[glenn911]

I have a 60919 and rhoads never used from a project years ago. I gave up on the alum head/roller cam upgrade due to supply issues. But, I do want to install an iron intake this winter to replace the performer. Remembering long posts of the past discussing the benefits of the 041 and rhoads in a large cube engine (461), I decided to install them this winter. I currently have HS 1.5 rockers. Those old posts also claim adding 1.65 rockers is beneficial to the combo. I would have to purchase the rockers and would add removing the heads to clearance push rod holes. Also, push rods and valve springs/valves may need replaced. Is it worth it for the 1.65's? (461, 4x heads (94cc), XE268h, hookers)

[25stevem]

You would likely gain anywhere from 8 to 12 hp, and this is assuming that the carb is jetted for the new air to fuel ratio.
Also if you do not have aftermarket 7/16” rocker studs then now is the time for them.

[Jay S]

If your 4X heads are unported I would stay with the 1.5s for what you have. Especially since you already have 1.50 HS rockers, you won’t really notice that much change in power on the street. At a track, if you are going for every last HP it would be different, the Rhoads work best with bigger rocker ratios, they increase the bleed action. The car would likely be a bit quicker with the bigger rockers combined with the Rhoads.

We did a swap from a XE268 to 60919 a couple years ago on 9.5 SCR 455 with 260 cfm ported iron heads and a RPM intake. The power band raised about 700 RPM and felt like it gained 50HP. If your a mid range power junkie though, it is hard to beat the XE 268, takes higher octane though.

[glenn911]

Its got 7/16 studs. The heads are reported to be ported by the PO that built it, but he is dead and I got no paperwork on porting because he did it himself (owned a machine shop) The carb was built by Cliff for the current combo. The car pulls hard and runs on 91 no problems (1st gear is useless) 4 speed, 3.23 but it is all done after 4500, idles like a stock engine.

[77 TRASHCAN]

My non expert thoughts, for quite some time about the subject:
Using higher ratio rocker arms, especially with a flat tappet cam increases lift and duration. My thought is the friction and energy required to move the rocker arm through a cycle is easier on the cam/lifter scrub deal, even though there is an increased load on the cam/lifter relationship with increasing the rocker ratio.

I believe this to apply, even with stock type stamped steel rockers. I am sure true roller rockers improve upon the friction situation of a stock type stamped rock, although I wonder how much. We know the roller rockers are much stronger. I used to have a Harland Sharp catalog. I didn't know they made 3 different levels of roller rockers for most makes of engines.

I plan to use higher ratio rockers on any build. Whether stamped rockers for a stockist build, or an engine in need of true roller rockers!!!

[lust4speed]

Not all stamped steel rockers have a long enough slot to support the Harland Sharp 1.65's. I've also seen too many stamped rockers end up with signs of heat damage from the increased travel and pressure. The ball and socket end up scorched blue.

[25stevem]

You guys it seems are not getting the full picture as to why the 1.6( rockers can help with stock heads besides the added lift and 3 to 4 degrees of over the nose duration that they add, and this is especially true with a 4,21” stroke or greater.

The 4.210” stroke motors have a larger demand for air flow much earlier in the intake cycle then a 3.750” stroke for example.
The faster opening rate provided by the 1.65 rockers gets more air to help fill the cylinders before the pistons even reach there fastest rate of decent down the bore.

[Jay S]

Steve25. Any tips for grinding or drilling out the intake push rods holes? With the heads bolted on top of the engine?

I have suggested bigger rockers on cams swaps for that exact reason you mentioned. They usually try to elongate 1 pushrod hole, then get discouraged about all the metal fillings from their efforts on that 1 hole, and go back with 1.5s. I don’t have any good answers for that.

You can run 1.65s on the exhaust with no grinding. The engine I mentioned basically has stock exh ports with very ported RA4 size intakes with 96 heads. The XE 268 in the 455 we did the cam swap on was done at 4500 just like what was described. It had comp roller tipped 1.52s. It still has 1.52 with the 60919 on the intake, and roller tipped 1.65s on the exhaust. The XE268 lasted about 10K miles, the 60919 has double that now.

[glenn911]

In my research I find articles where folks swap to 1.65 from 1.5 and do not change push rods or springs. Then others that make it seem way too complicated. The springs in the heads are comp 988 (or 995) and the push rods are also comp (I am looking for the receipts) to confirm spring # and push rod length. I was planning on removing the heads to elongate the holes (unless there is a better way).

[Jay S]

Your more serious about the 1.65 swap than most guys if you are willing to pull the heads to elongate the pushrods.

[zippy]

Ran that combo for many years!! 041,, Rhoads and 1.65. Actually, I am back to a 041 cam and same 1.65. But going Crower Cam saver lifters. For me, the idle change the Rhoads had from cold to hot I didn't like. My engine was sweet when cold. And spring/fall was OK at stoplights for lope. But mid summer, she would sometimes be real smooth. Hotter the oil, the thinner, the more leakdown with Rhoads.

[RocktimusPryme]

Not to thread jack, but just for informational purposes, would aftermarket E-heads be immune from needing to elongate the pushrod holes?

Im considering a few winter upgrades to try to get from 12.2 to the 11s. I was considering going with a bit more cam, but maybe going to 1.65 rockers might be an easier change.

[glenn911]

I have read the earlier E heads do need elongation. Later heads do not.

[Formulas]

i had to clearance my early Round port E's
but it was so much easier than cast iron

[RocktimusPryme]

Originally Posted by Formulas

i had to clearance my early Round port E's
but it was so much easier than cast iron

That’s exactly what I have so I likely would have to as well.

Probably easier to cam swap then.

[Jay S]

Originally Posted by glenn911

In my research I find articles where folks swap to 1.65 from 1.5 and do not change push rods or springs. Then others that make it seem way too complicated. The springs in the heads are comp 988 (or 995) and the push rods are also comp (I am looking for the receipts) to confirm spring # and push rod length. I was planning on removing the heads to elongate the holes (unless there is a better way).

The only concern of the parts you listed is possibly the 988 springs combined with the HS 1.65 rockers. HS 1.65 rockers arms are closer to a 1.7 actual ratio. Which will be about .53” lift. That is usually max lift on 988 springs with a 1.58” install height, the installed height and coil bind needs to be double checked running that close to max lift.. The 995s have plenty of room for more lift.

[MidnightAuto]

My current set up is same as yours with 1.65. Runs good. Before my kre heads I had stock 77 heads and added the 1.65 then. I elongated the holes with the heads on the car. The answer to “how” is very carefully. I lined and taped off the area above the lifters and had a shop vac pulling the fillings out as a opened up the holes. Not a short/ easy task on iron. But I got it done and did not contaminate motor with shavings.

[lust4speed]

I sure wouldn't want to do any grinding with the heads on the block. Not only chips but metal dust is flying everywhere. If the engine is in the car are you laying over the fender grinding away? If the engine is out of the car spring for a new set of head gaskets and get the heads over to the workbench.

I clearanced my Edelbrock heads for the Crane 1.65's and had plenty of room and ran them for years. Swapped the Cranes over to another engine and went with Harland Sharp 1.65's and the pushrods were up against the pushrod wall and I had to go back in and take some more off.

If I had a set of good 1.5's and was ordering a new cam, then I would simply spec out the cam to include what the final specs would be with the 1.65's. Street cams are just not that near any critical point that would prohibit mirroring results.

[Half-Inch Stud]

Street advice: 1.5:1 on exhaust, and do what you tink on the Inhale. I would use 1.5:1s all 16.

Run to ground these tings:
Seek TUNING the Timing for 34* total adv at 2400 rpm, firm springs and set dizzy centerpost-weights to get the idle initial you like.

Tune the Carb SEC for WOT pullaways at 25-30 mph (only need to optimize pull to like 50mph) by selecting Damper valve tension (Q-JET) pump shot Holley. and SEC rods (Q-JET) , JETs Hollley.

Tune Carb PRI for highest idle vacuum by dialing Plates closer to closed, richening the Pri mix (Rods/Jets Q-JET), Hammer and ditch toss (Holley) or ask Tom Vaught 'cause i haven't mastered the Holley Pri-Side because of the 50cc Pri Accel Pump.

Then ponder if the engine is responsive, breathing, or is the TQ converter stall (or rear gear) a mismatch. Suspension tune.

1.5:1 on EXH should be fine, while 1.65:1 on the 8 Inhales may wake it up for WOT. Factory Iron is a fun pursuit for my combo in 2023. Presently drive a Spreadbore Dual-plane of no name (could be a Weiand?!) and thinking iron ought be better.
Rarely is the cam profile too bad to cause a replacement. Somebody picked the profile, with rationale, on the build.

[Lee]

Find somebody to flow the heads. Then you'll KNOW what sort of lift will work best.

Here is a graph, showing airflow of a stock set of 6x heads vs a set ported by Dave @ SD Performance. "Lift" itself does not make power, rather airflow makes power. If, by adding lift, you increase the airflow, THEN you will make more power.

Adding lift to stock heads will add very little (if any) noticeable power. But with well-ported heads, the gains can be significant.