[firechickenman]

Great thread! A lot of god info here! Click the link in my sig for a video of mine. If you click on my name or pic below the video, I have several videos of it. In car and outside. Comp 290B6, 290/304 dur. 255/266 @ .050 106 LSA installed at 103 ICL.

[PAUL K]

Originally Posted by firechickenman

Great thread! A lot of god info here! Click the link in my sig for a video of mine. If you click on my name or pic below the video, I have several videos of it. In car and outside. Comp 290B6, 290/304 dur. 255/266 @ .050 106 LSA installed at 103 ICL.

You might want to look at post #73 . Maybe you can by-pass running deeper into the ten's and go straight to the low ten's.

[funkybird]

Very interesting thread

Totally hear what your saying ref big cams in a 455

Question
For a mostly stock street only driven 455 automatic car, how big a cam can you go?

I fell into the trap of a small cam with a big CU unit at the last rebuild (sadly before I discovered this forum). Whilst driveability is great, it needs high octane fuel to stop pinking.

Based on the generic advice from the cam manufacturers, I was more concerned about keeping vacuum for the brakes & my stock convertor.

Im thinking a cam change is needed at the next rebuild, but ideally, without the expense or trouble of switching the converter, which (as a novice) is another area of black magic to me

Consider that my car had the 068 cam (288/302). I dont think Pontiac ever fitted 041 (308/320) to an automatic car, but please correct me if Im wrong on this

So how 'big' should I go?

[AG]

I have the 041 cam in my 9.1 cr 455 with Rhodes lifters and an automatic that works very well with a 2000 rpm stall converter. Vacuum is 14" at idle and the carb is easily tuned, really a very mild combo with RA manifolds and 2.5" exhaust with Dynomax super turbos.

[77 TRASHCAN]

Originally Posted by AG

I have the 041 cam in my 9.1 cr 455 with Rhodes lifters and an automatic that works very well with a 2000 rpm stall converter. Vacuum is 14" at idle and the carb is easily tuned, really a very mild combo with RA manifolds and 2.5" exhaust with Dynomax super turbos.

How do you like your v-max lifters??? Do yours make much noise??? Last time I heard Jim Hands wagon @ Ark City, Kansas he had the v-max lifters in his engine. They were not very noisy at all. When he had the original Rhoads lifters in his engine they were VERY noticeable....

[scott70]

With my vmax lifters,,when i first start it up cold,,theyre fairly quiet but as the oil gets hotter,,the noise is definitely noticeable. I had regular Rhoads in a different engine,same car years ago and it seems to me the vmax are louder than those were,,,,,,but that was years ago.Setting the preload on the vmax is different the reg rhoads. Great vac for the brakes and a fairly smooth idle. Comp. cams 1.65 roller tip rockers.

[77 TRASHCAN]

Originally Posted by funkybird

Very interesting thread

Totally hear what your saying ref big cams in a 455

Question
For a mostly stock street only driven 455 automatic car, how big a cam can you go?

I fell into the trap of a small cam with a big CU unit at the last rebuild (sadly before I discovered this forum). Whilst driveability is great, it needs high octane fuel to stop pinking.

Based on the generic advice from the cam manufacturers, I was more concerned about keeping vacuum for the brakes & my stock convertor.

Im thinking a cam change is needed at the next rebuild, but ideally, without the expense or trouble of switching the converter, which (as a novice) is another area of black magic to me

Consider that my car had the 068 cam (288/302). I dont think Pontiac ever fitted 041 (308/320) to an automatic car, but please correct me if Im wrong on this

So how 'big' should I go?

You need to post more information about your car/engine. Compression ratio would be most important thing for cam selection

[Steve C.]

"Compression ratio would be most important thing for cam selection"

Important consideration, but most important ?

Often a 'catalog' suggestion is general and can be vague.

"The charts are often nowhere near scientific or definitive in its scope. Larger or smaller cubic inches, different lobe separation angles and other variables will alter these figures, but at least it's a starting point in the explanation of using a certain range of cam with a certain range of static compression ratio."

Good read and indicates the importance if interested:

http://www.badasscars.com/index.cfm/...prod/prd68.htm


.

[ponyakr]

I'm not one of the experts here, but just thought I'd chime in anyhow. If you got enuff CR the "041" cam with Rhoads lifters is a real good cam for a 455 Auto, with stock converter.

We ran this combo in several 455 bracket engines over a period of many years. With the Rhoads lifters, they idled smooth enuff for us to launch from an 800 rpm idle with a stock 13" converter. We were not going for max hp, or ET, so we shifted at 5000rpm. So, for idle to 5000 rpm operation, I couldn't have asked for anything better.

Would our cars have run quicker with bigger cams ? Certainly. Later on, a track we ran, switched to 1000ft, instead of 1/4 mile, and they set the minimum for Super Pro bracket at 9.99. We were running 10 teens. So I switched from 4.11 to 4.88 gears and switched to a CC cam with 244/253 @ .050 dur and just over .500 lift, and of course, Rhoads lifters. Still had a TH400 with stock 13" converter. Still left from an idle, cut good lights, ran 60ft times in the 1.60's, and ran a 9.85.

CC still has these lobes available, but only in single pattern cams. I'm sure they'd grind a custom dual pattern with these lobes. But I'm thinkin these lobes may need a bit more than 9.5 CR to work well. We were running the '68-'70 big valve heads--16, 62, 64. I have not done any cam testing like these other guys have, so I'm sure they would know if these lobes are usable or not. With today's technology, there are probably many better lobes available.

http://www.summitracing.com/parts/cc...w/make/pontiac

http://www.summitracing.com/parts/cc...w/make/pontiac

http://www.summitracing.com/parts/rh...w/make/pontiac

Cliff has done LOTS of testing with the 041. I think he used the Crower 60919. I used the Crane and Melling versions, because they were cheaper at that time. The Melling SPC-8 is still only about $100 on Ebay. Jim hand wrote one of the best articles I've read on using the 041 cam and Rhoads lifters.

http://community.fortunecity.ws/silv...build/cams.htm

Hey, all I'm sayin is that the RA4 cam with Rhoads lifters worked great for us, for what we were doing, and helped us win lots of races. I'd like to hear from the experts here, at exactly what CR the RA4 cam becomes "not so good". Like, will it work OK at 9.5 but not too good a 9:1 ? I assume there is a CR number, below which, it is a bad choice.

[Steve C.]

Dyno test changing compression only

Page 51 here:

https://books.google.com/books?id=5L...hWCC6wKHaMbAFo

Not discounting the importance of adequate compression, but many will suggest the often small difference in increased compression has little impact on street driving. Especially in all weather conditions, including stop-and-go traffic, fuel quality, and never knowing what the tune up is going to be for "John Doe".

"I have found in my experiences tied to track results that higher compression and then having to go to longer LSA to kill the compression/bleedoff has resulted in lower ET's at the track."
Pontiac Dude

"Me,I see no valid reason to push the CR envelope for mostly "street" oriented cars."
Screamingchief

http://forums.maxperformanceinc.com/...ght=leave+shop

.

[scott70]

I run a 462 ,,, 9.3 to 1 ,,crower 60919 cam with 1.65 rockers with Rhoades max lifters and idles very well,,,actually wish it had a little more lope to it. Pulls hard from idle to 5300. Probably further but just havent pushed the rpms any higher than that.

[steverino]

Lots of great info , I'm following closely and learning quite a bit.

I'm curious ponyakr and AG, what rockers do you use with your RA4 style cams and rhoads lifters ?

Also lots of good info in the Jeff Smith sbc article, although they did use alum heads, maybe it had an effect on the detonation (or lack there of) ?

My builder's experience was similar in dyno testing of circle track racing engines as well as (mostly bbc) customer's street engines, insofar as the compression ratio net gain (for a street car certainly with unknown quality variances in pump fuel) was no worth even approaching 10 to 1, I had to plead with them to plain the heads to raise me to 9.4 (could even be 9.25-9.3)

In any case, many folks shared their insights with me before I selected cam for my 455 with tripower and stock 6X (milled for 99cc chambers), and I appreciate it, one o fthe things that this forum is great for !

I deliberated between; 1) RA4, but wasn't certain if it would perform as expected with 1.5 rockers . 2) crower 90243, and finally the choice I made, 3) the xe274

The scary thing is that some reputable builders as well as cam manufacturers were highly recommending the 268, I am glad I read Jim Hand's book, and decided to go "one size up", due to the larger displacement, I don't think I would've been happy with the 268

I am probly lucky that after almost 3k miles, the lobes and lifters seem to be ok thus far .

Now I am more "in tune" with the "sewing machine sound" , the engine can be a bit "ticky even with great oil pressure at steady rpm's
It does like a bit extra timing 16 initial (36 total), and 91 octane, but as long as gas is reasonable, I'm ok with that

The performance is great in fairly heavy 66 gto conv with 4 sp and 3.23

I know the power band is shortened, done by 4900 rpm, but that again is ok for my use, actually favorable to me, I do love the torque, which the 455 excels at anyway

I have had a few issues with the combo, we had to change valve seals to positive style, again , help from here on the forum helped me to pinpoint the issue (the builder had miscalculated the valve lift/seal clearance)
but with a stock cooling system, we've been running great and never too hot

So I'm sure my bottom end is good
I'm pretty certain that my heads are going to be a limitation to the total power I can make, but that is fine, I really want to keep the stock look under the 66 tripower

My question is, If I do decide to make a cam change at some point down the road ( I have considered it, but it's on the back burner for sure), what hydraulic flat tappet would I go to ? My heads are no clearanced for the 1.65 rockers, so I'm thinking maybe the crower 90243 still ?
I do see that respected builder Len Williams advertises a good power number from the RA4 style cam (which I believe is what he uses), and with 1.5 rockers and rhoads lifters, so maybe that would be a better route ?
I know that a roller and aluminum heads are where "all the power" is at nowadays, but
As I said, just thinking about it for now
Thanks for the info and all the great input !