just wondering if my heads off a 70' 350ci was worth using. The Casting number is 3947041. Theres a shape of a triangle on the side of the heads where the normal camel hump castign would be. Are these heads good? worth anything? hi performance application? any info would be appreciated.

Other than being ancient technology and probably needing hardened seats for unleaded fuel,, it's a damn decent head. That's the head on the 69-70 302 and 350. Be cautious with compression, it's a 64cc chamber. Flat tops and standard deck height will get you around 9.7:1 Any block decking and you'll be at 10.4:1 in a heartbeat and on the dangerous limits of pump fuel.

same head i use with pump gas and 100 thou. domes, I wouldn't sink too much money in them without buying new heads.

[This message has been edited by Mwilson (edited April 26, 2005).]

those are the same heads 64cc's and my valves bent for a reason which i will only know of since im a youngster, but my 350 block and heads are from the 68-70's and im still trying to do as much research as possible

what do you mean by dangerous limit of fuel?

awesome heads!! two valve relief flattops and a .015 compressed head gasket gets you right around 10.3:1 comp. I have a spare set in my garage for another small block project one day. Just sold the ones off my 350 to a member...you will not go wrong with these heads at all!!!

Built in 69-70 on the 300hp 10.25:1 350 4 bbl engines are an excellent head. Same fuelie ports as 186, 492 etc heads but with 1.94-1.50" valves. Which means 2.02-1.60" valves are just a cut away from being installed. The seats aren't hardened, but I never encountered any problems with seat recession with them.

just wondering if my heads off a 70' 350ci was worth using. The Casting number is 3947041. Theres a shape of a triangle on the side of the heads where the normal camel hump castign would be. Are these heads good? worth anything? hi performance application? any info would be appreciated.

They are a descent head, Below is a post I made to a guy on here showing an example of our combo, which we have done for a couple people. Simple combo yet budget and will run great.

As to the seat issue, the FIRST GRAM of lead in the gas protects more than every gram after that. 100LL AV Gas has ran the same ET's as Sunoco Blue Race Fuel and spec'd the same when it was tested on the automotive scale. Keep some around and dump some in there such as 2 gallons before you fill it up with fuel

Some people choose to run straight 100LL AV Gas, as its $1 or $2 higher than premium pump gas and its better on the engine than this CRAP we have now

Iron Eagle's are a good head, use a standard 6° to 8° split 99% of the time, and have the duration @.200" do a reversal, works well for a small block with these heads

If you use Sportsman II heads, you would have to understand the exhaust runners are factory sizing, VERY CLOSE, and pour within 5cc's, so when these are used the camshaft will be moderate, but the exhaust will need a typical 14° split, or a 6° to 8° split with 1.6 exhaust rockers

Another option is a little work to GM heads, We have made ~530hp and backed it up in a few different rides.

The 400 (Very similar to a well built 383, we have had them run hand in hand) in the Camaro ran 10.13 to 10.22 at 131-133mph every pass in the summer, with 1/8 times of 6.40's to 6.50's at 104-106mph every pass. Below is the combo, which is very basic but there is a great deal of oiling system mods I did along with block, heads, crank and rod mods and I have no issue sharing it if needed

- 400 GM 4 bolt main with GM bolts, filled with Hardblok to bottom of water pump holes, oiling system mods
- GM 400 nodular iron crank, ground 10/10 to specs needed for proper clearance
- Scat I Beam 6" Rods, 4340
- Flat Top Pistons, .005" out the hole, standard 1/16" ring pack
- GM 291 Camel Hump Heads, 2.02"/1.6" valves installed, bowls ported to proper sizing with larger valves, exhaust runners ported smooth so they could be polished, no intake runner work, no chamber work other than blending out from the valve job around .050" to .060", heads step cut for 1.46" Dual Springs at 160/420+ spring pressure with steel retainers
- Crane Solid Flat Tappet .018"/.018" cold lash, 292/300 @.020" 256/264 @.050" 164/172 @.200" .545"/.563" 105° lobe center installed at 102° intake center line
- Victor Jr 2975 as cast
- 1000 Barry Grant modified by us

The car weighed 2850 pounds, used a glide transmission with a brake, an ATI 5200rpm stall, 4.88 gears with 32" tires (About 4.30 with 28" tires). We shift at 6000rpm and ran through the lights around 6500rpm

After Nate left the team, the engine was fair to go with him due to our split although I did the engine and have a lot of time in it, he put it in his 1850 Dragster and it runs 8.60's at 150mph+

Very basic combo, and in 3 speed cars have proven excellent with aftermarket heads and solid rollers.

The point is, you can do a very basic combo and spend the money on the correct converter and gearing, and its gonna ET if the CAM, CONVERTER, GEARS and HEADS are correct for the intended RPM that will be run off the line to the stripe

A key fact is, the engine will have some of the highest VE around peak torque, due to the small heads you MUST keep the engine away from peak torque or the heads will indeed choke, this is why we run RPM and MPH people with 200cc heads can't do in similar weight cars/set ups

The 041s used on the 300hp engines had 1.94 valves, but there were also some 041s with 2.02 valves used on the 350hp Corvette engine in 1970.

Casting wise, they are the same head as the more popular 186.

The 041s used on the 300hp engines had 1.94 valves, but there were also some 041s with 2.02 valves used on the 350hp Corvette engine in 1970.

Casting wise, they are the same head as the more popular 186.

I thought "492" was the big valve copy of the 041???

Those are good heads but I had some that had an x after the 041 on my 70 Monte Carlo it had the 300 HP 010 or 014 4 bolt main block and the 041x stamped on the heads in the rocker area. If I remember right the were 202/160 valves and 64 cc. When I rebuilt that engine and changed to a Comp Cam 284/450 cam with TRW 10:1 flat top forged pistons and no block on deck with Holley 750 vac secondary it went 15.50 in the 1/4 with 2:73 gears and would roll on out in high gear. I put the same engine into a 73 Vega and went 13.40s with unknown stock rear that blew pretty quick. Put in the 12 bolt from MC still with 2:73 and went 8.20's. I changed to a 9" with 3:50 gear later and a 280/480 cam and went 13.00's. would run 11.80 with a 125 powershot from 2nd gear out. You could not hit N20 in 1st as it would blow the tires because the car was so lite. With a double pumper and slicks would run 12.70s NA.

They also had Accesory holes drilled, at least mine were.

I thought "492" was the big valve copy of the 041???

I don't know what the 492 head was. It isn't in my books. The 041 and 186 were 64cc 1969-70 only heads, and they shared the basic same casting. Both were built in 1.94 and 2.02 applications.

By 1971, all high compression engines were non-existent so the 64cc heads were no longer made or used.

I believe the 492 (I think I have a set) were over the counter purchase Bow Tie heads. I don't think they came on production cars at all. The 291 and 292's did though I think.

Those are pretty good old school heads....I had a set of the 327/350 heads from the 60's and they woke up that low compression 350 L-48 in my 74 corvette ( back when the earth was still young;) )

I have a set of 64cc with big valves sitting in the storage shed. Ran them for several years on the '79. They're a decent head but modern technology certainly has passed them up.

I believe the 492 (I think I have a set) were over the counter purchase Bow Tie heads. I don't think they came on production cars at all. The 291 and 292's did though I think.

The 292's I do know were the Turbo Heads over the counter. Crane Cams had these marketed as "Fireball Heads". There is also a Big Block 292 head I believe but not 100% sure

The Dart Sportsman, Dart II, now Sportsman II from World Products, is a refined Bow Tie head with enough meat to do anything you want to do and is excellent head. The only down fall on the Dart Sportsman, Dart II aka Sportsman II is the exhaust runners are the same as the GM's, and they measure 67-70cc's just a hair larger in volume and cross section to the GM's but with much better intake flow, while not being a huge CFM number, they make EXCELLENT HP at the cfm they flow. A huge positive to them, is the pockets are step cut, including the Motown's, which allow a 1.255" spring to seat in the step without requiring a locator or spring cup

The GM 291 Heads are what we run on the engine that was in the Camaro. The 492 heads had screw in studs.

I like the 291 heads, 461 heads, 492 heads and if your gonna use a 292 Turbo head you might as well get a Sportsman II because they will not have the casting problems on the Turbo Heads

The turbo heads fully prepped by a local out here, on a 292cid went 11.0-11.20 @3900 pounds race weight in a friends car with a 4 speed. The camshaft in that 292 (283) was 276/280 @.050" .670"/.630" 108° lobe center ;)