Thread: Building a new motor

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Hey! I'll take thos "trips" off your hands for a song; I don't sing real well, but I'd sure give it the old college try.



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Reading through this thread it seems to me that it would be a crying shame to give up on the three 2’s. Unfortunately, this particular offering from Demon (Barry Grant) was short lived and there’s not a lot of information out there. I was able to dig up the information below from several sources. While it seems pretty good, I cannot vouch for the validity of the content and I have yet to see the Demon 98 in person, but there’s some good information that may encourage you to keep after this setup or if you sell it to another CHR member this may be helpful.

There are actually two different types of Demon 98: the primary carb, which includes a choke mechanism (electric or mechanical) and idle mixture adjustments; this carb can be used in single-carb applications, as well. The other version is intended as a secondary carb, without a choke or mixture adjustment. Each carb is rated at approximately 205cfm and operates with 6-7 p.s.i. of fuel pressure, rather than the 3-4 required for Strombergs.

The center-mounted carb serves as the primary carburetor (P/N 9801), and the front and rear carbs serve as secondaries (P/N 9802). One very nice design aspect involves servicing, since the 98 shares common parts for the Demon 4-barrel carbs (bowl gaskets, jets, needle & seat, etc.), so there’s no need to hunt for oddball specialty service parts down the road.

The Demon 98 can function as a single unit or in multiples. When running two 98s, BG recommends using two primary-style carburetors. When running three 98s, you’ll need one primary and two secondary carbs. The primary carburetor is responsible for starting, idling, light off-idle acceleration and cruising. The secondary style carb(s) provides additional power when the primary carb throttle opens wide (this secondary actuation is handled with the adjustable linkage). The secondaries usually begin to open when the primary throttle plate reaches approximately 35 degrees. Because of a special high ratio linkage, both the primary and secondary carbs reach wide-open-throttle at the same time.
The primary carburetor features four adjustable metering circuits, including idle, main, accelerator pump and power valve. Float levels are also adjustable. The secondary carburetors feature both idle and main circuits, but offer no provision for adjusting either idle speed or idle mixture (these are pre-set at the factory). However, adjustments can be made to the float levels and to accelerator pump operation.

The primary carb (center carb) will be connected to the throttle. The upper rod activates the front secondary carb, while the lower rod runs the rear secondary carb.

The primary carb linkage features a slotted rod end that (once properly adjusted) will allow engine operation only fed by the primary carb, with the secondaries opening under determined throttle position.
The linkage rods feature both RH and LH threads (for equal thread adjustment at each end). The LH thread end is identified by a machined groove for easy visual identification.

Carb-to-manifold base gaskets are the standard gaskets for any 2-barrel Demon 98, Stromberg 97 or Holley 94 - Fel-Pro gaskets, part number 9264. Considering the 205 cfm per carb rating, at WOT, with all three carbs kicked in, theoretically we should have a combined 615 cfm.

In terms of air intake, the Demon 98 carbs accept the standard 2 5/8” neck stacks or air cleaner necks used on Stromberg 97s and Holley 94s.

DEMON 98 PART NUMBERS
9801 - Demon 98 primary carburetor
9802 - Demon 98 secondary carburetor
9901 - Demon 98 electric choke
9902 - Demon 98 manual choke
9903 - Three-carb linkage kit
9904 - Three-carb fuel log kit
142115 - Demon 98 inlet banjo fitting kit (one per carb)

DEMON 98 SPECIFICATIONS
Idle air bleeds - 0.063”
Idle fuel restrictors - 0.035”
Idle well diameter - 0.070”
Idle discharge orifice - 0.033”
Idle transfer slot thickness - 0.006”
High-speed air bleeds - 0.033”
Main jets - 0.049”
Emulsion holes (3) - 0.028”
Main well diameter - 0.136”
Main well exit diameter - 0.098”
Siphon break - 0.022”
Boost venturi (straight leg) orifice - 0.107”
Power valve (6.5) fuel ports - 0.040”
Accelerator pump - 30cc
Accelerator pump nozzles - 0.031”
Throttle plate thickness - 0.062”
Throttle bore diameter - 1 3/16”
Main venturi diameter - 0.980”
Airflow volume - 205 cfm

I'd disconnect the two outside carbs and warm the engine up to operating temp and dial in the center one in terms of idle and off idle. Then add the others back one at a time.

Best,
Glenn

Nice work Glenn.

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Thanks Glenn. After all the input I will be giving the 3 deuces a second chance. If all fails I will run it off the center 2 barrel. I spoke with my buddy and he is confident that he can get them up and running right. He is old school and gave me some tips and things to do while I have the motor out. I gave him all the specs that I now and my compression test results and he said unless the cylinders are screwed not to mess with lower end. He said I would probably have 700-1000 in the heads to get them redone. With that said I may just get a set of 64cc heads new. After some research I found that double hump heads can have some problems when getting work done(putting bigger valves). I have not gotten the heads off to see what in them yet. I looked at a set of Blue Print 195 cc runners with 2.02/1.60 64cc heads. They are 64cc. $895.00. They have to be better than the 192 castings I have. I need to get the motor apart and see what the bottom end looks like. After that I will know what Im doing. Just trying to get a good motor together as cheap as I can. I know if your in for a penny, your in for a pound but I have a lot of other things I want to do while its down and to make that happen I need to be smart about my spending. I have all the ignition stuff..so thats done. Now on to the motor, paint, new pulleys, braided lines, chrome suspension parts(replacing oder parts), and other stuff.

Be careful here....choosing heads for a 283 is not the same as choosing heads for a 350 or a 383. You need intake runners around 170cc's, not 195. Those larger runners on a smaller motor will kill all of your bottom end and most of the mid-range.
And there is nothing wrong with 1.94"/1.50" valves for your smaller motor. Oftentimes, the heads will flow better with smaller valves because the valves are not shrouded against the cylinder wall as badly as they would be with larger valves. Funny how it works, but that's the truth of the matter. And you need smaller chambers than 64cc's.
BOTTOM LINE: This is not a 350 or a 383, so stop trying to buy stuff for a 350 or 383.

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I'll echo what Tech says. If you're not going to race it, don't go for the big valves, it'll be a dog around town and you'll hate it / regret the decision.

This is one of those times when bigger isn't better! Been there / Done that / Bought the T-shirt.

No, Im choosing heads for a 327. After the compression check on the 327 and everyone more or less saying it was ok, I decided to build that one. Yea I know Im all over the place. I took the motor out yesterday and Im in the process of tearing it down. I will know more tomorrow when I get the heads off. Don't know if its a stock bore or .030 over. I don't even know what valves are in the 192 heads.

Even so, you don't want to use more than 180cc intake runners on a 327 or a 350 if the motor is to be driven on the street. 195's work good on a 383.

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You should be able to find casting number 14014416 at your local bone yard. They were used in 80-86 267/305/350 5.0 H.O engine and have 58 cc combustion chambers and 1.84/1.50 valves. With light porting and a good polish with the stock valves the flow numbers are as follows:

Lift........CFM@ 28"
.10...........57.4
.20.........122.1
.30.........172.9
.40.........201.8
.50.........217.8


I have used these heads on several 305 rebuilds and they are really pretty good with a couple hours at the shop. My local U-Pull It sells heads for $75 a set and guarantees no cracks or leaks. I'd be willing to bet they have a pallet of 416 heads.

My local Craig's List has a couple listings for 462 (Camel Humps) for $400 and a set of 333882 for $50.

If you have the budget, I'd always recommend a new set of aluminum heads as they'll be the best performance overall; however, when working on a tight budget, I know that I like a challenge. If you're willing to get creative, i.e., bone yard, Craig's List or local swap meet you may be surprised what you can come up with.

In addition to 416, I've used 601 and 081 castings for 305 engines. Make sure their stock and wait until it's time to pack up and a lot of guys will be willing to deal as they don't want to tote the heads home again. Show up with your little red wagon and make an offer.

Take a 24" framing square along to lay along the head and if it's nice and flat you're probably okay. I know there's always a risk of getting a stinker, but I've "re-purposed" a lot of heads and had very few bad ones - just stay with known good casting numbers.

And remember, this is supposed to be fun! Use a few of the buck you save and take flowers and candy to your wife - goes a long way (just trust me here!!)

Glenn

What Aluminum heads would you recommend? Is it the same as TechInspector recommended for the 283? Do I need to look for something with a 175 cc runner?

Something like this Brodix head:

Brodix Cylinder Heads IK 180 Cylinder Heads for Small Block Chevy IK 180 PKG - Free Shipping on Orders Over $99 at Summit Racing about $1,320

or this AFR:

AFR 180cc SBC Eliminator Street Heads 0918 - Free Shipping on Orders Over $99 at Summit Racing about $1,600

Both are 180cc intake runners and available with 64cc combustion chambers (I think smaller would be better) both have 2.02/1.60 valves. Brodix will handle .525 lift and the AFR will take .600 so there would be no cam issues in terms of lift. I have not used either of these heads but have used other models of AFR on 383 build and found them to be very high quality.

Hopefully Tech will weigh in as he has a lot of good info in term of flow and overall performance with a wide variety of heads.

OK, first let's get you to understand that bigger is not necessarily better, particularly on a mild street 327. Here are four basic tutorials from Summit Racing through TrickFlow Specialties.....
Trick Flow® Super 23® 175 Cylinder Heads for Small Block Chevrolet TFS-3031B001 - TrickFlow.com
Click on the left side of the page to go to the next video, Part 1, Part 2, Part 3.

Part 4 is Trick Flow at the SEMA show and has nothing to offer for your motor.

Another example of smaller is better is the L31 5700 Vortec production Chevy cast iron cylinder head. It's runners are 170cc's, yet it outflows EVERY OTHER cast iron production cylinder head that was ever produced by Chevrolet and it will embarrass most small runner aftermarket heads as well.

As I have said over and over, building a strong motor is all about PACKING THE CYLINDERS with a runner that exhibits HIGH VELOCITY for your particular cubic inch package and rev range. A large volume runner on a small displacement motor is for high rpm racing, not street driving.

If I were going to buy aluminum heads for your 327, it would be the Trick Flow® Super 23® 175cc Cylinder Heads, part number TFS-30310001, with the block decks cut to zero and using a Fel-Pro 1003 head gasket, resulting in a 0.041" squish/quench clearance. They will require pistons with more volume in the crown though, such as a Keith Black KB158, so it will be a pretty expensive build.
http://www.trickflow.com/parts/tfs-3.../documentation
http://static.trickflow.com/global/i...41b012-m72.pdf
Here are the flow figures....
http://static.trickflow.com/global/i...75%202014c.pdf

If I were going to buy iron heads for your 327, it would be L31 production heads, 170cc intake runners, bone stock, no mods, using a cam with lift not to exceed 0.430" due to the close proximity of the underside of the valve spring retainers to the valve guide seals. If you wanted a little more cam lift, you could take the retainers to a machine shop and have 0.060" to 0.080" surface ground off the bottoms of them for additional clearance (known in hot rodding circles as a ghetto grind), but be aware that the heads stop gaining flow at about 0.500" valve lift, so cam lift over that will not benefit the package. I'd use the stock rail rockers and stock valve covers. Casting Numbers: 10239906 and 12558062. The 062 heads use induction-hardened exhaust seats and the 906 heads use a hard insert seat for heavy duty use. Both head numbers flow the same. If you decide to use these heads, make a deal with the seller that you can return them and get your money back if the heads fail magnaflux inspection. They are thin-wall castings and have a tendency to crack when overheated. From a "bang for the buck" standpoint, these are the best small block Chevy heads on the planet. Using pistons with a -6cc crown, zero decks and a Fel-Pro 1003 head gasket, the static compression ratio would be 9.58:1, max for an iron-headed motor on pump gas. Squish/quench would be 0.041". Use a cam that closes the intake valve at around 35 degrees ABDC.
L31 flow....
0.100"...70...49
0.200"..139..105
0.300"..190..137
0.400"..227..151
0.500"..239..160

No matter which way you go, just remember that you will need to address the squish/quench. It is probably the most important part of building a motor in the first place.

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These are the pistons in it. They are marked B496. Its a pic I got off-line not the ones in the motor. Also has a forged crank.





http://image.superchevy.com/f/techni...ed_pistons.jpg

Only thing I'd use those pistons in would be a Demolition Derby car. Insufficient squish band area and too much dish for a 64cc head.

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Dam! Now what to do. Maybe its time to stat looking at a long block. I just can't see putting a couple grand into the 327 for it to make any kind of power. By the time its said and done, I could probably buy a crate motor for around 3K or less. Im sure by the time I do all the machine work and parts I will have at least that in the 327.