Discussion Forum - Northstar Chevelle Club

Enganeer · Mega Poster

Revamping 400 sbc...anyone know about Howards Roller cams

67ss · 1K+ Club

I gotta think your cam is bleeding off some of that compression keeping it from pinging right now. I am worried if you step down in the cam the motor is going to be more prone for detonation. I would try the calculator below to double check your compression ratio and do the dynamic compression calculation to give you a better idea how the cam is affecting your compression.

http://www.kb-silvolite.com/calc.php?action=comp

Mitch is right the pushrods are shorted on roller cams, depends on the cam manufacture as to if it requires a special distributor gear. The Isky in my 350 did not require a special gear.

-- Edited by 67ss on Friday 16th of March 2012 09:56:44 PM

Lost in the 60s · President

Bobs_Place wrote:
If you think the engine is over cammed try a set of Rhoads lifters.
They should settle down the low end without loosing much on the top end.
They would be easy to install and less money.
I had a neighbor that ran them in his 69 GTO, he like the way they ran.
The Rhoads could be an alternative. They collapse slightly at idle and don't open the valve as far.

-- Edited by Lost in the 60s on Friday 16th of March 2012 10:12:19 PM

67ss · 1K+ Club

Are you running aluminum heads or iron heads? If you are running aluminum I think your compression would be fine. I have a buddy with a 406 and AFR aluminum heads running the same compression as you with no problems.

I asked my machinist about there cams awhile back and he said he has never had any problems with them. But I would not run hydraulic roller lifters if you plan on going over 6500 rpm. There are some that can handle it but are usually more money. You might think about going solid roller if you plan high RPM.

Enganeer · Mega Poster

Iron heads - they are the (Aussie) Topline Pro lighting iron heads 72 cc heads with 200 CC runners. The engine block was decked to 9.000", so I get a around a .038" quench with gasket.

I don't plan on spinning past 6.5K.

I was trying to find a cam card to play around with DD2K but their site is non responsive.

I was wondering if anything else needs to be special...they say retro fit but what about pushrod length, special fuel pump rod and a cam button? Is this a straight swap from hyd flat tappet?

Thanks,

Lost in the 60s · President

You will need shorter push rods to keep the roller tip centered on the stem. You will need a set-up push rod (adjustable) to measure the right length.

Bobs_Place · Vice President

If you think the engine is over cammed try a set of Rhoads lifters.

They should settle down the low end without loosing much on the top end.

They would be easy to install and less money.

I had a neighbor that ran them in his 69 GTO, he like the way they ran.

Chris R · 2K+ Club

Didnt Gary Heddon at Magnum build that motor and spec out the proper cam for you when he built the motor John? I still remember that meeting we had there when he did the assembly that day.

Enganeer · Mega Poster

He assembled the components I had for the demo.

The motor does get a like a raped ape when you get on it but I want to be able to have my wife enjoy a ride in and not have to sit and baby it when warming up and sitting at stops signs.

I looked at the Rhoads lifters, and they run from $96 to $177 depending on features you want. I prefer not be a zddp junkie and worry about wiping a cam lobe.

Lost in the 60s · President

The lobe center will have an effect on behaviour. The closer they are (lower number), the more overlap and rougher idle. Getting a center of 112 to 115° will smooth out the lower end somewhat, even on a high lift and long duration grind. Or do I have that backwards....

Bobs_Place · Vice President

Are you going to a roller cam?

Bobs_Place · Vice President

anyone know about Howards Roller cams

I got it now- roller cam

67ss · 1K+ Club

John, here is a good web site talking about dynamic compression ratios to help you pick a cam.

http://cochise.uia.net/pkelley2/DynamicCR.html

Enganeer · Mega Poster

Ran through some scenarios using three cams

Current Cam Comp XE294 2-254-3

294 306 250 256 .519 .523 110
2800-7000 HYDRAULIC: Pro street/ bracket, good intake, headers, gear, 3300+ stall.
DCR 7.8:1

Roller cams

Howard roller 245-112
int Exh
278 284
1800-5400 Fair idle, Street & mild Performance usage. Crisp throttle.
DCR 8.2:1

Howard roller 255-112
284 288
2000-5600 Fair idle, performance usage. Great mid-range torque & horsepower.
DCR 8.0:1

Howard roller 265-112
286 294
2400-6000 Lopey idle, Hot Street & Bracket Racing. 10.0:1-up CR advised.
DCR 7.92:1

I am leaning towards either the 255 or 265 cam.

-- Edited by Enganeer on Thursday 22nd of March 2012 10:27:20 PM

67ss · 1K+ Club

I think I would go with the 245-12 since you have 1.55 rockers it is going to act more like the 255-12 cam. My opinion is to run slightly less duration to make it more friendly but try to get as much lift as you can to try and match the peak flow of your cylinder heads.

Enganeer · Mega Poster

Thanks for the comments.

That was one bouncing around in my head - looks to be great torq down low. My only concern was that the DCR would be at 8.2:1 rather than 8:1 but further reading on Pat Kelley DCR webpage 'staying below 8.25 DCR is probably best for trouble free motoring, so it would work.

67ss · 1K+ Club

Most machinists that I have talk to have always said with a 0 deck engine and tight quench the motor is less likely to ping even with a higher compression.

Enganeer · Mega Poster

Going to ordered the Howard roller 245-112 cam and lifters plus some adjustable pushrods so I can figure out the new length.

Bowtieman427 · Active Member

I would drop Howards an email or call ask to talk to John Steely. Let him know exactly what you want the car to do and all the specs.

Enganeer · Mega Poster

I worked through the-mail with John since I was at work regarding my current springs and whether I needed a special fuel pump pushrod.

Installed the cam and lifters and figured out the proper pushrod length that gave me the best wipe pattern on the valve stem.

Scott Parkhurst · Super Poster

If you want a little more detonation insurance, I'd sure have to recommend getting the piston tops, chambers, and valve heads coated before you assemble everything. I got mine done at TPIS in Chaska. Coating these parts will smooth out the roughest edges and spread the heat out a bit so you don't get any hot spots where detonation can begin. I do this on all my hot engine builds now.

Lost in the 60s · President

Scott Parkhurst wrote:
If you want a little more detonation insurance, I'd sure have to recommend getting the piston tops, chambers, and valve heads coated before you assemble everything. I got mine done at TPIS in Chaska. Coating these parts will smooth out the roughest edges and spread the heat out a bit so you don't get any hot spots where detonation can begin. I do this on all my hot engine builds now.
Race Coatings in Forest Lake can do that too. May be a bit closer to you....

Enganeer · Mega Poster

Scott,

The engine already assembled. I did clean up the chambers and knocked off any sharp edges. The block is a zero deck and the quench is at about .039 (gasket).

Enganeer · Mega Poster

All back together now. What a weekend...It's a pain do that swap with the engine in. 10 steps forward, 2 steps back and sanity in the end.

Double checked everything, degreed the cam like 5 times I think (learning curve), figured out new pushrod length for the smallest wipe on the valve stem, ponied up for the fancy dandy cloves timing cover with adjustable thrust button for the roller cam, 1/2 turn preload on the valves and even primed the oil system and rotated the crank and verified oil was flowing out of all rockers.

Fired it up and at first it did not want to run good at all (initial thought was the carb did need to get fuel as I tipped it back cleaning the intake manifold of rtv when I removed it), then run about 5-10 seconds and then die, repeat numerous times. I reset all the carb settings to baseline and started it back up and it ran better but just seemed weak and would quit on a whim for no apparent reason and then it finally stone cold just quit. Turns over fine and would fire about 1 second then nothing. Repeat until your ready throw a wrench.

So some more dinking around...move the dist this way and then that way - did not seem to make much difference, pop off for a second then nothing. So I started on the electrical side. Disconnected the HEI terminal and stuck the volt meter probe into plug...meter showed 12.4 volts when 'on' around 12 volts while cranking, check good, while muttering bad thoughts about this car and the next step, I had left the switch in the 'on' position and noticed the meter showing 12 volts started to flutter and then dropped to 10,8 then 0...with the key still in the 'on' position. What the H@ll? Turn it back off and on and it would do the same thing...12+ volts initially then would drop off to nothing...the time interval it did this was not consistent, from mostly right away to 30 seconds. So I found need to exercise an electrical gremlin out of this harness. Same issue affect my fan relays and even my gauges. So my HEI had just enough juice to charge the coil and fire but not enough to keep going after that.

Swapped the HEI line to battery spade in the fuse box and it fired right up...all happy as can be. Same with the fan relays. I swapped the gauges to the accessory terminal.

So after all that, I got it running great by bypassing the issue for now...just have to reach down and pull the wires of the bat terminals spades.

Next item to fix...my mechanical advance for the distributor. I am running new bushings and weights with the medium springs (which should give me 20° advance per the chart). I have my initial timing set to 16° btdc, idle is steady around 800 rpm and with the vacuum advance disconnected, I only get about 10° advance at 2K rpm (26° total btdc) and only 14° (30° total btdc) at 4K rpm...so something is sticking or the springs are wrong. I would like to get total of 34°-36° by 3K rpm. I think I will stab in an other HEI to see if it makes a difference.

Scott Parkhurst · Super Poster

I've got another good complete one if you need it to check stuff.

Enganeer · Mega Poster

Well I took apart the distributor and I think I know why I would only get such little advance. (see distributor on the right). I could only advance it very little before the backsides of the wear buttons would contact the plate 'cross'.

Regular HEI on the left, unique HEI on the left.

Note the vacuum advance was removed because I was transferring it to another HEI.

Does anyone know what this HEI (right side of pic) was from?

-- Edited by Enganeer on Wednesday 11th of April 2012 09:01:14 AM

Enganeer · Mega Poster

Never mind, looks to be a variation of the HEI through the years.

Lost in the 60s · President

Run the stamped number off the body on a search engine and it will probably come back with the application.

Enganeer · Mega Poster

I think I have vanquished my curses.

Carb issues
Gone with swapping to my Holley which I rebuilt this weekend. The eddy carb I pulled off my old 350 ran good but somewhere along the line the floats got stuck (have pressure regulator set to 5.5lbs) and kept flooding out...hence why it was such a pita to get running.

Figured I would rebuild my Holley since I bought a kit last fall. So after taking apart the Holley, I found that the 'reconditioned' carb floats were never set properly, so they never quite shut off the fuel flow and were dumping fuel in. Wow, I am cursed - new stuff is crap sometimes.

Cleaned and replaced the gaskets and set the floats per the dry method and it fire up and ran great with my only surprise being that I did not fully tighten the rear float height adjustment set screw resulting in a small gusher of fuel out the vent tube. Talk about jumping around quickly.

Got it all running again and check the float level with the wet method. The front float setting was perfect...just a small dribble of fuel out the float view hole. The rear was more touchy....either an 1/8 below or gusher coming...learned to do baby steps and wait about 30 seconds between adjustments. Seems good enough for me, fuel is just below the float view hole.

Ignition
Springs were the issues. They appeared to be the middle springs but were too stiff. Swapped out a set from another kit and works fine.

Fuse box
Intermittent voltage to ignition solved. Sitting upside down with some good light on the fuse box and found the fuse clips had rust on them. Cleaned them up and back in business at the terminals for the HEI and electric choke.

The car runs scary good now...no longer having to nurse it until it gets good and warm. It idles happy along, I even idled it down to 500 rpm when I was checking the timing for the mechanical advance, and starts within half a crank of the engine.

Lost in the 60s · President

Congrats, John......you will love driving it now...