Several years ago I was able to find and talk to the fellow that built my car, and its engine. He said that he ordered the biggest cam Clifford had at the time, c. 1992. Using this [url=http://users.hal-pc.org/~bwhitejr/Slant_Six_Cams.pdf]camshaft chart[/url] it looks as if my current cam is #16 Clifford. Since he built it the head was changed, and when I got the car I had the head shaved 0.075", oversized valves installed, and ported it.

A few years ago I measured my mystery cam and came up with the following:

Intake 235* @ .050â€￾ - 315* @ .006â€￾ Lift @ lifter .321â€￾ @ valve ~.445â€￾
Exhaust 236* @ .050â€￾ - 314* @ .006â€￾ Lift @ lifter .324â€￾ @ valve ~.444â€￾
Center line 113* Overlap 23* @ .050â€￾

Lift at valve changes as lash is monkeyed with over time.


Currently running lash between 0.024â€￾ to 0.028â€￾ on both intake & exhaust based on static compression test per each cylinder to achieve equal cylinder pressures between all six; presently ~ 165 psi.


This cam has poor fluttering vacuum 3 – 8â€￾ Hg. at 700-800 rpm in gear, and ~ 11â€￾ Hg at 1100 rpm in park, and on the road under 4500 rpm 16â€￾ Hg and above 4500 rpm 18â€￾ Hg. This engine in present dress begins to pull real hard around 4300 rpm, and all the way to 6000 rpm. With a rear gear of 3.55:1 60 mph gives 3000 rpm, 70 mph – 4000 rpm. The power band is too high to be used on the highway except second gear passing. Incidentally, torque converter is rated at 2600 stall, but acts closer to 2200 rpm.


It had been suggested that a bump up in compression would possibly improve idle vacuum and somewhat lower power band. The engine is soon to be pulled; barings, rings, bore, and valve condition are going to be assessed. Perhaps some of the unequal cylinder pressures may be caused by worn or broken rings that I have worked around by varying lash. We’ll see.


Hopefully dear reader you made it this far, sorry for all the blather, just trying to get all the cards out on the table.


What I’m looking for is a cam that will deliver predictable steady vacuum at idle in gear to be able to tune a Holley 390. Have more useable low end torque, and still pull hard into 5000 rpm to 6000 rpm.


I suspect a regrind with new lifters & springs would be most economical.


Suggestions welcome.

Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Very interesting read, reminds me of the Big Isky cam I rallied on for years and years in an Opel 1.9L; nothing below 3800 rpm, but pulled like mad to 7.5-8k. Too narrow a range for good rally use but I lived with it.

I have built up 2 engines in my time that were reeeally good wide RPM engines. I bring these up as they may give you some ideas:

1. 351C Ford Cleveland with 2 BBL heads (smaller valve version) using a torque/gas mileage cam and 10.3:1 CR. The thing would pull great from 1500 to over 6000 rpm. It had the standard large Cleveland intake ports, a single plane intake, and 1-7/8" header pipes. Those all seem to contribute to good top end breathing. The torque cam and small 600 cfm vacuum secondary Holley (List 6199 I think), with the high CR, seemed to compensate for the large breathing ports and manifolds at the low end. Using 18" long collectors was a distinct improvement on the low end.

2. 1.6L Mitsubishi Colt engine. It was almost flat torque from 2500 to 6500 rpm. The standard Mitsu hemi-head was a good breather in stock form and this was ported out to flow almost as much as a 426 hemi per the head shop (who did Bob Glidden's heads back in the day). Big 327 stainless valves, header, and dual DCOE 40's rounded out large breathing intake and exhaust. CR was 9:1. A long collector helped a bit. Cam in that case was a C2 Direct Connection cam: .378" lift/300 duration (at minimal lift I presume).

The common themes between these 2 engines seem to be:
- Large breathing manifolds, headers, and valves/ports for the top end
- Smaller/medium carb(s), torque cam, and moderately higher CR for the low end and responsiveness (as well as good gas mileage; the 351C above got 18-19 mpg with a 3.08 rear and C4 auto trans)

The issue that I would expect in the /6 is that you won't get the top end RPM range nearly as far as on these 2 other engines as the valves and ports just are not there. But, you can do a lot better IMO than the limited range you have had.

One more comment on CR for the low end: I rallied a 2.6L Turbo Starion for many years. At one time I dropped the actual CR from 7.5:1 to 7.1:1 with a poor piston choice: god, was the non-boosted low end just worthless! I put in forged VW flat tops and got the CR up to a true 8.2:1; holy cow, it was a whole new engine at low end RPM's before the turbo spooled. In fact, the bottom end torque is so good now, that it is like there is no turbo lag....really. So, the idea of higher CR seems spot on from that experience plus the other 2 engines I discussed.

BTW, the lifter vs valve lift numbers you site don't seem to compute right for a 1.5:1 rocker ratio.

I'll be interested to hear what you do and how it works out.

Cam , compression , convertor and gears....


whats your static compression ratio?

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Can your head handle .558" of lift?


Take a look at the 1192D intake lobe from Oregon cams:

https://app.box.com/s/a00t8svaib0jqevitapq


231 @ .050
252 @ .020

My guess is it's about a 263 duration.

Playing with desktop dyno and using this lobe on intake and exhaust blows every other cam out of the water (at low rpm too).

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Wjajr-

Looking at your previous posts, it looked like you were previously at about 9.5-ish for SCR, and idle vacc readings in the 8-11" range... which is a little low for a 230 @ 50 cam (about 280 advertised)....it acts kind of like the engine that I put together using the OCG 174 cam grind similar to the early racing cam based on the chrysler 300 cam profiles (high duration lower lifts)...that kind of flopped with a high 9 SCR and the 240 @ 50 duration even though the lifts were only at .435

Since you are looking for less lump, better idle/vaccum, useable power, you have two paths to follow:

1) A little less cam and keep the 9.5 SCR (say nothing higher than 220 @50),
set the LSA at 110 for better idle/vacuum and street but keeps the overlap shorter and builds DCR... (something like the Isky 268 cam would be good), lift will be something you will decide on...the isky was only about a .44 lift, whereas the Erson 270/270 had a .470 lift...
2) "Lou" Build....shave the head to get you in the 10-10.3:1 SCR range, then use a slightly heavier cam to bleed the DCR down a bit (even the Erson 270 is still provides a useable street DCR at this SCR)...

Having actually built a number of slants (and my 10.3:1 with the Erson 280/270/111+4 was very streetable and able to use 87 octane by limiting the vacc. advance a bit, but got the same mileage as running full advance and throwing money out the window on super- idle vacuum was about 16-18" depending on fast idle or under 800 rpm and threw my fat duster into the mid-16's with the Holley 390), and with the equipment you have (4 barrel, headers, automatic, nice rear gears) I would head in this direction to keep the fun but make it more tame for daily driving....note that this build will not limit your top end like the short cam does, so if you need to run the revs up she will keep giving all the way to 6K...


Some sage advice on using Desktop dyno:

Set the airflow file to a moderate yet known flow quantity that has been posted here, conservative keeps things close to reality when you build off the program and take your build to the track

Ensure that the valve sizes are right, the program defaults to Chevy 2.02/1.94 valves and unless you set the valve sizes and airflow charts, the program will use a chevy head flow and cut the flow proportionally (so for intakes you state a 1.70 valve, the reduce a 2.02 flow chart to that restriction which is still much better than our ports can do even with Jeffries help).

The program was primarily written for the large bore short stroke V-8 in mind, and the program will 'dip' in that direction and not be real world true with the small bore long stroke 6, so headers with a long duration lobe will always show large number gains due to expected scavenging.
There is a tip over point with the slant on scavenging, a our engine has reasonably efficient exhaust, but fairly lazy intake characteristics (hence the amount of RDP grinds recommended vs. normal assymetric grinds).

Streetability...Note the program doesn't advertise a useable DCR, but when looking at the MEP numbers if the engine looks good on the screen and the pressures are over 160-ish...race gas, and street driving will be your top issues...at 200 that mini-starter may need a can of spinach to get it rolled over... Make sure to run the cam phasing and compression choice through a DCR calculator to see where you land 8:1 is a good street DCR...

The program also does not take into consideration some real world issues/loopholes: Example:
A while back the dirt track guys were able to exploit a rules hole for a couple of years before they closed it. In this case, the limit was placed on the carburation being only provided by a Holley 350 cfm 2 barrel and a chevy 350 engine.... A few creative guys had figured out that you could run a high SCR engine, but knock the DCR down heavily by limiting the intake into the engine....so a few guys for two years outran their competition until someone complained because they were running a 16:1 SCR Chevy 350 but since the carb was not the full 700+ cfm 4 barrel to properly feed the engine the resulting lack of breathability lowered the DCR enough to get the engine by on race gas and allowed the engines derated power curve to still be better than the guys that were building their engines from the other direction centered around normal engine building with lower race compressions (12-13:1 SCR), it probably also was a little hard on the pistons and rotating assembly with the higher vacuum produced with the restricted carb size.

Look at Cam durations at 50 and your lobe separation angle....I've already ran a slant with a 250 @ 50 duration with a 111 LSA, 4 barrel and clifford headers ....it was at 11-13" at idle at 1100 rpm, at 2000rpm it picked back up to 16", nice and "lumpy"...not very useable on the street, and I had to go with high 11-low 12:1 SCR to keep it happy...(made for great 15 second passes in a heavy car assuming the clutch doesn't roast because of it).

High idle vacuum and best torque at street rpms will keep your mileage and have good idle...

If you have some hard numbers I can run the DCR calc for you and see how your path is going to compare to some of the real world data I have (one of my neighbors considered my engine build evolutions to be like the US space program- including my one hi-SCR Apollo 13 block that had a failed melling oil pump 15 minutes into the break-in).


But you need to kind of have an idea of your purpose and whether you just want to plug and play a cam with existing engine conditions or if you are going to do a couple of mods in the grand scheme of things.

Are you talking BMEP or IMEP valves from the desktop dyno?


FYI: I entered flow numbers for ported and unported slant 6 heads with the correct valve sizes for the desktop dyno

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Have you tried advancing it? That small cam with that powerband leads me to believe it is way retarded.

_________________
Official Cookie and Mater Tormentor.

Yeah, that is not such a big cam, unless you have less than 9:1 SCR. Before making a decision, you need to find out what is your SCR.

Lou

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Home of Slant6-powered fun machines since 1988

225 ci Engine dimensions as built:

Valves intakeâ€￾ 1.70 exhaust 1.44â€￾
Peanut head cut 0.075â€￾ combustion chambers 44cc
Calculated SCR 9.5:1
Piston down hole 0.153â€￾
Bore 3.430â€￾
Stroke 4.125â€￾


Last checked cylinder pressure about 163 to 165 psi with varying lash settings as needed to even out pressures over all six cylinders.


Using one lash across all intake and exhaust yielded such as 0.012â€￾ & 0.21â€￾ gave pressures varying between 140 and 145 psi., and fluttering 0â€￾ to 5 “ Hg at in gear idle of ~700rpm. As vacuum moved up & down, idle rpm ran up and down. I have yet to figure out if vacuum variation caused carb idle mixture to move, or carb idle mixture caused vacuum readings to move. At any rate the two readings would rhythmically roll up and down with timing moving as well.


Around July 2010 on advice from board to loosen lash I set lash to 0.018â€￾ intake, and 0.026â€￾ exhaust yielded cylinder pressures 145 psi to 160psi attempt to settle down idle speed & vacuum levels. I continued to try various settings in a quest to get engine to settle down at idle. Currently cylinders 1 – 6 are set as follows: (E & I) 24 & 23; 24 & 24; 24 & 24; (I&E) 26 & 26; 24 & 24; 25 & 25. These settings create a bit of ticking.


When cylinder pressures were evened out, and vacuum at low rpm stayed above 3-4â€￾Hg the rolling rpm settled down but did not fully go away, and idle mixture became more stable and tunable as indicated by o2 sensor and digital voltage readings.


Because of pressure disparity over all cylinder pressures using constant lash, and a hunt or random misfire manifesting at idle, a ring problem and or perhaps a lazy valve hanging up can be suspected.


As for cam being installed retarded, I’m not clear on that. Based on a graph created from degree wheel measurements from a few years ago center line of intake is 99* & exhaust 113* yielding center line of 105.5 degrees.


At 0.050â€￾ lift, overlap is 22* and at 0.006â€￾ lift 101*.


To be honest the degreeing measurement process was a bit challenging at the time taking a reading at every 10 thousandth of lift over 620 degrees, and I see no reason for that challenge to lessen for my atrophied brain four years later.


I hope this additional information helps.


As for changes, increasing compression is an available option, as are fitting new rings provided bores are all still in acceptable condition. I really don’t want the added expense of a reboring, and new pistons. New baring’s, and timing chain & sprockets I can live with.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

It took a total of .160 milling to get 9.5 SCR on my build.....

I used a 280/270 Ersom with a Super6 manifold and BBD.

It made a super streetable, torquey street motor.

The right DCR and conservative manifolding make for lotso vacuum and stable idle.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

The block has been milled, most likely when the 30 over pistons were installed. Just how much was taken I don't know.

What it the average distance piston is down in hole with an unmilled block?

When conversing with guy that built this engine early 90's, he said the car was quite fast, faster than it is now, when racing he would pop in a set of 4.11's. He also said he blew up five engines before figuring out how to build one that would stay together; for what it's worth.

This little story is telling me that whatever he did involved higher compression than what I'm at now.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

My stock '64 block has the pistons 0.185" down in the hole. From what I've read, that's fairly typical.

_________________
Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

After reading post about Guzzi engine build Doc [url=http://www.slantsix.org/forum/viewtopic.php?t=26159]illustrated[/url] one way to figure how much material has been removed from block by measuring little depression center of lifter galley; stock being about 0.100â€￾.

I haven’t disassembled anything yet or lately, but recalled an old head gasket I kept when the head was last off. Measuring height of bump in gasket which filled said depression is less than 0.002â€￾ high; so about 0.100â€￾ has been removed. Add that to the 0.076â€￾ I had cut from head that makes about 1.76â€￾ total material removed.


Frank:
[quote]My stock '64 block has the pistons 0.185" down in the hole.[/quote]


Since making this post, and taking in some readings on the subject posted here, I see Spacefrank chimed in, now I'm back into unknown territory.

.185"-.153"=.032" milled from block.

Anyway I suspect actual measurement of how far down in hole piston resides would be all the info I need to calculate static compression, which is how I arrived at 9.5:1 when head was worked on in 2009.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Yeah, your measurement is all you need for CR calculation. I've been using this calculator:

http://www.csgnetwork.com/compcalc.html

Using your numbers posted above and what I think are standard Fel-Pro gasket numbers (3.5" bore diameter, 0.040" compressed thickness), I also get right at 9.5 SCR.

_________________
Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Bottom line is that there is something wrong with the measurements, or centerline, or there is a vac leak somewhere in the intake/carb tract. Your cam specs and 9.5 SCR should idle fine and pull a steady 8-14" Hg vacuum. I might go a little smaller on the cam, but not much.

Lou

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Home of Slant6-powered fun machines since 1988