426 hemi head prep

[Geri]

thinking back to 1974 I bought a crane RR-296 roller cam for my 426. they were called rocker arm breakers- but I never had any issues with the cam, in fact it was the best cam of the day back then. they were 296 degree's duration and .750 lift intake and exhaust.
they id require head and valve massage however to get them to live. the rockers had to be big foot with lash caps, the rockers had to be rockwell hardened to 53?? if I remember right.
the tops of the intake valves had to be cut back on a 29 degree angle from the top, and there had to be .296 distance between the valves faces when closed. the only way that could be done is smaller diameter valves(yeh right like I'm going to do that) or -sink the exhaust valves to get the clearance. I was kinda worried about sinking the valve's by grinding down the seats- but I did. this is what had to be done to keep the valves from hitting each other through their cycles. this in total took about 35 hours or maybe more- been a long time, the results were astonishing to me. the car had been laboring in low 11's sometimes high 10's. speeds only 128-130 with the previous cam, I don't recall what it was.. this was a basic 426 hemi, super rods (worst rods ever) heavy TRW 12.5 pistons, balanced, Accell ignition and hilborn injection. mostly stock -no port work and no real attempt at bluprinting the engine. the first pass with this configuration- was 9.60's on pump gas at 145. that was awesome for a mid 70's car. (41 willys pro gas) the point of this being much attention had to be in the heads or it would have killed itself instantly- worth it..
with this cam. high gear acceleration felt as strong as low gear with other cams , wonderful days drag racing..

 

[SSjunkie]

Hi Geri,
I'm a new member here and was poking around and found this thread. I'm doing a 65' Super Stock tribute car. It just so happens that I was looking at the R296 as a potential cam based on the older MP data stating that back in the day this was considered a very good race cam.
My question is, has anyone made one of these live on the street? I looked at the seat and open pressure requirements and went a bit pale lol.
My basic combo is as follows:
500' Hemi - New world block
12.5 to 1 comp.
Ported MP aluminum heads. I would look at using Jesel lifters etc.
Original aluminum 64' crossram
Milodon dual line oiling system c/w swinging pickup
TTI 2-1/8" headers
I also looked at the R274 which is a fair bit milder.
The car will see limited street/strip use and I tend to be pretty easy on my stuff. I'm looking to build as close as possible a motor that would represent the old style SS motors. tks

 

[Fran Blacker]

Remember an article in CarCraft (I think) about installing one of those cams. It had a funny cartoon at the start about if you did it wrong. Shows a professorial looking guy holding up a pen and a drawing of a Hemi blowing parts through the valve covers and backfiring through carbs.

 

[SSjunkie]

LOL..I'm sure there are a lot more ways to install it wrong then there are right!
Still, I wonder just how well it would work...installed correctly

 

[Geri]

Hi Geri,
I'm a new member here and was poking around and found this thread. I'm doing a 65' Super Stock tribute car. It just so happens that I was looking at the R296 as a potential cam based on the older MP data stating that back in the day this was considered a very good race cam.
My question is, has anyone made one of these live on the street? I looked at the seat and open pressure requirements and went a bit pale lol.
My basic combo is as follows:
500' Hemi - New world block
12.5 to 1 comp.
Ported MP aluminum heads. I would look at using Jesel lifters etc.
Original aluminum 64' crossram
Milodon dual line oiling system c/w swinging pickup
TTI 2-1/8" headers
I also looked at the R274 which is a fair bit milder.
The car will see limited street/strip use and I tend to be pretty easy on my stuff. I'm looking to build as close as possible a motor that would represent the old style SS motors. tks

VERY interesting notion. if you read what I had to do to the heads it was involved but not difficult. the part that bothered me the most was after doing the required work to the intake valves- back cutting the lip margin at 29 degrees. seating the intake valve as it would be run the exhaust valve had to be sunk in the head till .296 distance between the two valves installed. possibly little smaller exhaust valves or even cut down the OD would have sufficed but the instructions were to sink them so I did. I may do that different today.
they recommended the Rockwell hardened exhaust rockers which I had done and the use of the big foot rockers and lash caps a must. that being said,I never had a valve train failure from any source or reason. I don't recall the open valve spring pressure, in mycase with the crane triple springs I think (think) they were around 600 pounds open, but un supercharged they could have been a lot less and they were not designed for superchargers anyway- for all around I'd think 400 lbs open would be sufficient
the also recommended over 200 lb seat pressure that is unnecessary as in the words of cyl head guru Barry Gerolomy -California the valves "spend most of their time open anyway". my seat pressure was just 120-130 lbs. Barry was a great help in directing my work on these heads and cam. I had worked with him at Aerojet in the 60's before he opened his cylinder head shop so I knew him as a trusted friend..
my engine was a terrible cheap build- the TRW pistons were way to heavy, with the wrist pin far to low on the sides. in my opinion, do day with the light pistons may not be an issue, if I'd had the $$ then I'd have used longer rods and moved the wrist pin up the side of the piston. I had the kellogg crank, cheap super rod alum rods ,thank God they went out of business. of course balanced and other than that near stock, no porting work at all and I ran pump gas. with the 5:13 gears -14/32 15W firestones launching at 3500 it easily ran 9:60's the class minimum for pro gas. possibly launch at 6-7 RPM may have netted a near 8sec pass- who knows?
THAT being said after the willys crash I put the engine in a '64 Plymouth Savoy street car and found performance not as good as I'd thought. when I too k the hemi out and looked into it, my demises was not putting a cam bumper behind the timing cover- the race car had a hilborn pump /alum cover which held it in place, with just the stock cover and timing chain the cam walked forward almost enough to have the rollers come off the lobes. performance would have been awesome had I known to restrict cam fore/aft movement. yes- it was very streetable.
(long way around to answer your question) mostly wish I still had a Hemi, they were so cheap then. at one point I got everything Ron Kassis (SS/DA) had in hemi's and parts for $500.00 when he got out of racing.

 

[SSjunkie]

Thank you for your reply Geri. It's very cool to be talking with someone who used this cam.
I bet the willys was a blast to race. Crane lists the spec's as 2.100 installed height with 362 lbs
seat pressure and 857 Ibs open The operating range is 4600 - 8600 which is find pretty broad.
There is no way my combination is going 8600. I should be in the 7000 - 7200 range "I think"
That makes me wonder if I really need that big a spring as valve float is at 9200. Sorry to be a pest , but can you let me know what you were turning for rpm with the cam?
BTW, this site is amazing...I wish I'd joined long ago.
Oh and no Hemi's are not cheap!!!
Thanks so much!

 

[Geri]

Thank you for your reply Geri. It's very cool to be talking with someone who used this cam.
I bet the willys was a blast to race. Crane lists the spec's as 2.100 installed height with 362 lbs
seat pressure and 857 Ibs open The operating range is 4600 - 8600 which is find pretty broad.
There is no way my combination is going 8600. I should be in the 7000 - 7200 range "I think"
That makes me wonder if I really need that big a spring as valve float is at 9200. Sorry to be a pest , but can you let me know what you were turning for rpm with the cam?

first- you are certainly not a pest OK? I like the racing days wish I was still at it, my car ran 9:60s EASY launching at 3500 RPM ,when the Chevs of equal size launched at 6-8000 .I never hurt a part in 3 years of racing once I had the good parts in it. the car was so strong in high gear it was amazing a difference of some15 MPH from prior cam, and a cam change only.
I stupidly installed the cam using the timing gear is gospel even though crane said don't do that- it is a reference only, I thought-Crane is one of the best- they would not put the pin in wrong (nope) first time with it- the car launched like it was going to run 200 ,but fell on its face about 5000 rpm and lugged through at a mid 10. then I dialed the cam in as suggested- I had to advance it a full 17 degree's to get the numbers to align.lesson learned. it then ran 9.60s at 145. I never tried to improve that as the class was 9.60 minimum.

my spring pressures never came close to what they wanted- and it went over 9000 in the lights a couple of times -still pulling strong. bottom line- if I had a 426 Hemi and a RR296 I'd run it, street or track, just use the cam button - the alum front cover with access to install a button looks to be the best option.. I never paid more that $500.00 for a Hemi. I sold my last one in 2007, a new 1974 nickel fuel water block , Chrysler D-port 16 plug heads, ( I bought new in 75 from mopar $75.00 each bare) Chrysler big foot rockers- Kellogg crank, Brooks T/F rods (new), M/T alcohol blower pistons -11.5-1, racer brown stx-22 roller cam***,milidon duel pickup oiling system, for 5 K, stupid me...
*** the roller version of the stx-22 superstock cam was my idea and a bad one. Racer Brown only made them as a flat tappet that required mushroom lifters. I had the cam grinder transfer the spec to a roller. it was OK in my street willys, but sucked at real performance.




BTW, this site is amazing...I wish I'd joined long ago.
Oh and no Hemi's are not cheap!!!
Thanks so much!

 

[SSjunkie]

Thank you again for your time and insight...it's a pleasure!

 

[SSjunkie]

Well , my Hemi went into the shop today to get taken apart and gone through. I bought the motor new with no time on it, but it had sat for 5 years. I sat on if for another 2 years, so it needs to come apart and be gone through piece by piece. Will do some upgrades to the valve train and oiling system and see if we can stick in the Crane R296 cam. Then on to the dyno to see the numbers. Can't wait!!
Car will go in to get roll bar , mini tub, sub frame connectors, Hemi hood scoop , Cal tracs etc and a total repaint + Super Stock interior.

 

[biomedtechguy]

Hemis are amazing engines!