350 SBC build for Jeep. Need Help !!! Intake, carb, cam, efi and mileage. - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board
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Old 03-29-2010, 03:46 PM
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I would go smaller on the cam. I would stay in the 190's. Bowl blend the heads, 1-5/8" headers. The more you can get out of those heads to flow at low lift the better. Keep compression around 9.0:1.
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  #17 (permalink)  
Old 03-29-2010, 03:54 PM
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190's are you talking about duration @50" ?
Since these heads have 64cc combustion chamber's wouldn't that set my compression around 9:1 in stock form ? or do the original pistons have 50cc D-dish or so !
Wouldn't thinner head gasket's help the compression,, like the 1094 Fel-Pro ?
Is it absolutely out of the question using these stock exhaust manifold's ?

Best regards.
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Old 03-29-2010, 04:02 PM
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Quote:
Originally Posted by Icejeep
190's are you talking about duration @50" ?
Since these heads have 64cc combustion chamber's wouldn't that set my compression around 9:1 in stock form ? or do the original pistons have 50cc D-dish or so !
Wouldn't thinner head gasket's help the compression,, like the 1094 Fel-Pro ?
Is it absolutely out of the question using these stock exhaust manifold's ?

Best regards.
4" bore, 3.48 stroke, 64cc combustion chamber with a 16cc D-Dish and a .045 quench will put you at 9:0-1. A flat top with 4cc's will put you at 10.24:1. A bit high for those heads.

It's not out of the question using anything stock. The problem is when you want to increase torque and ultimately horsepower there are parts that you have to change. Stock manifolds are very restrictive costing you hp and tq.
There is always a big noticeable difference when you go from stock manifolds to headers.

In the end the only limit is your wallet.
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Old 03-29-2010, 04:14 PM
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As far as I'we seen there are good engine combos out there using only the stock exhaust manifold's and they are making acceptable power for what is.
I think that's what Icejeep is looking for. Thus having grate low end power with acceptable horsepower, since we all know that off idle torque is the winner during harsh off-road'ing condition.
I think it's just a matter of finding the right part's that fit good together, and If he want's to use the stock manifold's we, as true hotrodder's can hopefully sort out the ultimate combo that utilizes the part's he has, including the long block, that will still deliver decent gas mileage.
At least he has somewhat of decent compression ratio to make grate power for off-road'ing...

Monzter.
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Old 03-29-2010, 04:33 PM
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Quote:
Originally Posted by monzter
As far as I'we seen there are good engine combos out there using only the stock exhaust manifold's and they are making acceptable power for what is.
I think that's what Icejeep is looking for. Thus having grate low end power with acceptable horsepower, since we all know that off idle torque is the winner during harsh off-road'ing condition.
I think it's just a matter of finding the right part's that fit good together, and If he want's to use the stock manifold's we, as true hotrodder's can hopefully sort out the ultimate combo that utilizes the part's he has, including the long block, that will still deliver decent gas mileage.
At least he has somewhat of decent compression ratio to make grate power for off-road'ing...

Monzter.
Agreed, but he is keeping the stock heads, stock intake, stock tbi, and now stock exhaust manifold. The only thing that is left is the cam. So what combination of parts are you referring to?
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Old 03-29-2010, 04:49 PM
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Far as I'we read he is also considering going with a good aluminium Intake manifold and small 4 barrel carburetor, this might be better in term's of performance over the TBI along with similar mileage !

Monzter.
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Old 03-29-2010, 05:20 PM
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Quote:
Originally Posted by monzter
Far as I'we read he is also considering going with a good aluminium Intake manifold and small 4 barrel carburetor, this might be better in term's of performance over the TBI along with similar mileage !

Monzter.
You are right. I just re-read all the posts and he did not mention he was going to keep the TBI.

But, for a cold climate and off roading you can't beat efi (This was my train of thought and that's why I thought he was keeping the TBI). I know I'm going to get flamed for this but, I think with efi mpg's will be better than with a carb under normal circumstances. Unfortunately, his are not normal circumstances. With a huge lift and 38" meats, I don't think much can be done to increase mpg's. So how can he make this engine more suited to his application? I believe headers are a must as well as an RV cam since changing the rest of the parts are out of the question.

Keep the TBI and put the money you were going to spend for a carb and intake into headers. You are willing to change the rest of your exhaust but not the manifolds. Is it because headers are very expensive or hard to get in Iceland? Just trying to understand you better.
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Old 03-29-2010, 05:33 PM
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Hello fellow's
I'm not decide'd to go to Carburetor yet. But that's mainly because I don't have the computer, and loom for the TBI. but it's probably not that hard to get at some salvage yard here in Iceland.

Getting long tube header's might be a problem since the only thing i can use is some fender-well header's and that way it's kinda hard to run the exhaust all out the back of the Jeep, Also thought it might run more quiet with stock manifolds.
I don't have an exhaust yet, so I wanted to get your opinions about muffler's that would keep the 350 shut at highway speed's.
My friend's over here At Iceland say that it wouldn't be out of reach getting 15 MPG since these Jeep's aren't lifted more than maybe 2" as you'we seen on the picture's.

I'we heard very good stories about the Q-Jet but then again some guy's have flame'd all over it and called it QuadraJUNK
Myself have alway's ran Holley 4160, and my experience with them off-road'ing is that they are awesome, at least the carb's I'we ran. they ran really good at all kind's of angle's.

RV cam you say, I'we heard this phrase a lot lately but then again what does that mean, is this some kind of particular camshaft or is this just any stock/mild camshaft ?

Take Care.
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Old 03-29-2010, 05:49 PM
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I'm starting to understand you better. Ok, so clearance is a problem with longtubes.

I can't really comment on intake and carb. I always like to build with fuel injection but I'm sure someone will chime in.

An RV cam is a smallish cam (duration). Lower duration will give you more torque down low at the cost of hp up top. With more low end torque comes better fuel economy. You want to shoot for low duration, good lift and low overlap. With smaller cams you need to keep your compression ratio lower since they have low overlap and don't bleed off too much pressure.

My comments on mpg's are because you own a Jeep. They are bricks on wheels to begin with and when you lift them they are even worse off aerodynamically. When you install large wide tires you create more friction and weight causing the engine to work harder. My estimate on mpg's for your rig is around 12-14 mpg if perfectly tuned.

I own a 1984 Toyota Land Cruiser. With the original engine (4.2L I6) I was getting about 12-14 mpg with a carb which is decent for that engine. With a 3" lift and 33" tires I lost 2-3 miles per gallon.
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Old 03-30-2010, 06:10 AM
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it sounds like you don't want to change any parts. Which is fine, but if you don't intend to change anything then this thread should be about doing a stock rebuild.

Will a larger cam lose milage- yes. It'll also give you more power.
Will headers make a difference- yes. They also cost money.
Will better heads make a difference- yes. They also cost money.
Will a carb give you more hp- it can.
Will TBI give you better milage- yes.
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Old 03-30-2010, 08:28 AM
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As I said above It would cost my about 1000 $ just to get vortec's and that's a bit over my budget for now.
Header's are an option, IF I can find them cheap here in Iceland, but as for now I would like to stick with the exhaust manifold's just because of clearance issues, getting the exhaust all the way back.
I'm willing to change the camshaft, but i don't need a hi-performance camshaft with rpm range 2000-6000. just because far as i'we read my head's don't make much power above 4500 rpm. So I would just like to slip in a very mild 4x4-off road camshaft, that has very smooth idle and good off idle power. So I would use the most of my engine.
I'm still considering going with 4 barrel carburetor and intake. or just get the computer and loom for the tbi somewhere !
Is it true that pre '87 intake manifold's need to be modified a bit around the bolt holes to match up with '87 up cast iron heads ?

Greetings from Iceland.
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Old 03-30-2010, 11:11 AM
How fast is fast enough?
 
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If you need the computer controls, and don't run any really wild rock courses a holley vacuum secondary 600cfm carb would probably be fine, and they are cheap.

You can do work to the heads you have to gain 30hp.

headers make a BIG difference

a cam with about 210/215 duration @.050" is a VERY mild cam, it won't sound quite like a stock engine but its far from a high hp cam.
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Old 03-30-2010, 11:24 AM
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Thank's Ap.
I'm not into rock-crawling stuff, I'm mostly going to wheel in snow. At least NO big n bulky rocks
If I go the carburetor route, would you recommend any specific intake manifold or would stock cast iron be fine ?
I don't have anything against header's but for this particular application I had my thought's on running the stock manifold's just because them headers are so god damn loud during, especially during long trip's, and I thought it might be quieter with the exhaust manifold's.
I had my mind set on Edelbrock Performer Plus Cam Kit for this engine, since they say it's a good cam for towing, 4x4 - off roading. and has smooth idle.
what about LSA ? I see most cam be grounded on 110-114 LSA, would I benefit from going with narrower LSA ?
Also what lift should I aim for ? What can these stock head's handle ?

Thank's
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Old 03-30-2010, 12:12 PM
How fast is fast enough?
 
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Quote:
Originally Posted by Icejeep
Thank's Ap.
I'm not into rock-crawling stuff, I'm mostly going to wheel in snow. At least NO big n bulky rocks
If I go the carburetor route, would you recommend any specific intake manifold or would stock cast iron be fine ?
I don't have anything against header's but for this particular application I had my thought's on running the stock manifold's just because them headers are so god damn loud during, especially during long trip's, and I thought it might be quieter with the exhaust manifold's.
I had my mind set on Edelbrock Performer Plus Cam Kit for this engine, since they say it's a good cam for towing, 4x4 - off roading. and has smooth idle.
what about LSA ? I see most cam be grounded on 110-114 LSA, would I benefit from going with narrower LSA ?
Also what lift should I aim for ? What can these stock head's handle ?

Thank's
Lift around .450" or a little less will be fine on stock heads, you'll still need to replace the springs though. I wouldn't use a Edelbrock cam on a dare, there's nothing great about them except their marketing. HEADERS DO NOT MAKE IT LOUD, they won't change the noise level any appreciable amount. If you have a free flowing exhaust a 108-110 LSA would be ideal, if its choked up a 110-112 usually works better. A stock intake will work, but a USED performer or performer RPM from Edelbrock would be best, they can be had for about $50-$70 here in the states, not sure what it is over there.

If you're buying a carb I would consider a offroad type carb, something in the 500-600cfm range, 4bbl with manual choke and vacuum secondaries. the manual choke is because of high water, if you don't have to worry about running through really high water an electric choke is easier to use.
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Old 03-30-2010, 12:26 PM
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Quote:
Originally Posted by ap72
If you need the computer controls, and don't run any really wild rock courses a holley vacuum secondary 600cfm carb would probably be fine, and they are cheap.

You can do work to the heads you have to gain 30hp.

headers make a BIG difference

a cam with about 210/215 duration @.050" is a VERY mild cam, it won't sound quite like a stock engine but its far from a high hp cam.
Wouldn't a good running Q-Jet be better for his application, because of the smaller primaries and therefor he would gain mileage, and response ?
Have you consider this cam for your engine ? http://www.summitracing.com/parts/CRN-10004/
A friend of mine is running it in his 350 powered truck, and this thing has very good low end power along with good midrange. it's a real blast to drive.


Monzter.
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