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Old 06-07-2017, 11:30 AM   #1
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87 lg4 cam swap questions

Hey guys I'm looking to do a budget cam install on an 87 lg4 305 non cc carbed. Ive been reading about options on this site but was unable to answer some of my questions regarding by specific application.

It looks like a stock lt1 cam is my best bet for the money?
Is it recommended to replace the springs? Do I need new push rods? What else would I need to complete the job?

Right now I've got an edelbrock carb, intake, shorty headers and true duals all the way back, no cats. Was about to pull the trigger on a comp kit that came with springs, seals and a timing set and then I found out I needed rods too. It was getting expensive quick. Hopefully someone with more knowledge than me can give me some advice. Just want to get the right stuff and I'm a little intimidated by all the different options.
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Old 06-07-2017, 06:31 PM   #2
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Re: 87 lg4 cam swap questions

Ok upon further research I think I've answered a lot of my questions. My 87 LG4 has a roller hydraulic set up so I can reuse lifters and pushrods, but I should get a new timing set, springs and valve seals. Correct me if I'm wrong here, and is there anything I'm leaving out (besides gaskets and assembly lube)

If I do go with a stock LT1 cam can I expect a noticeable mid to top range performance increase? What year model LT1 specifically do I need for a smooth install?
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Old 06-07-2017, 07:24 PM   #3
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Re: 87 lg4 cam swap questions

might want to confirm that you have the hydraulic roller - 87 was that pain in the **** year where "anything goes" was the credo Chevy lived by. My 87 LG4 by all accounts should have been a roller - it was not.
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Old 06-07-2017, 09:31 PM   #4
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Re: 87 lg4 cam swap questions

The following link is to a video and write up on my 85 Z28 LG4; https://youtu.be/Fle9A6RC1E8

Good Luck
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Old 06-08-2017, 05:07 AM   #5
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Re: 87 lg4 cam swap questions

Thanks for the responses guys. That 85 is very nice.
So it looks like I need to pull the intake to find out? If it does happen to be a roller is the lt1 cam a good choice? Could someone help me with some options?
I can probably have the intake off tomorrow afternoon so it would be cool to get some parts ordered right away
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Old 06-08-2017, 06:29 AM   #6
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Re: 87 lg4 cam swap questions

There are better choices than an LT1 cam. It's a wide LSA cam with a delayed ICL that will be a bit short on torque in the low/mid range compared to a better cam.
What are some of the vehicle specifics? ..... trans type, gearing, weight, goals/intended use.
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Old 06-08-2017, 07:21 AM   #7
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Re: 87 lg4 cam swap questions

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Originally Posted by baker440ex View Post
Thanks for the responses guys. That 85 is very nice.
So it looks like I need to pull the intake to find out? If it does happen to be a roller is the lt1 cam a good choice? Could someone help me with some options?
I can probably have the intake off tomorrow afternoon so it would be cool to get some parts ordered right away
The casting numbers on your block might be a good place to start with?

Good Luck
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Old 06-08-2017, 08:01 AM   #8
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Re: 87 lg4 cam swap questions

Thanks for the responses.

Intended use is street machine with power on a budget. Emissions aren't an issue and I don't race. Just the best seat of you pants performance upgrade i can get without sinking a grand into a 305 with 80k on the odometer.

Will the casting numbers identify whats inside? I certainly would like to have everything in hand before a rear down but definitely don't want to order the wrong stuff
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Old 06-08-2017, 08:04 AM   #9
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Re: 87 lg4 cam swap questions

Trans is 700r stock converter, gears are 3.27 limited, weight unknown, driven not far from home on weekends only
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Old 06-08-2017, 08:08 AM   #10
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Re: 87 lg4 cam swap questions

You could pull a pushrod and measure the length to determine if it's roller or flat tappet.
Flat tappet will have about a 7.8" pushrod. Roller about a half inch shorter.
As zed said above, looking at casting numbers won't tell the story.
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Old 06-08-2017, 11:00 AM   #11
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Re: 87 lg4 cam swap questions

I'll pull a rod out when I get home and post the results tonight.
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Old 06-08-2017, 01:15 PM   #12
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Re: 87 lg4 cam swap questions

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You could pull a pushrod and measure the length to determine if it's roller or flat tappet.
Flat tappet will have about a 7.8" pushrod. Roller about a half inch shorter.
As zed said above, looking at casting numbers won't tell the story.
Don't know about the LG4. I know that trucks after about 89 got the roller block but with a flat tappet cam stuffed in. Switching to roller is easy since all the factory roller stuff bolts right up. Need to find the spider lifter retainer and dog bones from an engine recycler, along with cam retainer. Then get the lifters and correct length pushrods. The blocks were already machined for the anti-rotators, retainer and cam retainer.
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Old 06-08-2017, 01:23 PM   #13
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Re: 87 lg4 cam swap questions

It won't let me copy and paste, but if you go to the GM Heritage site and click information kits and '87 Camaro, GM lists the '87 LG4 as a roller cam.
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Old 06-08-2017, 01:34 PM   #14
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Re: 87 lg4 cam swap questions

I like the suggestion of pulling a valve cover to take a look. Sounds like a good way to save alot of wasted time and expense.
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Old 06-08-2017, 05:19 PM   #15
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Re: 87 lg4 cam swap questions

Rod measures 7 3/16 end to end. 86LG4Bird, Does that mean it's a roller?

Was eyeballing the "Xtreme Energy XR270HR; 1600 to 5400 RPM Range" on Comp's website today at work. Would this be a good choice?
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Old 06-08-2017, 08:26 PM   #16
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Re: 87 lg4 cam swap questions

That does appear to be a roller cam motor.
XR270 cam is much too large IMO for a 305 ci and stock TC.
My preference for useable powerband with the stock TC would be the XR258. Replacing the TC rather than doing a cam swap would net you mucho more bang for the buck.
I assume you're aware that you'll need a complete spring and retainer upgrade to accommodate the added lift of any of these cams being discussed.
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Old 06-08-2017, 08:33 PM   #17
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Re: 87 lg4 cam swap questions

thats sounds like a roller to me

P.S. I only just realised how much i dislike your units of measurement. i keep having to convert everything to mm to work it out!
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Old 06-08-2017, 08:34 PM   #18
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Re: 87 lg4 cam swap questions

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That does appear to be a roller cam motor.
XR270 cam is much too large IMO for a 305 ci and stock TC.
My preference for useable powerband with the stock TC would be the XR258. Replacing the TC rather than doing a cam swap would net you mucho more bang for the buck.
I assume you're aware that you'll need a complete spring and retainer upgrade to accommodate the added lift of any of these cams being discussed.
2nd'd - that lift is way too high
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Old 06-08-2017, 09:43 PM   #19
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Re: 87 lg4 cam swap questions

Thanks for the advice. Would a torque converter upgrade make a noticeable difference while already cruising or is it mainly from a dead stop?

For the price of the comp package maybe there is a way I can do a cam and a converter, for instance the LT1 cam (or some other factory cam) and I briefly read something about an S10 converter providing 2200 something stall in a Camaro. There are also rebuilt units online for cheap, not sure if these would be recommended or not. Thoughts? Any insight appreciated.
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Old 06-08-2017, 10:42 PM   #20
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Re: 87 lg4 cam swap questions

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Originally Posted by 86LG4Bird View Post
That does appear to be a roller cam motor.
XR270 cam is much too large IMO for a 305 ci and stock TC.
My preference for useable powerband with the stock TC would be the XR258. Replacing the TC rather than doing a cam swap would net you mucho more bang for the buck.
I assume you're aware that you'll need a complete spring and retainer upgrade to accommodate the added lift of any of these cams being discussed.
Definitely, get a converter and perhaps a 3:73 gear far and away better performance gain than a cam swap.
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Old 06-09-2017, 05:24 AM   #21
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Re: 87 lg4 cam swap questions

Thanks guys. Gears are out of the option because i just did a rear swap about 2 weeks ago. Going to take a stab at re gearing the 10 bolt that came out but that will be over the winter.

I could probably do the lt1 cam and s10 converter for less than choosing an aftermarket one or the other. With the savings I could probably add a timing set. Would this yield better results than choosing either a good cam or converter? Hope this makes sense.
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Old 06-09-2017, 05:53 AM   #22
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Re: 87 lg4 cam swap questions

I'd stick with your present 3.23 gears; not worthwhile or cost-effective to bump up to 3.73's.
The S-10 converter is a very cost-effective upgrade. If you do an LT1 cam, I'd look for one from a B-body (ImpalaSS/Roadmaster/Caprice LT1/Fleetwood); it will be better for maintaining lowend torque with just 305 ci. The L31 cam from the Vortec 5.7 truck motors is the same grind as the B-LT1, except it is advanced 5 degrees for even more lowend, so that's an option too. LMK if you want help finding either.
Yes, doing both cam and converter will give you the best of both worlds - better dig out of the hole plus added oomph when punching it at highway speeds.
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Old 06-09-2017, 08:33 AM   #23
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Re: 87 lg4 cam swap questions

86lg4bird, thank you for the excellent advice! Yes I would definitely like help finding both. Also with the cam can i reuse everythi or should i do new springs and seals?
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Old 06-09-2017, 02:13 PM   #24
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Re: 87 lg4 cam swap questions

I read online the converter I want is p/n 24202310 code dblf. It then goes in to detail explaining the four letter code, with the letter B regarding the highest stall (2025).

The only two I can seem to find is:

p/n gm35cw code dclf @ 1800 stall
Year 2000 lists a p/n gm90 which just says "high stall" and doesn't provide a letter code.

I would like to get it in town so I would have something to do this weekend. Having trouble finding the right one. Any help would be a

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Old 06-09-2017, 03:50 PM   #25
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Re: 87 lg4 cam swap questions

Autozone lists a B29DCLF and a B29DCNF @ 2075 stall. And it's cheaper. Is this the one I'm looking for?
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Old 06-09-2017, 05:41 PM   #26
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Re: 87 lg4 cam swap questions

I woul not waste my time to put anything smaller than a F-car LT1 cam in a 305. B-car/Vortec truck cam is a waste of time.

I have a flat tappet Lunati HE 268 grind in a 305 Vortec in a Tahoe and it makes very good low-end torque. It has NO problem pulling that Tahoe around in Overdrive on the highway with 3.42s and P305/50R20s on all 4 corners. It is only turning about 1,700 rpm @ 70 mph and rarely downshifts for hills.

If you put an S10 converter in it the converter will stall around 2,400-2,600 behind the 305. Salled 2,200 behind the stock 1996 S10 4.3 my brother had.

The cam I feel would work very well in the 305 is the GM SPO 350 357 HP cam. It is 215/223 @ .050 and .474/.474 lift.

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Old 06-09-2017, 06:34 PM   #27
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Re: 87 lg4 cam swap questions

Sounds like good solid advice, fast355. I think I will go with the F car LT1 cam.

So I pulled the trigger on a converter. It's the GM35CW from Advance. Says ID code is DCLF, DCNF so according to GM codes that is approx 2075 stall, although Oreillys lists this converter at 1800 stall. It's 12" Dia. with a 10 3/4" bolt circle. Hopefully I got the right one. The "High Stall" GM-90 was listed as an 11" bolt circle so I think that wouldn't fit?

Back to the cam (Hopefully you guys can help me hash out the details, and I can get it ordered first of the week)
What year LT1 cam can I use? Does it have the fuel pump lobe? Is it necessary to change springs? Lastly is it ok to install a used cam?
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Old 06-09-2017, 07:33 PM   #28
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Re: 87 lg4 cam swap questions

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Sounds like good solid advice, fast355. I think I will go with the F car LT1 cam.

So I pulled the trigger on a converter. It's the GM35CW from Advance. Says ID code is DCLF, DCNF so according to GM codes that is approx 2075 stall, although Oreillys lists this converter at 1800 stall. It's 12" Dia. with a 10 3/4" bolt circle. Hopefully I got the right one. The "High Stall" GM-90 was listed as an 11" bolt circle so I think that wouldn't fit?

Back to the cam (Hopefully you guys can help me hash out the details, and I can get it ordered first of the week)
What year LT1 cam can I use? Does it have the fuel pump lobe? Is it necessary to change springs? Lastly is it ok to install a used cam?
The LT1 cam does not have a fuel pump lobe. If you need one you could always go with the GM 395 Marine cam. It is less than $200 new and specs 196/206 @ .050, .431/.451 lift on a 109 LSA. In an otherwise stock Vortec 350 it makes a very noticeable difference in both HP and TQ.

I would change the springs the LG4 springs might as well be slinkies.
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Old 06-09-2017, 08:35 PM   #29
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Re: 87 lg4 cam swap questions

Will the 395 cam work with my stock heads? Could you make a recommendation on valve springs? I would like to do seals and a double roller timing set while I'm in there.
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Old 06-10-2017, 06:35 AM   #30
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Re: 87 lg4 cam swap questions

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Will the 395 cam work with my stock heads? Could you make a recommendation on valve springs? I would like to do seals and a double roller timing set while I'm in there.
Yes it will work with the stock heads but I would still recomeend a strong set of springs. I used a set of generic K-motion Z/28 springs.

I would use the GM Performance parts single roller timing set. Its good to 6,500 rpm and alot more lift/spring pressure than you would be running.
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Old 06-10-2017, 08:09 AM   #31
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Re: 87 lg4 cam swap questions

Thanks Fast355. I'm gonna focus on my torque converter swap today and tonight when I get in I'm probably gonna try to build a cam package and hopefully place an order
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Old 06-10-2017, 07:42 PM   #32
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Re: 87 lg4 cam swap questions

Trans is out. Was going to do rear main seal but after removing flex plate it looks like it's actually the oil pan gasket. Did some reading. Is the best approach to undo motor mounts and jack from the oil pan, then place wood between the separated mounts? Any other pointers to accomplish this task?

By the way. One of my flex plate bolts rounded. I had to cut the head off. In doing so the flex plate took some damage. Would you guys think it's still safe to use?
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Old 06-11-2017, 08:04 PM   #33
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Re: 87 lg4 cam swap questions

Ok just a little update...Torque converter is in. I did run out and pick up a new flexplate just to be safe. I also passed on the oil pan gasket. I can't tell why it's "wet" looking but I know for a fact my car doesn't drip any oil. So i think i'll just keep an eye on it for now.

So If anyone wants to chime in here, it looks like I'm gonna go with the 395 cam, I'll also pick up some springs, seals and a single roller timing set. Just gonna ask the guy over the phone what's good but cheap. If I place an order tomorrow morning I'll probably have it here to start the install next weekend
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Old 06-11-2017, 09:51 PM   #34
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Re: 87 lg4 cam swap questions

Just to verify, the 395 cam is p/n 14097395?

And could someone give me a recommendation on springs? Part numbers would be helpful. Thanks for all the help!
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Old 06-13-2017, 03:42 AM   #35
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Re: 87 lg4 cam swap questions

Guys I still need help with this. For the 395 cam, do I need to pull a spring to get a measurement or can I simply order "stock replacements" ? Would somebody have the dimensions I need to place an order?
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Old 06-13-2017, 07:31 AM   #36
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Re: 87 lg4 cam swap questions

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Guys I still need help with this. For the 395 cam, do I need to pull a spring to get a measurement or can I simply order "stock replacements" ? Would somebody have the dimensions I need to place an order?
Measure the O.D. of your stock springs. Should be around 1.25" IIRC. Then get a single spring with around 90-110 lbs of pressure at installed height. 330 lbs/inch should be sufficient well past the redline of the 395 cam. That part number looks correct for the 395 cam.
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Old 06-13-2017, 10:20 AM   #37
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Re: 87 lg4 cam swap questions

The guys at Summit were able to help me. Ordered p/n 16848-16, along with the cam, valve seals, single roller timing set and gaskets. Should be here by Friday which is perfect. Thanks for the help fast355 and for the rest of you I'll return with the results if anybody is interested
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Old 06-13-2017, 03:24 PM   #38
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Re: 87 lg4 cam swap questions

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The guys at Summit were able to help me. Ordered p/n 16848-16, along with the cam, valve seals, single roller timing set and gaskets. Should be here by Friday which is perfect. Thanks for the help fast355 and for the rest of you I'll return with the results if anybody is interested
It should run good. The 305 marine Vortec made 250 hp and over 300 tq when it was still offered.

http://www.gmpowertrain.com/2013_pdf...ine_010713.pdf

Your 081 heads flow little less than the 520/059 Vortec 305 head castings but the carb intake should breath better. The Marine wet manifolds are also very restrictive compared to headers on a car.

Last edited by Fast355; 06-13-2017 at 03:30 PM.
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Old 06-14-2017, 09:31 AM   #39
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Re: 87 lg4 cam swap questions

For the timing cover some are saying the front pan bolts need to be loosened, others say only for reinstallation. Also read the cover can be notched and rtv'd with good results. What can I expect with my 87?
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Old 06-14-2017, 04:46 PM   #40
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Re: 87 lg4 cam swap questions

There are ways of getting around it, such as chopping the corners off the timing cover and packing the gaps it leaves with RTV. However, the one way to do the job right is to drop the pan. The SBC was designed to have the pan go on after the timing cover. Anything else involves hacking parts up.
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Old 06-15-2017, 06:58 AM   #41
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Re: 87 lg4 cam swap questions

Thanks ase doc. I have also been reading about dropping the pan. It was said I can get enough clearance by removing motor mount through bolts and unbolting y pipe at the headers? My transmission is back on but I will remove my starter and oil filter. Is this correct peocedure and is there anything else I should remove to make it easier? Through bolts looked difficult to access but maybe once the starter is out of the way...
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Old 06-15-2017, 10:01 AM   #42
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Re: 87 lg4 cam swap questions

To completely remove the pan, and forgive me if this isn't everything because it's been a while and a whole bunch of vehicles since I did a 3rd gen, you have to raise the motor more than is possible without either dropping the trans or pulling the radiator and sliding the motor trans assembly completely out of the car. The trans stops you from raising the motor very far as it runs into the body at the tunnel, rear of the firewall. The flexplate also prevents sliding the pan out to the rear. You have the crossmember that you have to clear as you slide the pan out, but the flex plate/flywheel pretty well stops you short of dropping the pan. Honestly, even though you just stuffed the trans, your best bet is to yank it again. Up side is that since you just did it, the job should go real fast.

I've done the pan gaskets in many GM rear drive vehicles with the same basic geometry and cross member clearance as the 3rd gen. There are ways to get the job done, but the one thing that almost always makes or breaks the job is pulling the trans and flex plate.

You can slide the one piece pan gasket out and back in with the pan lowered but not completely removed. You have to get things real clean and be sure there is no oil or sludge in the corners where you apply RTV at the ends of each hoop seal. It's a pain but I've done it in a pinch. Having the trans out is once again the key to making the job doable.

Definitely gotta pull the y-pipe, starter and oil filter. Wood blocks stuffed between the motor mounts and brackets work for making clearance. Support the rear of the motor with jack stands at the corners. If you have an engine crane to raise the motor, great. If not, use a cheap bottle jack and work your way around lifting at the corners of the block. Use pieces of wood or whatever you have to hold the motor up at each step as you get it to where you need it.
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Old 06-15-2017, 12:11 PM   #43
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Re: 87 lg4 cam swap questions

Thanks for the help ase doc. Still intrigued by the guys who have claimed success w/o pulling the trans. They are saying the crank has to be in the right position. If anyone wants to chime in....i can't start till tomorrow afternoon.
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Old 06-15-2017, 01:50 PM   #44
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Re: 87 lg4 cam swap questions

You can always try it that way. Worst case is it won't work, then you can pull the trans if needed. Having the trans and flexplate out of the way does give much better access.
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Old 06-15-2017, 06:41 PM   #45
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Re: 87 lg4 cam swap questions

The old G-van is not much difference clearance wise than a F-car between the pan and crossmember. I have pulled my oil pan several times on different engines for different reasons over the years. The crank DOES have to be rotated to a specific spot or else the front of the pan hits the counter weight and stops the pan from coming out. I did mine with the engine still on the frame pads and the transmission still bolted in place. Nearest I can remember the F-car is not any tighter.
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Old 06-15-2017, 07:10 PM   #46
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Re: 87 lg4 cam swap questions

Thanks fast355. So I can leave the torque arm and driveshaft in place? I plan on leaving the crossmember on but removing the center mount bolt.

My order was here when I got home so I pulled my radiator, alternator, water pump, carb, intake and distributor. Tomorrow Ill pick up the harmonic balancer puller.

By the way...I asked for a single roller timing set but received a double roller. Fine by me, but will it clear the stock timing cover?

Right now my plan is to continue with the cam install, and tackle the pan right before I need to put my timing cover back on. Would this be the correct order of operation?
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Old 06-18-2017, 05:13 PM   #47
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Re: 87 lg4 cam swap questions

Hey guys, cam is in, along with the springs, seals and timing set. The stock cover does fit the double chain BTW.

So I found out this afternoon I have the one piece oil pan gasket. Should this be replaced? (thought it may have been weeping. Not exactly sure) And if so has anyone ever tried squeezing the new one in without lifting the motor, etc.?

Second question: I messed up my timing cover gasket the first time by not having the oil pan low enough. I dry fitted it the second time after pulling all the pan bolts out and it fits right on now. I'm gonna pick up another gasket tomorrow. Can this be put on dry or should I use RTV, and if so how.
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Old 06-18-2017, 05:28 PM   #48
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Re: 87 lg4 cam swap questions

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Hey guys, cam is in, along with the springs, seals and timing set. The stock cover does fit the double chain BTW.

So I found out this afternoon I have the one piece oil pan gasket. Should this be replaced? (thought it may have been weeping. Not exactly sure) And if so has anyone ever tried squeezing the new one in without lifting the motor, etc.?

Second question: I messed up my timing cover gasket the first time by not having the oil pan low enough. I dry fitted it the second time after pulling all the pan bolts out and it fits right on now. I'm gonna pick up another gasket tomorrow. Can this be put on dry or should I use RTV, and if so how.
I just noticed you said they shipped a double roller. Most of then will not fit without clearancing the block either.

That being said you should have silicon on the four corners of the oil pan. The factory GM engines have it already applied and you should be able to tell where it belongs.
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Old 06-18-2017, 05:54 PM   #49
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Re: 87 lg4 cam swap questions

What's the part number of the timing chain you received?
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Old 06-18-2017, 06:00 PM   #50
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Re: 87 lg4 cam swap questions

What do you mean by clearancing the block? The timing set is P/N CCA-2136. It seems to fit fine. Is there another way to check?
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