PONTIAC ZONE TECH FORUMS
 

Go Back   PONTIAC ZONE TECH FORUMS >
Engine Tech
> Engine Buildups in progress
User Name
Password

Engine Buildups in progress Tell us what your latest project is, and post a few pics.

sponser links

Reply
 
Thread Tools
Old 01-30-19, 10:25PM   #76
Mb125
Registered User
 
Mb125's Avatar
 
Join Date: Mar 2005
Location: AZ
Posts: 4,122
Default

Here is the flow sheet for my #16 d ports on my 462. Solid flat tappet cam. I shift the car regularly at 6500 rpm and still pulls to 7000 RPM.
The intake port volume is 164 CC
Attached Thumbnails
Click image for larger version

Name:	2019-01-30 19.16.02.jpg
Views:	47
Size:	65.3 KB
ID:	29609  
__________________
You can shear a sheep many times, but you can only skin them once.
Mb125 is offline   Reply With Quote
Old 01-31-19, 12:31AM   #77
Steve C
Verified User
 
Join Date: Dec 2002
Location: .
Posts: 1,075
Default

On those sheets intake at 28" or 25"

My engine builder on his SF600 bench did the intake at 28 and exhaust at 25.
Steve C is online now   Reply With Quote
Old 01-31-19, 04:18AM   #78
keith
Stubborn old goat
 
keith's Avatar
 
Join Date: Mar 2008
Location: Pittsfield NH
Posts: 617
Default

No one is impressed with the Nunzi 2041 cam I am starting with, that's ok .. to each his own. I am starting conservatively with something that was a highly desirable street cam for 455 by reviews I have read. I guess I would point out that a cam is not a difficult thing to change and if I am unhappy with it I will. I did not want to go roller for this mainly street application as the valve train elements get heavier, requiring heavy springs and as far as I'm concerned creating more possibility of engine component damage not to mention initial expense. Was also looking for the "feel" of the 69GTO I used to drive which had a similar cam I believe. Want to pound on this a bit to gain experience racing without breaking expensively alot. I think it will feel nice in the 71 Formula its going into. I thought the RA IV might be a little too much for a flat tappet though I have a Speed Pro clone I could use instead.

I realize cam mainly opens and closes the gate for (volume * speed) of the ports to fill the cylinder with charge and relieve it, and as rpm increases time segments get smaller for it to do that. Eventually the charge inserted is not enough to accelerate the crankshaft speed. I would expect increasing displacement to lower that point. I don't believe using factory heads that are ported will produce a negative performance gain with the cam I have because it isn't enough cam, although it might coupled to larger port aftermarket heads. It may not be enough to get them to my desired rpm range, but I believe it will make a performance gain coupled with them till charge inserted is not sufficient to build more. Eventually we'll see I hope, and I will post. Then maybe post again when I boost with the same cam if I keep it in place. Am spending some money making valvetrain lighter, less float-prone and better flowing hopefully ... safety-factor if not ready for future improvements. May not make for easier acceleration but might as well. I believe porting a Pontiac factory head is mainly increasing port speed as the port volume is not significantly increased so I don't think bottom or mid-range will be negatively affected by an enlarged/modified port slowing speed. I could be wrong Just sticking my toe in the water of engine modification.
keith is online now   Reply With Quote
Old 01-31-19, 08:15AM   #79
blykins
Registered User
 
Join Date: Jan 2019
Posts: 29
Default

Keith, there are several of us who go through and have done what you're doing on a daily basis.

Just trying to help.

A smaller valve does help flow to a certain point. It's a diminishing return. With the valve spring pressure necessary for a flat tappet camshaft, it's more of an exercise in seeing how much money you can spend. With an 11/32" valve and the typical hydraulic flat tappet, you only need about 280-300 lbs of spring pressure to keep it all happy to the rpm ranges you're wanting.

A roller cam is more expensive.....until you lunch a flat tappet on break-in. Then it's not expensive anymore.

I experiment quite a bit with hydraulic rollers, especially in engines that weren't equipped with them from the factory. I can hit 7500 rpm with a hydraulic roller in a Ford FE engine, without valve float or any drama. I'm getting ready to do the same thing with my 350 Pontiac....

Your rpm goal was 6200 and you're spending a ton of money in custom valves, guides, port work, etc., to hit that goal......that camshaft is gonna make sure that you fall way short.
__________________
Brent Lykins, Lykins Motorsports
brent@lykinsmotorsports.com
IG: brentlykinsmotorsports
blykins is offline   Reply With Quote
Old 01-31-19, 10:36AM   #80
Mb125
Registered User
 
Mb125's Avatar
 
Join Date: Mar 2005
Location: AZ
Posts: 4,122
Default

Quote:
Originally Posted by Steve C View Post
On those sheets intake at 28" or 25"

My engine builder on his SF600 bench did the intake at 28 and exhaust at 25.
Steve
They were at 28 h2o
They were on Paul carter's bench
__________________
You can shear a sheep many times, but you can only skin them once.
Mb125 is offline   Reply With Quote
Old 01-31-19, 11:48AM   #81
tjs44
Ram Air V Guru
 
Join Date: Jul 2002
Location: long beach,california
Posts: 1,907
Default

Brent,you are just reinforcing what some of have been trying to tell him!Joe Sherman was a great tutor,he would tell me what things were worth doing and what were not.Tom
tjs44 is offline   Reply With Quote
Old 01-31-19, 12:05PM   #82
blykins
Registered User
 
Join Date: Jan 2019
Posts: 29
Default

It's my job as an engine builder to help customers decide on which routes to take. Now Keith's not my customer, but I just feel like there's a lot of wasted effort and money on things that won't make any difference, especially when the camshaft is totally askew from the goal.

Sometimes we do things just because we have never done them before though, and I'm guilty of that. If he were to say, "I just want experience with smaller stem valves because I've only used 11/32" in the past." then I can jive with that. And I will also say that I like factory engines that are modernized and optimized and kick booty.

However, with the goal that he proposed on page 1, there are a lot of parts that are not necessary and some parts will not help him meet his goal. I would be spending more money on port work, trying to find a cylinder head that will support a 290-300 cfm small volume port. Once port work is done and the heads are flowed so that the flow/velocity/lift is mapped, THEN you can choose a camshaft based on the numbers.

A 220-ish .050" duration on a long lobe center with a 260-ish port on a 440ci engine will be done at around 5200 rpm based on my experience.

Some guys want to experience things the way that they came from the factory, but I'll be the first to say that there is 50 year old technology there and it's nowhere optimal.

A 7mm valve stem diameter combined with a 50 year old factory camshaft just doesn't jive to me....
__________________
Brent Lykins, Lykins Motorsports
brent@lykinsmotorsports.com
IG: brentlykinsmotorsports
blykins is offline   Reply With Quote
Old 01-31-19, 02:48PM   #83
keith
Stubborn old goat
 
keith's Avatar
 
Join Date: Mar 2008
Location: Pittsfield NH
Posts: 617
Default

Thanks for the input, really, I read and consider every bit. I don't have a lot of experience or access to equipment to map head flow etc., that's why I will let someone do my port work that does, at least on first set of heads . My basic idea for matching intake, cam and heads was to stick close to factory pieces that worked well together. Increasing all 3 in similar amounts to the increase in displacement, modernizing for improvement as I can afford. Figuring I would end up with a fun to drive street car I could take to track and not break a lot as well as modify down the road when I learn more. Its a bit of a game to me, mentally stimulating and fun to play. I will end up with something I can call my own and measure myself to see what I accomplished with the seat of my pants. If I ever get my @#$%^ crankshaft that is.

I am increasing displacement roughly 11%. 240cfm heads would be a roughly 20% increase, the 2041 cam 5/5 % @.050 duration increase from factory 068 and 10/12 % lift increase @ 1.5, 20/24% @ 1.65 with change to dual pattern. The Offy DQ will have 900 cfm to start, a 12% increase, between the 2 4360 carbs and may fall short as Tom says … will try to see if Holley book is right about them giving my best effort to making them work under a plain steel hood as I like that look on a 71 and like to diddle with carbs. May try to fit 2 Edelbrock 600's to it as I have 1 already if the 4360's are duds.

Did not spend a great deal on the 7mm valves themselves though I will spend some on fitting them to application. There is 20% less cross-sectional area to block flow through port. In addition the valves are lighter whether in Ti or stainless. They will require less spring and/or be less float prone IMO. They might be a worthwhile mod to a factory head for those who choose to keep their original heads but are searching for more HP/RPM, Im throwing my hat in the ring. Chalking cost up to research as I wanted a dead nuts valve train with new guides, hardened exhaust seats and custom length valves optimized for my desired 1.800IH. I also wanted an excuse to shell for shaft rockers and don't think I would try slimmer valves without them.

I may run the 2041 cam a season then slide in my Ultradyne NR100 next season and see which I like better. Should be quite a difference.
keith is online now   Reply With Quote
Old 01-31-19, 03:03PM   #84
blykins
Registered User
 
Join Date: Jan 2019
Posts: 29
Default

Shaft rockers have the adjusters on the rear of the rocker arm, which adds weight to the system. Non-adjustable rockers or rockers that use polylocks are the best scenario for weight.

On a Ford FE engine, which uses shaft rockers by default, I get an extra 300-400 rpm from non-adjustable rockers. In fact, it's such a benefit that I developed my own non-adjustable bronze-bushed, roller tipped rocker arm for the FE.

It's fun to experiment and exchange cost for research, but it's also prudent to listen to guys who have already been where you're going.
__________________
Brent Lykins, Lykins Motorsports
brent@lykinsmotorsports.com
IG: brentlykinsmotorsports
blykins is offline   Reply With Quote
Old 01-31-19, 04:05PM   #85
keith
Stubborn old goat
 
keith's Avatar
 
Join Date: Mar 2008
Location: Pittsfield NH
Posts: 617
Default

Was thinking more about lateral movement of stud mounted rockers causing an issue with the slimmer valves than weight. It would be a trade-off I guess. I am opting for the more precise movement of the shaft rocker with valves that would bend easier.
keith is online now   Reply With Quote
Old 01-31-19, 04:28PM   #86
blykins
Registered User
 
Join Date: Jan 2019
Posts: 29
Default

No problems there as long as guideplate alignment is good. Again, you’re working with 280-300 lbs of spring pressure. I have ran 7mm and 5/16” valve stems with 600-700 lbs of pressure and a stud mounted rocker. They don’t bend...........unless they hit something..........
__________________
Brent Lykins, Lykins Motorsports
brent@lykinsmotorsports.com
IG: brentlykinsmotorsports
blykins is offline   Reply With Quote
Old 01-31-19, 04:59PM   #87
Steve C
Verified User
 
Join Date: Dec 2002
Location: .
Posts: 1,075
Default

Years ago it was Dick from Indian Adventures that commented about watching under strobe lights the rocker studs move around like "hula dancer girls" without a stud girdle.


.
Steve C is online now   Reply With Quote
Old 01-31-19, 05:13PM   #88
blykins
Registered User
 
Join Date: Jan 2019
Posts: 29
Default

Well, everything flexes and deflects. But there's no bending that occurs because of rocker arm motion across a small diameter valve stem. Even shaft mounted rockers will have a few thou of lateral movement; they have to in order to keep from binding.

We're also talking about a hydraulic flat tappet camshaft here, not something that will require 600 lbs of spring pressure.

A 7mm titanium valve that's around a 2.08-2.100" head diameter will weigh about 80-85g. If emphasis is held on lightening the valvetrain in order to help maintain valvetrain control, then a 15-20g rocker arm adjuster hanging off the rearend of the rocker arm will negate that lighter valve.

In addition to all of this, a titanium valve will also need to have a hardened tip or a lash cap. I don't like hardened tips as I've seen them break the top of the valve stem out and I prefer to use a lash cap. A lash cap is much larger than the valve stem diameter and gives more of a surface for a rocker arm tip to ride on.
__________________
Brent Lykins, Lykins Motorsports
brent@lykinsmotorsports.com
IG: brentlykinsmotorsports
blykins is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Differences of an 88 Formula & a regular Firebird with a v-8? NSMK377 Late Model Tech '81 to present 3 08-07-14 12:55PM
Looking at an 1980 Formula Wingnutks Grape Vine - General Discussion 9 01-21-13 06:11PM
Spring selection - 1971 Formula 400 keith Suspension 9 04-23-12 07:28PM
Looking for 70-73 Formula or T/A in the Texas area Camaro Man Parts & Cars For Sale & Wanted 0 09-02-11 04:19PM
71 Formula 350 worth?? bajatoy 1958 - 1981 Pontiac Tech & Restoration 7 06-24-06 01:27AM


All times are GMT -3. The time now is 12:43PM.

Featured Ads
Ken's Speed & Machine
Mayhem Turbocharging

Carter Cryogenics.  What can we freeze for you?

Pacific Performance Racing

Central Virginia Machine Service.  Home of the Injun Engine!

All Pontiac Engine Kits

Larry's Auto Machine.  Full serivce auto, marine machine shop, domestic and foreign.

Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
2001 - 2007 PontiacZone.com
Page generated in 0.12396 seconds with 41 queries