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Post by sobeit on Aug 17, 2008 9:58:51 GMT -5
so this one is probably for fields i think you could use the chevette rocker and a solid adjustable lifter to correct the valve train on the pontiac swap, or just use the sunbird rockers and take off material between the mating surfaces. i tried the chevette carrier w/ cam today on the sunbird head, the sun bird rockers werent tall enough to reach the cam. you would probably have to machine some off the carrier and the top of the head. there was about a little more than 1/8 of an inch between the cam and rocker using the sunbird rockers. the chevettes are taller and a little longer, the gap between these i would have to use a feeler or something to measure b/c i couldnt see. i have some pics. CHEVETTE ROCKER SUNBIRD ROCKER CHEVETTE ROCKER CORRECTION SUNBIRD ROCKER CORRECTION CHEVETTE ROCKER LENGTH SUNBIRD ROCKER LENGTH
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Post by hydroli on Aug 17, 2008 11:15:32 GMT -5
One thing is that the chevette rockers are longer. Another one is that taking the gap with the lifters without giving the same correction to the valve stem would change alot of things on how the cam works. If I go with the mechanical lifters it's essentially because I cancel the oil passages in the sunbird head, so no possibility for hydraulic ones. The cam configuration has to be similar to the stock chevette valve train, though there is differences... I can't solve the valve train problem cause I have to measure the exact position of each components. Unfortunately I won't have access to a height gauge and dead flat stone until two weeks maybe. But still, on the sunbird head: valves are closer to the lifters by roughly .200" and more distant to each other in a longitudinal way or in front to rear direction; distance between intake and exhaust valves of same chamber. Also, cam position has to be verified so it's clear that its center is lined correctly with the sunbird cam followers. Valve train configuration: Valve to lifter distance may not be such a problem, if, they are both closer to the center in the same rate, meaning it keeps the same ratio (distance from lifter to cam, to distance from cam to valve) and if the radius on which the cam touch is greater, respectively to the greater levering angle of the shorter rocker. If there's a cam alignment issue, there's a big problem... no solution other than machining the cam journals and putting in brass bushings to correct the alignment... I hope it's at the right place where it is. The other kind of configuration problems with the use of a chevette carrier on a sunbird head is lobe to cam follower alignment and it is a concern for longevity if the rocker touches one side of the cam lobe more than the other. It can be corrected by narrowing it, grinding the rocker both sides to make a stable touching surface. I tried to explain what I understud but I may be wrong on something, I can't tell for now, only time and right tools can help me figuring out any posible issue. Next week maybe...
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Post by DOCTOR FIELDS on Aug 17, 2008 13:52:12 GMT -5
It's been 4 years since i did the exact same thing you're doing now, i have very similar pictures. If i remember correctly, i think the Sunbird cam and carrier would be the best way to go. That way you have no problem with the cam being offset and no corrections to the valve train geometry is required. We wanted to try the Chevette carrier for visual purposes. In other words, so it didn't look obvious we had a different head. Money ran thin, racing died out, so we never finished the project. Here's a website i found back in 2004 that carries aftermarket parts (inlcuding cams / degree pullies) for the Sunbird. Go www.mantapart.com then click on Engine Parts. The Sunbird engine is the 8th one down on the engine page. Click on the 1.6/1.8/2.0 OHC 4 Cylinder link and it takes you to a page with a list of aftermarket parts for the Sunbird.
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Post by hydroli on Aug 17, 2008 14:13:20 GMT -5
I mentioned the cam alignment to stay conservative and try to point out every possible problem. I didn't verified.
Are you saying IT IS offset?
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Post by hydroli on Aug 17, 2008 14:31:12 GMT -5
Great website, these are rare racing parts.
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Post by DOCTOR FIELDS on Aug 17, 2008 15:22:42 GMT -5
What i was refering to was the cam lobe centerline compared to the centerline of the rocker arm. As you could tell when you put the cam carrier assembly on, the lobe was not in the centerline of the rocker. If you use the Sunbird cam carrier and buy an aftermarket cam and valvetrain from Manta Part, then you can eliminate the use of the Chevette carrier. That seems to be the most logical way to me anyways.
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Post by hydroli on Aug 17, 2008 15:56:27 GMT -5
Ok, I'll considere this option. Thanks for the help.
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Post by sobeit on Aug 17, 2008 17:57:45 GMT -5
if i go this way the water output will be on front of engine and intake will be on passenger and exhaust on driver side which shouldnt be a problem, i have the whole head unit minus the intake and exhaust. modding an exhaust will be easier than the valve train. i was looking for various ways to do this. i need the timing gear tho prolly 5 bucks or so. hey hydroli the yard i got my rocker from has the water neck or w/e its called and the cam w/ carrier. u would only need rockers which autozone has em for like $3 usd each i think i have like 4 or 5 sunbird extra rockers.
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Post by DOCTOR FIELDS on Aug 17, 2008 18:43:59 GMT -5
The head is mounted backwards on the Pontiac engine, but when you modify it to fit a Chevette, you turn it around just like the Chevette head is. Exhaust on the passenger side Intake on the drivers side.
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Post by sobeit on Aug 17, 2008 18:58:39 GMT -5
if i do it this way with the sunbird carrier and cam the lobes would be backwards. ex turning the chevette head on block w/o moving carrier and cam.
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Post by DOCTOR FIELDS on Aug 17, 2008 19:22:06 GMT -5
You still have to mount it just like the Chevette, so modifications will have to be done either way.. i had forgot that the cam carrier was backwards too..
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Post by hydroli on Aug 17, 2008 19:25:23 GMT -5
I really want to go with the chevette cam carrier. I found, like you did sobeit, that the rockers don't touch the cam lobe all its width. There's a .08" slice that don't touch to the cam lobe on the intake side. The exhaust side has its edge just lined with the edge of the exhaust lobe. I could modify the "C" clamp that centers the cam with a .040 offset so I would have to remove only .040" on each side of both rockers instead of removing .08" on each sides of the intake rocker. I don't know how is made the sunbird rocker. It will be less to remove if the rocker is narrower. I really want it to looks like a stock engine...
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Post by sobeit on Aug 17, 2008 19:36:33 GMT -5
it could be easily done with the sunbird cam and carrier but you would have to mod the exhaust and throttle cable which shouldnt be too hard, it would look real sharp with the 2.0 aluminum valve cover and carrier b/c you could paint it and all, plus you know everything would be right, yea i would like it to look stock too but hey i have no reason for it to look stock. like i said hydroli you can have some material removed from the head and a little from the chevette carrier and use sunbird rockers and should work fine. better to remove less and have more taken off after you figure out your measurements. at least i would believe this would work. havent been around engines long enough and havent modded a chevette yet. i have just did work to mine(still stock) you know carb timing ect.
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Post by hydroli on Aug 17, 2008 19:56:03 GMT -5
I sent an offer to an ebay seller last week for the sunbird rockers you've pointed out for me sobeit. I hope it lines up right.
I have a machinist formation so modifications doesn't affraid me if you care. Other than this, I'll work alot in the following days so I'll miss time to work on this project.
I whish you both a good week.
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Post by sobeit on Aug 17, 2008 20:53:53 GMT -5
i am going to make my own intake manifold and bolt a holley 500 to it, idk bout turbo yet
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