sparky1340

I have a 350 Goodwrench engine with 2 1/2" exhaust using ramshorn manifolds. I'm assuming it's around 8:1 compression. It has an Edelbrock Performer intake and carburetor. 4-speed with 3:55 gears. It's a daily driver. I'm looking at Edelbrock heads and cam. I'd like a noticeable lope in a cam and nothing over 9:5 compression. Any suggestions on which heads/cam, or other manufacturers ???
I'd like to get closer to the original 365hp it had from the factory.
Sparky

65tripleblack

If you build in 9.5 compression with a camshaft with duration long enough to give a noticeable lope, the engine will be a "dog". 9.5:1 compression is generally acceptable for cams with durations in the 200-220 degree range @ .050. A lopey cam, or one with a duration of at least 230 degrees, requires at least 10.5:1 C/R.

Please do not read this "literally". Duration is merely a "yardstick", since inlet valve closing will primarily determine required SCR. Overlap determines idle quality, and duration coupled with lobe centerline all blend together to determine optimal SCR requirements.

Follow cam manufacturers recommendation for SCR. If you decrease SCR much below recommendation, your engine will be a "dog".

Shurshot

We need to figure out your real world compression and go from there

Since you are willing to move to aluminum heads (that is good) before you take off the old ones get your cranking compression numbers and then be careful to try and keep the intake gasket as intact as possible when removing it. Then you can get some cc measurements and we can go from there knowing what it takes to get what you got so to speak

There are lots of good up to date SB horsepower gurus here and they will all have proven products to recommend to you. Personally I prefer a holley style carb and then use the BB drop base for the most room for a tall air cleaner. A BB hood will help you where all corvettes need it most.........room under the hood.

Would you consider headers?....... new heads are nice for getting air in but you need to get it out and without headers you are setting a cap limit.

This will be fun to watch.......... I am going to sit back and let those who know your motor help you do what they do best.

Good luck

Doug

ghostrider20

All above is good info. The long desired Holy Grail of engines. A loopy cam with low compression and good low end torque. Keep looking.

Study up on static and dynamic compression. You will need more static compression to make a high overlap cam work at all. If not you will have the worst of both worlds, a soggy dog down low, and hindered power at the top.

I run the LT-1 cam, it is a solid lifter with 10.5:1 compression. Nice lope and a livable amount of low end power. Pulls to 7000 RPM. I don't know much about the aftermarket world, other may chime in with their experience.

Mark

knight37128

First thing I'd do is get rid of everything that says "Edelbrock" on it.

They may look good but looking good doesn't make it go.

MikeM

If you're going with the Edelbrock heads, cam and intake, I'd call them and see what they recommend for a co-ordinated package and what results to expect.

I don't know much about their stuff but I'd think they have a combustion chamber size that'll get your compression up into the 10+-1 range where you need it as others have said.

jdk971

sparky, these guys will guide you right. but first how old is the short block and what shape is it end. also what pistons are in it. i assume
these guys would need to know that also. just a guess jim

Mr D.

Kensmith

That Goodwrench comes with dished pistons and about 8.3 compression. You can use the Edelbrock 64cc RPM heads and maybe achieve close to 9.5 compression. I would call Comp Cams and give them the information on your motor. They have some cams with nice lope and yet will do well with the lower compression. Your Goodwrench motor probably comes with 290HP as a long block. To get up to 365HP you will need to go with the air-gap intake and headers. Some of the bolt on top end systems are good also. Holley and Edelbrock have them. Call their tech line and see what they say. They do this bolt on stuff all day long.

aaronz28

if you are running Ramshorn manifolds.. stay away from any modern cam with tight Lobe Seperation Angles.. and durations figures above 230...

they will not work well together..

as it has been said... low compression and lopey idle are not two things that work.

to get the lopey idle, you need long duation..
to make long duration work, you need alot of compression.

my suggestion would be to get your compression as close as you can to 11 to 1... with the aluminum heads.. you can run a point higher and not have to worry about detonation...

i run 11.5 to 1 with iron heads, the 30-30 cam, and 93 octane all day long.. never an ounce of detonation so i know it can be done.

if you can get to the 10.5 to 1... run the LT1, 30 30, or the old 097 cam. it will have the idle you want, and the performance you are looking for, and you can run pump gas.

anything less than 10.5... stay away from the 30-30... you might be ok with the LT1, and the 097...

especailly considering thatyou have a 350... those extra 25 cubes will really help.

good luck

A

sparky1340

Aaron,
Appreciate the info, especially with such a positive note.
Will call CompCams for cam with 10:5 CR. What would be a good
GM aluminum head ??
Thanks Again,
Sparky

aaronz28

i'm not really up on the modern aluminum stuff... but i know that i've seen aluminum heads with 58 cc chambers... if you have dished pistons on that 350.. then you might need very small chambers to get you to that 10.5 to 1... or at least close to it..


be weary of any of the "modern" cams with your rams-horn manifolds...

i've learned this the hard way... i'll try to explain it briefly...

modern cams have one thing in mind... more power under the curve..

what they try to do is keep the valve closed longer, snap it open - keep it open longer, and then slam is closed... designers keep cams on tighter Lobe Separation Angles as well...

in theory, this builds cylinder pressure, which relates to more torque, and the tighter LSA makes the engine peakier... and when the valve slams open... ideally, the port velocity is increased, which means more air/fuel into the chamber... and with a higher compression ratio, you get more torque and more power....

This theory is only as good as its weakest link however...

i've tried 5 modern cams, and tried to make them all work with stock type exhaust... everyone failed miserably....even modern cams on wide lobe seperation....

comp is gonna try to sell you on their THumper Cams (if they can talk you into hyd roller) or the XE cams...


both have increased ramp profiles and really will not perform well unless you have a good intake and exhaust headers on the car..


i don't believe that the oe manifolds can handle the increased velocity and thus power goes down. sorta like trying to run 6 lanes of 80mph highway traffic into 1 exit ramp at the same time... making everyone get off at the same time... well you get the idea.

as long as you are running the OE manifolds.... you will not outperform the Factory HiPo grinds... or if you want aftermaket... stick to OLD aftermarket.. like the comp Magnum stuff, or the old Crane Fireballs

Just recently, I installed headers and a fancy exhaust on my 69Z.
i removed the old 30-30 cam, and installed a new Lunati Custom Ground Solid Lifter Cam... i was guaranteed that it would blow away the old 30-30 or any of the factory GM cams... boy was I excited... untill I drove the car.... i ripped that sucker out within a week, and installed the old GM offroad cam... which is ENORMOUS in terms of a street cam for a 302.... the offroad cam with its 50 degrees more duration actually has better street manners than the custom cam that was guaranteed to blow the OE GM stuff away... figure that one out.

if you compare the old cams advertised duration and the duration at .050.... you might see a cam with 290 degrees advertised with 245 at .050 vs a modern cams advertised duration of 272 and its .050 duration something like 249...
this shows how much faster the new cams get the valve off the seat (in terms of duration degrees)

the old cams generally do not have as high of lift either..

i hope I didn't confuse the situation....
the cam tech guys only know how to read a catalog and they do not understand how the exhaust pulses create problems when using cast iron manifolds... or even the shorty block hugger headers.

even though the 2.5 inch ramshorns are about as good as you can get in terms of manifolds... i can speak from multiple cam swaps worth of experience on the issue.

If it were me, and I couldn't get to 11 to 1... i'd run either the LT1 or the old 097... and advance them 4-6 degrees in the engine. that will help out a tad with your lower compression and make the engine much more responsive.

Good luck

Aaron

sparky1340

Aaron,
Thank you so much for taking the time to do such a lenghty response.
I really appreciate it and will use your info to help me make a decision.
Sparky

65tripleblack

That is an EXCELLENT explanation, Aaron.
It also points out the importance of using API CJ-4 motor oils and, having any "fast action" modern cam nitrided, if you are installing a flat tappet camshaft. Hardened exhaust valve seats also become important when using vintage heads.
As a comparison, the old 30-30 has MEASURED durations (the on-the-seat durations are not published, anywhere AFAIK) of 254/254 @ .050" and 310+/310+ seat-to-seat.............this makes for an extremely mild ramp, since we are talking a difference of more than 50 degrees between seat-to-seat, and .050" durations. By comparison, many modern "fast action" cams, like the High Energy series, have differences down into the low thirties!
There is a metric, called "ramp rate", which is a zero-100 per-cent scale which ranks aggressiveness of cam profiles. If I remember correctly, I arrived at about "5" intake and "5" exhaust with the 30-30. The cam that I'll be installing in my engine build has ramp rates of 57.2/60.4

Kensmith

Aaron,

If he truly has the Goodwrench 350 (made in Mexico) he will never come close to 10.5 to 1 compression even with 58cc heads. He might get close to 10 to 1 but more realistic about 9.8 to 1. But I do think with the upgrade aluminum heads, good matching cam, air gap intake, headers, he can get very close to 365hp without changing pistons. Like I said, call Comp Cams, Edelbrock, Holley system as they all have systems that will work for your Goodwrench motor. They have been doing this for some time.

63 340HP

Aaron's advice is on the spot for ramhorns, and for exhaust restricted engines.

One of the concerns with "modern" aftermarket performance cams, heads, intakes, and advice is that everyone building a "modern" small block is working with 383 ci or larger engines. Many of the advertised packages that work with a 383 or 396 do not work well with a 350 (and very poorly with a low compression 350).

I highly recommend that you or your friends (team up to) buy an engine modeling program like EA 3.2. The link is to the demo download, but you can page up to the home page link and more of a written description of what the program offers. The money you spend on the program is less than the cost of one camshaft or intake (the price of the wrong parts you buy before getting the program).

I ran some quick models of a low compression 350 (9.3cr) in a ramshorn undercar exhaust configuration with Performer RPM heads and intake. Aaron's recommendations of the 70' LT1 or 56-63' 097 early Duntov cam lead the way for GM cams. The 70' LT1 has more upper rpm hp (5500+), the 097 more low rpm hp. Both run to 7000+ rpm, and have a mild lope to turn heads during the idle through the lot. Unless you want to experiment with custom grinds these two cams are hard to beat for power, and none of the modern high-intensity grinds have similar soft long-life lobe ramps (they can be beat, but the extra power comes with a service life compromise).

A modern cam comparison point is the 93' late LT1 roller cam, with the 097 Duntov. They both make almost identical peak and average torque and hp. The late LT1 is a higher lift hydraulic roller with short duration and a very wide lobe centerline (117), compared to the 097 with longer duration and close lobe centers (110). The difference in power is the late LT1 roller falls flat after 5500-6000 rpm, and the LT1 roller idle is smoother than the vintage 300hp cam (the LT1 roller pulls 20+ inches of vacuum at idle, compared to the 097's lope at 15 inches). The late LT1 roller has almost no overlap, a great combination to exploit modern free flowing heads, but the hydraulic lifter kills the top end power above 5500 rpm (but both cams still produce ~350 ft.lbs. of torque and ~335hp @ 5500 rpm).

The modern aftermarket performance roller cams run longer duration than the 93' LT1 from GM, and the low rpm torque suffers (unless you have the long stroke of the 383 engine). This is where the "modern" performance era aftermarket is looking, for more power below 5500 rpm and the need filled with a longer stroke SBC. These cams in a 350 just lose low rpm torque, with the same peak rpm of the hydraulic lifter mass and limitations (where the 70' LT1 and 097' keep spinning).

sparky1340

Again, I can't believe the knowledgable and lengthy replies from the members of the forum. Thanks again to all, I've learned a lot. Will post results after the mods.
Sparky

aaronz28

Agreed,
my only concern still lies in the exhaust side.

If they spec their system with headers, then it is likely that they were designed around headers and not the manifolds.

I think he was planning to keep the Ramshorn manifolds..

if he will move to headers, than I agree with you that a proven combo is probably the best bet.

A