Whats the differences in the cams between the 91-6 bolt and the 93-7 bolt blocks? I did a head for a friend and we used the 91 head on the 93 bglock. I would of changed the cams also when I did the head, but the cams were "beat" out of the 93!
Steve.
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Originally posted by fivestardsm Whats the differences in the cams between the 91-6 bolt and the 93-7 bolt blocks? I did a head for a friend and we used the 91 head on the 93 bglock. I would of changed the cams also when I did the head, but the cams were "beat" out of the 93!
Steve.
91-94 cams are all the same for 5sp, turbo cars. AT's used different cams (at least one of them was NT speck, as I recall).
So as long as both engines were 5sp and turbo, you are all set.
actually the 93-94 cams have a slightly higher lift..(someone did a test)..but it is a minor detail..so basically all 1g m/t cams are the same profile, more or less.
According to the service manuals I have the 90-92 4g63s all had the same cams. 1993 and later cars were as follows.
90-92
intake 1.3974 lobe height
exhaust 1.3777
Intake cams
NT & Turbo w/manual trans 1.3974 lobe height
Turbo w/ auto trans 1.3858
Exhaust cams
NT & turbo with auto trans 1.3858 lobe height
Turbo with manual trans 1.3974
Since we know that all year's cams were ground on the same base circle
one can conclude that there was at least some changes in maxinum lift, based on this data. One could conclude that the most desirable choice would be an intake cam from a manual trans car, and a exhaust cam from a 93 and later turbo manual car. This is interesting since mitsubishi listed a BHP change in the turbo cars between 92 and 93 of 190 to 195 respectivly.
on early dsms, you may not find letters stamped on the cams, toward #1 cylinder, but if you do see them it goes like this:
intake: ID mark A,D: 1.3972-1.4138
intake: ID mark B,C,E,F:1.3858-1.3661
exhaust ID mark A:1.3858-1.3661
exhaust ID mark C:1.3972-1.3776
exhaust ID mark E,F:1.3744-1.3547
[QUOTE]Originally posted by Big Woo
[B]According to the service manuals I have the 90-92 4g63s all had the same cams. 1993 and later cars were as follows.
Hi BigWoo and Insane147:
Did your manuals give overlap degrees for each year?
For the less informed it should be noted that maximum lift is not always the answer to more H.P. Once you get off the quieting ramp many things can happen to affect performance. This is also material on how much overlap, where you want the torque range to reside, fuel economy, turbo boost, air columns in motion, ignition timing including advance or retard etc., are all key factors.
The quieting ramp is that portion of the cam grind which looks to be flat as it approaches the lift, in fact it is not flat for it has a slight arc to prepare the valve for opening. It does this for some 30 or more degrees just to close the designated clearances in a gradual manner before it accelerates the valve opening. If you didn't have this ramp you get noisy valves and perhaps more serious is valve float. I've deliberately induced valve float by increasing the valve lash, in effect the cam follower no longer sees the ramp at all, instead it hits the lift with such force that it throws (accelerates) the valve up so fast the spring doesn't force it to follow the top of the lobe and thus you have more opening at higher RPM. What you must know is where the piston is so you don't foul the valves on a hemi. or inclined valve design, this is where having vernier cam gear makes a lot of sense so you can play with the overlap.
being dohc with a belt, the overlap can vary because the intake and exhaust is independant of the other, so milling the head / block or a stretched belt can toss the figures off. my book does not tell me duration or overlap, but i think im going to get my dial indicator and cam wheel out to see.
"my book does not tell me duration or overlap, but i think im going to get my dial indicator and cam wheel out to see. [/B]
"
That would be useful info, best done if you have a complete assembled spare head and some means of keeping oil pressure feed. Another useful measurement can be taken on an assembled engine with a second dial indicator and a long extension through the spark plug hole to the piston top to record piston travel and cam timing relationships.
While thinking about it, I used a 1/4" drill and a socket to spin the oil pump/ balance shaft sprocket to prime the oil gallery and hydraulic lash after the head was torqued and cams in place. Use assembly lube or white grease on cam bearings without cam followers, throw a rag over everything unless you don't mind oil everywhere. This fills any collapsed lifter which I realize some books say not to worry; however; with our experince of cam followers falling off and bending valves this was not an option.
It should be noted on my son's TSi that the piston eyebrows were not correctly placed and the intake valves fouled the tops. Some of the resultant damage could have been averted had they just used modeling clay and pulled the engine through a couple of revolutions when they selected the lowest possible bidder for pistons. Argh!!
As an aside, I had read that the head was designed by Coventry Climax, can anyone confirm this?? It does resemble a redesigned upgrade to the Lotus twin cam of some years back. Those engines use a domed slipper piston with significant valve cutouts and a steel skirt insert to control piston expansion. Wonder if the pistons are interchangeable, Heppolite(sp?) made a decent after-market racing piston which could be substituted for production engines but needed high octane or aviation gas.
why would i need to supply oil pressure? i was just going to give readings from the cams base circle on. i would do it with a crank degree wheel and a dial indicator for each cam. every degree you move the crank, write down the results and by the time you get done with 720 degrees of rotation you should have all the numbers you need to graph out the entire valve train operation..
Of the manual's I have on DSM's Haynes, Chilton's, 1990 Eagle talon factory service manual, and a 1993 Mitsubishi service manual, none list the number of overlap degrees. This makes since, since factory/ dealership/ home mechanic repair work will not require such information.
Checking it is not hard but you do need to have the necessary equiptment for degreeing a camshaft. Degree wheel, pointer, TDC stop, dail indicator with mount, for DOHC motoes its nice to have two or four so you can watch intake and exhaust simultaneously. Four can be helpful if the cams your using do not open and close the two intake or exhaust valves at the same time. Some start one a few degrees ahead of the other to promote swirl. Something else that is handy is a four inch travel dial indicator so that you can map piston posistion in relationship to cam timing.
I could dig up some of the overlap numbers from the cams I have degreed in. I have some info on HKS, WEB, Crower, and Reed cams, but I have never taken the time to do the stock cams. That may be a good winter project, I will post the results after new years.
Originally posted by Big Woo Of the manual's I have
...
" none list the number of overlap degrees. This makes since, since factory/ dealership/ home mechanic repair work will not require such information."
That's no real surprise, it's the trend to include 10 pages of how to remove a door panel that just thrill me to pieces instead of a 1/2 page graph.
...
"Four can be helpful if the cams your using do not open and close the two intake or exhaust valves at the same time. Some start one a few degrees ahead of the other to promote swirl. Something else that is handy is a four inch travel dial indicator so that you can map piston position in relationship to cam timing."
I've never used four, (probably because I never owned that many at the same time (hehehe). Two has worked best but even one will work ok, just requires more paper and repeating the procedure which isn't so bad when checking for repeat accuracy of recording the data. I've used 1/4" wooden dowels to substitute the 4" extensions and actually prefer them, the length isn't critical, patience is when chasing pistons. I'm not fond of poking anything metallic down a spark plug hole with inclined valves for fear of something getting bent.
...
"I could dig up some of the overlap numbers from the cams I have degreed in. I have some info on HKS, WEB, Crower, and Reed cams, but I have never taken the time to do the stock cams. That may be a good winter project, I will post the results after new years.
I hope this helps
"
That would be useful for even with stock grind relocating cam opening and closing could improve performance especially when operating at higher RPMs.
.........................
insane147:
The only reason for having pressurized the oil system besides the obvious lube would be if you are trying to determine where the piston is in relationship to the valve opening. Since you have no adjustment available to the cam follower which is ascribing a slight arc, having it reflect running position when chasing pistons is necessary. This is not to say you can't temporarily shim the top of the valve to keep the follower in the approximate position, all this is _only_ necessary if you want to know the relationship between valve and piston _IF_ you are going to play with the cam timing. It's all useless info if you are building a stock engine and never get close to redline, tweak the ignition timing, spark plug gap or torque, etc. for performance. To perform these checks you don't need to use a new head gasket or torque to specs for you can even assemble without and then know you will have a bit more clearance as a safety factor. All this can be done with just one 1" throw dial indicator and 10¢ 180º protractor projected on a piece of 10" cardboard cut round with a hole in the center. (necessity is the mother of invention)
Just sanding new valve stems with #800 paper parallel will get you 200-600 rpm when running knurled guides (less friction) before float occurs. Adding a reverse helix valve spring will greatly reduce spring bounce harmonics and valve float rather than a single heavier spring. I've not followed racing rules for many years so don't know what's permissible if class racing is your thing, but if you enjoy tweaking things for cost effective performance then having a good grasp of where to look for reliability vs performance it then becomes critical to have the info available. I don't recommend playing around with some mom's, housewife's or girlfriend's engine for hard starting, rough idle, poor stop light acceleration may suffer if not prepared to kick the rpms up which is especially true with an automatic and playing stop light grand prix.
ah, i see where your coming from, i was just interested in taking it from the cam lobe, but the valve would definately be the best place as you put.
on the side here, have any vendors or tuners played with degreeing their cams? if so, what were the ranges you got? what cams and piston combo do you have also, thats very important, from the intake and exhaust valve also as they are different sizes and have different clearance issues?
Originally posted by Big Woo Of the manual's I have on DSM's Haynes, Chilton's, 1990 Eagle talon factory service manual, and a 1993 Mitsubishi service manual, none list the number of overlap degrees. This makes since, since factory/ dealership/ home mechanic repair work will not require such information.
Maybe I don't know what I'm doing but it seems that you can calculate the overlap by simply looking at when the intake opens and when the exhaust closes.
Based on what I can tell from the service manual the 1G 2.0L cams differ as follows: (specifications pages, timing is in one place, lobe height in another)
Intake NT opens 26 BTDC close 46 ABDC lobe height 35.493 (34.993 limit)
Intake MT opens 21 BTDC close 51 ABDC lobe height 35.493 (34.993 limit)
Intake AT opens 21 BTDC close 51 ABDC lobe height 35.200 (34.700 limit)
Exhaust NT opens 55 BBDC close ATDC 9 lobe height 35.200 (34.700 limit)
Exhaust AT opens 55 BBDC close ATDC 9 lobe height 35.200 (34.700 limit)
Exhaust MT opens 55 BBDC close ATDC 9 lobe height 35.493 (34.993 limit)
From this I come up with the NT intake cam being 252 duration, the turbo intake at 257 and a duration of 244 for the exhaust. NT has 35 degrees overlap (26BTDC + 9ATDC) and turbos have 30 (21+9). These are seat timings. From the point where the valve first starts to move.
Is my math correct?
Steve
Last edited by steve; 06-23-2005 at 01:15 PM.
Reason: Correct terms
[QUOTE]Originally posted by steve
[B]Maybe I don't know what I'm doing but it seems that you can calculate the overlap by simply looking at when the intake opens and when the exhaust closes.
Yeah Steve:
Ya could have fooled me!!! Do correct any typos or math but yes this was what I was looking for.
...
" From this I come up with the NT intake cam being 252 duration, the turbo intake at 257 and a duration of 244 for the exhaust. NT has 37 degrees overlap (26BTDC + 9ATDC) and turbos have 30 (21+9)."
As has been discussed elsewhere in this forum air flow (gas) is crucial and my experiences are with natural aspirated tuned intake engines. I would take a long look at a cam setting of 33º if pistons will permit.
..............
I think it was insane47 that posted a good bit of info including math on sonic waves inside the engine. With exhaust gasses flowing at supersonic speeds it may mean nothing until you consider the shock wave generated by a jet plane flying overhead that will knock your socks off, rattle windows 5 miles away and every motion detector alarm system 3 levels down in a subterranian garage.
I think I saw some company selling a nice set of vernier cam gears for $135, so without investing in aftermarket cam grinds you can pop these jobbies on and play to your heart's content. Then when you have satisifed you are getting everything consider a different grind and start all over with the verniers.
BTW it is possible to pull the exhaust cam off by removing the P/S belt, removing upper side cover bolts and driving a wooden wedge on top of the tensioner to keep it from slipping. Not tried the intake yet...
damn, wish i remembered the days when planes flew supersonic over houses... i always wanted to hear/see that.
the NT has 35 degrees overlap...everything else looked right. if you increase the overlap to 33 how luch will you suffer from reversion. the main reason they try to limit the overlap is so the high turbo backpressure does not blow the intake charge back up the intake.....then again if your going all out, want top end and have a really well flowing manifold and turbo this would be a good move...btw, thanks for the cam numbers and math.
Originally posted by insane147 damn, wish i remembered the days when planes flew supersonic over houses... i always wanted to hear/see that.
We only get it once in a great while from the space Shuttle landing at Edwards AFB when weather is bad back east. There are actually 2 shock waves produced, from the nose and the 1/4 wave aft which because of the speed is a full second later. .........
I understand some of the rational behind intake plenum designs but see some very pretty polished stainless exhaust manifolds which have made no attempt to utilize sequence or even displacement.
This sort of takes the design beyond the home garage design bundle of snakes when trying to project how a paticular size and length will behave if you are looking for those shock waves for an additional push. What then happens to the down stream turbo??
if you made runners and primaries the proper length for say a 7500rpm+ target, you may have weak low band power and then a sudden wooosh of power, light bulb on off type thing. all types of racing use long exhaust primaries, look at the lemans cars for example, works of art in stainless steel. much the same as a race preped motorcycle, you get the power where you need it, dont worry about the low end cause you didnt design it for that purpose. as an avid race fan and driver, i would love to drive a car like this (i do) and have fun, but it is such a pain to get around in traffic with an ill mannered vehicle that draws attention (the wrong kind mostly) because you just cant drive it in its sweet spot on the public roads....
GTM Good idea with the protractor and cardboard. Makes more sence for the do it yourselfer. And yes it can all be done with a single dial indicator just more time consuming.
Steve yes you can figure overlap with the opening and closing time numbers. I guess I overlooked that page in the book.
It would be difficult to sugest a specific overlap duration, without alot of additional information. Idealy it should increase with RPM. If you have dataloging capibilites plumbing an additional 3-bar MAP sensor into the exhaust manifold will allow you to map exhaust manifold pressure, vs RPM, throttle posistion, and boost. I have a set up like this on my 93 and am using the AEM EMS for logging.
I would suggest that one should check the cam posistions before moving them. I have found variences of up to 9 degrees on cam posistion, and yes all the timing marks were lined up correctly. This simply comes down to production tollerences. If you think about it there are many variables that can effect final cam posistion. Such as dowel pin posistion, woodruf key posistion, orientation of crank gear teeth to wooruf key groove, orientation of cam gear teeth to dowel pin posistion, ect, ect.. Anyway you get the idea, some typical production tollernces are +,-.005 on three place decimals, +,-.5 degrees on most angles. Then if you think about how many differnt parts make up the entire cam timing system it is easy to see why actual posistion will vary.
Also there are some other tricks that can be used to move camshaft posistion. Offset keys on the crank gear (moves both intake and exhaust in same direction), Offset dowel pins can be made for the camshaft, and the Small block chevy offset bushings can be modified along with the cam gears to move the intake and exhaust cams seperatly up to + or -8 degrees. Just some more food for thought.
[QUOTE]Originally posted by Big Woo
[B]GTM Good idea with the protractor and cardboard. Makes more sence for the do it yourselfer. And yes it can all be done with a single dial indicator just more time consuming.
.......
I've used gift boxes type cardboard for making degree wheels and gaskets, they hold up to compression and the slick side can be wiped clean. Using a Xacto knife you can scribe lines which then can be highlighted with fine marking pen but grease and oil can wipe off. I suggested 10" only for accuracy if you are splitting hairs, you don't even have to bolt them on for I've used masking tape. It's not even necessary to set them to "0", just be able to add and subtract.
Like doing anything else for the first time it will be involved until everything falls into place. Most important when working with variable cams is the ability to _repeat_ with certainties you have obtained the correct result. Thus there can be no hurry to get the process over with for that's when errors will be introduced which can spell disaster. I can't talk and dial an engine, brain just doesn't allow doing both no matter how many times I've been there. Nor do I recommend everyone consider an attempt, some people just can't work that careful and even changing a spark plug may tax their abilities.
" I overlooked that page in the book. "
Wazzat, ... book!! Ya got to be able to read too, hmmmm nobody told me tat.
"It would be difficult to sugest a specific overlap duration, without alot of additional information. "
This is true, yet the factory gave us numbers which were calculated for the average driver for X performance conditions. A cam grinder recommends a "street" grind which he knows will be less conservative and yield better performance. My point is knowing some sort of ball park number besides 0º overlap @ TDC gives a reference of where to start looking. Suffice to say, 50º overlap with an idle of 1500-1800 RPM is probably not what most people would consider acceptable but the engine would run.
"Idealy it should increase with RPM. If you have dataloging capibilites plumbing an additional 3-bar MAP sensor into the exhaust manifold will allow you to map exhaust manifold pressure, vs RPM, throttle posistion, and boost."
Brings me to another question: Does anyone know what the voltage output is for the data logger?? .01, .1, 1.0v??
"I would suggest that one should check the cam posistions before moving them."
Absolutely, unless it's broken then back to the book for starting reference.
" I have found variences of up to 9 degrees on cam posistion, and yes all the timing marks were lined up correctly. This simply comes down to production tollerences."
Are you talking specifically about these engines for that is a huge number for a production engine?? I've seen my share of factory screwups by people who knew the difference yet sent it out the door without a QC recheck tag.
One more memorable was a threaded 3/4" casting plug in the plenum, either the threaded plug was undersize or the hole was too large. Factory solution was screw another plug in the hole and leave the old piece to rattle around. After 2K it finally wore down enough to lodge under a valve which fortunately only bent. You would have thought it was an "international incident", never saw so many suit and ties speaking foreign languages hovering over that engine.
"Offset dowel pins can be made for the camshaft"
...
Lancia used camshaft with something like 12 holes and cam gear with 13, which would give 2º increments if memory serves.
GTM don't know about the data logger, but the EMS will allow mapping of any auxiliary analog input so long as it is scaled correctly. 0-5v if memory serves.
I think that the furthest I've seen a 4G63 off cam timing wise is 6 degrees. I believe the 9 degrees off was on a olds 2.3l quad4 back in 89 or 90, when I was involved in their showroom stock, and firehawk programs.
Slient2g I think if you look closer you will find that the 93 and 94 turbo 5-speed cars had slightly more exhaust cam. 90-92 turbo 5-speeds were the same. Since all of the cams were ground on the same diameter base circle having a slightly larger lobe height sugests that at least the maximum lift is greater on these cams. When I get home I will look at the opening and closing times (I have to remember to read ) to see if there is a duration change as well.
[QUOTE]Originally posted by Big Woo
[B]GTM don't know about the data logger, but the EMS will allow mapping of any auxiliary analog input so long as it is scaled correctly. 0-5v if memory serves.
Thanks Big Woo, was looking at a single pen chart recorder on eBay which went from .0001 to 1.0 v. on the input but don't want to get involved with dropping resistors. Besides the seller didn't answer email on shipping weight costs so it closed for $15.50 without my bid. I have a dual trace osciliscope which if I can find the pin-outs will give me some readings. Know anyone who has made their own harness connector??
"
I think that the furthest I've seen a 4G63 off cam timing wise is 6 degrees."
I've still not counted sprocket teeth but that might be fixable just by jumping a belt notch.
"
I believe the 9 degrees off was on a olds 2.3l quad4 back in 89 or 90, when I was involved in their showroom stock, and firehawk programs."
You start talking big Detroit iron and I'll be lost. If memory serves on a block mounted cam you couldn't hope to move the chain that small an incriment?? Do you remember the eventual fix?
...............
Almost have my son's Talon running, actually did but leaked oil at the turbo oil supply fitting on the head. Bummer for once everything was repaired or replaced and set right it started within 2 seconds and purred like a kitten on fast idle. Looks like I'll have to make some substitute fitting from a hose barb and cut the banjo off the line.
"For some reason my cams have a R8 number on them. I belive they came from a 1990 Galant j spec.
The new exhuast cam I got in with my head say R8. I double checked them one is a b and one is an 8. Which one is better?"
are you sure your looking at the right area....the end towards the cam wheels, not the cas sensor. my 1990 talon engine and my jspec engine both have no marking...i think this was because there was only one set of cams for them in the early part of production. i started seeing the I.D. marks in engines after 1991
GTM I have modified pin out locations on the factory connectors, and of course tapped into certain signals. ON the other hand though I do have several sets of the factory ecu connectors, if your interested no charge, just e-mail me an address or something. You can then pull the connectors from the holder and replace the wire or move it to a differnt location.
The quad 4 is a DOHC 4 cyl that uses a chain to drive the cams. This was part of Oldsmobile's IMSA road racing program, so the ultimate fix was unique. We made a set of custom adjustable cam gears. Most cam in block V-8s can have the cam timing changed +,- 8 degrees by using offset dowels, bushings, or keyways. Not difficult just more time consuming than adjusting gear rotation.
Sound like you may just need to replace the copper crush washers on the oil supply line.
Originally posted by GTM Almost have my son's Talon running, actually did but leaked oil at the turbo oil supply fitting on the head. Bummer for once everything was repaired or replaced and set right it started within 2 seconds and purred like a kitten on fast idle. Looks like I'll have to make some substitute fitting from a hose barb and cut the banjo off the line.
Road Race Engineering has a nice replacement oil feed line kit for $55 and their close to you. It picks up the oil from the filter housing and come with a new bolt and washers to plug the head outlet. Really nice folks.
Originally posted by steve Road Race Engineering has a nice replacement oil feed line kit for $55 and their close to you. It picks up the oil from the filter housing and come with a new bolt and washers to plug the head outlet. Really nice folks.
Many thanks Steve, that was a winner. Old pipe is out, braided hose, oil filter mount plug removed using 1/2" drive 2' breaker bar, elbow fitting required removing oil pressure sender, loosing alternator and swing it up. The supplied plug for the head wasn't long enough to really pick up any new threads but I was able to substitute a small "O" ring for the copper washer. I'll eventually pull it back out and add a few drops of Devcon epoxy aluminum and never worry about it.
It runs!!! Smoke is 25% of original once run for a while, none at start again unlike before. It continues to drip oil / antifreeze/ water out the exhaust which requires a plastic dish pan, the initial throttle blips sent this liquid emulsion about 8' down the drive. More problems have now been revealed, temp gauge in-op as is the radiator fan, pulled electrical plug on top of thermostat housing (temp sensor / fan switch relay???) and probed both wires with test light to find no voltage and gauge did not move. Looks like book time to circuit trace those items, any good location for a bypass fan switch?? Until I get the fan operational, the broken solenoid nipple which mounts on top of the air cleaner(??) repaired can't really road test and blow / burn the crud out the exhaust system. Oh, got a water leak at boiling point under P/S pump, hope it's just the hose and not the W/P. And find my timing light to set the timing... just guessed at it from previous nut settings. If anyone can identify from memory those items and easy tests / repairs it will save some time pawing over the wiring charts.
In neutral and revving the engine, the most boost on the factory gauge was about +1 psi, idle is about -3.5 psi and drops to -7 > on slamming throttle shut.
I could have made that oil line assembly but just opted for the shelf item and the 44 mile round trip on the '83 Venture. It will be interesting to see if this thing can keep up with my bike. Again Steve, thanks for URL referral, hope I can return the favor.
