[William Hennke]

Isn't that cam a bit big for just a street car? What's the specs on the rest of the engine? Compression ratio will be a big factor with a bigger cam like that.

 

[Billdini]

I don't think we can assume anything at this point without knowing what is in the lower end. My 68 L79 327 large journal crank, rods and pistons will drop right into a 350 block and keep it a 327. We can't suggest a runner size or cc chamber without knowing what pistons you have. I suggest a complete teardown, inspect to determine what you have before you go any further. Things have to work together.

 

[MW69Chevelle]

Head casting number is I-03XX or I-05XX. Get the 5 digit number to figure out what world heads you have. Those are probably sportsmans 200cc would be my guess.

 

[tmicallef]

Isn't that cam a bit big for just a street car? What's the specs on the rest of the engine? Compression ratio will be a big factor with a bigger cam like that.

Here's what I know...TH350-guessing 2-2500 stall. 12 bolt 3.73 posi. 17x9 rears on 255x50s. Dual plane intake (see pic in 1st post), 1" spacer, Holley 650 dbl pump mech secondary. MSD pro billet w/separate blaster coil (no 6AL).

Engine builder from Skip White assured me 200 cc intake runners would be ok and 64cc combustion chambers would work with my cam. Other guys are saying don't go over 180. This is a street car...not strip. Looking at Hedman 68298 with 1 5/8 primary. 2.5 exhaust through 3 chamber Flows.

 

[tmicallef]

are those port plate adapters for the headers?

No he spaced them out so he could fit the Cyclone 1.75 tubes plus used Accel 276s shorties.

 

[nitrofox]

Let's start from the beginning..... Why did you tear it down to begin with and how did it run before the teardown

 

[Billdini]

No he spaced them out so he could fit the Cyclone 1.75 tubes plus used Accel 276s shorties.

It sounds to me who ever built that engine was thinking bigger is better and although that may be ok for the track a street cars need to make power off the line with low end torque with a nice midrange and good power to 6k. 1 3//4 headers are not needed for a 327 or a 350, usually a 406 could use that size. Headers need gas velocity to work best and as you already stated 1 5/8 is a good street size. Your engine builder can only say a cam can work with 64cc heads with 200cc runner but he can't say that head will work with a high compression piston on the street without additives. That is pretty hot for a street cam and I suspect you are running into streetability issues and why you want to change things up. Set your goals and build what meets those requirements. It is very possible you may buy a head that makes less power then what you may already have especially if it doesn't work with the rest of the parts you wasted $. It sounds like you realize this and why you are planning on changing things up. I do like your carb choice even for the street,

 

[tmicallef]

Let's start from the beginning..... Why did you tear it down to begin with and how did it run before the teardown

Here's the reason why I'm considering new heads...
I discovered 2 broken roller rocker arms when I took the valve covers off for a basic inspection after I bought the car. The pushrods were fine "straight" so I was suspect that there may have been an underlying issue. Plus...the insides of the heads just looked nasty and heavily sooted and the water passages were caked with crud. I haven't pulled the heads so I don't know current combustion chamber volume nor do I know what pistons I have...flat-dished-domed. These heads are iron and angle plug...can't find a casting number (may be underneath a guide plate).

The car ran like crap before the teardown but that may have been more carb related since it was leaking fuel and vacuum due to a worn out throttle body plate.

So that's where I'm at. I thought I'd be further ahead getting a better flowing head instead of spending money having these rebuilt. I definately want all the parts to work together and I appreciate everyone's comments!

 

[msmith1.wa]

I had a 327 in a Monza with the same cam and 64cc Trickflow heads, domed pistons, Edelbrock air gap manifold, 3.08 gears and 26 inch tall tires. I really liked how it ran on the street. It also was a manual transmission. Now the bad, when idling in 1st gear like driving in a parking lot the rpm's would go up and down. Lower gears would probably have helped with this.

I think for a heavier car with an automatic you would need a higher stall converter to be happy with this combo.

Sent from my SM-A716U using Tapatalk

 

[tmicallef]

Here's the reason why I'm considering new heads...
I discovered 2 broken roller rocker arms when I took the valve covers off for a basic inspection after I bought the car. The pushrods were fine "straight" so I was suspect that there may have been an underlying issue. Plus...the insides of the heads just looked nasty and heavily sooted and the water passages were caked with crud. I haven't pulled the heads so I don't know current combustion chamber volume nor do I know what pistons I have...flat-dished-domed. These heads are iron and angle plug...can't find a casting number (may be underneath a guide plate).

The car ran like crap before the teardown but that may have been more carb related since it was leaking fuel and vacuum due to a worn out throttle body plate.

So that's where I'm at. I thought I'd be further ahead getting a better flowing head instead of spending money having these rebuilt. I definately want all the parts to work together and I appreciate everyone's comments!

Here's a pic of the cam that was on there...custom grind so no idea what size. Solid lifters however.

 

[tmicallef]

Head casting number is I-03XX or I-05XX. Get the 5 digit number to figure out what world heads you have. Those are probably sportsmans 200cc would be my guess.

You think I might be further ahead getting these heads rebuilt? They claim they make more power over stock OEM irons. I know...casting numbers would reveal combustion sizes and we need that to dial everything in

 

[Billdini]

You think I might be further ahead getting these heads rebuilt? They claim they make more power over stock OEM irons. I know...casting numbers would reveal combustion sizes and we need that to dial everything in

I really think you need to find out what you have and what you want . I am at a loss how you could have two broken roller rockers yet the pushrods are straight. That can happen but two. Same cylinder? As I mentioned before I am running a # matching and completely stock 68 L79. 2.02 double hump 64 cc heads, stock 11 to 1 forged pistons, stock exhaust manifolds through a 2.5 exhaust system, L79 222/222 cam with a .447/447 lift. Will go up a hill in 4th at 1000 rpms with no hint of a buck or a ping with a 2.20 first gear M21 and 3.31 12 bolt. Gets around 18mpg if being gentle, is quick and a joy to drive. All stock except it’s .030 over pistons so it’s a 331 now. My point is everything matches and that famous little mouse just works and Grumpy Jenkins showed the world that it could beat down that badass 426 hemi in stock class. The little engine that could😎

 

[tmicallef]

Ok...were

Head casting number is I-03XX or I-05XX. Get the 5 digit number to figure out what world heads you have. Those are probably sportsmans 200cc would be my guess.
[/QUOTE

Ok...

Head casting number is I-03XX or I-05XX. Get the 5 digit number to figure out what world heads you have. Those are probably sportsmans 200cc would be my guess.

Ok...I think we're making progress! Found the casting # (see pic)
Just need the part # now to verify combustion size

 

[Rmchevelle]

Here's a pic of the cam that was on there...custom grind so no idea what size. Solid lifters however.

Comp Cams 294 solid. If the cam is in good shape I may know someone who'd be interested in buying it.

 

[MW69Chevelle]

So what are your goals with this sbc? To try and give you the best advise, I need to understand what you are doing. Looking for 350-400hp? Use the XE274 you bought and go through the sportsman heads. They definitely aren’t the best flowing head by today’s standards but they do decent for what they are. Believe it or not, I’ve run that exact cam XE274 with those heads in a 355 10:1. Was a great little street motor.

 

[tmicallef]

Comp Cams 294 solid. If the cam is in good shape I may know someone who'd be interested in buying it.

Yes I've still got the cam and lifters. Yes I would consider selling.

 

[tmicallef]

So what are your goals with this sbc? To try and give you the best advise, I need to understand what you are doing. Looking for 350-400hp? Use the XE274 you bought and go through the sportsman heads. They definitely aren’t the best flowing head by today’s standards but they do decent for what they are. Believe it or not, I’ve run that exact cam XE274 with those heads in a 355 10:1. Was a great little street motor.

Just a good street car with mid to upper range power. The 373 posi should help with that.

 

[tmicallef]

I really think you need to find out what you have and what you want . I am at a loss how you could have two broken roller rockers yet the pushrods are straight. That can happen but two. Same cylinder? As I mentioned before I am running a # matching and completely stock 68 L79. 2.02 double hump 64 cc heads, stock 11 to 1 forged pistons, stock exhaust manifolds through a 2.5 exhaust system, L79 222/222 cam with a .447/447 lift. Will go up a hill in 4th at 1000 rpms with no hint of a buck or a ping with a 2.20 first gear M21 and 3.31 12 bolt. Gets around 18mpg if being gentle, is quick and a joy to drive. All stock except it’s .030 over pistons so it’s a 331 now. My point is everything matches and that famous little mouse just works and Grumoy Jenkins showed the world that it could beat down that badass 426 hemi in stock class. The little engine that could😎

The cracked rocker arms were 1 on each side...different cylinders. Thank goodness they didn't crack completely through.

 

[tmicallef]

Water passages were nasty.

 

[Billdini]

The cracked rocker arms were 1 on each side...different cylinders. Thank goodness they didn't crack completely through.

Well I am not a machinist but my guess either the guides or the head openings for the pushrods got in the way somehow and caused stress either sideways or back to front. Possible coil bind.. It is a pressed in hardened steel insert where the pushrod seats in the rocker. Solid lifter cam with aluminum rockers wouldn't be my choice. At least they are USA made, who makes them? And someone needed to use antifreeze. Was this engine raced? I would be concerned about a freeze issue or even a possible overheat problem. Where has this car been? Lots of questions I know but soon you will be ahead of it. That motor needs to be disassembled and fully inspected by a machinist for sure. Obviously checking all castings is a must including the block