What heads were used on the 1969 350 300hp motor. can these heads hold up to new cast iron heads? who makes the best new cast iron head? can the stock heads make 400hp with some mods. what valve size was on the 300hp '69? where these heads the same as the '70 LT1 heads?

The heads you have are 186's with 64 cc and 1.94/1.50 inch valves. They made 10.25 compression ratio with the factory flat top pistons that came on the L-48. Yes, these were the same heads used on the 1970 LT-1 with one diff...the LT-1 heads had 2.02/1.60 inch valves. These heads (big valve version) were also used on 1969 Z-28's...so, they're as good as anything Chevy put out in this era. They're also increasingly rare.

For stockers, you're in business with 186's.

I know about the 186's in 69/ but if I can change the question, where did the 041's come into play?

041's were used on 350/300's from '69-'70; had 64cc chambers, 1.94/1.5 valves. They were used interchangeably with the small-valve 186's on 350/300's. 1970 LT-1's used the big-valve versions of both the 186 and the 3973414 heads (with screw-in studs and guide plates; 69's had press-in studs and no guide plates). 461's, 186's, and 414's that were factory-machined for 2.02 valves also had the intake side of the chamber machined to unshroud the intake valve.

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JohnZ
'69 Z28 Fathom Green

I believe Chevy also had a screw in stud for an application without guideplates. When installed it was easy to mistake it for a pressed in stud. My 69 Z had these back in 1980. I can't remember the casting number to know if they were the original heads or not.

As for how they compare to todays cast iron heads, take a look at this web site which was in a post yesterday. It has some flow comparison data:
[URL=http://www.topher.net/~bearman/gmheadcomp.html]

For comparison, the 461s are almost identical to the 462s. You can expect to give up about 15-20CFM over a modern cast iron head on both the intake and exhaust sides.

These heads definitely don't suck!! And, yes, they will make 400 HP with very little trouble. After all, they made 370 HP on an LT1 which had a very mild cam and no headers!! I have a set of 462s with 2.02"/1.60" valves on a well massaged 331 and it makes 450 HP on a dyno!

Since these heads were built to run with leaded gas, I would recommend that you have them modified for hardened valve seats. This is a perfect time to cut in those 2.02" and 1.60" valves and it will keep you from having to regrind the valves every 15-30K miles!!

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Paul D.

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68RS, 331, 10.5:1, 4spd, 3.90 9", lowered, 245-45-16's all 'round

If you have them re-cut for 2.02's, make sure they also machine them to unshroud the intake valves, or they'll flow less with the new 2.02's than they did with the 1.94's - trust me.

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JohnZ
'69 Z28 Fathom Green

If you have them re-cut for 2.02's, make sure they also machine them to unshroud the intake valves, or they'll flow less with the new 2.02's than they did with the 1.94's - trust me.

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JohnZ
'69 Z28 Fathom Green

Yeah, ditto on what John Z said.

Also, a little time spent with a die grinder gasket matching the intakes and blending the intake and exhaust bowls will help a lot!!

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Paul D.

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68RS, 331, 10.5:1, 4spd, 3.90 9", lowered, 245-45-16's all 'round

Just for the record, my 041 Chevy heads took my car to an 11.23 @ 119mph. This was with a 355ci, street solid roller cam, LT-1 bottom end (Chevy forged crank, Crower Sportsman rods, TRW 11:1 pistons), 8" convertor, and 5.13 gears. I was winding it to about 8,200 rpm. My heads had 2.055/.1600 valves and MAJOR port work (even added some epoxy at the pushrod juncture). Like pdq said, these heads can make some very good power if modded right.

Shane

wow 69SSRS, 5.13s http://www.camaros.net/forum/eek.gif As we say up here in NH, that's a pretty seveah geah!!! http://www.camaros.net/forum/smile.gif

My last 331 powered '68 (back in 1984!) was sportin' a set of well massaged 461's with 1.94 and 1.60 valves. With a Crane CC300NC mechanical cam, 11.0:1 compression and 4:56 gears it ran a best of 11.90 @ 117MPH it went through the traps at a nice, "sane?" 7900RPM!!

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Paul D.

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68RS, 331, 10.5:1, 4spd, 3.90 9", lowered, 245-45-16's all 'round

He, He!! I've seen 7200rpm and climbing w/3.08's on the highway in my crippled buddy's '58 Vette w/ a 375hp/327 fuelie engine had a Z-30 Isky solid in it! Now, that night was a ride!

Yes, these are the stock heads you are talking about! pdq67

Yup! That old 331 powered 68 would turn 8300 on the highway with those 4.56's and go 135MPH!!! My buddy still has a 64 vette that I built a 302 for, also with 4.56's. We used to cruise 'em down the road at this speed late at night every so often back when we were young-n-dumb! Not bad top end for a couple of severely over geared cars!!

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Paul D.

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68RS, 331, 10.5:1, 4spd, 3.90 9", lowered, 245-45-16's all 'round