[65madgoat]

Ok so doing a 455HO which presently is still stock bore and stock virgin heads. Just want a fun street motor. Have all the power I need in other cars.

Wish to go roller cam though and will not be touching the 108cc 7F6 heads other than new valves and rocker arms etc. Compression should stay under 9:1 with flat top pistons.

Keeping stock crank but getting forged Molnar stock length Pontiac rods.

What roller cam specs will work best? Been leaning towards around a 230/236 at .050 with a 112LSA.

What roller rockers would you recommend?

Does the stock intake and heat shroud assembly work with the tomahawk style valley pan needed to clear roller lifters?

Stock exhaust manifolds.

Lets hear it.

Thanks.

[nas t eh]

Sounds fun,

Crower Endro RR, they are pricy, but you get what you pay for and like those connecting rods you picked, this is no place to cheap out.

[JB Eng Wis]

Maybe push the compression a tad.....9.3to 1 if possable,, but not a deal breaker. Deck the block and heads untill there FLAT!
Your cam (roller) numbers are definitely in the range of a fun street engine.
Might I suggest a tad more on the exhaust side......(240*-242*) to help out the use of stock manifolds &
full exhaust. I think a Bullet/UltraDyne grind HR14 Intake 284* adv 230* @.050" .530" valve lift w/1.5 rocker
HR16 Exhaust 296* adv 242* @.050" .530" valve lift...... LSA 112*/113*
Happy Building

[Verdoro 68]

Mine is close in spirit to a 455HO, just as a stroker and with more compression (9.5:1). Butler recommended a 230/236, but the crew here talked me into a 236/242. I'm really happy with it.

I'm using a Tomahawk valley pan with a repro RAIV intake so I would imagine you'll be fine. I believe those are patterned off a 455HO intake?

IIRC, the machinist did have to mill a little off the spring seats to get the pressures where they needed to be for the roller so you might not get away without touching the heads.

I have Harland Sharp diamond series rollers. So far so good.

[65 Lamnas]

Bore it .030, get an accurate valve job. You'll have about 8.5:1 to run cheap gas...like 87 octane. Run a slightly smaller duration (226/232°) cam on a 114LSA, at about .575-.585 lift. Run HS 1.5s (or Crower enduro if you have the $$). Bring the advance in right away at 1000rpm, and have it all in by 2000-2200rpm. You don't need a Tomahawk valley pan unless you have no pan....if you have a stock 68-72 pan, just massage it.

[lust4speed]

Originally Posted by nas t eh

Sounds fun,

Crower Endro RR, they are pricy, but you get what you pay for and like those connecting rods you picked, this is no place to cheap out.

These SS rockers along with the Crower short polylocks almost always allow you to run the '67 and later stock valve covers.

[steve25]

What trans and rear gearing does the car have?

[grivera]

Harland Sharp 1.5 rockers fit under 67 and up valve covers - I have them with an HR that has .567/.570 lift.

[65madgoat]

Trans may most likely end up being a TKX with still 3.08 rear gears.

[tom s]

I have and am running H&S 1.65s a 400 lobe lift with late style valve covers with the 5/16th gaskets.FWIW,Tom

[SD455DJ]

My brother Dan has built many 455HO’s for the Pure Stock Drags and stock, they are easy 400 hp/500 lbft engines with 8.5 to 1 compression and 068 style cams (Summit 2801). He built a nice ’71 455HO with good forged rods and small dome forged pistons to get 9.5 to compression and a HR cam with 230/242/112 at .550” lift (custom CC roller) with HS 1.5 RR’s. The ports were stock, the manifolds were stock (intake and exhaust) and it was a beast. It made 485 hp/575 lbft torque. This HO wasn't built for the Pure Stock Drags btw...

Dennis

[Verdoro 68]

Originally Posted by SD455DJ

He built a nice ’71 455HO with good forged rods and small dome forged pistons to get 9.5 to compression and a HR cam with 230/242/112 at .550” lift (custom CC roller) with HS 1.5 RR’s. The ports were stock, the manifolds were stock (intake and exhaust) and it was a beast. It made 485 hp/575 lbft torque. This HO wasn't built for the Pure Stock Drags btw...

Dennis

Wow! If he could pull that out of a 455HO with stock manifolds, it makes me wonder what I left on the table with my build.

[i82much]

Originally Posted by 65 Lamnas

Bore it .030, get an accurate valve job. You'll have about 8.5:1 to run cheap gas...like 87 octane. Run a slightly smaller duration (226/232°) cam on a 114LSA, at about .575-.585 lift. Run HS 1.5s (or Crower enduro if you have the $$). Bring the advance in right away at 1000rpm, and have it all in by 2000-2200rpm. You don't need a Tomahawk valley pan unless you have no pan....if you have a stock 68-72 pan, just massage it.

man .575 sounds like a lot of lift for a 226 cam with 1.5 rockers? Is that a typo or do you know of a lobe with that kind of lobe lift?

[65 Lamnas]

Originally Posted by i82much

man .575 sounds like a lot of lift for a 226 cam with 1.5 rockers? Is that a typo or do you know of a lobe with that kind of lobe lift?

To answer your question, I'll tell you a little story.....

Back in the 90's when I would occasionally drag race my street car, I got a lot of help from an older guy that was into racing Pontiacs. We talked quite a few times about Pontiacs in general and my car in particular. He even helped to port a set of iron heads of mine.

He taught me a lot about head flow and cam choice, and introduced me to the CompCams Master Lobe Catalog. https://edelbrock-files-v1.s3-us-wes...be-Catalog.pdf

Been using the catalog to order custom cams since. If you go to page 26, you'll find the QNI lobes. 13540/13542 are the lobes I'd have put on a 114LSA for the OP.

The helpful older Pontiac racer guy was Pete McCarthy.

My point is you can find just about any lobe you'd ever want to run if you browse the catalog.

[JLMounce]

Having had a couple cams now in a 455, I would go slightly bigger than the 230/236 cam. The first cam I had was a 232/238 on 112 that utilized XFI lobes. Even at altitude here in Colorado, that cam was vary tame. It made 15" of vacuum (again at altitude) with a smooth idle, but also had a broad powerband. That was on a set of as cast KRE D-ports. I'm not entirely sure if stock D-ports are going to change much in that regard.

For stock manifolds, I would put the LSA out on a 114. That is going to help make some power there, but again will further tame the engine and should bring vacuum up a bit.

I currently run a 240/248 on 112 with the QNI lobes that Lamnas mentioned above. With the KRE 310 cfm dports, its a beast. You can plod around in the car all day long, but as soon as you put your foot into it, things can get stupid real fast. Point being, don't be afraid to put some duration into that 455. You won't kill the low-end on this type of deal. I really think 232-236 is a sweet spot on the intake for a mild performance application.

[i82much]

Originally Posted by 65 Lamnas

To answer your question, I'll tell you a little story.....

Back in the 90's when I would occasionally drag race my street car, I got a lot of help from an older guy that was into racing Pontiacs. We talked quite a few times about Pontiacs in general and my car in particular. He even helped to port a set of iron heads of mine.

He taught me a lot about head flow and cam choice, and introduced me to the CompCams Master Lobe Catalog. https://edelbrock-files-v1.s3-us-wes...be-Catalog.pdf

Been using the catalog to order custom cams since. If you go to page 26, you'll find the QNI lobes. 13540/13542 are the lobes I'd have put on a 114LSA for the OP.

The helpful older Pontiac racer guy was Pete McCarthy.

My point is you can find just about any lobe you'd ever want to run if you browse the catalog.

Thanks! Any thoughts on longevity of the valvetrain with those lobes instead of something softer?

[65 Lamnas]

Originally Posted by i82much

Thanks! Any thoughts on longevity of the valvetrain with those lobes instead of something softer?

I don't consider the QNI lobes to be all that "aggressive" to be overly concerned about longevity. But I'm also assuming a person running a cam like this isn't going to "cheap out" on other valve train hardware like a good quality spring package, and thick wall pushrods, etc.

[JLMounce]

Originally Posted by i82much

Thanks! Any thoughts on longevity of the valvetrain with those lobes instead of something softer?

If you read the literature on the Q series lobes, they're designed to actually be more stable than previous lobe profiles. I changed lifter brands with my current build, but I can tell you that my curren valvetrain setup at just shy of .6" of lift with .398 QNI lobes is much quieter than my old setup with XFI lobes at .545" gross lift.

I have no issues with valvetrain stability on these at 6000rpm where I shift the engine. I'll reiterate though, I changed from the old design morel (lunati branded) lifter to Johnson short travel lifters. There may be a combination of things there that are working better, not just the lobe design.

[Verdoro 68]

Originally Posted by JLMounce

Having had a couple cams now in a 455, I would go slightly bigger than the 230/236 cam...

For stock manifolds, I would put the LSA out on a 114. That is going to help make some power there, but again will further tame the engine and should bring vacuum up a bit.

I think you were one of the folks that encouraged me to go bigger with my build. Glad I listened

The specs of the cam Dennis mentioned above has less duration on the intake side - 230 vs. 236 with the same 242 on the exhaust side. Wondering if that had to do with the unported nature of the heads? Maybe this is a dumb question, but can you give up power by having too much duration in the intake without the airflow to make use of it?

[JLMounce]

There's always going to be a point of diminishing returns, and the exhaust to intake flow ratio will have some bearing on what works well on the intake side. For simplicity sake though, if a port flows X amount of air for a given valve lift, you can't force it to flow more air by adding duration. However, even at that same maximum flow, keeping the valve open longer does increase the amount of air that has been consumed.

That's obviously a really bad over-simplification because things like atmospheric pressure, scavenging effects, reversion all will have an effect on that. I have pretty rudimentary but observation based knowledge and my general understanding is that increasing the exhaust duration is beneficial specifically in situations where you don't have a high flowing exhaust. That's done for the same reason. If the exhaust straw is small and restrictive, keeping the valve opened a bit longer can help evacuate a bit more exhaust gas, making room for the fresh fuel/air charge. An engine using the stock manifolds isn't going to have a lot of scavenging going on, nor does it flow well. Keeping that exhaust valve open longer while the piston is pushing the spent charge out seems logical.