KC John

I have a 1970 350 that produced 297 hp at the wheels with camel hump heads. The heads need seals and they have no accessory holes in the front. I'd like to replace the heads, but I have a few questions.

Can I bring that block as is to a machine shop and have them check out the entire engine and tell me what I have? What should it cost to have this done? I know just enough to get in trouble. I read that I need to know the specs of the engine before purchasing heads. I also don't know what cam it has.

How would you proceed if this was your engine. I was going to make it a 383, but I'm not sure I would gain much more power for the expense it wold cost to convert it.

DUB

Not that it matters...but I thought by 1970, the cylinder heads had accessory holes in them.

Not that it matters to some people....but if this is the original engine and the 'numbers' match the car...some would leave it alone and go get a 383 already built.

Some would get this one built and the costs are somewhat comparable ...depending on what may be wrong internally in the engine you have now....and what grade of parts are used in the rebuild.

If it were me and I DID NOT care what anybody thought....I would buy a new engine and that is it. This way if I ever sold the car...and the engine that was in the car was the one that came in it from the facotry...THAT often times is what some people are looking for.

Rule of thumb is.... more cubic inches that an engine has allows for more power to be produces...BUT...you can get a 350 to really be powerful. And why stop at 383 when you can go to 400 cubic inches and get more....because I have a customer that has a DART 400 engine with a Quadrajet carb in his 1974 with a 700R4 automatic from Bowtie Overdrives and he is getting 23 MPG when he is not ON IT.....and has all the power he would need. If you need his info...PM me and I can get you two together.

DUB

Vet65te

Just guessing here but it sounds like it's a 1970 350 with earlier heads?
I think they added the auxiliary attachment holes in '69 because I have a set of #291 2.02 heads from '68 on my 66 L79 and no holes.
Mike T - Prescott AZ

SDVette

I have a 1970 350 LT-1 shortblock in my '61, but the heads, intake, manifolds are from the original 283. The LT-1 was the king of the Gen 1 SBCs. Solid lifter.. dome pistons, 11:1 CR.

Perhaps that's what you have as well?

KC John

The engine is not original to the car, it was in my '63 when I bought it. I thought I heard detonation, but was unable to confirm it. When I started noticing smoke at take-off, I figured I needed valve seals and I had another engine ready to go so I swapped it out. The engine ran fine and I figured it had about 350hp or so because it made 297 at the wheels on a dyno.

I pulled a head off and it appears to have flat top pistons and hydraulic lifters. There is no ridge at the top of the cylinder walls and the engine is extremely clean inside.

So that is why I thought I could just put a set of decent heads on it and maybe a cam and for under 2k have a nice engine again. I just don't want to do all that work if I don't really know what I have to work with.

These are the heads that are on it now.




I was told this was a 1970 truck engine, but I don't know that for sure.




.

karkrafter

My opinion, you will be hard pressed to turn your 350 into a 383 for what it cost to buy a crate 383...Blueprint and Smedling come to mind,

Another option,sell the 350, buy a 400 core, use the 400 crank and rods, .030 over and build a 406. Better engine than both the 350 or the 383 with the right cam/head combo.

383's only exist due to the scarcity of 400 cores...but they are still out there.

R66

You have "Double Hump" or "Fuelie Heads" 300 hp heads pre late 68. They are good heads and desirable to someone looking for the right heads. In the 70s, they increased the combustion chamber size to lower the compression from 10.5 : 1 down to as low as 8 : 1 (I think) due to poor quality fuel and air pollution. The heads and cam make the engine breath and are more of a key to HP than any other component on a carbureted engine except adding cubic inches (e.g., 383, 400, or big block). If the short block is in good condition, the only thing you can do to increase HP (without cu. in. increase by stroking) is to better the breathing (cam, intake, carburetor, Fuel Injection, etc.) Go with a professional engine builder or buy a crate engine from a reputable retailer. I think if you are going with a 383, there little advantage to using what you have as you will be replacing most of the major components (crank, pistons, etc.) anyway.
Sell the double hump heads on the forum or other locations as they are still worth some bucks to the guy with the right year block to fund your upgrade.
Just my $.02. Good luck.

GUSTO14

Your block shows it could be a 302, 327 or a 350...
3956618....302.....69....4...Z-28 Camaro
3956618....327...68-69...2
3956618....350.....69....2 or 4
http://www.mortec.com/castnum.htm
If you post the info on the front (rt side stamp pad) of the block it may reveal more of where the engine originated.

The difference is going to be in the length of the rods. If you drop the pan you'll be able to tell if it is 2 or 4 bolt mains which would be good information to know. Since you have flat top pistons (not dished pistons?) I would go with a 64cc combustion chamber head such as these Dart Iron Eagles (or similar head). These will flow much better than any stock head (and most modified) available back in the day.

Yes, you can take the engine to most any reliable engine builder and he should be able to tell you most everything you want to know about what you currently have mechanically.

Good luck... GUSTO

71scgc

Ima send a PM directly...

Carter

65tripleblack

Those are 461 heads from late 1965. Cast July/29/1965.
They can be either 2.02/1.6 or 1.94/1.5 valves.

R66

The big question is, what do you want to do with it???? Are you looking for a dependable cruiser? A weekend drag racer? Looking for long cruises? Gas mileage? Gearing? That has a lot to do with what heads, cam, carb, etc. you will be happy with. I built a full tilt 302 for a vega back in the day only to find I couldn't street it without constant maintenance. Loved the power, but loved cruising more. Bragging rights aren't always worth the price.
You have a good basis for a street cruiser now (block and heads), with minor changes and tuning if you are happy with the power. IT's your car, build it for how you want to drive it the most.

KC John

I like torque, I generally cruise about 35 to 45 miles an hour on mostly back roads. Don't get me wrong I love to jump on it every once in a while and go through the gears but I don't do a lot of high-speed driving. I have 3.73 gears and a wide ratio Muncie.

I like the idea of the 406, will all my other stuff bolt on just like on a 350? I don't know a thing about the 400. I also have power brakes, so the engine has to have vacuum and the valve covers can't be the tall ones or they'll hit the brake booster.

R66

A 400 has a larger bore (4 1/8") and is externally balanced using a different harmonic balancer and flywheel. The heads and block have "steam holes" as the cylinders are "siamized" (spelling error - spells like those gray and black cats). Back in the day, they were plagued with heating problems.
One might want to consider a good roller cam and electronic fuel injection for waking up the 350 and still maintaining a good torquey driver.
Larger valves (e.g., 2.02" / 160") generally are only an advantage at higher RPM (5000 plus) and can hurt low RPM torque. Keep in mind that you can go with the large valve heads, but they won't breath without the right intake and large exhaust. Stay away from single plane intakes if you want low end torque and vacuum.
I am not up on the new technology of this century, so maybe the PRO engine builders can give you some guidance on a good torquey cruiser that you can build for a couple of thousand. I am betting you may even be able to use your existing heads.

68post

GUSTO , the actual difference lies only in the piston head height,(the "pin height") , from the pin top to top of piston and crankshaft stroke. All use a 5.70" length rod.
350ci pin hgt. 1.550", stroke 3.48".
327ci pin hgt. 1.665", stroke 3.25".
302ci pin hgt. 1.79", stroke 3.0".
Just thought to add this for further clarification of the difference.

GTOguy

I think these gents probably figured this out nearly 6 years ago, when this thread was posted and active.

68post

Okay, Sorry, I hadn't read the date - and not sure how this thread came up in front of me, thought it must have been a notification of a recent thread subscription response. But since nobody had caught that someone inferred that the diff was a rod length - it now stands corrected in case some fool such as myself comes across it again.

Thanks for pointing out the date !! It's all good !!