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Discussion Starter #1
I want to build a SBC w/a ( 383 ci- I would have to buy ) or a stock bore 400 ( I have now ), w a 350 trans or I can switch to a 700 R4, use reg pump gas in a 1980 GMC 2 w drive truck. I use this truck to pull a slide on camper and a small boat at the same time. What heads to use, cam, pistons C.R., or carb., or I can use a older bolt on the intake Holley adjustable injection system. To get the most HP and torque, and MPG. Any ideas would be great. I can do some of the work my self. I been away from the game too long.
 

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Discussion Starter #2 (Edited)
I have the matching heads, pistons,rods, and crank for the SBC 400 ci motor. But I do have a new set of sportsman 64 cc - 202 heads in stock. As far as a cam I have a new crane 454 lift, 290 duration w 1.5 rockers. Or I can use a complete Isky roller set up.. 510 lift..but the duration is too high I think ( 320 ) I was told that using roller rockers will change and lower the duration by 25-35 is that true ?
 

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you want 9 1/4:1 compression ratio with what ever heads you choose.For your purpose I would use brand new Vortecs,RPM spread bore intake and a Q-Jet carb,1 5/8 headers. Choose cam for peak power at or around 4800 rpm.I would expect 360 hp and 425# torque.Mileage should be 17 plus
 

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you want 9 1/4:1 compression ratio with what ever heads you choose.For your purpose I would use brand new Vortecs,RPM spread bore intake and a Q-Jet carb,1 5/8 headers. Choose cam for peak power at or around 4800 rpm.I would expect 360 hp and 425# torque.Mileage should be 17 plus
X2 on the Vortecs if mileage and driveability are your top priorities. It's well documented that Vortecs are one of the best flowing heads ever produced at low lift. And that is exactly what you need, big flow at lower rpm's with out having to jack the cam duration through the roof. I'd also recommend to steer clear of a tight LSA cam so as to keep the bottem end (sub 4000) stout - think low rpm, flat torque curve from 2500-3500 rpm's.

Good luck - Jim
 

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Discussion Starter #5 (Edited)
My SBC heads choice!

Hi Jim, what is a tight LSA on the cam? So my sportsman new heads are no good, w 2.02 valves, triple cut,screw in studs, 64 cc etc. to use on this 400 stock bore block.? What about using the 454 lift, 290 dur. cam I have ? The block is still put together from the factory, crank, pistons. Stock bore with hardly no wear.
 

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Discussion Starter #6 (Edited)
Heads -Valve Lift--------.300 --.400 --.500 --.600 --.700 --.800
Flow Int:---2.020 ------- 186 -- 217 -- 235 -- 222 -- 219 -- 217
Flow Exh.- 1.600 -------- 137 -- 146 -- 151 -- 153 -- 154 -- 154
Hear the specs for my new heads I have on hand.these are cast iron heads., straight spark plug._______*** Sorry all, I was talking about roller lifters I have, will lower the duration of my cam spec's. This is what Isky told me about the type of roller cam set-up I have will lower the duration by 30-35...Also I have 2 roller cams on hand, a 510 lift- 320 dur. and a 525 lift- duration 310 ....I think these cams are just a little too munch for me, more of a track cam? Thanks for your input.
 

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Hi Jim, what is a tight LSA on the cam? So my sportsman new heads are no good, w 2.02 valves, triple cut,screw in studs, 64 cc etc. to use on this 400 stock bore block.? What about using the 454 lift, 290 dur. cam I have ? The block is still put together from the factory, crank, pistons. Stock bore with hardly no wear.
LSA 112 or greater and ICL at least 108 is all you'll get out of me - I don't recommend cams - I leave that to the cam grinders. Think roller! I think the 400 SB will work out great, but the 454 would work and I'll bet the mileage will suffer at the expense of much more torque. I've yet to see anyone build a BB that gets mileage.
 

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I have the matching heads, pistons,rods, and crank for the SBC 400 ci motor. But I do have a new set of sportsman 64 cc - 202 heads in stock. As far as a cam I have a new crane 454 lift, 290 duration w 1.5 rockers. Or I can use a complete Isky roller set up.. 510 lift..but the duration is too high I think ( 320 ) I was told that using roller rockers will change and lower the duration by 25-35 is that true ?
Roller rockers wont change duration like that, perhaps you are confusing that with the effect that roller lifters have on effective valve duration as compared to flat tappet mechanical or flat tappet hydraulic lifters?

BTW-The Vortec 350 062/906 heads are the highest flowing cylinder head that GM ever installed on a 1955-2013 GEN 1 SBC, regardless of lift. Plus it has a much more modern combustion chamber than ALL of the "desirable" double hump and mid 60's fuelie heads.

Keep in mind that the stock Vortec L31 heads are known to crack. The GM Bowtie smallport Vortec heads are more durable as are the Summit Racing copycat Vortec heads.

peace
Hog
 

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X 2... Hogg is correct, you misunderstood what Isky said about roller rocker arms... As to cam duration, they can be whatever you specify when buying...

Nailhead misspoke... tight LSA (lobe separation angle) is about 104 - 109 degrees... you want more like 110 - 116 degrees for good MPG... (tight LSA's act like a vacuum leak at low RPMs)

.050 cam duration you want to be in 194 - 204 degrees range... GM's RamJet 350" engine's roller cam and 1.6 rockers would be a good choice... your Crane .454" lift cam is likely a 216/216, great cam, but a bit too big for your purposes... your roller cams sound even bigger durations... a Summit K1102 would also be good at a budget price...

64cc heads (Sportsmans or Vortecs) on your stock 400 shortblock would give a good boost in compression ratio to 9's (stock actually about 7's) and better MPG over it's stock 76cc heads... also more HP and torque...
 

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The specs for the head look a little strange.
Older World/Dart heads like Sportsmans are a little constipated on the exhaust flow side if that's what you are noticing... for high performance use, need exhausts hogged out... short turn radius smoothed...
 

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Discussion Starter #11 (Edited)
Match duration to piston C.R. and cam's

Update, Motor 350 or 400 ci. The cam spec's are Dur.-216, Lift- .454, LSA-110 , So a max piston C.R. is 9.75 is what I have look up. Update on my cast iron sportmans 2.02 heads are 68cc ( I can make changes to exhaust side and match heads to gaskets too ). With 1.5 Roller rockers,. I am trying to keep my cost down, by using these heads over the stock 400 heads. So if I have to change something I would change the cam. I have a 2-RPM intake to use, square or spread bore carb and matching carb spacers, also I do have a older intake too. I would like to use the 400 ci, because of the torque it has with the ci too. So any new idea's on the cam choice? Thanks Duker
 

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Discussion Starter #13
cam , piston, motor and trans choice

Yes old guy here, got sick and lost job, but I am back now....I have now have a 350 turbo ready or can have my 700R rebuilt. And now have 2- RPM intakes (Square or S-bore )+ old school one. Carbs 600 or 750 carter perf. or a holly EFI unit. Headers w/ 1-5/8 tubes and X over too. Rear end 3.42 gears. Motors , 327, 400 are ready to go, ( a 350ci need rebuilt ) and the older truck crashed and -crack frame, so now motor going into my 42 truck. I have 2 full race ISK cams total setup, too munch for street, but I have a crane 216 dur., .454 lift, 110, 105 LSA, 290 duration. I have look up pistons need to match cam is 9.75 max comp. new pistons are not ordered. I can go with a different cam if needed and or forge pistons to match. Any advice, so many new cam spec's out there.
:) Thanks Duker. :thumbup:
 

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OMG, this thread is nearly 3 years old and you haven't built the motor yet????





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Time flies when you're having fun, or not having fun.Time just seems to fly no matter what - lol. Guess I'm getting old.

Duker - glad to hear you're in good health and finances. I stand by my original post - camper, truck, daily driving, all the cubes (400) and mild cam. I didn't mis-speak aboutt LSA as someone mentioned previously. I would not go with anything tighter than a 112 LSA. You need a stump puller, not a high rpm red light racer from what you described in your original post.

Your 110 LSA low lift cam isn't a deal breaker, but is this cam new? If not, then don't use it. Also, I know very little about your heads.
 

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Time flies when you're having fun, or not having fun.Time just seems to fly no matter what - lol. Guess I'm getting old.

Duker - glad to hear you're in good health and finances. I stand by my original post - camper, truck, daily driving, all the cubes (400) and mild cam. I didn't mis-speak aboutt LSA as someone mentioned previously. I would not go with anything tighter than a 112 LSA. You need a stump puller, not a high rpm red light racer from what you described in your original post.

Your 110 LSA low lift cam isn't a deal breaker, but is this cam new? If not, then don't use it. Also, I know very little about your heads.
Now, depending upon your SCR, you can also tune your intake valve closing. Being a heavy vehicle, I would either keep the compression at 9.0:1, or use a later intake valve closing to keep detonation at bay.
 

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Discussion Starter #16
Thanks Greg....Yes my cam is new and matching lifters too. But the change was in the truck (old camper truck is gone). So going into a street rod 1942 truck, 3.42 gears.......( I do a lot of long hall drives 5-6 hours, leaning to a 700R , not in stone. ) RPM intake, + old school one. Carbs 600, 750 carter perf. or a holly EFI unit. Headers w/ 1-5/8 tubes and X over too. I have a crane 216 dur., .454 lift, 110, 105 LSA, 290 duration. Pistons need to match cam is 9.75 max comp. ( I don't want to go over 10.0 CR) new pistons are not ordered. I can go with a different cam if needed. Any advice, so many new cam spec's out there.
Thanks Duker.
 

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Your Crane cam is similar to what Pontiac used stock in GTOs 389"/400" with 10.75:1 compression ratio... they averaged 17 MPG in easy driving... of course, we had higher octane gas available back then at all the streetside pumps...
I assume your " '42 " is an older, not too heavy pickup truck, so your current parts in/on a 400 should move it easily...
 

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To use those Sportsman heads with their 64cc chamber on the 400, you need to find a piston with a 17 to 21cc dish volume to stay under 9.75:1 compression.

On the 327, a 5cc eyebrow flat top piston will get you right around 9.5:1 depending on head gasket thickness.

The 327 won't be any where near as much power or fun as the 400 IMO. Easily the 400 will make 100 more HP and torque, and be a lot more low rpm street friendly doing it.

When you look at pistons, watch out for reduced height "rebuilder" grade pistons, they will murder compression ratio and kill good quench characteristics at the same time, making the engine MORE octane sensitive even though they deliver a reduced compression ratio..
Stock 400 Compression Height is 1.560" with a 5.565" rod, if you use a 5.7" long common SBC rod from a 327 or 350, then the correct CH spec is 1.425".

Correct CH spec for the 327 is 1.675"
 

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OK, you have a 400 small block with stock bore, 4.125". Will you try to hone the cylinders for new rings or do you think the block will have to be cut 0.030" and then honed?

Have you measured the block deck height? Stock measurement is 9.025".

You're certain that the iron heads you have are 68 cc's? Will they be flat enough to run as is, or will they need a skim cut to flatten them out and make them compatible with a new steel shim head gasket?

What transmission will you run? An overdrive transmission WILL NOT work well with the 216 cam you have. You need an almost stock cam (max 206 intake @0.050") that begins making power down around 1000 to 1200 in order to be "up on the cam" (at 1700-2000) cruise rpm's with the overdrive transmission. It's not that the motor won't pull the truck using the 216 cam and an OD transmission, it will. It's just that the cam will not be in it's efficiency rpm's at road speed (1700-2000 rpm's) and will not make any appreciable fuel mileage. If you want to use a 3-speed transmission, the 216 cam (1800-5600 power range) will work and might make about the same mileage as the OD trans using the 216 cam.

Finding the proper piston will be the problem. You may have to pay the piper for forged pistons from SRP or other high-buck supplier and buy rods to make the combo work.

.
 
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