Heads

[corvette66]

I was wondering if anyone could tell me what the casting #'s on the 70's GM heads were. Only for the 350 ci. Vettes and camaros had the same heads didn't they. Do you know if they used mainly 64cc or 76cc etc.

And whats a "3 angle valve job" whats its purpose

thanx

 

[waterboy1976]

993 castings were pretty common for early 70's...they were a basic 1.94/1.50 head...nothing too fancy common on the l48 motors. l82s and lt1s not sure, someone else will chime in im sure

 

[JohnZ]

Twelve different head castings were used from 1970-1979 on Corvette 350's; the NCRS Spec Guide shows all the usages by year. A three-angle valve job (vs. the production single ground primary seat) smooths airflow by machining the rough-cast area that transitions from the primary seat into the port, which normally has a fair amount of casting flash.

 

[SG4206]

Dano-
A 3 angle valve job on the seat , usually includes a back cut on the valve head also. This improves low and mid lift flow numbers through the intake port.

 

[mike weyman]

my 75 has a 333882 head casting 76cc chambers. these flow pretty well and are concidered to be the best of the "junk" heads.
the 461, 461x,462,462x are the 64cc fuellie heads. these 4 are the best production heads.
word to the wise (i wasn't) if you are going to re-build a set of heads with the 3 angle valve job,opening them up for flow, new spring seats, etc. check the price of aftermarket heads, these may be cheaper solutions with more power per dollar invested.

 

[corvette66]

hey thanks guys, thats what i needed to know.

Would it be better to go with 64cc or 76cc? I have heard pros and cons of both. I'm building a race motor, but I have to keep it all STOCK, and i really don't know much about stock parts, or what stock parts will help build the best motor.

thanx

 

[curtis]

If you can't get the fuelie heads, the 487X is pretty decent, but hard to find . We use these in our stock car. the chambers are 76cc. mill the head .030 and it leaves you with 73cc. Use a very thin metal shim type head gasket ( spray paint some high temp barbeque paint on both sides before you install it) and you can gain a point or so on the compression ratio. that'll wake up any engine. If you want better valve springs but still a stock type item, Comp Cams has the beehive style like inthe newer vettes. ... no valve float so far and we have run up to 7600 rpm.


What kind of race motor are you building?:confused

 

[corvette66]

Curtis, I am building a stock motor for a "Factroy Stock" race car. The motor has to be stock production. Problem is, i don't know much about the stock parts. Also says that the valve springs must remain stock diameter and hight. So the beehive type srpings prolly aren't allowed cause of the tappered end.

And the heads: "Cylinder heads must reamain stock cast iron production only. No VORTEC heads. No port matching or flow work is permitted. Only OEM valves, and 3 angle valve jobs alllowed. Grinding or cutting in the port bowl between the valve seat and valve guide is not permitted. Only factory production stamped steel racker arms."

Pistons: "Must have 4 valve relives in top, OEM production style replacements only. Cast or Forged, may not protrude above top of block."

Engine: "Compression ration may not exceed 9.5:1. Max 360ci. Only OEM procuction steel or cast iorn cranks. Camshaft must be cast iron. Cam dimentions (lift and duration) must remain similar to stock production. Vacuum minimum, at 900 and at 2000 RPM's will not be less than 16 inches."

So that is what I am dealing with. I assume the only way to build power is through the CAM and HEADS. Nothing else can really vary to much. All stock junk more or less. So Im am just trying to figure out what would be the best CAM and HEAD combo.

thank you much

 

[curtis]

Dano, are you permitted a four barrel intake? Can it be aluminum? I would choose the fuelie heads w/64cc chambers and go with 2.02 and 1.60 valves. Older camaros had a stock aluminum intake that breathes pretty good. As for the cam it says "similar to stock". That is a very broad term. It could be read to mean a camshaft that makes the valves open and close. With no specific limit to duration and lift it is wide open. Or you could get a cam ground with a little more duration and lift than the say 375 HP 327 cam. It would be "similar" but not exact match. The beehive springs on the new Vettes are a "stock" item so they should be perfectly legal. What makes them shine is the lack of harmonics and the lighter retainers etc., which all means more power. Back to the cam, You could have a cam with the identical lift and duration of a stock cam, but change the opening and closing ramps to a more aggressive profile. Comp has some XTP ramps for the opening side and another for the closing ramp profile. We use them and they make a huge difference in power, better yet that type of change to a cam takes some very special measuring to figure out that is isn't exactly a stock item. No race track I ever ran at could tell the difference. The compression ratio is the killer for you. You must be certain of your measurements when the machining is done so you are not too high (decking the block and milling heads as well as head gasket selection). One other definate power adder would be gapless piston rings. they are good for about 15 to 20 horse on a 400 horse motor. then you use a good windage tray and crank scraper in the pan for another 15 horse. Sounds like your rules give you lots of leeway to improvise. God ,, isn't this fun?

 

[corvette66]

Hahaha fun it is, but a huge headache. Thank you for that good info. I left a few things out that I had forgoten about. Only a rochester 2 barrel is permitted with an iron intake manifold and iron water pump. Can you belive that crap!!!!! No aluminum permitted anywhere on the motor. Stock exhaust manifolds as well. I'll have to ask about the Beehive springs, see what they say. Thanx for your help..

 

[curtis]

Sounds like a circle track hobby stock motor inthe works. That's what we run also. We won the track Championship at Madison , South Dakota this year. It was our second year of competition. Our driver is just 15 years old. Just ran Cheaters Day races and kicked everybodys butt real good. We put on the full alcohol induction system from a sprint car (carb intake fuel lines fuel pump). Talk about turning a motor into a screamer. Wow!!!

I have the ram horn manifolds off my 76 if you need em.
Here's a picture of our driver with the trophy at Huset's Speedway after Cheaters Day races.

 

[corvette66]

Sorry bout the delay.

Yeah it is a circle track car. THats the way to do it there, start young and by the time he's 20 he'll whip everyones butt. Plann'n on moving up to a late model? We got some real young 16-17 year old drivers down here pounding everyones A$$.

 

[curtis]

One more year for us in Hobby Stock. We need to defend our championship and shooting for first in NMRA. We got second this year. After that I believe it will be 360 sprint cars. Wanna sponsor us? ha ha ! One other thing you could consider is boring out lifter bores for the bigger Ford lifters, This allows you to run a steeper ramp on the cam and get the valves open quicker and closed later (more power). of course the cam needs to be made to accomodate this to get any advantage. Hope you went with the beehive springs.

 

[corvette66]

Oh wow, I didn't even know you could use the ford lifters like that. I still have to find out about the bee hive springs see if they are legal or not. You guys racing dirt or asphalt? We have a new dirt track opening up here close to our asphalt track, I think we may lose a lot of people to the dirt track. A lot of our grand american modified racers prefer dirt. Along with our factory stock racers. Car count has been low to begin with. Oh well just easier for me to win hahaha

dano

 

[curtis]

Mostly run 3/8 dirt track around here. I think the closest pavement is up around Minneapolis, about 5 hours drive. Got any pictures of your race car? Heres one of ours before the season started. The driver's mother and father are behind the car and our engine builder is leaning onthe pop machine. Oh yeah, don't let em deny those springs, they have been a stock item of vette motors for at least the last 2 years.

 

[Jack]

FYI ... The folks at www.camcraftcams.com grind real good cams for asphalt circle track cars ... particularly 2 barrel and vacuum rule cars. Here's our late model asphalt car #21 Zoom-Perfection Clutch. From L to R, crew pic shows Co-owner (Michael), Driver (Stacy) and Painter/Attitude Adjuster (Ricky). I'm not shown but I build the motors & throw $ at it.
JACK:gap

 

[corvette66]

Thats a good looking car Curtis. I think what they will probably tell me about the bee hive is that it wasn't a stock option in the 70's. Since we have to run the old 76-81 camaro's. Well atleast thats all people run out here, one guy has an olds cutlas. Our officials out here are impossible to reason with. Unfortunalty I do not have a pic of my car, I still have to pick it up. It's ready to go, just needs to have the motor dropped in. I am also working on a mini stock. I might actually be running it this year instead. Which ever one i can get runn'n the best. The mini stock is a Ford 2.3L 4 cylinder. They are actually running faster laps with the 4's than the stock 8's. About a second fatser. The mini stocks have no rules really, just can't have DOHC must be SOHC, and a 350 holley at max. All else goes. We'll see how much changes in the next few months, when they open up this dirt track., maybe they will cut us a break, just to get the car count back up. They know they are going to lose people to the dirt. unless they start cutting back on these nutty regulations.


Hey Jack
What size track you guys on? 3/8 1/4 ? I am hoping to move up to the late models in a few years. If I can pull it off fundage wise. What engine regulations do you guys have? Can you run alluminum heads on the limited lates? Im am just curious how similar the rules are nation wide. BTW nice car!

dano

 

[Jack]

Hey Jack What size track you guys on? 3/8 1/4 ? I am hoping to move up to the late models in a few years. If I can pull it off fundage wise. What engine regulations do you guys have? Can you run alluminum heads on the limited lates? Im am just curious how similar the rules are nation wide. BTW nice car! dano

Thanks. All tracks we run are 3/8 to 1/2. NO aluminum heads at our tracks. Stock stroke & up to 4.060 bore. The list of regs are very long and do vary slightly amongst tracks ... not just motor rules but also clutch, carrier etc. Most tracks have regs on their websites. Rules do change from season to season also. And yes, you'll need mucho dinero for late model ... we buy ALOTTA tires. G'Luck.
JACK:gap

 

[corvette66]

Jack

do you guys have a tire limit each week? I mean is there a limit to the number of tires you can buy? The late model drivers here are only allowed to purchase 2 new tires a week. I guess it helps keep the cost down for those with small sponsors.
Hey just out of curiosity, I have never been in a late model so i have no idea what it takes to drive one. Do you guys on your 3/8 mile track, have to shift at any point, or can you run it all in one gear? do you guys do the left foot breaking or heel toe? Or do you even need to use the break much, if you are in the lead, can you ease off the gas and feather it around a corner without the use of the break?
Just wondering what its like in those cars.

dan

 

[Jack]

Jack

do you guys have a tire limit each week? I mean is there a limit to the number of tires you can buy? The late model drivers here are only allowed to purchase 2 new tires a week. I guess it helps keep the cost down for those with small sponsors.
Hey just out of curiosity, I have never been in a late model so i have no idea what it takes to drive one. Do you guys on your 3/8 mile track, have to shift at any point, or can you run it all in one gear? do you guys do the left foot breaking or heel toe? Or do you even need to use the break much, if you are in the lead, can you ease off the gas and feather it around a corner without the use of the break?
Just wondering what its like in those cars.

dan

Tire rules vary at each track ... some 6 new, 4 new, 2 new, Hooter's scuffs ... yada yada ... lotta tire cheating goes on. Rolling start in third gear, then to high and stay there unless there's a SLOW restart. Trans must have all gears in it but there's trans cheating too. Most of these cars' brakes ain't much anyway ... but only enough brake to set the car. I don't drive but there's lotsa different ways to brake/slow ... folks do whatever they think'll get them where they wanna be ... even if it's stupid.
JACK:gap