Roller cam cost effectiveness

[53' Stude]

Originally Posted By: A_Harman
Here's a video that's relevant to the discussion.
https://www.youtube.com/watch?v=AScojLj139A

Engine Masters took a 305 Chevy with a stock bottom end and progressively increased the nitrous shot until it blew up.


Yeah I remember that one

 

[OVERKILL]

Originally Posted By: turtlevette
301

I know. It's a pos engine, but it's number matching and only 213 made.



With some better heads, something in a roller profile similar to the TFS #1 would be an excellent choice and should be inexpensive. My old 302 made 270 to the tires (~310HP flywheel) with that grind with some ported GT40 irons.

Operating characteristics were:
- Good idle @ ~750RPM, only mild lope
- Broad powerband from ~2,000RPM to >6,000RPM. Peak occurred around 5,800RPM IIRC. Stock rev limiter was 6,250RPM, but she didn't fall off after peak.

I ran it with 1.7 ratio rockers to get more lift.

Specs are:
Basic Operating RPM Range: 2,000-5,500
Intake Duration at 050 inch Lift: 221
Exhaust Duration at 050 inch Lift: 225
Duration at 050 inch Lift: 221 int./225 exh.
Advertised Intake Duration: 275
Advertised Exhaust Duration: 279
Advertised Duration: 275 int./279 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.499 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.510 in.
Valve Lift with Factory Rocker Arm Ratio: 0.499 int./0.510 exh.
Lobe Separation (degrees): 112


With the 1.7's, lift was 0.530/0.532.

 

[funflyer]

Originally Posted By: turtlevette
301

I know. It's a pos engine, but it's number matching and only 213 made.



This forum might not be the best place to get advice about your 301. Try the 301 forum.

 

[turtlevette]

Originally Posted By: funflyer
Originally Posted By: turtlevette
301

I know. It's a pos engine, but it's number matching and only 213 made.



This forum might not be the best place to get advice about your 301. Try the 301 forum.


I'm on there too and the firebird forums 79se301m. They average a post every 6 months whether they need to or not. Pontiac guys are the most dismissive of the 301 engine and I get tired of it. The standard answer is to put together a 455. In general those big long stroke engines are like tractor motors. I like something that sings a higher song. I'll have to get some sound clips of the 350 in the vette.

 

[userfriendly]

Right. It takes lighter connecting rods, good heads and lots of camshaft to get a 455 over 6000 rpm, and actually make power up there.
First, get rid of the stock 1.5 rockers, valve springs and retainers. New parts can always be transferred to different heads down the road.
I have one 455 stored in a 77 station wagon, still starts with 15 year old gasoline waiting for a project to materialize.
Soon those BOP 400T transmissions are going to get hard to find.

 

[turtlevette]

Originally Posted By: A_Harman
Here's a video that's relevant to the discussion.
https://www.youtube.com/watch?v=AScojLj139A

Engine Masters took a 305 Chevy with a stock bottom end and progressively increased the nitrous shot until it blew up.


I believe the only reason it blew was a lean #2. That nitrous is coming out at high pressure. I don't think the fuel pump really keeps up as you jet larger.

 

[turtlevette]

That sounds like an aggressive but reasonable profile. I used to run the flat tappet L82 cam in the vette with Rhodes lifters. I guess I overreved it too much as it pulled the pressed in rocker arm studs out.

 

[turtlevette]

Originally Posted By: userfriendly
Right. It takes lighter connecting rods, good heads and lots of camshaft to get a 455 over 6000 rpm, and actually make power up there.
First, get rid of the stock 1.5 rockers, valve springs and retainers. New parts can always be transferred to different heads down the road.
I have one 455 stored in a 77 station wagon, still starts with 15 year old gasoline waiting for a project to materialize.
Soon those BOP 400T transmissions are going to get hard to find.


Yea, I don't know. I think Pontiac guys are worrywarts. I put a 455 olds in my jet boat, right out of an old delta 98 and didn't touch a thing. I used to run it at 6000 rpm for 20 minutes at a time. I did have a water/oil cooler that kept the oil temp in check.

The Buick 455 is supposed to be the best design of the BOP because it has bigger bores.

If I decide to put together my aluminium rodeck 400 sbc block, I'll just use an adapter plate to mate up to the BOP st10.

 

[userfriendly]

Also, the more N0S the higher the rpm needs to be to keep the cylinder pressure in check.
For example, a 250 HP shot increases torque 250 LBS @ 5250 RPM and 500 LBS @ 2625 RPM.
Watch a mud bogger go into the pit @ 7500 RPM, BBC with 400 HP shot all in.
The truck gets stuck, the rpm goes below 5000 and the engine blows up.
The cam solution to stupid proof their engines? 296 @ .050" on 116: 32/84 84/32
The air filter will still blow off with the fireball, but the engine will live to fight another day.

 

[A_Harman]

Originally Posted By: turtlevette
Originally Posted By: funflyer
Originally Posted By: turtlevette
301

I know. It's a pos engine, but it's number matching and only 213 made.



This forum might not be the best place to get advice about your 301. Try the 301 forum.


I'm on there too and the firebird forums 79se301m. They average a post every 6 months whether they need to or not. Pontiac guys are the most dismissive of the 301 engine and I get tired of it. The standard answer is to put together a 455. In general those big long stroke engines are like tractor motors. I like something that sings a higher song. I'll have to get some sound clips of the 350 in the vette.



Since your car is '79, I assume it doesn't have the 301T block? Later 301 N/A 4-barrels were built with the turbo block and rolled fillet crank. Those would be the parts to start with if you really wanted to make good power. Then the cylinder heads are the next problem. With a 1.72" intake valve, it won't breath above 4500, so then you need to put better heads on it, and there are many available, but designed for the standard Pontiac deck. I guess they'll bolt on, but the trouble is there is no intake manifold available for the short deck 301 with good heads. The stock intake manifold has shared ports between adjacent cylinders and is DOA for high RPM breathing.

This is the cam I was thinking of:
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1215&sb=2

212/218 effective duration, .487 lift, 110 LSA. It requires screw-in studs and guide plates, different springs, distributor gear upgrade, and machining on the heads. So a simple cam change gets more pricey because of the extra work and components required to make it work.