Starting with 350 base engine for 72 with 3.08 rear end. Have engine in for machining and installation of rotating elements. .030 over bore with flat top pistons and keeping crank/rods. Right now plan for Edelbrock 2101 Performer intake, headers or 2 1/2 inch ram horns and pipes, E-210 Edelbrock heads (#5085) and getting ready to send carb to Lars. Also adding 2300 to 2500 B&M torque converter. The short block builder recommended the Comp Cam high energy 268H camshaft but a very knowledgeable person suggested a cam with more than 110 LSA would be much better (made couple mods to plan since then). I've read all kind of stuff but how the combination works in practice is beyond my experience. I'm seeing and getting a lot of good comments regarding the 268H. Just looking for a good street combination that will get attention. I want stock look and just couldn't justify going to stick conversion (before someone mentions that).

 

I believe the heads are going to have too big a port volume for your cam and compression selection. 180 to 190 port would benefit you more for what you are describing. 110 LSA is fine unless you are looking for a bigger cam or wanting a bigger cam sound

 

What kind of power are you looking for and how do you want the engine to behave?

 

Sauterindy,

That rear axle ratio is just awful unless the majority of your cruising will be at the Bonneville Salt Flats.
Most street / strip cam durations will not like that gearing.
Choose your torque converter wisely with 3:08. Or it could be really sluggish.

The exhaust manifolds you spoke of, are hardly worth the swap.
Most people that go that route don't want to invest in a modified exhaust system, money & labor.

Regardless of which heads & cam you choose, the restricting manifolds will be choking everything upstream.

You are designing / building a big air-pump. Let it breathe.
Most of your power is made at higher RPMs.
I think you will run out of road by the time your mill starts breathing right.

 

I’d put your build at high 200s to the wheel hp.
if that’s what you want, go for it.
A high stall converter will help out the 3.08 gears. I’d say 2500-2800ish stall. Make sure you add a trans cooler.
the good thing about that hp level is that you are less likely to break downstream components.

I think the intake and exhaust will be more limiting to your power production than your heads and cam

 

Burning Brakes-350 to 400 hp is fine and I want it street friendly.
Rescue-thought that head might be too much so the E-street version is still 64cc with 185 cc runner, cheaper also.
HeadsU.P.-an upgrade to taller diff was on my xmas list but finding good US differentials was unobtainable and GTR's backlog was longer than I could wait so just had it rebuilt. I can definitely go with some good headers but are you saying the 2 1/2 exhaust would still be too confining?
Randall steel-planning 2300-2500 but could go higher. good point on trans cooler. tks
thanks

 

Kicking ideas on engine builds on here is no different than pub talk. Everyone's an expert.
I run the 2 1/2 inch manifolds and 2 1/2 inch exhaust. Chambered exhaust, no mufflers.
Does it breath as well as long tube headers? Probably not at full noise. But it's a street car.
E Street heads work well with a xtream energy 268.
So, I'm thinking that build with flat tops would be more like 350 - 375 at the crank. Automatic transmission and those rear gears just isn't optimal as others have stated.

 

Sauterindy,

I am saying those exhaust manifolds do not have the key word like headers do.

For example. On one bank of cylinders with headers, when just one cylinder is on the exhaust stroke the force of those gases withdraws the other three cylinders exhaust at the collector. This event is called scavenging. And that is what makes headers worth several more H.P. They clean the cylinder of spent gases.
Manifolds do not scavenge.

Ram horn manifolds might be worth 5- 10 horse.
Where headers are worth 40 on up.

 

I learned the same old lesson the hard way that Horsepower is not something that can be made "cheaply". You can be very creative with what is available and make horsepower using all the engine tricks learned in the past 125 years.

When time for a rebuild I wanted to build my 427 into an L88. This is not as hard as many think and you end up with a beast of an engine to play with. The high compression certainly makes power but has a few detractors that you have to deal with. I did my homework and do not have a detonation issue with my 12.25-1 compression ratio 427. I do have a measure in place to handle the high engine temperature situations. There is a Water/Methanol injection system that both cools down the engine as well as boosting the octane to 116 octane which makes a high compression engine very happy.

The one thing that I use that makes a difference is compression. Higher compression engines have a personality of their own. When building the engine for my C3 we were surprised that Comp Cams would not sell me a cam if they thought the real axle ratio was too low. For my engine they recommended that I have a 4.11 or at least a 3.70 to get the best performance and get the best cam specs. When they heard I was using a 3.36 rear they freaked out and suggested that the combination might not work as well.

Another suggestion is to do the rebuild over time so the parts can be gathered at better (lower) prices. We spent close to a year to build and install my new engine. I stuck a 1970 LT1 350 SB in it for the year and continued enjoying the car while building the new engine. The SB let me really appreciate the 427 after putting it back in the car.

If I had a SB Corvette I would rebuild the engine to be just like the 1970 LT1 engine was. That 11-1 compression ratio really makes the SB wake up and perform, a good pair of heads and you might have a real beast that would be great in a Corvette. Following GM's design for the engine you can reproduce one fairly easily without having to design it from scratch. GM had a pretty good idea of what they were doing back in the early days of the C3.

 

Really good input from all. Where I think I am at is go with the E-Street heads, go with headers and 2 1/2 inch exhaust and just see how it performs. The compression estimate is around 10.2 and not sure how to get higher without drastic rethinking. If not happy with performance (and after I get it back on the road for a little while) then look for used differential and have it rebuilt by GTR with taller gear when time is not concern, or maybe go back and retrofit clutch. Right now don't want to lose momentum and will see how I feel once back and running. If I am really happy with the results and feel up to it, I won't mind spending the extra bucks over a winter for those type of upgrades. The learning process has been great and sure I will have the confidence to tackle either if needed.
thanks

 

First, little person in avatar is cute as a button !

64cc + flattops at 355" makes about 10:1 scr. On a NON-computerized street piece, that's just about tops for pump pee.
Build for street torque, not hi-rpm race horsepower.
Keep the 110 LSA (or even 108) because that helps torque in lower rpms; that's where this street motor's gonna thrive right?
Don't exceed that HE268H's 218* intake duration; On street & in traffic, your auto trans + gear combo performance becomes soggy beyond 218* (as does an OE auto L46 or L82 motor does).

Runners under 210 might be a better match for your stated purpose (and my understanding of that). Smaller runners help improve charge velocity.

Reduce friction: review piston choice; pistons with thin, metric ringpak make a real difference. Those old-fashioned thick 5/64 in. x 5/64 in. x 3/16 in tractor ringpaks are out. All OEs abandoned that farm junk decades ago. Thin metric holds up Longer + seal better while much less friction; win-win. Also, quench height is Very important; it's primarily pre-determined by pistons' compression height. OE CH is about 1.560" But many replacement pistons are shorter (about 1.550") some much shorter (1.540"). Nominal quench height in a well-prepped street motor typically 0.035" - 0.040". Other quench determinants are gasket thickness and blocks' deck height.

Unless builder specifically fits large oil-clearance bearings, do Not install a High Volume pump. It won't help, might hurt and will rob-waste horsepower and causes higher oil temps. One improvement is to use a pump with a larger diameter pickup tube. GM made that very improvement to SBCs in mid-nineties. SBC pump tube (& inlet) enlarged from 5/8" OD to 3/4" OD; that improves Low-to-Mid rpm performance (where a street motor thrives). Old 5/8" = Melling M55; while newer 3/4" = Melling M155.

With your cam & valve spring choices, No need for any double-roller timing set. Instead, a good quality, Large pitch, true seamless, H-D Single-roller set is more than adequate (and doesn't require clearancing-grinding face of block as some double-roller chains do).

Seeing as how this is a flat-tappet build, exercise caution during break-in; perhaps by temporarily reducing valve spring pressures.

Seems you plan to run Qjet; good choice of both carb & rebuilder.
But if you choose a squarebore carb, I'll recommend Edelbrock EPS 2701 over & above 2101; again, squarebore only w/ 2701.

 

Sauterindy,

Better double check those part numbers. Those heads fit a Mopar.
I think you mean 5089? Smaller 185 runner which is better on the street anyway.

Is this your first pair of aluminum heads?
There are hidden costs and tricks to be aware of.

And for what it's worth, quality premium pump gas will support 11: 1 compression w/o issue.

 

right, typo
The Edelbrock #5089 E-Street cylinder heads are designed for use with 1955-1986 SBChevy engines.

 

Sounds like a nice build and a nice street set up.
I think your rear gearing will be fine for a street cruiser especially if you do any highway driving.
That cam seems to add some lower rpm torque and I think when you push down on the go pedal, you’ll be happy.
But many of us start that way, then you’ll want more and end up like the rest of us.
I’ve got 3.08’s in my rear end, and I hope I can keep the rear wheels planted on the pavement.

 

The e streets with that cam will be fine.I would have the heads checked out by a competent machinist to make sure the guides are not too tight and that the supplied valve job is up to par. Worth a little extra $$$ to know you won't have a problem down the road.

If it doesn't break the bank look into a hyd roller cam with similar duration @ .050. Yes it costs more but flat tappet cam failures is real. I f going flat tappet find a machinist who can check the taper on the new lifters and a tappet grinding tool if needed. Stuff costs too much to start over.

Should be a responsive street motor with good manners.

An upgrade to a 3.36 gear later on will get you in the power band sooner and not suck the life out of freeway driving.

 

Yea a roller would be nice, but I have to stop spending money somewhere with this frame off I'm doing. Thanks for the tips. Plan to be very careful on the break in.

 

I keep telling myself the same thing!.