383 Quench Question

Posted By: JoesMopar

383 Quench Question - 02/11/11 04:35 AM

Can anyone tell me the best way to get quench from a 383 using the 906 heads? I looked at the Edelbrock closed chamber heads on Summit and I don't know if it was a misprint or what but it listed the bare 84cc heads for $900+ each. I think I want to use the 906 heads anyway, and if I don't like them I can always change things later on.

I'm not building a racing engine, just a nice street engine. I'm shooting for 375-400HP.

If it helps my other list of parts will be a Performer RPM, 750 carb (not sure which), XE 274 cam and matching springs, stock rockers, MP ignition, Dougs headers, and 2 1/2" exhaust. Not sure on the pistons, that depends on what you guys recommend for the 906's. The car also has a 727/3.23 SG set up.

Thanks

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/11/11 04:49 AM

http://www.summitracing.com/parts/EDL-60929/

$735 ea for complete head assemblies

If you build it with 906's & try to obtain quench you'll need quench pad pistons designed to work only with open chamber heads...The short block won't accept closed chamber heads later without a piston swap... Plus to obtain quench with your 906 heads is gonna require machining each chamber to equalize the depth plus machining each piston the set the quench pad height... It would be cheaper to build a zero deck short block & buy closed chamber heads whether you get Edelbrocks or Stealths...

Posted By: ahy

Re: 383 Quench Question - 02/11/11 04:51 AM

With 906 heads you would need a "quench pad piston" with a pad that extends up into the head cavity. The pad and/or chamber is machined to get quench clearance (.035-.040"). Only trouble is KB who makes quench pad pistons doesn't seem to make one for the 383. It would likley have to be a custom piston.

The Edelbrock's at $745 each (assembled, Mancini) may not look so bad if you can find a shelf stock flat top piston that gets you zero deck.

Posted By: JoesMopar

Re: 383 Quench Question - 02/11/11 04:56 AM

I just searched for those before I posted this and didn't see them. Thanks for the link.

This is what I found before http://www.summitracing.com/parts/EDL-609219/

So the KB 400's will not give you any quench with the 906's?

With a flat top, I could always figure what the comp height is and just have the block zero decked right?

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/11/11 04:58 AM

No! Leave those KB400's out of your motor or you'll be doomed to a 8.2 C/R...

Posted By: JoesMopar

Re: 383 Quench Question - 02/11/11 04:59 AM

Really? So even shaving the deck height wouldn't help? Or would that end up putting a valve into the top of the piston? What application are the KB 400's even for?

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/11/11 05:30 AM

Quote:

Really? What application are the KB 400's even for?

That's a great question.. Wish I could answer.. Off the shelf piston selection for 383's is terrible, to build a quench engine you'll want a compression height of around 1.9345, so far the best shelf piston I've found is a Diamond @ 1.92 which leaves the piston .0145 in the hole assuming a blueprint deck height of 9.98 & also assuming stroke & rod length are at factory specs... So to obtain a quench of .040 would require a head gasket .0255 thick... If you use a standard gasket at .039 + .0145 you wind up with a quench distance of .0535 which is right at the upper limit of being effective...

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/11/11 05:48 AM

To give an idea of how hard it is to get decent compression in a 383 with a piston that gives true zero deck height, a .039 gasket & a chamber volume of 84cc you'll have right at 9.5-1 C/R & you really need a small valve notch which would drop the C/R down to 9.25.... And with aluminum heads & good quench you really want to be at 10.5+ ........... To get there with 4cc valve notches in the pistons would require cutting the chamber volume to 70cc... The short stroke makes chamber volume critical... Another reason why guys build strokers..

Posted By: Pale_Roader

Re: 383 Quench Question - 02/11/11 02:13 PM

Quote:

To give an idea of how hard it is to get decent compression in a 383 with a piston that gives true zero deck height, a .039 gasket & a chamber volume of 84cc you'll have right at 9.5-1 C/R & you really need a small valve notch which would drop the C/R down to 9.25.... And with aluminum heads & good quench you really want to be at 10.5+ ........... To get there with 4cc valve notches in the pistons would require cutting the chamber volume to 70cc... The short stroke makes chamber volume critical... Another reason why guys build strokers..

If you're spending money on heads for this combo, the Brodix B1BS has 65-66cc chambers with a very good design that will net you some compression with zero deck. Last i checked they were around a couple grand a pair... not much more than the Edelbrocks, and a way better head overall...

Posted By: 71383beep

Re: 383 Quench Question - 02/11/11 02:29 PM

You could just go find some closed chamber 516 or the even better 915 head if you're looking to keep your project cheap. You would need to put a bit more $$$ into the 516s but they can be made to work.

I have 396/430 hp/tq with a set on my 383. I had much less with the vaunted boat anchor 906's on there before for the exact reasons posted above.

let the magazine guys have the 906's and other open chamber heads. If you want compression and quench closed chamber is the only way to go...IMHO

Posted By: JohnRR

Re: 383 Quench Question - 02/11/11 02:35 PM

Quote:

No! Leave those KB400's out of your motor or you'll be doomed to a 8.2 C/R...

Nope , the 400's will give you over 9 , it's the flat top 162 that will create a low compression pig .

As stated you can't get quench with 906's unless you get a custom piston or mill the 906's into a closed chamber.

Just buy a closed chamber head if you have a set of 906's that need to be rebuilt .

Posted By: cjs69mope

Re: 383 Quench Question - 02/11/11 02:46 PM

My Dads 383 has kb 400 pistons , 84cc edelbrocks heads and .039 gasket the motor has been decked so the piston is .005 inthe hole and the final calculated compression was 10.2-10.4 to 1 .
The motor runs strong with rpm intake and 750 holley hp vac sec carb
and mp electronic ignition Chrome box .
with the comps cams 275hl cam strait up .and hedman headers with 2.5 exhaust . = good fun burning the tires with quick stab of the throtle

he has even been pulled over for it and really was not trying to rip them up at all so he says

Posted By: ademon

Re: 383 Quench Question - 02/11/11 05:56 PM

Look for some 516 heads they will work fine for that HP level. I have a pair if in the Chicago area

Posted By: JoesMopar

Re: 383 Quench Question - 02/12/11 12:50 AM

Ok, I know I'm changing the direction here.

Lets say I get a pair of KB flat tops, zero deck the block, and use the closed chamber (84cc) Edelbrock heads....would that be decent as far as compression and quench? With a zero deck the piston should be as far away from the head as whatever the compressed thickness is of the head gasket I'm using right? So how about this plan? Now I just need a head gasket thickness.

Posted By: JohnRR

Re: 383 Quench Question - 02/12/11 01:04 AM

Quote:

Ok, I know I'm changing the direction here.

Lets say I get a pair of KB flat tops, zero deck the block, and use the closed chamber (84cc) Edelbrock heads....would that be decent as far as compression and quench? With a zero deck the piston should be as far away from the head as whatever the compressed thickness is of the head gasket I'm using right? So how about this plan? Now I just need a head gasket thickness.

Do yourself a favor and do not buy the KB162's , they [self censored] , lower in the hole than they should be and a CANYON for a valve relief , spend a little extra money and buy a set of speedpro 2315 or a few more and get a set of diamond 383 pistons if you need valve reliefs ...

Posted By: RapidRobert

Re: 383 Quench Question - 02/12/11 01:12 AM

Quote:

With a zero deck the piston should be as far away from the head as whatever the compressed thickness is of the head gasket I'm using right? So how about this plan?

(1) right and a 35-39 thou gasket will get your quench spot on (w piston rock potential measure it carefully/meticulously) (2) A true flat top at zero deck may have too high of a CR, A KB type piston that has a flat plateau to get the quench and the perimeter is lower plus the valve reliefs will most likely be a more street friendly plan unless you're building a killer w a radical cam and racing gas to keep it from pinging

Posted By: ahy

Re: 383 Quench Question - 02/12/11 01:13 AM

Quote:

Ok, I know I'm changing the direction here.

Lets say I get a pair of KB flat tops, zero deck the block, and use the closed chamber (84cc) Edelbrock heads....would that be decent as far as compression and quench? With a zero deck the piston should be as far away from the head as whatever the compressed thickness is of the head gasket I'm using right? So how about this plan? Now I just need a head gasket thickness.

With that setup and a common head gasket at .040" thickness you would have excellent quench and around 9.0:1 compression. If you had the heads milled to 71 cc's - which is quite feasible - you would be at about 10.25 CR. About ideal in my book for a slightly conservative mild performance pump gas engine.

Posted By: JohnRR

Re: 383 Quench Question - 02/12/11 01:57 AM

Quote:

Quote:

With a zero deck the piston should be as far away from the head as whatever the compressed thickness is of the head gasket I'm using right? So how about this plan?

(1) right and a 35-39 thou gasket will get your quench spot on (w piston rock potential measure it carefully/meticulously) (2) A true flat top at zero deck may have too high of a CR, A KB type piston that has a flat plateau to get the quench and the perimeter is lower plus the valve reliefs will most likely be a more street friendly plan unless you're building a killer w a radical cam and racing gas to keep it from pinging

KB doesn't make a quench pad piston for a 383 , which is absolutely stupid on their part.

I would also think a person would have some really loose fitting pistons to have piston rock that would contact the head using a .039 thick gasket ...

Posted By: HYPER8oSoNic

Re: 383 Quench Question - 02/12/11 03:17 AM

Do your RESEARCH on ALL of these routes (ideas)for more
compression. Then decide which is feasible to you in effectively giving the compression you need for the LEAST amount of cash outlay.

Posted By: JohnRR

Re: 383 Quench Question - 02/12/11 07:07 AM

Quote:

Do your RESEARCH on ALL of these routes (ideas)for more
compression. Then decide which is feasible to you in effectively giving the compression you need for the LEAST amount of cash outlay.

it's going to end up costing alot whether he gets a diamond or a flat top KB , with the KB you have to cut more off the block and the heads because of that canyon ...

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/12/11 07:25 AM

Quote:

Quote:

Do your RESEARCH on ALL of these routes (ideas)for more
compression. Then decide which is feasible to you in effectively giving the compression you need for the LEAST amount of cash outlay.

it's going to end up costing alot whether he gets a diamond or a flat top KB , with the KB you have to cut more off the block and the heads because of that canyon ...

Which is why I think a stroker makes so much sense... zero deck & decent C/R are easy to achieve, you actually need the flow good heads will provide & I wouldn't be surprised if it costs less than trying to accomplish the same quench & C/R with a stock stroke in a 383....

Posted By: JoesMopar

Re: 383 Quench Question - 02/12/11 09:02 AM

Ok, but the bottom line is this is a half ass budget build. I wasn't aware that there were such crappy piston choices for 383's and that 906's were essentially useless.

My setup, with the parts I listed, with a block that's been zero decked, KB flat tops (with the 5cc or whatever size valve reliefs), closed chamber 84 cc Edelbrock heads and a .039ish head gasket sounds like it should make decent compression and quench. Does that sound about right? I'm just hoping for a decent street motor.

Posted By: DblOJoe

Re: 383 Quench Question - 02/12/11 12:58 PM

I'd just go with the KB 400's and 84cc Eddy heads. I think on a budget build the extra compression is gonna do more for you than quench and you can save from having to cut up your heads.

Posted By: lokalik

Re: 383 Quench Question - 02/12/11 01:17 PM

this is my combo. stock rods and crank, 162s, eddy rpm performers cut to 72cc, the block was cut so that 162s were .005 in the hole (iirc), 6pk for carbs, tti exh. rear wheel hp 325, trq 350. i found out later that the 162s were so unpopular. have had no problems with the pistons or the motor, been together going on 5 years now. at next rebuild i will stroke it.

Posted By: RapidRobert

Re: 383 Quench Question - 02/12/11 02:44 PM

Quote:

I'd just go with the KB 400's

there's a set of em for sale right now in the parts section

. For sure cheaper than full retail

Posted By: 71383beep

Re: 383 Quench Question - 02/12/11 03:03 PM

I am using the 162's with a fair amount of block decking and upsized 516s. The CR is an actual 9.2:1 with the felpro gasket. With a street dom intake and 650 mighty demon and the nostalgia plus .474 cam she is dyno'd at 396/430. It runs great so yes you can get the 162's to work.

Posted By: ireland383

Re: 383 Quench Question - 02/12/11 03:22 PM

Quote:

I'd just go with the KB 400's and 84cc Eddy heads. I think on a budget build the extra compression is gonna do more for you than quench and you can save from having to cut up your heads.

I agree, that's what I'm running with an 80cc head. 9.9:1 compression ratio with no detonation and no quench really (.063). Let's say it's enough to through you back in the seat and leave 50 foot slabs down the road.

Without power braking.

Posted By: cjs69mope

Re: 383 Quench Question - 02/12/11 06:09 PM

The KB 400 is a dome top i told you this in the first post earlier .
I slapped together my dads 383 with the kb 400 edelbrock heads ,rpm intake ,comp cams 275 hl .525 cam and the cheapest headman headers summit sells . The car is a 68 charger with 727 trans and 3000 stall from PTC with 3:55 sure grip . I put a out of the box Holley 750 hp vacuum secondary , never tuned anything except the normal carb and timing adjustments .
I think i built the engine under 3 grand and the performace is awesome the car is a fun street car with unbelievable top end power .
IF you build it like this you will be happy ! you will be able to burn the tires with out brake tourqeing at will .
I would not buy the 162 pistion unless you want to take alot off the deck and heads . to get 9.0 to one compression !
the kb 400 will easy get 10to1 .

Posted By: HYPER8oSoNic

Re: 383 Quench Question - 02/13/11 02:19 AM

Quote:

Quote:

Do your RESEARCH on ALL of these routes (ideas)for more
compression. Then decide which is feasible to you in effectively giving the compression you need for the LEAST amount of cash outlay.

it's going to end up costing alot whether he gets a diamond or a flat top KB , with the KB you have to cut more off the block and the heads because of that canyon ...

There are other avenues of approach to get to the
anticipated compression ratio, than just the pistons.

Posted By: HYPER8oSoNic

Re: 383 Quench Question - 02/13/11 02:24 AM

Quote:

The KB 400 is a dome top i told you this in the first post earlier .
I slapped together my dads 383 with the kb 400 edelbrock heads ,rpm intake ,comp cams 275 hl .525 cam and the cheapest headman headers summit sells . The car is a 68 charger with 727 trans and 3000 stall from PTC with 3:55 sure grip . I put a out of the box Holley 750 hp vacuum secondary , never tuned anything except the normal carb and timing adjustments .
I think i built the engine under 3 grand and the performace is awesome the car is a fun street car with unbelievable top end power .
IF you build it like this you will be happy ! you will be able to burn the tires with out brake tourqeing at will .
I would not buy the 162 pistion unless you want to take alot off the deck and heads . to get 9.0 to one compression !
the kb 400 will easy get 10to1 .

Good combination!!

Posted By: HYPER8oSoNic

Re: 383 Quench Question - 02/13/11 02:25 AM

Quote:

Quote:

I'd just go with the KB 400's and 84cc Eddy heads. I think on a budget build the extra compression is gonna do more for you than quench and you can save from having to cut up your heads.

I agree, that's what I'm running with an 80cc head. 9.9:1 compression ratio with no detonation and no quench really (.063). Let's say it's enough to through you back in the seat and leave 50 foot slabs down the road.

Without power braking.

Nice!!

Posted By: JohnRR

Re: 383 Quench Question - 02/13/11 03:34 PM

Quote:

Ok, but the bottom line is this is a half ass budget build. I wasn't aware that there were such crappy piston choices for 383's and that 906's were essentially useless.

My setup, with the parts I listed, with a block that's been zero decked, KB flat tops (with the 5cc or whatever size valve reliefs), closed chamber 84 cc Edelbrock heads and a .039ish head gasket sounds like it should make decent compression and quench. Does that sound about right? I'm just hoping for a decent street motor.

What is your definition of DECENT COMPRESSION ?

Posted By: JohnRR

Re: 383 Quench Question - 02/13/11 03:37 PM

Quote:

Quote:

Quote:

Do your RESEARCH on ALL of these routes (ideas)for more
compression. Then decide which is feasible to you in effectively giving the compression you need for the LEAST amount of cash outlay.

it's going to end up costing alot whether he gets a diamond or a flat top KB , with the KB you have to cut more off the block and the heads because of that canyon ...

There are other avenues of approach to get to the
anticipated compression ratio, than just the pistons.

That goes without saying, but a better designed piston makes the other avenues less costly.

Posted By: JoesMopar

Re: 383 Quench Question - 02/13/11 04:31 PM

Quote:

Quote:

Ok, but the bottom line is this is a half ass budget build. I wasn't aware that there were such crappy piston choices for 383's and that 906's were essentially useless.

My setup, with the parts I listed, with a block that's been zero decked, KB flat tops (with the 5cc or whatever size valve reliefs), closed chamber 84 cc Edelbrock heads and a .039ish head gasket sounds like it should make decent compression and quench. Does that sound about right? I'm just hoping for a decent street motor.

What is your definition of DECENT COMPRESSION ?

I think you know more about it than I do, but I was thinking 9.5-1?

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/13/11 05:16 PM

Quote:

Quote:

Quote:

Ok, but the bottom line is this is a half ass budget build. I wasn't aware that there were such crappy piston choices for 383's and that 906's were essentially useless.

My setup, with the parts I listed, with a block that's been zero decked, KB flat tops (with the 5cc or whatever size valve reliefs), closed chamber 84 cc Edelbrock heads and a .039ish head gasket sounds like it should make decent compression and quench. Does that sound about right? I'm just hoping for a decent street motor.

What is your definition of DECENT COMPRESSION ?

I think you know more about it than I do, but I was thinking 9.5-1?

That number is obtainable but the thing is the aluminum heads pull so much heat out of the combustion chamber you really need another ,5-1.0 points of compression to start taking advantage of them....

Posted By: ireland383

Re: 383 Quench Question - 02/13/11 05:26 PM

I'm on the border with 9.9:1.

Posted By: HYPER8oSoNic

Re: 383 Quench Question - 02/13/11 07:24 PM

Quote:

Quote:

Ok, but the bottom line is this is a half ass budget build. I wasn't aware that there were such crappy piston choices for 383's and that 906's were essentially useless.

My setup, with the parts I listed, with a block that's been zero decked, KB flat tops (with the 5cc or whatever size valve reliefs), closed chamber 84 cc Edelbrock heads and a .039ish head gasket sounds like it should make decent compression and quench. Does that sound about right? I'm just hoping for a decent street motor.

What is your definition of DECENT COMPRESSION ?

Ah, like 100% PUMP gas friendly. BUT will make
great power with the highest allowable compression
for the octane used in HIS area!!

Posted By: HYPER8oSoNic

Re: 383 Quench Question - 02/13/11 07:29 PM

Quote:

That number is obtainable but the thing is the aluminum heads pull so much heat out of the combustion chamber you really need another ,5-1.0 points of compression to start taking advantage of them....

I'm on the border with 9.9:1.

Still do-able!!

Posted By: JohnRR

Re: 383 Quench Question - 02/13/11 07:29 PM

Quote:

Quote:

Quote:

Ok, but the bottom line is this is a half ass budget build. I wasn't aware that there were such crappy piston choices for 383's and that 906's were essentially useless.

My setup, with the parts I listed, with a block that's been zero decked, KB flat tops (with the 5cc or whatever size valve reliefs), closed chamber 84 cc Edelbrock heads and a .039ish head gasket sounds like it should make decent compression and quench. Does that sound about right? I'm just hoping for a decent street motor.

What is your definition of DECENT COMPRESSION ?

I think you know more about it than I do, but I was thinking 9.5-1?

The specs you give above ASSuMEing a 4.280 bore , 6cc valve canyon and a .041 head gasket , not sure what gasket is .039 , gets you 8.85 , .039 gasket is 8.88, 5cc/.041 - 8.92, 5cc/.039 - 8.96, you need to cut the heads to 76cc to get your 9.5, the 162 just plain sucks for the intended application.

Posted By: HYPER8oSoNic

Re: 383 Quench Question - 02/14/11 12:49 AM

Quote:

Quote:

Quote:

Quote:

Ok, but the bottom line is this is a half ass budget build. I wasn't aware that there were such crappy piston choices for 383's and that 906's were essentially useless.

My setup, with the parts I listed, with a block that's been zero decked, KB flat tops (with the 5cc or whatever size valve reliefs), closed chamber 84 cc Edelbrock heads and a .039ish head gasket sounds like it should make decent compression and quench. Does that sound about right? I'm just hoping for a decent street motor.

What is your definition of DECENT COMPRESSION ?

I think you know more about it than I do, but I was thinking 9.5-1?

The specs you give above ASSuMEing a 4.280 bore , 6cc valve canyon and a .041 head gasket , not sure what gasket is .039 , gets you 8.85 , .039 gasket is 8.88, 5cc/.041 - 8.92, 5cc/.039 - 8.96, you need to cut the heads to 76cc to get your 9.5, the 162 just plain sucks for the intended application.

The 162's are out of the question as you stated, unless used with an UNDER 78cc closed chamber type head (516's or early 60' 413's - non M-W's). The kb 400
works well with an 80 - 86 cc aluminum head, OR the "516" iron head (with larger valves) depending on how "strong" of a 383 you want!!

The 375-400 hp level is easy, it's
when you break the 475-500 hp level things start to get lot tougher (for streetability).

Posted By: JoesMopar

Re: 383 Quench Question - 02/14/11 12:57 AM

Ok, how about the KB 400's, zero deck the block, 84cc Edelbrock heads (don't want to machine them incase I want to use them on a 440 later on), and a .040ish head gasket.....what CR are we talking about? Does this sound good?

Posted By: ireland383

Re: 383 Quench Question - 02/14/11 01:18 AM

Quote:

Ok, how about the KB 400's, zero deck the block, 84cc Edelbrock heads (don't want to machine them incase I want to use them on a 440 later on), and a .040ish head gasket.....what CR are we talking about? Does this sound good?

I come up with 9.890:1. I used the .040 KB400's on my build to achieve the 9.9:1. Use this calculator. http://www.kb-silvolite.com/calc.php?action=comp

Posted By: JohnRR

Re: 383 Quench Question - 02/14/11 01:54 AM

Quote:

Ok, how about the KB 400's, zero deck the block, 84cc Edelbrock heads (don't want to machine them incase I want to use them on a 440 later on), and a .040ish head gasket.....what CR are we talking about? Does this sound good?

No need to zero deck the block just a cut to make it SQUARE to the crank centerline is all you need to do.

Posted By: JoesMopar

Re: 383 Quench Question - 02/14/11 02:10 AM

Any idea what that combo would put the CR at?

Posted By: RemCharger

Re: 383 Quench Question - 02/14/11 02:11 AM

Quote:

Can anyone tell me the best way to get quench from a 383 using the 906 heads? I looked at the Edelbrock closed chamber heads on Summit and I don't know if it was a misprint or what but it listed the bare 84cc heads for $900+ each. I think I want to use the 906 heads anyway, and if I don't like them I can always change things later on.

I'm not building a racing engine, just a nice street engine. I'm shooting for 375-400HP.

If it helps my other list of parts will be a Performer RPM, 750 carb (not sure which), XE 274 cam and matching springs, stock rockers, MP ignition, Dougs headers, and 2 1/2" exhaust. Not sure on the pistons, that depends on what you guys recommend for the 906's. The car also has a 727/3.23 SG set up.

Thanks

To the original question..
My thoughts, to get quench with a 906 and a .039 gasket , the piston would need a quench pad of around.120 height above deck.
On my street 383 I used .060 milled 516s with .080 in the hole pistons. It will not run on reg gas and makes somewhere around 425 hp. Its cheap and ez, works well. With my cam choice and 3.23s it needs to see 25-30mph before it turns on.

Posted By: DblOJoe

Re: 383 Quench Question - 02/14/11 04:38 AM

Quote:

Ok, how about the KB 400's, zero deck the block, 84cc Edelbrock heads (don't want to machine them incase I want to use them on a 440 later on), and a .040ish head gasket.....what CR are we talking about? Does this sound good?

That's the best thing to do, I used the KB 162's and cut my heads down to 70cc to get compression. It runs pretty good but was pretty costly for what it is. The KB 400's weren't out when I built it though.

Posted By: Fury Fan

Re: 383 Quench Question - 02/14/11 10:02 PM

Quote:

You could just go find some closed chamber 516 or the even better 915 head if you're looking to keep your project cheap.

Fixed. Just in case anyone comes researching thru this thread at a later date...

Posted By: 71383beep

Re: 383 Quench Question - 02/15/11 12:24 AM

Quote:

Quote:

You could just go find some closed chamber 516 or the even better 915 head if you're looking to keep your project cheap.

Fixed. Just in case anyone comes researching thru this thread at a later date...

Well i'll be humdinger...whoops! my bad. I am glad you caught that!

I fixed my post too, but yes kb 162's some meat off of the block, and worked 516's with a decent cam will get you 400 hp which is what the OP is after. I also receomend a full point more if going to edelbrock in which case different pistons are the better route.

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/15/11 01:57 AM

Quote:

Quote:

Quote:

You could just go find some closed chamber 516 or the even better 915 head if you're looking to keep your project cheap.

Fixed. Just in case anyone comes researching thru this thread at a later date...

Well i'll be humdinger...whoops! my bad. I am glad you caught that!

I fixed my post too, but yes kb 162's some meat off of the block, and worked 516's with a decent cam will get you 400 hp which is what the OP is after. I also receomend a full point more if going to edelbrock in which case different pistons are the better route.

But as JohnRR mentioned earlier in this thread the KB162's are the ones to avoid, the KB400's are a better choice, still not ideal but much better than the 162's.. It would be nice if one of the piston manufacturers stepped up & gave us a real good choice, currently none exist...

Posted By: JoesMopar

Re: 383 Quench Question - 02/15/11 02:21 AM

So with the dome of the KB 400 are there any issues with valve clearance or?

If I don't zero deck the block and just slap on a set of Edelbrock 84cc heads, .040ish head gasket and KB 400s what would be CR be?

Posted By: Dean_Kuzluzski

Re: 383 Quench Question - 02/15/11 02:23 AM

Quote:

Quote:

Quote:

You could just go find some closed chamber 516 or the even better 915 head if you're looking to keep your project cheap.

Fixed. Just in case anyone comes researching thru this thread at a later date...

Well i'll be humdinger...whoops! my bad. I am glad you caught that!

I fixed my post too, but yes kb 162's some meat off of the block, and worked 516's with a decent cam will get you 400 hp which is what the OP is after. I also receomend a full point more if going to edelbrock in which case different pistons are the better route.

Holy doorstops Batman!! There's still a use for them old 516's!?!?!?

I've asked the question on the Race forum before, got no definitive answer..................Which is better quench w/compression (516 closed chamber) or the marginally better airflow of an "no quench" open chamber head (906,902,346,452)??

Posted By: 1_WILD_RT

Re: 383 Quench Question - 02/15/11 02:30 AM

Quote:

So with the dome of the KB 400 are there any issues with valve clearance or?

If I don't zero deck the block and just slap on a set of Edelbrock 84cc heads, .040ish head gasket and KB 400s what would be CR be?

The standard answer is you need to check for your application but generally the KB400 does still have valve clearance notches they just put a raised dome that fills some of the dead space in the combustion chamber... The dome will impede flame travel & may lead to less than ideal combustion but you need to do something on a 383 to raise the C/R & a dome offers more gains than losses...

Posted By: DblOJoe

Re: 383 Quench Question - 02/15/11 03:53 AM

Quote:

So with the dome of the KB 400 are there any issues with valve clearance or?

If I don't zero deck the block and just slap on a set of Edelbrock 84cc heads, .040ish head gasket and KB 400s what would be CR be?

If you don't zero deck it the pistons will likely be around .030 in the hole and only give you 9.43 with a .040 gasket or you could use a steel shim and be around 9.87.
Zero deck and a .040 gasket would be 10.11

Posted By: JoesMopar

Re: 383 Quench Question - 02/15/11 04:12 AM

Quote:

Quote:

So with the dome of the KB 400 are there any issues with valve clearance or?

If I don't zero deck the block and just slap on a set of Edelbrock 84cc heads, .040ish head gasket and KB 400s what would be CR be?

If you don't zero deck it the pistons will likely be around .030 in the hole and only give you 9.43 with a .040 gasket or you could use a steel shim and be around 9.87.
Zero deck and a .040 gasket would be 10.11

Cool, would there be any chance at that point with the pistons interferring with the XE274 cam?

Posted By: DblOJoe

Re: 383 Quench Question - 02/15/11 04:21 AM

Quote:

Quote:

Quote:

So with the dome of the KB 400 are there any issues with valve clearance or?

If I don't zero deck the block and just slap on a set of Edelbrock 84cc heads, .040ish head gasket and KB 400s what would be CR be?

If you don't zero deck it the pistons will likely be around .030 in the hole and only give you 9.43 with a .040 gasket or you could use a steel shim and be around 9.87.
Zero deck and a .040 gasket would be 10.11

Cool, would there be any chance at that point with the pistons interferring with the XE274 cam?

No, but you should still check to see how much clearence you have.

Posted By: JohnRR

Re: 383 Quench Question - 02/15/11 05:41 AM

If you go with the KB400's I wouldn't bother doing anymore than a clean up cut to square the decks , if you zero deck it then you also need to cut either the heads or the intake to make up for the at minimum .024 off the block deck , that is the same as cutting .024 off the heads , the intake surface needs to be cut also, and don't forget the valley end rails will also need to be cut. But once you either cut just the heads or the intake that part is now married to that 383 block , otherwise later you will need to cut something to make it fit on another block.

I'm getting 10.0 with my 383 using 906's, Diamond flat top at zero , 3cc valve reliefs and heads cut to 79.8cc.

Posted By: Pale_Roader

Re: 383 Quench Question - 02/15/11 11:52 AM

Quote:

Quote:

Quote:

Quote:

You could just go find some closed chamber 516 or the even better 915 head if you're looking to keep your project cheap.

Fixed. Just in case anyone comes researching thru this thread at a later date...

Well i'll be humdinger...whoops! my bad. I am glad you caught that!

I fixed my post too, but yes kb 162's some meat off of the block, and worked 516's with a decent cam will get you 400 hp which is what the OP is after. I also receomend a full point more if going to edelbrock in which case different pistons are the better route.

Holy doorstops Batman!! There's still a use for them old 516's!?!?!?

I've asked the question on the Race forum before, got no definitive answer..................Which is better quench w/compression (516 closed chamber) or the marginally better airflow of an "no quench" open chamber head (906,902,346,452)??

I've got this same conundrum right now, or well, had it. I've decided that i'd rather have a crappier flowing head with quench for a nicer, more efficient engine than say, a possibly more powerful engine, thats less efficient, with an open chamber head and no quench. I'm still trying to figure out how far to go with porting my 516's. They dont quite port as well as the newer heads, but thats all i know. Never done a set. Until i can get a solid answer on that, i'll just clean 'em up a bit, big-valve the exhausts and shop for something better while i'm driving around on them.

And it must be just me, as i've seen no one else comment on this, but am i the only one here that has a problem with the whole quench pad idea? I understand the idea, and the need, and the lack ov better options, but it just seems so hokey to me. I'm not a fan ov domes on pistons either generally. From what i've seen, a cheap newer brand (Probe, Diamond, Ross) forged piston isn't that much more than a KB (at least where i live), and to move a pin (compression height) on a set ov pistons doesn't add that much more to the cost. I'd pay $200 more for pistons to get the true zero deck, even if it did mean i'd be stuck with 516's for a while.

Posted By: Dean_Kuzluzski

Re: 383 Quench Question - 02/15/11 03:10 PM

Quote:

I've decided that i'd rather have a crappier flowing head with quench for a nicer, more efficient engine than say, a possibly more powerful engine, thats less efficient, with an open chamber head and no quench.

"Possibly more powerful....that's less efficient" Not to bash but sounds like an oxymoron.

With the variance on combustion chamber from cylinder to cylinder (w/open chamber), bowl & template porting, exhaust valve update to 1.74, cubic inch size considered, using a flattop piston, and ultimately good quench................I'd be surprised to see an open chamber combination actually make better power. And then it would only be in the upper rpm range.

Not that anyone would ever waste the time to do an actual build/dyno comparison.

Posted By: 71383beep

Re: 383 Quench Question - 02/15/11 08:44 PM

Quote:

Quote:

I've decided that i'd rather have a crappier flowing head with quench for a nicer, more efficient engine than say, a possibly more powerful engine, thats less efficient, with an open chamber head and no quench.

"Possibly more powerful....that's less efficient" Not to bash but sounds like an oxymoron.

With the variance on combustion chamber from cylinder to cylinder (w/open chamber), bowl & template porting, exhaust valve update to 1.74, cubic inch size considered, using a flattop piston, and ultimately good quench................I'd be surprised to see an open chamber combination actually make better power. And then it would only be in the upper rpm range.

Not that anyone would ever waste the time to do an actual build/dyno comparison.

Well what happened to me was a comparison. With the 906 heads and KB 162's with just a freshened deck the car ran like crud and would barely hold a tune. I had other issues, but could tell that something was not right.

On the 2nd rebuild I knew better and I had the shop pull the motor apart and we figured out that the old combo was running 7.8:1 CR...

For the second build I gave them a set of 516s I had laying around and they put in the larger exhaust valve and ported them for better flow. they also cut the deck some and I had a true 9.2:1 CR. With a CC nostalgia .474 cam and a mighty demon 650 on a street dominator intake the motor was dyno'd and ran 396/430 hp/tq. I was happy as my target was 400 hp and the car runs great. So if you already have the 162's they can be made to work.

If I had to do it again I would go with diamond pistons and I would have hunted down a set of 915s. But my next build for the car will be a stroker 400.

Posted By: RapidRobert

Re: 383 Quench Question - 02/15/11 08:52 PM

Quote:

[ I'm still trying to figure out how far to go with porting my 516's.

from what I gather they can flow very well but the prob is iirc the exhausts (short side??) has to be dead on by someone who knows how to do them. Might check the Muscle Motors archives & see if you can access any of Dulcich's porting articles (also has articles on other iron heads, excellent stuff)