Dakota Forumz banner

41 - 60 of 113 Posts

·
Registered
Joined
·
235 Posts
Discussion Starter · #42 ·
In regards the camshaft, yes it is a mild improvement over stock. I'm not taking a big swing at anything. A little here a little there looking for an overall boost. I guess it depends on how you look at things. Along with a compression increase of roughly one point the rods and pistons are lighter reducing reciprocating weight roughly 1.5 lbs that does not have to start and stop ever revolution. Maybe that does not count.

I had mentioned earlier this engine core came down from up north. I also had a thread about these plug tubes. While at first glance they look awful you work with what you buy. The Mature Marine put me on a replacement set from my thread. My approach is remove the plug tubes knowing more were on the way. Steve
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #44 ·
Once the tubes are wiggled out I began the process of cleaning up the heads. Starting with a scraper removing flakes of rust, then wire brush in drill and by hand. After each brushing I spray with rust converter and allow it to do it's thing. Once it turns black I start over scrape, brush and treat. Steve
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #46 ·
As you can see it really does turn the rust black. Once pretty much back to bare metal a coat of paint will protect them from here on. While no real performance advantage it cleaning them up they will look better. I have and will continue to work the ports intake and exhaust. Steve
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #48 ·
In spite of the crusty outer layer the important part is great. No signs of water in the chambers the gasket surfaces are good no rust in the water jackets. I have been ask about O/S valves and it is clear there is no room for bigger valves. The exhaust seats are lightly pounded and a bit wide. The valve guides are fine, so new valves with chrome plated stems and a slight back angle will be fine. The old valves could be cleaned ground and re used, but the new cam has about .075 additional lift. Any wear pattern on the stems would be an issue and I believe in duty cycles. The ports are very hard to work and get a good feeling about. The Serdi will handle much of the bowl blending and cut the seats all the same height. The spring kit with springs, caps and keepers are still on back order. While mild the new cam has a little over .500 lift which exceeds the stock springs lift limit. We don't need a ton of spring pressure so no double springs, this is a low rpm build*. Once all head valve and seat work is done a check of valve retainer to seal clearance. It is not uncommon to shorten the guide a little if required. Installed height and seat pressure checked and shimmed if required they will be cleaned a couple more times and assembled properly lubed. Steve

*While I restore classic street cars the Vintage race cars I support rev to 9000 and beyond now and then with cams that don't wake up till 3500.
 

·
Registered
Joined
·
123 Posts
The cam is listed as 197/203 114 LSA with 507 / 516 at 1.6 rocker ratio. Steve
Can you choose a narrower lsa or did you already buy the cam? 110-112 would be better in my mind especially that you boosted the curve already w your manifold mods. Then again your valve openings remain smallish so I can't be sure. A narrower lsa is simply what I would bet on at this point if it were I.
It sounds like some type of boost cam as of now. Why have that much lift on such short duration while lengthening the lobe separation unless you were gonna force a lot of air in?
I'm thinking 9.5 or less compression doesn't ideally support a 114 lsa unless there is boost. I'm thinking the truck as being a logy at lower rpms with that cam.
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #50 ·
So we want to talk about Lobe Displacement angle. If going may as well go deep. A little light reading. Widening the angle reduces overlap. "All it does is make the engine much more drivable and is an easy way to allow a longer period cam without throwing away driveability ".I have been building English engines for a long time. In recent years there has been a shift to short duration high lift cams. Yep, high valve acceleration rates but revs held to 5000 or less.

Have you read any about a second compression ring gap 50 percent larger than the first ring gap produces more HP? Thanks for your input. I have no plans for a super charger make my HP on motor. Steve
 

·
Registered
Joined
·
123 Posts
So we want to talk about Lobe Displacement angle. If going may as well go deep. A little light reading. Widening the angle reduces overlap. "All it does is make the engine much more drivable and is an easy way to allow a longer period cam without throwing away driveability ".I have been building English engines for a long time. In recent years there has been a shift to short duration high lift cams. Yep, high valve acceleration rates but revs held to 5000 or less.

Have you read any about a second compression ring gap 50 percent larger than the first ring gap produces more HP? Thanks for your input. I have no plans for a super charger make my HP on motor. Steve
I recall Bill Jenkins who proposed a tighter second ring gap on the 350 Chevy engine. It was later to be discovered that by widening the second ring gap, the top-ring seal is enhanced with minimal pressure present underneath the top ring.
I'm not certain on an engine of minimal hp, that it would make that much difference. I'd rather have a good oil seal.

At any rate, the cam in my 5.9 is at 112 lsa. It is ground w 4* advance. I've given away some bottom end torque. My compression is at 9.5. I have 3.90's gear set. The 5.9's produce the most hp on a 108 lsa.
There is a guy I know who built his 408 on a 114 lsa with 227-236 duration @ .50 and .567 lift. Not a big cam at all for a 408 stroker. He had his cam custom ground from Comp after he made the mistake of mentioning to them that he was thinking of super charging it later.. His compression is 9.3. His truck is an absolute dog until 3000 rpm. So much so he wants to rip out the cam. In my mind he needed at least 10 or 10.5 cr to substantiate that cam as his engine is simply not creating the low end velocity his truck needs even with the added cubes.
Yes, there is less overlap and yes, it makes for a smoother overall driving experience but I split the difference between a 110-114 lsa and I'm happy with it.
The LS Chevy engines have come in with cams of 116-119 lsa. Their heads breathe like we the people. Plenty of bottom end air flow.
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #52 ·
There are a number of factors involved in selection of cam center line angle, bore to stroke ratio, valve size, rod length to stroke ratio, port velocity and low lift valve flow. As we all know there is a very limited market for 3.9 V6 performance parts. I need to call the supplier to check on back ordered spring kit. I'll ask a few more questions about this cam. You are comparing larger longer stroke engines and are they running on the factory ECU? If I had something like a rat rooster intake and could run 13 to 1 and have a Cam 2 pump in the back yard we'd see what she could make. Trying to think out of the box but color between the lines. I stopped by the machine shop yesterday it seems everyone is busy but my parts were no longer in the drop off area. rather than pull anyone off a machine I waved and left. Rings have still yet to be made so the build slows. Steve
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #54 ·
Don't worry I used a red grease to seal the clear plate. After wire brushing the chamber I CC ed one chamber to see where we are on C/R. I have found a number of references that have the chamber at 52 CC s. I also see the C/R listed at 9 to 1. My checking leads me to think neither of those figures is correct. It's clear you can not assume anything and have to measure and check everything that is why they call it blueprinting. Steve
 

·
Registered
Joined
·
123 Posts
There are a number of factors involved in selection of cam center line angle, bore to stroke ratio, valve size, rod length to stroke ratio, port velocity and low lift valve flow. As we all know there is a very limited market for 3.9 V6 performance parts. I need to call the supplier to check on back ordered spring kit. I'll ask a few more questions about this cam. You are comparing larger longer stroke engines and are they running on the factory ECU? If I had something like a rat rooster intake and could run 13 to 1 and have a Cam 2 pump in the back yard we'd see what she could make. Trying to think out of the box but color between the lines. I stopped by the machine shop yesterday it seems everyone is busy but my parts were no longer in the drop off area. rather than pull anyone off a machine I waved and left. Rings have still yet to be made so the build slows. Steve
Yes but the truck is not tuned as yet. And his exhaust is quite stifled. His truck may just be constipated.
These trucks are heavy. I would be looking for as much bottom end torque as I could get. A tighter lsa puts the power band lower. You could easily do 112 and not be too compromised.
That's what I put in my 95 DaK with the 318.
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #58 ·
I was busy with other projects yesterday and failed to call for additional info on cam. I may have mentioned on another thread that I was told I was purchasing the very last cam of this type. I was also told due to no demand they would not be having any more made. Looking this morning I noticed it has been removed from their on line catalog. Good bad or other wise this is the one we will use. I did notice they list their 108 degree cam as best for supercharge / turbo. Steve
 

·
Registered
Joined
·
235 Posts
Discussion Starter · #60 ·
While I haven't quite finished cleaning up the outer crust I have done a little port work. I think the exhaust are fine at the face. If you look down the exhaust ports you can see though and out the vale seat area. I'll get all I feel comfortable with and figure that's good. A call from a couple of machine shops would be welcome come monday morning. Steve
 
41 - 60 of 113 Posts
Top