Ok... i know nothing of pontiac so i thought i'd ask. I have a 70's 400 i just picked up for 150 bucks, machine shopped 5c-4 heads off a 75 350, edelbrock intake and 750 carb. The car I want to put it in has a TCI turbo 350 with 2000rpm stall (sat night special) and a 12 bolt posi rear with 4:11's. 1.5 ratio roller tip rockers too. Only thing i've figured out so far is that with those heads being milled i *should* be somewhere between 8.5 - 9:1 range on compression, not sure exactly how much they milled off. Basically trying to find out if i can just get a cam (and which one) or what i'll be dealing with. Ya know... trying to do it on the cheap and still have a lil fun Basically... i bought a car that was built for race... had all the goodies bought by a 19 year old. For whatever reason.. he put a 350 in it after spending wads on the 12 bolt, frame connectors, summit trans, etc. So... i'm just trying to slap a 400 together for it on the cheap rather than try to figure out what he did wrong on the 350... other than the intake being bolted down a quarter inch from the timing cover (lovely watching the flourescent green shoot out under shop lights).. and the tons of other little problems it had.
Pontiac 400 aren't known for there revving ability, you may want to change the rear gears for something in the mid 3s.
the 3:42 in my 72 TA is nice and Drivable. 3:55 would be good. Get rid of those 350 heads and look for some 96 casting, 71 400 heads, common Grand Prix. Look up Jim Hand, very respectable build using GM parts. Pretty low budget. HO Racing Specialties had a book out with his wagon running 12s, testing all the intakes, cams, exhaust, back in the late 70s. Its worth picking up if you can find it. no gasket between the water pump & intake, never saw that one done! Ed
What's wrong with 350 heads? Do a search of the thread I started about Pontiac 400 cams, lots of good advice in there...and go do an intro...good luck, see ya at the track...
Can be a VERY powerful motor. #16 heads on a 400 will give great power as well. They are like '68 and '69 Grand Prix and others. Tons of torque, and at low RPM. True, don't really rev up, but perfect street motors with tons of torque. Lots of guys put Edelbrock aluminum heads on 'em, allowing a little less octane and coupled with appropriate cam and gears giving awesome performance. Plus, it's a Pontiac motor! Pontiacs are awesome!
Gooter Welcome! When it comes to Pontiacs I think they are a diamond in the rough. I'm a recent convert to the Poncho power Big bores, low rpms = longevity + torque out the wazoo = big fun With just a few changes you can get a real torque monster and the cool thing is the few parts can be stock GM parts! Some real tough motors out there using the right combo of parts and the Ruiner post can tell you alot of info.....such as those cool 70's aluminum aftermarket intakes and Holley double pumpers have nothing on the "proper" stock intake and a properly setup Buick 800cfm Rochester!.....talk about a sleeper motor Here are a two of many places to look. http://www.wallaceracing.com/ http://forums.performanceyears.com/forums/
I was happy with the tons of info I got from my thread...and you can bet I'll be putting all that info to good use while trying to lift the front wheels on my '40 Plymouth...
The 1975 5C-4 350 heads (2.11/1.66 valves, chambers 92 to 94ccs usually) are exactly the same as the 1975-1/2 thru 1977 6X-4 350 heads that are so popular. Every bit as good on a 400 as the 1971 #96 400 heads (96ccs + chambers), even though the #96 heads have a 1.77 exhaust. All of the common Pontiac D-port heads whether they came on a 350, 400, or 455 have the same size ports. It's not like a 350 and 400 used different heads, other than the chamber sizes. So just choose whatever combustion chamber size you need for the compression ratio you want. Even the 2-barrel heads with smaller valves and press-in studs have essentially the same ports as 4-barrel heads, just open up the throat under the seat when you put in the bigger valves and you've got a very good set of heads. We're talking '67 and later heads here, the '66 and earlier 326, 389 and 421 heads can't match up (forget about the rare early '60s Super Duty heads for a moment here). Personally I'd rather have the later castings, they're actually a better candidate for porting due to the improved short-turn radius that became a feature in 1975 on the 5C heads. In stock form the 5C heads will run dead-even with the #96 heads anyway. Compression with either will be hard to get up to 9:1 without a pretty healthy cut and good sized piston overbore. For the strip the 400 will like the 4.10 gears, but put a 28" tall tire on there and shift it at 5700 or so or else you'll be tossing the cast rods. You don't need to shift 'em very high anyway, they'll do the job for you in the mid-range.
I guess what i'm aiming at is getting the most power i can out of it for the cheapest possible. I've been looking at all the options with heads and will probably stick with the 5c's since they're the large valve and have all new valves, springs, and have had the $$$ sunk into them. I was just wondering if i could cam it and have it run well with the components i have. I do have another set of heads... the 7j2's... but they're small valve. The last site i looked at said they have an 8.4:1 CR (but that info seems to vary from site to site). I know just about every thing i've read on here and on poncho sites warned that going over 9:1 and you'll have to worry about detonation, so... Thats why i'm leaning towards using the 5c's. They should land me ballpark. The big question for me is... could i just stick a cam in this thing and get decent power with the components that are already in it? the turbo 350/2000 stall/4:11's. I could always change the rear (was actually debating on that since i saw how much those 12 bolt rears are grabbing on ebay), lol. But... it would be nice to have that strong posi for some track time.
I run a 400 in my Bantam altered and it does well, I would lose the gear. a 3.73 would be the highest I would go with your combination, a 3.55 would be better. Its hard to make over 9 to 1 compression with some of the Pontiac heads because most availible ones that are out there were the smog type but with the 400 you can run 8 to 1 and still have lots off grunt an go. Your cam selection is very important so that it works with your compression. Check out the thread that Ruiner started about Pontiac cams, also The idea of getting Jim Hands book is great. Jon
As already stated, the heads you are choosing are very similar in size(chamber wise)to the 6x heads. These 400's in the mid-80's that came in the T/A's had less than 8:1 compression as advertised by Pontiac. Trying to cut these heads enough to get upwards of 9:1 is going to create more issues than will be worth. You can find many other Pontiac heads that will be more cost effective to swap if that is your goal. Also one tip for your water leak behind water pump. Before you run the intake bolts down, snug the bolt for the water pump with the rubber gasket on it first so that it will pull up against the intake. Then tighten the intake bolts....
His 350 heads will put him right at 9:1 on his 400, no need to look for other heads...everyone's got their opinions and preferences...how's about we get some cam suggestions for this boy?
gooter, Is this going in the 75 formula in your list? If so, you arent going to want more than the 3:55. My 72 TA is a 455 HO 4 speed, with the stock 10 bolt 3:42 rear. Plenty of tire melting power in all 4. There isnt enough weight in the back. The 068 cam is in both the 455HO and the RA III in the 70 Formula 400, plenty of power, great drivability. I realize that the 455 has more low end, but neither motor will be much good after 5500 RPMs. Pontiac Parts are expensive, but there isnt much difference when it comes to motor size in cost, so keep your eyes open for a 455. If the 350 heads flow better and the only loss is the exhaust from 1.77 to 1.66. Give them a quick Gasket matching and Run them on that 400. Id say to go to Ruiners Thread, check with Tom Hand. The book his dad is involve with took and compared all kinds of set ups, making a 71 Lemans Wagon with heavy GTO front end run 12s on all stock GM parts and pump gas. Thats respecable. most of the research is done and in B&W.
Yup, the ONLY 2nd gen F body to sport a 12 bolt was a 70. There is a bunch of motor money sitting there! If the 10 bolt was OK for the 455HO & the 455SD......that should say something! Ebay that sucker!
you are going to love that poncho motor. as others have said they make tons of torque, just dont rev em up. 5500 rpm is about the rpm limit i put on them. an example of whats possible, 70's 455 used motor, 6x 400 heads, comp 525/305 cam, rpm intake, 850 holley, hooker headers, ATI 10 inch converter and 4.10 gears (too much gear) in my 69 pontiac custom s which with my 350lb butt in it weighs 4,000 lbs 60' 1.53 best et 11.53 118 mph. imagine how quick this engine would be in a rod that weighs 1000 or more lbs less. i presently have a 464 (.o40) over olds motor in the 69 pontiac. this motor went 11.31 in my 78 malibu. should go 11.50 in the pontiac too. olds motors are the same deal, tons of torque , just dont rev em up.
I have 463 Poncho in my Studebaker truck . Has 4X heads (around 9-1) a Ram-Air IV cam (comes on at midrange - fun lumpy idle) a Torquer 2 single plane and headers . A 350 trans won't live long behind a big Poncho . I'm on my second Turbo 400 now and I only romp on it occasionally .
Wallace racing and Performance Years are great starting points. Pick up Jim Hand's book as well. The Summit cams, 2800 and 2801 are great cams for those engines.
I'm guessing with his gears, compression and stall converter those Summit grind cams might be a little too tame...but I wouldn't know from experience...
I'd run the Crower 60243 hydraulic cam in that 9:1 400. Specs:228/235 duration @ .050, .479"/.495" lift w/1.5:1 rockers. It's a small step under the popular RAIV cam (230/240 @ .050,.470"/.470" w/1.5:1 rockers, .517"/.517' w/1.65s) and will run better with 9:1 compression. The RAIV cam really needs at least 10:1 to really shine in a 400.<!-- / message --><!-- sig -->
That seems like a nice step up from the 068 cam, but will that grind need the 2k+ stall converter he has? If I can get my posi rearend out to him with the 3.40ish gears in it I think it should scream...
He'll need the 2K+ stall converter at a minimum to take advantage of that cam, a 3K stall would be better. The 068 is pretty mild actually as it's pretty much used as a stock replacement. The 068 will be fine with a stock converter but a little added stall speed can only help, especially with a 350 engine.
Thanks for all the great info guys... i was expecting the one response a week like most other forums get, lol. I went out a while earlier with the calipers to see just what cam is in that 400 to start with... it looks like its a .490/.490... not sure on duration yet, have to figure that out before work some day this week (saw a lunati with that grind that was 230/230 at 50 on summit) dunno if thats good or not. I talked to a pontiac/olds lovin friend a while earlier and he echoed alot of what you guys said on cams... something in the 230-240 duration @ 50 range. The biggest cam summit brand offers for the 400 is 224/234 at 50 and 465in/488ex, he agreed with you on it being too tame, ruiner. Also may have a line on a 10 bolt with 3.70's if it doesn't respond well to the new cam. Planning on making a cam decision this week and getting it ordered, get the motor together and see how it works on those 4:11's. The poncho guy who was here earlier check everything out and thinks it should be pretty close to 9.1 with the milled 350 heads and said a quick port and polish wouldn't hurt and with a cam like you guys have been suggesting should be a lopey pig to drive with those gears, but fun at the track (which is fine with me). I did see a 400 poncho with 4:11's i think on rock n roll engineering, it was bored to 406 with srp pistons and edelbrock heads doing 11.80 with a comp cams 265/265 . If only edelbrock heads weren't worth more than the car, lol. That crower cam looks like a good way to go (thanks dragginGTO). The firebird's built for the strip with all the aftermarket goodies the last couple owners bought (the subframe connectors, 12 bolt, summit fuel pump, intake/carb/hooker headers, etc), so might as well take advantage of that. If i need a higher stall converter thats no big deal. I'm just trying to keep the whole job in the 500-700 range and have it ready for a little fun before june. Trying to stay on budget so i can afford to get it in the garage and paint it (purple isn't my color, lol). Worst case scenario if the 400 goes poof i could always fix the 350 that was in it (it was bored over, no clue how far) but the kid put a summit chrome air filter on it that didn't fit and it was just sucking dirt off the intake. Compression was around 100 on each cylinder. Considering the goof on the intake seal he might not even have the cam degree'd right. who knows, lol I saw someone mentioned a 455.. i did find one, but it was in pieces and he wanted $500 (he said it had surface rust on everything and needed shopped0. Seemed a bit much for a mystery pile of parts.
I've seen complete 455s bring $1000 on eBay, worn motors in need of rebuild. And I sold one years ago, a 2bbl small valve 455, to a guy for $400 who resold it and at least doubled his money, so... $500 wouldnt be bad if it wasn't rusted or cracked.
Yeah... they're out there... i saw one on ebay a couple months ago go with no bids for 500 that was still a good running motor. Unfortunately i work 7 days a week for a machines shop and couldn't go snag that bad boy. Of course.. there is a 500 caddy on craigslist 3 miles away that was definitely tempting, lol
The Jalopy Journal
