Vizard does say to err on the tight side is better, so at 108° say, that's in line with Mopar's SB cams in this range.
Camshaft Selection Information
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When You state "6000-6200 RPM max", are You referring to shift point? If so, that ain't gonna happen, figure upper 6K-7K. Peak power may be about there. 340's were born to rev!
The 6k to 6.2k came from looking at the advertised operating range of the XE274 and AirGap intake. I figure the Engineers probably were a little conservative on the operating rpm ranges for the cam, intake, valve springs and the new heads.
Will try to look for the best shift points based on where peak hp range of the setup just before the hp curve starts to fall over. Also wanted to leave a little buffer in case missed a gear. Had an incident running a SBC 350 in 73 Nova where I had a crapy shifter and missed 3rd gear. Had piston to valve contact. Was fortunate to have only bent an exhaust valve in that case. Had forged TRW pistons in it and only put a light scratch on the piston but it ran like crap limping it home. Good friend had a MR. Gasket Pro shifter he wasn't using, so I put it in the car and never looked back. Could shift it without letting off accelerator. Just watch for the shift light but I shifted it around that 5.8-6k point. It had a Comp 280H cam, LT1 intake w/center plenum divider cut down 1 inch, 2" open spacer, 750 Holley Dual Line and 1-5/8" full length headers.
With the 340 having a slightly larger bore and shorter stroke I though it might have a little more torque range and quicker rev response.
Putting a center console in this car with HURST box/handle combo. Not sure how large the shift pattern on it will be but guessing it won't be as close of a pattern as that Pro shifter given the special shifter handle design.
Killer, were the 340's designed to safely/consistently rev that high from the factory?
Will try to look for the best shift points based on where peak hp range of the setup just before the hp curve starts to fall over. Also wanted to leave a little buffer in case missed a gear. Had an incident running a SBC 350 in 73 Nova where I had a crapy shifter and missed 3rd gear. Had piston to valve contact. Was fortunate to have only bent an exhaust valve in that case. Had forged TRW pistons in it and only put a light scratch on the piston but it ran like crap limping it home. Good friend had a MR. Gasket Pro shifter he wasn't using, so I put it in the car and never looked back. Could shift it without letting off accelerator. Just watch for the shift light but I shifted it around that 5.8-6k point. It had a Comp 280H cam, LT1 intake w/center plenum divider cut down 1 inch, 2" open spacer, 750 Holley Dual Line and 1-5/8" full length headers.
With the 340 having a slightly larger bore and shorter stroke I though it might have a little more torque range and quicker rev response.
Putting a center console in this car with HURST box/handle combo. Not sure how large the shift pattern on it will be but guessing it won't be as close of a pattern as that Pro shifter given the special shifter handle design.
Killer, were the 340's designed to safely/consistently rev that high from the factory?
Don't believe the 390hp output from that magazine engine done years ago, not going to happen with a 268H and bone stock heads.
Running the XE274H, true 10:1, promaxx heads with headers and a good tune will get you in the 400+hp range. We had a 340 cleaned up eddys, XS282S, victor, 750dp, tti's and it made right at 435hp. Ran like it at the track too. Was a solid mid 11's car, 117-118 mph in a piggy weight 73 Duster.
Running the XE274H, true 10:1, promaxx heads with headers and a good tune will get you in the 400+hp range. We had a 340 cleaned up eddys, XS282S, victor, 750dp, tti's and it made right at 435hp. Ran like it at the track too. Was a solid mid 11's car, 117-118 mph in a piggy weight 73 Duster.
Be careful with Vizard's rule... if you read his books that rule is for factory mediocre heads and flow. If you really read what he has proven on hundreds of dyno runs is the LSA is a function of air flow at low lift, like 0.100. The better the flow at low lift the wider LSA the engine will want. He points at modern high performance 4 valve per cylinder engines have LSAs in the 118 degree range because they flow a lot of air at low lift. I don't know the specs on flow for the heads you have but if you want to follow Vizards building recipe if you calculate the LSA of 108 and those heads flow much better at 0.100" lift than stock his recommendations would be to maybe crank it up a notch to 110 maybe... I know that goes against some of the recommendations here but that is what the math and testing he has done recommends.
Also remember what Vizard IS NOT for making some single peak number like 400 HP. His recommendations are to create an engine that makes the most power across the RPM band, i.e. the total area under the torque curve is maximized not that you will get peak torque or HP numbers.
I have used his math/recommendations on my last 2 builds. The 225 slant 6 I went with an Oregon cams that was 106 LCA because the stock heads flow terrible (I also put oversized valves in but did what he said, err on the side of tight), Dutra Duals with the "Y" 45" back for peak torque at about 3000 RPM and decked the block to get just short of 9:1 compression. It won't make big HP number because I dailed it in to make most power below 4500 RPM but man does it run good in everyday driving. I did have access to performance trends software for these build too so I ran a lot of simulations for the 2 builds. The second is a 360 for the Valiant. I just got that running a few weeks ago and just getting it broken in. I have not really seen what it does so I can't tell how it came out. Again a Oregon cams grind and like you calculated about 108 with the Edelbrock heads but I went with a 110 because they flow much better than stock and the Vizard rules needs adjustment because of that.
With the low LCA numbers you can't run a lot of duration without getting into a lumpy idle and poor vacuum. That will kill lower everyday RPM power but give you the possibility for the 400HP if you plan on running it at 7000 RPM all the time. On the other side be careful with a lower LSA and very short durations and compression. The math says the low end torque is improved but it does be cause the cylinder pressure is growing. There is a place where the cylinder pressure gets too high. The typical 215-225 duration at 0.050" lift will be fine. I was experimenting with lower duration and pressures got to high. Like was said earlier with these smaller displacement engines you really need to pick your poison... do you want to maximize street torque in normal driving RPM or do you want to be able to say it makes 400 HP on a dyno at WOT, its hard to get both.
I personally hate headers and won't use anything but stock manifolds but you can really make a huge bump in the power in the street driving RPM range if you use Vizards math and get the header tube length AND diameters close to the RPM band you want the power. That was clear in the simulations.
Also remember what Vizard IS NOT for making some single peak number like 400 HP. His recommendations are to create an engine that makes the most power across the RPM band, i.e. the total area under the torque curve is maximized not that you will get peak torque or HP numbers.
I have used his math/recommendations on my last 2 builds. The 225 slant 6 I went with an Oregon cams that was 106 LCA because the stock heads flow terrible (I also put oversized valves in but did what he said, err on the side of tight), Dutra Duals with the "Y" 45" back for peak torque at about 3000 RPM and decked the block to get just short of 9:1 compression. It won't make big HP number because I dailed it in to make most power below 4500 RPM but man does it run good in everyday driving. I did have access to performance trends software for these build too so I ran a lot of simulations for the 2 builds. The second is a 360 for the Valiant. I just got that running a few weeks ago and just getting it broken in. I have not really seen what it does so I can't tell how it came out. Again a Oregon cams grind and like you calculated about 108 with the Edelbrock heads but I went with a 110 because they flow much better than stock and the Vizard rules needs adjustment because of that.
With the low LCA numbers you can't run a lot of duration without getting into a lumpy idle and poor vacuum. That will kill lower everyday RPM power but give you the possibility for the 400HP if you plan on running it at 7000 RPM all the time. On the other side be careful with a lower LSA and very short durations and compression. The math says the low end torque is improved but it does be cause the cylinder pressure is growing. There is a place where the cylinder pressure gets too high. The typical 215-225 duration at 0.050" lift will be fine. I was experimenting with lower duration and pressures got to high. Like was said earlier with these smaller displacement engines you really need to pick your poison... do you want to maximize street torque in normal driving RPM or do you want to be able to say it makes 400 HP on a dyno at WOT, its hard to get both.
I personally hate headers and won't use anything but stock manifolds but you can really make a huge bump in the power in the street driving RPM range if you use Vizards math and get the header tube length AND diameters close to the RPM band you want the power. That was clear in the simulations.
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Thanks for the information. I have been looking at the XS274S as an alternative to the XE274H. I have more hands on experience with the hydraulic flat tappet shafts is reason I was looking at the 274H. Never used a solid flat tappet. I assume just a few different install/setup procedures and possibly require revisit from time to time on the valve lash setup?
Only experience on solid lifters was on my wifes 73 Super Beetle she drove many years ago.
Plan to just bite the bullet and tear down the engine while on vacation this holiday week and see what is in there, it has been bored 0.030". Have read that it may be best on stock lower ( cast crank, stock rods/bolts etc) to keep piston speed at or below 4000 f/min. Is that a realistic. By formula I saw on I-net 6500rpm on stock stoke (6.123") comes out to about 3588 ft/min. I will be replacing all bolts with ARP fasteners at a minimum. Depending on how the existing rods check out, may upgrade them as well, we'll see once I get in there and see what the last rebuild folks installed.
Piston Speed (ft/min) = (Stoke (in) x RPM)/6
BTW, did you drive this setup on the street/highway any?
You are putting adjustable rockers on it. As others have mentioned, go with a soild and the 282S is a decent cam as well. Being a 4 speed you can get away with a little more cam, no converter idle in gear issues.
The mopar 528 mechanical is a good too, about the same as the 282s
The mopar 528 mechanical is a good too, about the same as the 282s
Thanks Jim.
Think I'm going to try to find David's book on How To Make HP and give it a read before I make final decision. From the head flow chart from ProMaxx these heads flow about 251/185 @ 0.500" lift and 28" water. That's about a exhaust-to-intake ratio of ~ 74%. I assume that may be better than stock 2.02"/1.60" heads???
If it were me, I'd consider just buying some new Scat I beam rods. I'm not sure what the price is these days, but considering cost of resizing your rods plus buying new ARP fasteners, it may be cost effective. Also consider the rods you have are 50+ years old, not a part you want failing, nevermind talk of 6500+ rpm. Not trying to spend your dollar, just offering an opinion.
I appreciate opinions. I am thinking on this engine those pistons look like KB pistons from the top view with bore scope. With those style pistons I am wondering if someone had originally built up the engine with better upper end than the stock iron that is on it now but when they wanted to sell the car they pulled the new upper end off and put the stock iron back on it. I'm just guessing here. Will know more when I get the pan off.
Someone mentioned on another post that the factory rods had an extra oil hole to lube the cylinder and that aftermarket rods don't have that hole and could be some concern about the overseas material quality of aftermarket rods now days compared to the original Detroit USA material in the original rods?
I have never ran aftermarket rods, so I have not practical experience on them.
Lots of stock rods with good bolts doing 7Ks with no problem, even with heavy old-school forged TRWs hangin' from them, that would be way down the list of concerns. An adjustable valvetrain like Yours makes the choice easy, go solid. Make certain You've got the right springs for the job & go.
gzig5
Well-Known Member
I have the same heads and I’m doing an engine with stock pistons stock bore. Intake will be air gap ot start and then and M1 single plane, and then a tunnel ram. Jones recommended the following solid cam for me for a more road course and street oriented instead of dragstrip oriented application. Four speed A833 and 3.55 gears but I may go to 3.91.
Cam# Chr340, M74365-76364-108
244/252 @.050"
.365"/.364" Lobe Lift
108 LSA
Cam# Chr340, M74365-76364-108
244/252 @.050"
.365"/.364" Lobe Lift
108 LSA
Rat Bastid
Dunamis Metron
Vizard frets WAAAAY too much overflow lift flow. He has since…who knows?
He did a series of articles back in the late 1990’s. In fact, it was is Super Stock & Drag Illustrated before Hot Rod bought it and killed it. It was 4 parts and I’ve never seen the 4th part.
At any rate, he was using a Quadrant Scientific flow bench, and as far as I know there were only a few made.
His theory was he was going to use a 30 degree seat and make more power than a 45 degree seat. As I said, I’ve never seen the last part.
I even PM‘d him on Speed Talk several times probably around 2006-2007 and he never replied.
If low lift flow was a determining factor in producing good, useable horsepower no one would ever use anything steeper than a 45 and that would be Comp Eliminator and Pro Stock stuff.
One of the first things I learned with my flow bench was most of what was published and is still being published is bullshit.
You can drop a ton of power right quick with a bunch of bad low lift flow.
What’s bad low lift flow? Flow the head backwards and it’s easy to see.
It'd be possible from a two to a four barrel. lol
I think He pushed that as a way to increase OL scavenge, and pick up port velo, w/o increasing the duration as much. That would supposedly reduce the reversion event enough to "trade off". This is really small cam street stuff basically, Dulcich tried the 30° routine as well, but as Vizard acknowledges the seat load needs to be increased to maintain a tight seal & control bounce...so now You're using more spring(drag) to do the same job. Lately, Vizard has been using a 39° seat for stuff that isn't all-out. Guess that's His compromise, I'll let Him spend His dyno time proving/disproving it, I'm sticking with 45° for what I'm doing.
Rat Bastid
Dunamis Metron
Hmmm…didn’t know he was using a 39. That’s interesting.
I know (until maybe recently) he was using a radius intake seat. That’s a big no no. Looks great on a flow bench but hurts power.
Actually it looks good on a flow bench flowing forward. It looks horrible flowing it backwards.
Now I’m wondering if he was using a radius with a 30 degree seat. I wish I had those old magazines as my memory isn’t what it once was.
Who is Jones? Tried to lookup that Chr340 number. RAn it through Google and found a old post of yours here on FABO from back in May 2020 with the spec mentioned. Looking for dyno data and where in the rpm range it would be making the most power/torque.
Thanks
Thanks
gzig5
Well-Known Member
My engine build has been on hold due to unforseen costs associated with hidden uni-body damage. I don't have any functional results yet. Hope to make some progress next spring. He has an online quoting tool where you feed him your specs and application and he will give his recommendation. I plan on calling and speaking directly with him before I order, but from what I've gathered his recommendation should be about as aggressive as I'm going to want to go and keep some level of street manners. I specifically asked for something that has good mid-range torque for powering out of the corners, so my guess is it won't all be at the top end. I think I gave him a 6000-6500rpm for max HP and 7000 redline.
You'll get the best results by filling out his form, or talking to him directly. Cam Recommendation | Jones Cams
I found his site and started filling out the form but noticed I have a few missing pieces of information that is requested on the form.
gzig5
Well-Known Member
You probably don’t need every single piece of data, but the more you have more accurate he can be. Probably still get a good recommendation.
Babyblue66
Cool dude
I've used 3 Hughes hydraulic flat tappet cams in different combinations and they've worked very well. I made 416 hp with a 7.5 to 1 1977 440, with heads I ported and a cam from them.
That's excellent.
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