70vetteguy

I have decided to bump up the hp in my base model 70. Rather than bolt on a bunch of after market parts i would like to keep the stock look. Looking for some correct date lt-1 heads that i can use to put my vette at about 400 hp stock style.

WayneB_LT1

Those are like hens teeth to find and very expensive. Might want to stick with after market.

spf72

I have a set but If you have the stock heads on your 70 just have them rebuilt with the larger valves as they are the same 186 casting. The other difference is the screw in studs and the guide plates that can be done as well.

Doing just the heads won't make a big change in performance as there are many more differences in a LT-1 then the heads.

70vetteguy

Thanks for the tip. I may still want the heads, what condition are they in and what would you want for them? As for the power, the heads are just the start, the engine will be completely redone.

boat196

Your 300hp (base) motor my have # 186 heads with 1.94 intake valve.
Bob

surfertom

correct me if i'm wrong but i thought 69 LT-1 came with 186 heads while 70-71 LT-1 had x heads. if your looking for x heads i have part#973487x fresh from the machine shop new springs , new valves completly redone. let me know if interested. tom

hotrod32

What ARE the date codes your looking for?

spf72

There was no 69 Corvette LT-1 and the 70 standard 350 had the same 186 heads as the LT-1 The LT-1 has the larger valves, screw in studs and guide plates. If the OP car has stock heads they can easily be made the same as an LT-1.

My heads are rebuilt and have not been used since the rebuild. I am away and will check what I have into them when I get home. Because I will include the price of the heads combined with machine work it will probably be twice what it would cost to have yours redone and they won't be any better.

1974ta

Actually the valves were the same size between L46 and LT1. Not sure of base motor. LT1 Heads did have screw in studs, different springs and guide plates. Based on testing the 2-1/2" exhaust and the high rise aluminum intake on the LT-1 accounted for most of the power increase. Yes it revs higher but torque characteristics seem to be very close to L46.

What is interesting is than unless he has a numbers matching block and wants the correct heads, he is WAAAY better of buying some brand new aluminum heads. They will flow WAAY better out of the box and save weight.

Just my two cents as I have an all original L46 that I would like to make more power.

Bill

spf72

I agree on the L46 but the op said his engine is base and I thought that has 1.94 although I may be wrong as I am using my base 72 for my info. I also would think the lower end and carb of the LT-1 has a lot to do with the difference.

The OP said he wants to keep his car closer to an original look and my only point is that rebuilding his stock heads is a less expensive way to go even if you put in larger valves.

There is a set on eBay for $1000 that are rebuilt. I will want more for mine as the dates are right for a 70 build and I am partial to that year and engine. You could rebuild yours for around half that. I also agree you can buy much better new heads for less just some of us like period stuff.

1974ta

Believe it or not the bottom end on an L46 and LT1 are identical. Both use the "pink" rods and upgraded crank.

I am not sure about a base motor either in terms of valve size.

Bill

70vetteguy

Thanks for all the help on the heads guys. I think i'm gonna have my original 186 heads rebuilt with the bigger valves, screw in studs and guide plates, along with a port and polish. If the price of the heads being rebuilt is unreasonable, i'll probably go with the performer rpm heads and paint them orange

spf72

I think that is a wise choice. I had a set done last year and it was somewhere between $500 - $600.

Sky65

Where are you located? I have a used set of Performer RPM heads I may be able to let go for the price of rebuilding your stock heads.

Tom