tips on squeezing HP out of a 400?

[blackhand]

Forgive my ignorance, but I am pretty unfamiliar with the Chrysler 400. It seems like this is a great engine to build if you're willing to replace the bottom end, mill the block or the heads, etc.

The problem is that I went a little over budget on the '67 Barracuda that I picked up and I really don't have the cash to make expensive modifications like that. Does anyone know how to get some decent HP, say 350 or so, out of a 400 using stock internals??

It already has some long tube headers, an Edelbrock carb, and a decent cam (.442int, .465exh, 214* int @.05, 224* exh @.05).

I would like to add a Performer RPM manifold and Performer RPM 84cc heads with a 0.020 compressed thickness head gasket.

Does anyone know what kind of compression ratio and HP this might yield? Any other suggestions for a low-budget build that doesn't require pulling the whole engine?

Thanks guys!

 

[oldkimmer]

...........The quickest easiest way is to offset grind the crank, find some .060 bearings.........1.2 jump in comp 12 more cubes.........kim.........

 

[blackhand]

That's a pretty good idea that I haven't thought of. Thanks Kim!

Let's keep the ball rolling.... any more suggestions anyone?

 

[superbyrd]

even with those eddy heads,you will still only be about 8.5-8.9 to 1 compression. the pistons on that 400 are anywhere from .090 to .115 below the deck. which is not a bad thing necessarily. hughes engines have developed a new line of whiplash cams that are designed to not bleed off so much cylinder pressure, and make great power in lower compression engines you can give them a shout with your plans and they can help.
another route,and can be alot cheaper,is to find a good set of "915" small chamber heads, or the old mid 60's 361/383 "516" heads. a set of the 516's on a low-comp 400 will bring the compression up to around 9.2-9.3 to 1. either of these ways will easily bring you into the 400 hp range without yanking the motor.

 

[Darter6]

Compression and the correct cam will make the world of difference as stated above.I really like the use if the "516" heads as a inexpensive start.9.1 is a good pump gas motor.Really research a correct cam.This can all be done for under $1000 bucks

 

[demon seed]

915 or 516 heads (make sure they've got the 1.74 exhaust valves) and shave the block deck to get the comp. up to 10 to 1.

 

[hw612]

here: http://www.hotrod.com/techarticles/engine/hrdp_0812_1100_hp_pump_gas_mopar_b_motor/index.html

 

[blackhand]

Ok, all great ideas.

If I went with the 915's or the 516's, would I still be able to run unleaded pump gas? What's a ballpark cost of getting the seats hardened?

 

[RustyRatRod]

There's not a lot you can do with stock parts to get compression even close to 9.1. Somebody sayin that has never tried...or has never actually blueprinted the compression. The actual blueprinted compression on the 400 is 7.6:1. Even with the 915 heads, you could not mill enough off to acheive 9.1 without milling so much off the heads and or block that you would also have to mill the intake heavily as well. That's a lot of money in milling, and really NOT the correct way to raise compression. KB makes a nice piston that'll get you there for around 400 bucks. Think of it this way. The 915 casting is VERY sought after. People who have them think they are frikkin gold. By the time you find some, buy them...if they are ready to bolt on, they AIN'T gonna be cheap....mill them, the manifolds and or block, you couldda popped for some KB pistons and probably Eddy heads as well. If you are gonna try to go the 915 route, I have ONE real clean one. It is a core, but I will garrantee it not to be cracked and let you have it cheap. I will never use it. It is the '67 big exhaust valve casting. I also have a 383 steel standard crank that is the same as the 400 but it's steel. It's a real nice piece and I'm probably gonna end up addin it to my scrap load to help pay for the heads on my truck. Unmodded, the 915s will only net you around 8.2-8.4 to 1. That still sucks for spending dough on heads when you could spend probably less on pistons and get up around 9.5 no sweat. The 400 can be made to run, but compression is dismal. Once you get the CC kit out, you'll see just how bad it is. Offset grindin the crank is a good idea. If you did that and the 915 heads and milled them some, I bet you would be in the 9.5 area....BUT look at the cash outlay for the heads and special crank work. By the time all that's added up, you couldda slammed you some good pistons in it and been ridin. Heck, do what I did. I was gonna do a 400, but I decided to do a 451. The pistons are $279 instead of $400, and you'll need a 440 crank, and there's some special grindin to do there. The mains have to be turned down to the 400 size and the counterweight diameter needs to be reduced by about 1/4". Also you'll need the 440 rods. Still though, you will have one hell of a better engine compared to the 400 for not too much more money. Just my opinion.

 

[1wild&crazyguy]

look at what mopar performance did with their duster and stock bottomed 400, they milled the heads a bunch, stuck a .528 cam in it, 3000 stall, 4.10 and ran 12's.

no eddy heads there...

 

[cudamark]

You don't say which heads you have now so we'll presume the 902's or 452's. For 350 HP, you should be able to get close with just a bigger cam/springs, and some minor head work....milling and porting. New pistons would get you there for sure but you said you didn't want to pull the engine. If it was me, I'd save my money until I could do it right.....stroker billet crank, aluminum heads, etc. How wild you go will depend on what you want to do with the car.

 

[efriedrich]

There's not a lot you can do with stock parts to get compression even close to 9.1. Somebody sayin that has never tried...or has never actually blueprinted the compression. The actual blueprinted compression on the 400 is 7.6:1. Even with the 915 heads, you could not mill enough off to acheive 9.1 without milling so much off the heads and or block that you would also have to mill the intake heavily as well. That's a lot of money in milling, and really NOT the correct way to raise compression. KB makes a nice piston that'll get you there for around 400 bucks. Think of it this way. The 915 casting is VERY sought after. People who have them think they are frikkin gold. By the time you find some, buy them...if they are ready to bolt on, they AIN'T gonna be cheap....mill them, the manifolds and or block, you couldda popped for some KB pistons and probably Eddy heads as well. If you are gonna try to go the 915 route, I have ONE real clean one. It is a core, but I will garrantee it not to be cracked and let you have it cheap. I will never use it. It is the '67 big exhaust valve casting. I also have a 383 steel standard crank that is the same as the 400 but it's steel. It's a real nice piece and I'm probably gonna end up addin it to my scrap load to help pay for the heads on my truck. Unmodded, the 915s will only net you around 8.2-8.4 to 1. That still sucks for spending dough on heads when you could spend probably less on pistons and get up around 9.5 no sweat. The 400 can be made to run, but compression is dismal. Once you get the CC kit out, you'll see just how bad it is. Offset grindin the crank is a good idea. If you did that and the 915 heads and milled them some, I bet you would be in the 9.5 area....BUT look at the cash outlay for the heads and special crank work. By the time all that's added up, you couldda slammed you some good pistons in it and been ridin. Heck, do what I did. I was gonna do a 400, but I decided to do a 451. The pistons are $279 instead of $400, and you'll need a 440 crank, and there's some special grindin to do there. The mains have to be turned down to the 400 size and the counterweight diameter needs to be reduced by about 1/4". Also you'll need the 440 rods. Still though, you will have one hell of a better engine compared to the 400 for not too much more money. Just my opinion.

What piston did you use?

 

[RustyRatRod]

I'm still acquirin parts. I have the KB280s though.

 

[efriedrich]

Are going to shave the block and or heads. What do expect your compression to be and what heads are you using. Thank for the info!!

 

[67valiant 100]

...........The quickest easiest way is to offset grind the crank, find some .060 bearings.........1.2 jump in comp 12 more cubes.........kim.........

Whats offset grinding the crank?

 

[ocdart]

Offset grinding is grinding the rod journals smaller and also moving the centerline of the rod journal away from the centerline of the mains. Offset grinding the rod journals by .060" will reduce the journal diameter by .060" and move the rod journal centerline .030" - the same as increasing the stroke by .030".

 

[superbyrd]

well,i am not god,nor some off-the wall super smart 'blah,blah,blah racin,but,i have put 3 different 400's together,running the "516" heads,fel-pro blues,and all three came out to 9.2 to 1. confirmed and verified static compression. period. not just pulled out of the *** guess. so,you can spend your money any way you want,or let the so-called "experts" tell you what to do. tear it apart and do one of the almighty "quench builds",blah,blah,blah,blah. or some bottomless pocket pro build.
516's are cheap. you can pick up a clean set for 50 bucks. time you put in bigger valves even,and freshen them,you still have in them way less than half the price of eddys. run one of the aforementioned whiplash cams,make 400hp without "PULLING OUT THE MOTOR". or atleast,that is what i read in your first post that you were trying not to do............

 

[Baxter61]

superbyrd you must be forgetting that since eddy heads and stroker kits came out that a "typcial" BB now makes 0 power, somehow the advent of these parts made old parts make less power than they used to and motors dont run without them. I personally seen some 400 stock bottom end motors with some 516s, a MP .474 cam and an eddy intake run like hell

 

[RustyRatRod]

Look man, nobody got snippy and smartass with you. Nobody insulted you, either. You gotta problem with how I do things? Mopar Muscle does it the same way. Read about the factory TRUE compression. "Well down in the 7s" is their direct quote. No way in hell is it a good idea to mill as much off heads and or block to make up that much compression. You wanna argue the point? Great. Do it with numbers, proof and good information. Not with insults and a smartass attitude. You don't know me from adam and I don't know you either. So let's lay off the stupidness, ok? By the way, here's the Mopar Muscle article. Go argue with them.

http://www.moparmusclemagazine.com/howto/mopp_0009_how_to_build_a_blueprint_bottom_end/index.html

well,i am not god,nor some off-the wall super smart 'blah,blah,blah racin,but,i have put 3 different 400's together,running the "516" heads,fel-pro blues,and all three came out to 9.2 to 1. confirmed and verified static compression. period. not just pulled out of the *** guess. so,you can spend your money any way you want,or let the so-called "experts" tell you what to do. tear it apart and do one of the almighty "quench builds",blah,blah,blah,blah. or some bottomless pocket pro build.
516's are cheap. you can pick up a clean set for 50 bucks. time you put in bigger valves even,and freshen them,you still have in them way less than half the price of eddys. run one of the aforementioned whiplash cams,make 400hp without "PULLING OUT THE MOTOR". or atleast,that is what i read in your first post that you were trying not to do............

 

[RustyRatRod]

Are going to shave the block and or heads. What do expect your compression to be and what heads are you using. Thank for the info!!

Nope. Not milling anything for compression. I will deck the block only to acheive the correct deck height. Chrysler was known for being a mile off with it. Only gonna mill the heads probably less than .005" just to clean them up. I do not recommend milling to get compression up. Some people go .020"-.030" thinking that will add some....and it does, but nowhere near what people think. In order to go from 7.6 to 9.5, you would have to mill well in excess of .100" off the heads. This will severely affect the valvetrain geometry, even when using adjustable rockers. It's just not a good idea. But can it be done? Sure. Oh and my compression will be no more than 9.7:1 when assembled.

 

[Baxter61]

Nope. Not milling anything for compression. I will deck the block only to acheive the correct deck height. Chrysler was known for being a mile off with it. Only gonna mill the heads probably less than .005" just to clean them up. I do not recommend milling to get compression up. Some people go .020"-.030" thinking that will add some....and it does, but nowhere near what people think. In order to go from 7.6 to 9.5, you would have to mill well in excess of .100" off the heads. This will severely affect the valvetrain geometry, even when using adjustable rockers. It's just not a good idea. But can it be done? Sure. Oh and my compression will be no more than 9.7:1 when assembled.

I agree with strokerscamp, milling is not the best way to build compression. I learned the hard way on a 360 by trying to use some lower compression pistons because they were $100 ish less than the more expensive ones. Well by the time I bought new pushrods, paid $80 to mill the deck, $80 to cut the intake face, and $120 to mill the heads, I figured out I shoulda paid the extra $100 for the pistons I wanted. Thats not to say trueing up a deck surface is a bad idea because its actually a good one. Just dont go crazy with the milling, cost yourself more in the end, and have a bunch of misaligned parts that have no resale value.

 

[superbyrd]

well stroker scamp,since you find it of importance to push your, "tear it down,add pistons",blah,blah,blah,when the OP stated he did not want to take the engine out of the car. he is looking for a cheap,up top,way to add some power to his current setup. you are the one that started the whole, "take it out,do this,do that". obviously you can't read,so,you are pushing your point. not everyone sees things your way,and the magazine guys are not the "holy grale" either. i agree with baxter,all you guys "think" old parts don't make any power since so and so said "quench build",or so and so do this",or so and so said do that". amazing,mopar guys were dominating the streets and the tracks way before all this "new" way of doing stuff came about. now,the guy asked "how to add some power to his 400 without removing the engine" do you have some insite to add,strokerscamp,or more blah,blah,blah,blah.......

 

[RustyRatRod]

lol

 

[superbyrd]

i have a 66 coronet 2-door sedan,77 400, uncut deck,stock bottom end,unported,un cut 516's with stock small valves,comp XE268,eddy perfomer RPM,box stock 750 holley VS,cheapie summit headers,2 1/4" duals with h-pipe and 40 series flows,727 with 2400 converter,8 3/4 with 3.55 gears and sure-grip,runs on 255/60/15 BFG drag radials. i have atleast 50 timeslips between 12.96 and 13.10. be glad to scan and send them,but,hey,you need fancy pistons and stroker kits,and all the rage to push a 3700 car down the track that fast with a low comp. 400 though huh? lol.

 

[blackhand]

Superbyrd, thanks for the lead on the whiplash cams, I will definitely look into that! You're right, I am trying to find ways to get some cheap horsepower... gotta make this barracuda run as fast as it looks!

StrokerScamp, thanks for your insight on the more in depth build. When I have the cash to do that, I will definitely keep that in mind but for now, I can only dream!

Gentlemen, you've all helped tremendously.