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Discussion Starter · #1 ·
Wanting to wake up the sound (mainly) of the 350/290 sbc crate motor in my 37 Ford coupe. I'm running a Turbo 400 with stock stall, 2.87 GM posi rear, Edelbrock EPS & 600 cfm Holley . Have heard the sound of the 270H & like it a lot hence the starting point for my search. Called Comp tech-line & they recommend the XE268 but have read that people complain about install failures with it. I realize that with this stall & rear gear combo, I'm looking for somewhat of a 'free lunch.' Anybody familiar with these grinds & willing to offer advice/opinions?
 

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The Comp. H270 s/b around 11:1 compression and some more gear. with 4 speed it’s nice with 3.73 gear. I have run it with 3.55 gear and a taller 1st gear and it’s ok. Both @ 3100 pounds. Runs nice in 327 so s/b even better in 350. Comp does not recommend anything bigger with automatic. I guess they would like to see loose converter. No experience with xe268.
 

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None of them work, not even the cam that comes in that 290 horse slug.
It’s only got 8 to 1 compression.
Then again if you want a raucous idle maybe a mutha thumpr is what you need.
It’ll sound wicked but not enough power to pull the hat off your head!
 

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None of them work, not even the cam that comes in that 290 horse slug.
It’s only got 8 to 1 compression.
Then again if you want a raucous idle maybe a mutha thumpr is what you need.
It’ll sound wicked but not enough power to pull the hat off your head!
I had to look that up to believe it.
There is tons of room for improvment here besides a cam.


350-290 Deluxe Tech Specs
Part Number: 19355659
Engine Type: Chevy Small-Block V-8
Displacement (cu. in.): 350
Bore x Stroke (in.): 4.000 x 3.480
Block (P/N 10066034): Cast-iron with four-bolt main caps
Crankshaft (P/N 93426651): Nodular iron
Connecting Rods (P/N 10108688): Powdered-metal steel
Pistons (P/N 93422884): Cast-aluminum
Camshaft Type (P/N 3896962): Hydraulic flat tappet
Camshaft Lift (in.): .450 intake /.460 exhaust
Camshaft Duration (@.050 in.): 222° intake / 222° exhaust
Cylinder Heads (P/N 93438648): Iron; 76-cc chambers
Valve Size (in.): 1.94 intake / 1.50 exhaust
Compression Ratio: 8.0:1
Rocker Arms (P/N 10089648): Stamped steel
Rocker Arm Ratio: 1.5:1
Recommended Fuel: Regular pump
Ignition Timing: 32° Total @ 4,000 rpm
Maximum Recommended rpm: 5100
Balanced: Internal
 

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The 290 horse crate 350 is in desperate need of head’s, you will find that the cam in it turns nasty in sound and fury with the compression gain from 64cc chambered head’s. The low compression that this engine has will garble the sound and performance of any new cam.

Just a pair of Ebay Chinese made low buck head’s will kick this thing in your butt.

There is a lot more that can improve this engine like D dish pistons and zero decking the block to absolutely optimize aluminum head’s but a set of inexpensive aftermarket aluminum head’s and a pair of .026 to .028 inch thick composite head gaskets will make this motor howl with your existing intake. A set of iron L31 Vortec’s will do much the same but now you have to add a new intake and change to self guiding rockers or totally rebuild the head’s for guide plates and screw in studs, mess around with guide to retainer clearance so by the time you dress a pair of L31’s your well into the cost of a set of aluminum head’s.

While on the subject of rockers the cam that’s in that engine along with 64 cc head’s will really rock with 1.6 rockers, the added lift will take advantage of the better port flow of aftermarket or L31 factory head’s. The GM cam in this engine is old school it really needs more compression, at the same time the long duration of the ramps and the moderate lift gives excellent lifter and lobe life. Back to compression; aluminum head’s will let you run a half to a full ratio higher than the much vaunted and deservingly so L31 Vortec compression gains.

So to repeat myself till I’m nauseated, the way to make this motor a meat eater is head’s.

Let us know before you buy and we’ll walk you through getting the best stuff for your bucks.

Bogie
 

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Cam is the original spec for the 350" / 350 HP engine from the 1968-70 time frame when they hade 10.25 to 11:1 compression.
It's also nearly the same cam that was in the 327" / 350 hp.....the most popular SBC cam ever made.

What the crate motor desperately needs is cylinder heads with smaller chambers and better airflow than the crummy smog era castings that come on it.
Get the compression ratio up above 9.5:! and better airflow and it will sound a lot better too.

Agree with Bogie....I'd be looking for heads. Current cam is fine. The heads are killing it.
 

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Yeah I wanted to come back to this a little to give some numbers that I’d expect based on experience with this engine. Where GM advertises this as 290 hp it actually usually does a little over 300 out of the box it came in. But the addition of modern head’s on that short block makes an easy 375 hp probably close to 6000 but still slightly under those revs.

With a little top end refinement on aftermarket or L31’s by cleaning up the ports adding a little stouter valve train components in like 7/16 th studs and roller 1.6 rockers, bigger primary headers like 1-3/4 inch diameter and a decent carb you can see 390 hp with a 650 cfm carb to about 410 hp with a vacuum secondary 750 cfm carb. You will see the torque move up into the 400 ft pound band as well. This is power you will immediately see and the engine will probably gain on less fuel burnt for the horsepower produced as well.

This is from not just better breathing than the SMOG head’s that came on this motor snd certainly the higher compression with smaller chambers but also modern chamber design that applies a heart shape and moves the spark plug as far to the bore center as you can get with colliding valves with the spark plug. For modern head’s this is a systemic change that makes power even more than the old camel humps which were mighty good in their day.

Bogie
 

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Discussion Starter · #9 · (Edited)
All due respect fellow members, I agree with most everything suggested. But, I am not concerned with making max power in the 37. The stock crate engine runs great & really has enough power for the way I use the lightweight fiberglass streetrod. With the deep tone of the headers & Flowmasters I have been reluctant to tear into it. I was just hoping to get a performance choppy lope & not lose the car's driveability/manners. If I can't get the performance lope without changing heads then I am willing to do that, but was hoping a simpler cam swap would get me the sound I want. I understand the comment about the 76cc head garbling up the sound of any new cam & if so I may have to go to a 64cc. I was trying to steer clear of the Thumper Cam series because of reading about poor driveability. Thoughts? Thanks for your time!
 

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Think you would be better off sound wise with just changing mufflers to get a more aggressive sound. I am a fan of Porter mufflers on dang near anything they will fit under.
 

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What is the big fascination with a sloppy idle that can’t get out of it’s own way?

It seems there are plenty of guys asking the same sloppy idle question over and over.

It reminds me of days in high school the saying was “all show and no go”.
 

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I guess some of the naysayers didn't read the first sentence of the OP's post. He apparently has a nice car that he likes to drive and he's satisfied with performance and is apparently not a "rip your ass' hot rodder since he's got that rear end ratio. Why criticize a fellow hamber? He is simply asking a question about a minor upgrade that he thinks he might like so either answer his query or don't.

When I built my 383 stroker with vortex heads and 9.1 dish Pistons, Edelbrock carb and air gap with a 2400 stall and a 288 Jaguar IRS and a 700R4 with selective lockup and a 270h Comp Cam I couldn't be happier with the performance and the sound, especially when I open up the electric cutouts. It's my daily driver it's not a race car. Who cares if you can turn a 10 second quarter? Add to that electric windows power steering power brakes tilt wheel air conditioning cruise control AFR gauge 1600 watt power amp with 12-in subwoofer in the trunk etc etc... When we build our cars we build what we want not what everybody else wants. The Judge is a schizophrenic luxury car that gets excellent gas mileage and I burn "regular". EDIT: The video doesn't work now. Just contacted the host and they said there's a problem with "short" videos.


 

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Wanting to wake up the sound (mainly) of the 350/290 sbc crate motor in my 37 Ford coupe. I'm running a Turbo 400 with stock stall, 2.87 GM posi rear, Edelbrock EPS & 600 cfm Holley . Have heard the sound of the 270H & like it a lot hence the starting point for my search. Called Comp tech-line & they recommend the XE268 but have read that people complain about install failures with it. I realize that with this stall & rear gear combo, I'm looking for somewhat of a 'free lunch.' Anybody familiar with these grinds & willing to offer advice/opinions?
The XE268 is somewhat modern split duration high intensity cam that opens valves more quickly (steeper lobes for same duration), thus putting more stress on the valvetrain. No reason to run it unless you are trying to maximize power. The 270H is really old school and would be a bit easier on the valvetrain and probably sound as you wish. I ran a XE278H in my 383 (10.3:1 w/65cc AFR heads) for some time and it really didn't lope - kind of a ratty sound if you know what I mean. If you know that you like the sound of the 270H in a similar engine and are not really concerned with power or mileage, I think it is the better choice for no other modifications. Remember the sound you will get is dependent on your CR and heads among other things. With the low compression you could probably advance the cam a couple degrees to get the dynamic compression up a bit and make the idle a slight bit rougher.
 

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To the OP, I’ll refer you back to your remarks at entry number 9.

This isn’t an exercise in max power, the recommended head change is for max efficiency. Max efficiency is best power for the fuel burnt and good engine lifespan.

There are two secondary fallouts from this.

- The first is the engine lasts a lot longer as these modern fast burn head’s do a much better job of mixing the fuel with the air for a more effective burn. Less fuel is pumped around the pistons or burned too late to contribute to power generation. The heads used on your crate engine are mid 1970’s through the 80’s specifically aimed at NOx reduction through cooling and slowing the burn. This was a time when there were SMOG devices that could deal with excess unburnt hydro carbons but not with NOx. So the OEM’s designed these large chambered, low swirl, low compression head’s with the spark plug way off to one side to slow the flame front and to reduce its temperature plus the use of EGR to get the NOx formation down to EPA limits. The cost was more fuel burnt or wasted in the exhaust combined with shorter bore wall, piston and ring life. The excess hydro carbon was torched off in the exhaust stream first by an AIR pump injecting air into the exhaust manifold and by the then available single stage converter technology. The advent of two and three way converters and electronic fuel injection opened the door to high efficiency head’s that returned compression ratios to a more effective burn that generates more power for the fuel used. It changed head chamber designed into the Ricardo heart chamber because with port injection putting the fuel on the backside of the valve all the mixing had to be accomplished on the intake and compression strokes inside the cylinder. So modern chambers are of high swirl design to break up fuel into a fine mist well mixed with the air and pushed into a pocket under tge valves closed off by the spark plug wall which moves inboard placing the plug toward the center of the bore to reduce burn time from the center out instead of one side across the n bore to the other side. These changes to the untrained viewer are almost innocuous but they are technically astounding in their result. This modern chamber carries through to improving carburetor and TBI injection because these mixtures as they pass through the manifold tend to stratify the mixture into an air and a fuel stream that modern head’s then remix similar as to how they mix puddles of fuel from port injection with the induction air inside the cylinder.

- The fall out from the increased efficiency of the burn besides an improvement in engine life and better fuel mileage is torque and power. Increased torque and power are just drop outs of modern head design, you don’t have to chase them they are there as an inclusion with all the other good properties of these head’s. Back in the SMOG head days getting 100,000 miles out of a 350 was a diligent effort, today with modern head’s 250,000 miles is typical. My Frankenmouse 350 in my S15 has 400,000 miles on the original pistons, bore walls, rings and bearings; knock on wood, it shows no signs of giving up. In its original build configuration it engine dynoed with 400 ft pounds and 412 horsepower using an old 454 TBI and modified program in the computer. Today I pulled the injection out for an Edelbrock AVS which costs some mileage compared to the EFI systems it mounted over the years being a shop test truck. On the street and driven sanely it would long distance commute at 22 mpg with EFI though the way I drive 15 to 17 was more common. Driving with the extra power just isn’t apparent unless you provoke it. As I said it’s just a design fallout of modern heads.

In your case you’ve got a classic muscle car era cam in the block with those crappy head’s. A head change will greatly improve power and efficiency in terms of reduced fuel consumption, greater torque and power and doubled or more engine life. The compression increase will pick up the cam’s innate characteristics of a crisp, sharp toned idle. Bolt on aluminum head’s with a 9 to 9.5 compression ratio will burn 87 octane in cool weather maybe want some 89 in hot weather. It gets you around this nonsense of cam and muffler changes in search of the “right” sound plus you get way better power and engine life span.

Do I get excited about other power enhancing changes well you bet I do but if you don’t want to push the envelope you don’t have to. The simple effort from where your at is just get a pair of cast iron aftermarket head’s from Summit, Jegs, Speedway with modern often called Vortec chambers as bare heads if you get a set that uses a 1.94x1.5 valves of stock length springs and accents your existing intake you can reuse those parts. If you want to lean on the envelope a little and are OK with bigger valves the aftermarket aluminum is a good way to go. Most aftermarket s will preserve using your existing intake and rocker covers.

The engine you have is a technological mistake it is nothing but the old Target Master bottom of the barrel truck engine with a L46/L82 cam stuck in it. It boils down to a good cam against crappy head’s. Any replacement performance cam will perform and sound the same as what is in the engine now because the root problem is the chitty heads.

Bogie
 

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Discussion Starter · #15 ·
Thanks for your time & concise input. I am sold, I understand & am now searching for heads. Would appreciate any specific suggestions. What should I expect to pay for suitable cast irons? aluminums? Any advantage to aluminum besides weight? Thanks Again!
 

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Aluminum allows more compression for a given octane fuel.

Head suggestions needs some budget brackets.

Cast iron tends to be less expensive and with some shopping may be able to use the valves and other valve train components from your existing heads. Generally iron head’s with modern Ricardo/Vortec chambers are good to about 9.5:1 this varies a bit with vehicle weight and gearing. Heavy vehicles with higher gearing want less compression, light vehicles or those with stiff gearing will tolerate more compression.

Aluminum head’s almost always use larger valve diameters and longer stems so this adds cost whether you buy them bare or complete. In the case of bare your existing valves can’t transfer. But springs and retainers can be reused. The additional parts are seals while you there these aren’t too expensive and actually are easy to damage in disassembly so it’s just wise to get new ones. Aluminum head’s require a piece of steel between the spring as either a spring cup or locator. The cup is what you think of as a cup it has a hole in the center that goes around the guide and a raised outer lip that keeps the spring inside. The locator has a raised center hub that fits over the guide and a flat base. The hub keeps the spring on the base, generally used for single wound or single wound with a flat damper but not used for nested double or triple wound spring sets. Aluminum head’s also require longer push rods as these head’s typically move the spring and rocker package usually .1 inch further from the head deck than OEM iron and in some cases aluminum head’s. Generally aluminum head’s do not have exhaust heat crossovers for heating the intake. So if you use an exhaust heated choke stove and or need EGR aluminum head’s don’t support them. This is a sometimes attribute of iron head’s as well so this is another constraint that needs to be on your budget list. Aluminum head’s are pretty happy with compression ratios of 9.5 to 10.5.

Heads with Vortec only intake pattern 1996 up require a matching pattern intake which in your case would be another investment. Head’s that accept both the Vortec bolt pattern and the standard pattern of 1955 through 1986 will accept your current intake. The pattern used from 1987 through 1995 looks like the old pattern but changes some bolt angles so these are an outlier that are a pain to mess with these can be done but not something to get into on purpose.

There are so many head’s on the market your head will swim prices range from Chinese imports in aluminum bare on ebay starting around 370 a pair to say race ready Brodix at the catalog stores for 3000 and some change for a pair which is why we need a practical budget. Don’t know about anybody else but I can’t just throw money away, I go at builds very carefully.

Just go slow it’s easy to get lost in this maze of head’s.

BOOT’s got several vids out on YouTube on this subject as do others. A lot of guys get hung up on cosmetics which is unfortunate as a rough casting surface isn’t the same as high guide wear, hard seats that fall out or valves that pop their head’s, etc. so you need to keep what’s important information in mind and reject the superfluous. Keep in mind that nobody is producing 100% perfection.

Bogie
 

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Discussion Starter · #17 ·
After doing a little research, thinking $900 to $1000 for a set of complete aluminums. Considering the cost of the other needed pieces, spending more would make buying a complete new engine a better option.
 

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I bought a set off Dart SHP fully assembled, 180cc, 64cc chambers about 4 years ago for 1200. I found them on Amazon via Speedway motors.
I also looked at some China copy’s for around 850 fully dressed,
I went with the dart because I felt 350 was cheap insurance because dart was a known business with a good reputation.
 

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And down the rabbit hole you go!
Your intended 900-1000 buck heads will soon blossom into 2 grand Or more.
That new found power will need a better intake, cam, bigger carb etc.
Been there, done that myself on many occasions. And I’d do it again in a heartbeat!
Horsepower is addictive!
Happy wrenching!
 

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Discussion Starter · #20 ·
I know exactly what you mean. I am not new by any means to hot rodding with a 50 year history of competitive big block muscle Chevelles/Camaros & high winding late 60s/early 70s small block Corvettes (all with LT-1 64cc head starting points). For the last 18 years I've been dwelling on/ building LS powered Corvettes. This is just my 1st experience trying to do anything with a low compression sbc, hence seeking help from you guys. This 37 streetrod is just a cruizer. Appreciate the help very much but just saying this is not my 1st rodeo, remember I initially stated I realized I was looking for a "free lunch." Thanks!
 
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