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| Extras in 1974 rebuild? https://slantsix.org/forum/viewtopic.php?t=61148 |
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| Author: | emsvitil [ Thu May 18, 2017 5:50 pm ] |
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DIY porting: http://www.pirate4x4.com/tech/billavist ... asives.pdf I would at a minimum clean up any irregularities in the ports and intake manifold.......... |
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| Author: | SlantSteve [ Fri May 19, 2017 2:50 am ] |
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The Slant is a very basic engine,any competent rebuilder should have handled many in their day. He will see if the cam is worn or useable very easily,if the lifters are worn,ie,no longer convex and worn to a dish then it's time to regrind both the lifters and cam,or buy new ones. The the way I look at the head is...well,the intake ports are average. Now,you can run a longer duration cam biased towards the intake,to me it's an easy way out,not ideal,but it helps,or ideally attempt to fix or at least minimise the issue and enjoy the same or better performance with a smaller cam,less emissions and quieter engine. I have never used the RV10 cam,the ones available are copies of the original that I'm sure are fine....but,I would research this choice very closely. I'd suggest get first hand reports from guys that are running it. I have read a couple of reports here of guys running pretty large lash in an attempt to smooth out idle . Opening up lash shortens the valve events,but makes it noisy in the valve train and the lash they were running is way beyond what I'd accept for a stock engine build. These people may well have had other tuning issues,that why I suggest get first hand experiences. I will say the lobes are very slow,advertised durations indicate a fair amount of low lift overlap and mid lift numbers are low compared to modern cams. The intake s a Erson Chev lobe and the exhaust is a Mopar profile. Have no doubt it works,but it may not be exactly the best option for you,but it of course a decision only you can make. I built a similar slant to your a while back,I used a better piston and rod package,but the head was as I suggested with larger intake,the cam is symmetrical with faster ramps to suit the Mopar lifter and has tight lash and is ground in a wide LSA,the engine runs very well,smooth,quiet,doesnt stink out the garage and motivates the car at a rate that easily motivates the old Valiant a a very respectable rate...and gets decent mileage. Even if the engine is in good condition and all you need is a set of rings, and a valve job (if this is the case you will be very lucky) I would still mill the block and head to increase compression and add a HEI ignition and home port the head,that's just my opinion. |
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| Author: | rich006 [ Fri May 19, 2017 8:31 am ] |
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Quote:
That article does a nice job justifying the "light porting" or "bowl work" that several of you have suggested. It seems I would be foolish not to clean up the rough edges in the head while it's removed. That's in contrast to a more significant porting job aiming to widen the ports overall, which would be overkill for my application.
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| Author: | DadTruck [ Fri May 19, 2017 1:22 pm ] |
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Quote: any competent rebuilder should have handled many in their day. He will see if the cam is worn
I spoke on the phone with Ken at Oregon Cam,,Ken has some experience with slant six cams,, per Ken they do inspection on incoming cores and about 70% of the slant six cams that come in have enough wear on the lobes to justify a regrind, or in the case of the fuel pump lobe a weld repair. Ken said he has been looking at cam profiles for 35+ years and still trusts actual measurement data off dedicated equipment over the human eye. a regrind with a core provided is < $95.00 My recommendation is, have your machine shop guy work within his area of compentency,, which should be: getting planes like the head and block decks flat with enough roughness to hold a gasket and cylinder bores round and straight, and let cam profile inspection and assumptions with those that work cam profiles for a living. Quote: I have read a couple of reports here of guys running pretty large lash in an attempt to smooth out idle
please link those reports, I have not seen those, thanks
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| Author: | 75valiant [ Fri May 19, 2017 2:27 pm ] |
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Quote: Quote:
That article does a nice job justifying the "light porting" or "bowl work" that several of you have suggested. It seems I would be foolish not to clean up the rough edges in the head while it's removed. That's in contrast to a more significant porting job aiming to widen the ports overall, which would be overkill for my application. |
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| Author: | DusterIdiot [ Fri May 19, 2017 3:04 pm ] |
| Post subject: | In a nutshell... |
I think before you get any further, pulling the engine and opening it up will give you the most information you need to be able to determine how your budget stands... Literally, looking at the bores to check for any scratches/scoring will tell you if it's a hone and rering or a 'needs another overbore'.... The head will be another matter, as you will need some tools to pull the valves and look and see if you need new guides or not... the machinist will have to check the springs to see if you have any that are toast (yes they may function fine, but 10 lbs of seat pressure isn't going to do you any good...). I also would re-ask your machinist about what he meant by port job... I don't expect more than 4 hours of work to take care of the business and do a little bowl blending... most likely he thought you wanted a full port job, bowl hogging, and flow tested... that would be $$$... just a few hours of blending and removing some casting flash isn't going to cost much...and he has to pull the valves out to check the guides anyway.... Upgrading the cam will add a bit more lift and allow the engine to breathe better, adding a bit more power for freeway merging (this will be an "adder" and will help when upgrading to a super six and replacing the exhaust with the 2 1/4" super six/ Feather Duster pipe...) Stock cam will possibly be OK, but you will also have to inspect the fuel pump cam as sometimes these can wear down. I think the wishlist would be: rebuild engine if necessary... otherwise rering and recam (have cam degreed and set advance 4 degrees for better torque...run DCR if you have all the information and measurements to do the calc) Have headwork done (street port, shave for compression boost, check guides and springs). Keep 1 barrel (rebuild Holley 1945 and rejet to #61 and reset linkages as a 1976 Holley 1945), upgrade to super six later as money, time, availability allows. Upgrade exhaust from stock noodle pipe to SSD upgrade (or super six/FD 2 1/4" exhaust) this is good for a 1/2 to 1 1/2 mpg increase depending on drivetrain and engine options... and a little seat of the pants power Upgrade rear ratio to 3.23 (if 7 1/4" rear)... this will allow the engine to motivate the car easier, and get the powerband into a useable rpm range... that being said... you might want to do an analysis of the tire size and ratio... currently this Aspen I'm working on with 3.21's and 195/70/14 will be at 3000 rpm at 65 mph... which might be annoying to a person used to 2.76's at 2300 rpm for longer distances...but I've set the cam and build on the engine to have peak torque at 3000 rpm which should yeild best mileage for cruise... Also, I can recurve your distributor... you can PM me for pricing (It's not as bad as that DFI race item). I will need some information on your build and drivetrain so I can best set the advance for the car. |
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