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#1
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New (to me) 400 - Help me build it
Hi all,
I recently acquired a disassembled 1968 400 with #16 big valve heads. Still has a standard bore with a slight .002 ridge at the top of each bore. Heads look good, to the point I can probably get by with lapping the valves and adding new springs and seals. Stock rods and pistons came with it as well as the crank, which has been cut .010 on mains and rods. The goal is to put this behind a th350 with 3.36 gears, currently has a 2000 stall. The car is a'71 Lemans convertible, and will remain a street cruiser. I drive this car sometimes 300 miles in a weekend on the highway and in town, but I'm not afraid of stop light heroics. I will be adding an overdrive trans at some point. I have a 200r4 to build, but may do a 4l80 instead, Should I use these heads? I calculate about 9.7:1 IF it stays stock bore. Not afraid of buying Aluminum heads. What roller cam size range would work? Custom grind or off the self? No more flat tappets for me. Pistons will be replaced, forged or is cast ok? I plan on buying Ramair restorations cast manifolds and exhaust system for a factory look, but not afraid of long tubes. I don't have a 1/4 mile goal, just want to make a great low maintenance engine that has decent HP and Torque. How about 350+ HP and 400+ torque at the crank? Any advice is welcome. I currently have an excellent running .030 over 350 I rebuilt about 17 years ago in it. Low compression #94 heads, '71 intake and '79 800 cfm Q-jet tuned for the 350. Runs great, but its no powerhouse. Last edited by rkraczek; 09-02-2021 at 06:11 PM. |
#2
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That motor stock was rated at 350 gross hp and if you don’t set and post up a hp goal you would like now then you might be twisted by others here into buying Aluminum heads when you should be dumping as much money as you can into the short block build.
You can always down the road swap heads out in a afternoons work!
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#3
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Good point, Steve. Edited my post. I'm at sea level and want to run this engine on 93 octane E10 pump gas.
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#4
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The Following User Says Thank You to rkraczek For This Useful Post: | ||
#5
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If me I would get everything measured,KNOW the numbers and order(if necessary)custom pistons to get you too the 9.5 or less CR and be able to pull into any gas station.Many dont have time to do it right but find the time(and money)to do it over.JMHO,Tom
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#6
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need 2 things with every build...
GOAL and BUDGET many folks on here can build you a 700 hp 400 cid engine......several can build you something that runs for $1500......without a posted GOAL and the BUDGET to achieve it with....might be a long thread |
#7
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First off I wouldn't hesitate to run a HFT cam. As stated, you should give hp goals and budget.
That being said, I'm guessing you're looking for 400/425 hp which is a really nice street car that doesn't require major upgrades to the drivetrain, exhaust, and fuel system. My old engine and current spare: 400 block .030 over with stock crank, Eagle rods, Speed Pro coated pistons, #16 heads(unported but gasket matched), 750 Holley, Torker 2 intake, Comp Cams HR288(236/242d, .520/.540L). 9.5-1 compression, RARE manifolds w 2.5" exhaust I put 30k miles on it and it went 12.90s@3950lbs. VERY good street engine that I drove year round and I used a 3500 stall converter
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Chris D 69 GTO Liberty Blue/dark blue T400, 9" w 3.50s, 3905lbs 461, 850 Holley, T2, KRE 310s, Comp HR288 w 165s, RA manifolds, 11.60@114, 1.58/60 The spare: 467, 850 Holley, T2, Edelbrock Dport 310cfm w RA manifolds, HFT 245/251D .561/.594L, 11.59@ 114, 1.57/ 60' |
#8
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Quote:
BUDGET is 4k or less. I posted my GOALS in my edited first post. 350 crank HP and 400 crank TQ on pump 93 octane. I will be assembling the engine myself. 13.5 quarter with 3.336 or 3.55 gears. Nice street manners with A/C on and an idle that doesn't shake the mirrors off. Last edited by rkraczek; 09-03-2021 at 09:16 AM. |
#9
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You will want a full evaluation of the heads. How are the guides? A quick lap on the seats is NOT really going to cut it....using 50 yr old stock valves is NOT a good idea either. So keeping the iron heads becomes almost ....ALMOST useless. Valves = $230, k-liner the guides = $100, real valve job = $200 , cut n clean =$150 and springs/assembly = $200., cut for seals and keeper clearance, new keepers/locks ...So you are into iron heads for almost $1000. With NO PORT IMPROVEMENTS (at 400 hp you either need SOME port work or...lumpy cam which requires RPM ..which MAY need more than 3.55 gear) OR $2500 bolt on alum heads...DONE
You need to cc the heads to determine your pistons as you will want to zero deck the block to achieve the proper quench height which should be .040 +/- .005 (which translates to 0.000 +/-.005 deck height using the common felpro head gasket @ .039") MONEY WELL SPENT: Block prep. clean, deck, bore, line hone. BAM $1500 rebuild kit with Forged 14CC pistons $1100 cam n lifter $400 At 4k $$$ AND you want a roller cam....your going to have to cheat or be lucky somewhere as a retrofit roller cam and lifter is $850 then you still need pushrods and POSSIBLE machine work to the heads for the springs. |
#10
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Quote:
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68 GTO,3860# Stock Original 400/M-20 Muncie,3.55’s 13.86 @ 100 Old combo: 462 10.75 CR,,SD 330CFM Round Port E's,Old Faithful cam,Jim Hand Continental,3.42's. 1968 Pontiac GTO : 11.114 @ 120.130 MPH New combo: 517 MR-1,10.8 CR,SD 350CFM E's,QFT 950/Northwind,246/252 HR,9.5” 4000 stall,3.42's 636HP/654TQ 1.452 10.603 @ 125.09 http://www.dragtimes.com/Pontiac-GTO...lip-31594.html |
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