Q-jets are "Air Dam" carbs, they only supply what the engine demands, this is why they were used on everything from 6 cylinders to 500 cubic inch monster V8`s. However, they do have to be calibrated for the given engine.
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Old 05-04-2010, 11:49 AM
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Quote:
Originally Posted by DoubleVision
The older intake you have, I`m thinking it has the the trough in front of the primary`s? If so make sure you use the correct gasket that blocks these holes off which is a gasket, metal plate then another gasket. If you use a regular gasket then exhaust gas will be plumbed directly into the intake and you`ll never get it to run correctly. A stock Quadrajet will run fine on your 327. Q-jets are "Air Dam" carbs, they only supply what the engine demands, this is why they were used on everything from 6 cylinders to 500 cubic inch monster V8`s. However, they do have to be calibrated for the given engine.
Thanks, intake/carb is that from my existing/original 327 cui vette engine
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Old 05-04-2010, 05:39 PM
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Even with a .015" steel shim head gasket your compression will only be about 8.8 to 1. Stay real mild with the cam or it will have a bad case of the "soggy bottom blues". 327's were not known for their low end TQ so with those gears I'd stick with something like the Summit 1102 which is the exact same cam as the Edelbrock Performer.
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Old 05-05-2010, 01:57 AM
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Quote:
Originally Posted by Hippie
Even with a .015" steel shim head gasket your compression will only be about 8.8 to 1. Stay real mild with the cam or it will have a bad case of the "soggy bottom blues". 327's were not known for their low end TQ so with those gears I'd stick with something like the Summit 1102 which is the exact same cam as the Edelbrock Performer.
yes that CR are on the low side, that was why I was considering milling the heads. How much can safely be taken off?

I dont know if the block has been decked, but I'll measure it later. I'm shooting at a CR around 9.2-9.5 if possible. Does that sound okay?

I was considering this cam

http://www.compcams.com/Cam_Specs/Ca...x?csid=85&sb=0

is that one too big?

Last edited by Roald; 05-05-2010 at 02:03 AM.
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Old 05-05-2010, 06:09 AM
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you're putting too much thought into this engine. Milling won't be worth more than maybe 5hp. Not a big deal. If you want good compression you need to run 64ish cc heads, you don't have them. In this case its no big deal since you just need an engine that runs. Just be happy it'll run on 87 octane and take full spark advance.
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Old 05-05-2010, 06:39 AM
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if you mill the heads enough to actually improve the car performance...

you will have removed so much material the intake will not port align and seal and the valve train geometry will be screwed up....
(so plan on the added cost of machining the the intake and custom length pushrods as well as decking the heads)

been proven 1000 times that each full compression point added only yeilds 2-3% HP gain...
numbers just to illustrate:
300hp a 8/1 is 309hp at 9/1....
with tall gears/3400lb car you need about a 20HP gain plus to have a difference you can "feel"...

it is fun to build what we used to call "a junk yard dog" motor but do you want to feed it a constant diet of 93 octane at 10.5/1 CR???

my $.02:
leave the motor stock,,, just swap in lower rear gears and strip every pound of weight possible off the car,,,then go have a blast....
with such limited TQ due to small cubes to make power,,,the rv or performer cam can't add add enough improvement over the oem 4V cam HP/TQ to make it worth while (with the tall gears)...

to really have a blast after the gears change,,,then add a 50HP shot of NOS in second gear!!!
(low compression can be a asset!!!)
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Old 05-05-2010, 02:50 PM
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Quote:
Originally Posted by red65mustang
my $.02:
leave the motor stock,,, just swap in lower rear gears and strip every pound of weight possible off the car,,,then go have a blast....
with such limited TQ due to small cubes to make power,,,the rv or performer cam can't add add enough improvement over the oem 4V cam HP/TQ to make it worth while (with the tall gears)...
I agree on the gears and weight but my personal experience with swapping the stock cam for a Summit 1102 says otherwise. It makes a difference you can definitely feel. The base 327 cam was pretty mild and GM used it in almost everything from 1960's 283's to 262's and 400's in the 70's up into the 80's in 305's and 350's. It is a "one size fit's all" and while for it's intended purpose worked well for any type of performance use just about anything is an improvement.

We swapped the 1102 cam into a couple 305's and it most definitely made a difference. One was a '63 Bel Air with a junkyard late 70's 305 2 bbl., 200-4R, stock 3.08 gears and 235/70-15 tires. While not fast it could easily haul 4 adults at 55 MPH in OD pulling 20 MPG without downshifting for hills and in fact rarely kicked out of lockup. The other was a 1980 Malibu coupe with a 305 4Bbl.,TH350 and 2.73 posi. Before it could barely squeak the tires, after the cam swap it could light 'em up fairly easy and keep 'em lit. That was with no other changes to the engine or car. Now everyone may not see as dramatic a difference but there IS a difference.

I would never reuse a flat tappet cam and lifters I hadn't personally removed so to me a new cam and lifters would be mandatory. For the difference in price between a Summit cam and lifters and a stock replacement what does he have to lose? A pass through the drive up window at McDonald's?
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