[wynter919]

Hi,

first of all its been a while since ive posted on here so i apolagise for just coming on when i need advice because tbh im no expert so i cant help anyone really

What im wanting is just for some of you guys here to have a read of what im doing to my 400 and just give me your opinoins on whats good bad or could do with this etc.

basically i have a 1981 TA which im putting a 1970 400 with stock 16 small valve heads in.
shes being setup for time attack events here in the uk and ive spent a fortune on suspension/brakes and had here made almost completly of carbon fibre etc so all good there

as for the engine this is whats being done.

Standard block with standrd crank /rods
stock 16 sm V heads (10 cr)
summit 2082 cam ntake
Duration at 050 inch Lift: 224
Exhaust Duration at 050 inch Lift: 234 .
alve Lift with Factory Rocker Arm Ratio: 0.465 int./0.488 exh. lift
Lobe Separation (degrees): 114 and lifters with stock springs and rockers

edel performer rpm intake
holly streetavenger 770 duel feed carb
Hedman 1/34 full headers
full 2.5 inch streight thru exhaust
holly 7.5 psi 110gph fuel pump
melling select high pressure oil pump
fuel mach light/underdrive pully set
no air con
stock converter
and also over here in the uk we run 97-99 octane

basically wht do you think of this setup as this is my first pontiac rebuild
now i know this is very tame on the scale of things but im not looking for huge HP at the mo as this is a steady learning procces for me.
Shes origionally 330hp stock so would i be right in estimating a 370 - 390 hp kind of numbers?
and also what do you think of the cam choice. im conserned it might be a bit to heavy for this. i was told that cam is on the limit of my springs and what my stock head would flow but after a bit of dyno sim play i think i might be better off with 2801 or sumthing similar or is this cam ok?

thanks for any advice

david

[68lemans462]

I just built an almost identical 400 except it is the '69 version with #62 heads. I'd recommend running a cast 67-72 intake or performer intake and a factory 068 grind cam. With the 2802, you should really upgrade your valve springs as you are right on the edge with stock springs. I'd also ditch that holley and throw a q-jet on there. What kind of pistons are you going to run? I used TRW forged with an additional 6cc dish (done at the machine shop) to get around 9.5:1. Use a standard melling 60lb pump and forget about the elec fuel pump, you wont need it. My mechanical pump seems to be more than sufficient for the 400 I referenced above.

My 400 has a small lope at idle, plenty of vacuum (15") and pulls like a freight train! To be honest, I'm very surprised how hard this engine runs. Have fun with your build!

[wynter919]

yea i heard ist on limit of my springs but i will stick with atock for now, and replace after a few months so they wont be on there long.
as for the intake i still have the old 1 but why would i want to got back to it. from what ive heard the differance between edels and cast intake performance wise is not much but the weight saving is worth doing alone?!? and i got it cheap

and as for holly carb.i got told that the street avenger is a great very tunable street carb and cant go wrong with it...why should i ditch it for q-jet??
and i have standard pistons, pistons rod crank are in great condition and havent long been rebuilt but are all standard.

[Mr. P-Body]

David,

"Your" 98 octane is measured differently than ours. It's more comparable to "our" 93. I agree, a small "dish" in the piston to get the compression down to 9.5:1 is called for.

While that cam is okay, it's an old "generi-grind". We (CVMS) use Comp XE grinds. Your combination is just right for XE262H. If you stay with the RPM intake, XE268H might even work a little better, but the small valves will hurt top-end power. I agree with 68lemans, a Q-Jet and the factory intake are more in line with your goals.

I would also invest in a set of aftermarket connecting rods. The stock cast rods, while good for stockers, aren't tough enough for the rigors of road racing. We use Eagles, but there are others out there for a little less money. Avoid the ones that are a LOT less...

Since this is your first Pontiac, Jim Hand's "How to Build Max-performance Pontiac V8s", published by SA Designs, is a "must read".

Lastly, the Pontiac engine will have an "onrush" of low-end torque you won't get from the small block Chevy or Ford. Make sure your chassis is set up for it!

Have fun and welcome to the higher echelon of GM performance cars!

Jim

[68lemans462]

Originally Posted by Mr. P-Body

David,

"Your" 98 octane is measured differently than ours. It's more comparable to "our" 93. I agree, a small "dish" in the piston to get the compression down to 9.5:1 is called for.

While that cam is okay, it's an old "generi-grind". We (CVMS) use Comp XE grinds. Your combination is just right for XE262H. If you stay with the RPM intake, XE268H might even work a little better, but the small valves will hurt top-end power. I agree with 68lemans, a Q-Jet and the factory intake are more in line with your goals.

I would also invest in a set of aftermarket connecting rods. The stock cast rods, while good for stockers, aren't tough enough for the rigors of road racing. We use Eagles, but there are others out there for a little less money. Avoid the ones that are a LOT less...


Jim

Jim, Great comments as always. I agree with you on the comp cam. My build was a "budget" build, so I opted for the melling cam/lifter package which was CHEAP! Wynter, it sounds like a chevy guy spec'd out your combo...... Take Jim's advice, he builds some MEAN motors and he is a hell of a guy.

[Will]

The heads are what determines how much power an engine can make, and the small valve #16s were never used on a 400 that made 330 horses...

With that cam you will wish you had a higher than stock stall converter. I would highly recommend you either use a smaller cam as Jim has suggested or get a better torque converter.

If weight reduction is paramount then the RPM is certainly lighter than stock but a regular Performer may fit the bill even better.

If you want to build an engine that can make use of the RPM then get those heads ported and install the large valves in them.

[wynter919]

funny you should say that about the heads because my local expert in the uk also said that. but ive checked via wallace racing, spoke to year one and mark at summit racing checked every web site i know as well as books i have and they all confirm that they are 1970 16 small valve rated at 330

right from wallace racing site :
1970 400 330 HP XV A 10.0cr 066cam 16/sm valve (1.96/1.66)1-4bbl 7040264 Block Casting 9799914
1970 400 330 HP XZ A 10.0cr 066cam 16/sm valve (1.96/1.66)1-4bbl 7040264 Block Casting 9799914

i showed my local expert who said no way there 16 small valve,they should be big valve. but the confusion seems to be that 1968 had 16 cast heads that were big valve and he didnt realise/hadnt worked on 1970 16 heads which were acctually small valve, most hear 16 and assume 69 big valve, just one of those unfortunate years they doubled up on numbers but changed the spec. i think that might be where your getting confused
there was a 290hp rate 16 that year as well and i asked year one and summit about that as well, they say only differance between them is that the 290 was 2bbl and the 330 had a 4bbl carb, heads were extly the same as well as cam , intake and the rest. but then my number all match up to the 330hp xv anyway

what will be the symtons of running this cam on a stock converter?

thanks for the advice ppl

[72blackbird]

David,
I agree with Will- get those no.16s ported, put some 2.11/1.77 Ferreas in your heads, and your 400 will make better use of the cam and extra RPM. A higher stall torque converter (2000 to 2500 rpm) will launch you off the line (or out of the corners) with more power.

I'd go with lighter forged units than the TRW/ Speed Pros- the JE (SRP), Ross, or Probe (SRS) units are much lighter and will help you accelerate out of the corners faster. The stock cast rods are only good for stock buildups and a grenaded motor in racing- a set of Tomahawk 4340 Lightweight I-beam rods are lighter and stronger than 4340 H-beams, and will help that 400 rev hard. Pacific Performance Racing has both the dished SRS pistons and I-beam rods at very reasonable prices. The stock crank will be fine for a 400 hp buildup, just be sure to prep and debur the crank as outlined in Jim Hand's Pontiac book. I would also replace the stock main and head bolts with ARP units- stud bolts for the mains and head bolts up top- these are far stronger than the factory pieces. Don't forget to get your rotating assembly balanced.

I run a modified Holley 3310 750 vacuum secondary- it has the jet extensions, nitrophyl floats, secondary metering block, etc. It is very easy to tune, and I never starve for fuel in the turns unlike those other carbs with side-hung float bowls. I'm using a port-matched e-performer intake, and the combo doesn't choke the motor even at 5800 rpms (past 6000 may be another story). I have a crane 284H cam (230@ .050, 284 dur., .480" lift), Hooker comps and 2.5" dual exhaust. I had a tired TH-350 w/ a 2000 stall converter, 3.08 10-bolt posi, and my 'Bird still ran a 13.04 @104 mph. Not bad for a 'Bird set up for road race.

Geno

[wynter919]

all sounds like good advice, will look into it,thanks. well took the first step and ordered that jim hands pontiac book

and also as im here and got your attention. what do standard pistons in a 400 1970 look like, i only ask as mine look very new, clearly havent been in there long, i know the guy before me did a basic rebuild but as this is my first 400 i dont know what the pistons as standard look like.
mine have 4 valve relifes in them and have STD stamped on all of them, are these standar or aftermarket?

[72blackbird]

I don't remember if GM stamped STD on the factory slugs, but if if you see L2262F stamped on them you're looking at a set of TRW forged pistons. These used to be about $200/set, but have risen in price to about $340/set now.

If the the bore has less than .001" taper from bottom to top, you could reuse the pistons to save money. I would only recommend cast pistons for a bone stock application- like the factory rods, they will only withstand standard loading. If you're planning to do any type of racing, use forged pistons and rods- the factory parts will fail in extended high rpm use.

Geno