El Guapo

Here is the situation. I have an 85 LG4 engine and an 87 LG4 engine. The 87, according to its previous owner, threw a rod. (Im assuming, at the moment, that it was a con rod, will verify upon pulling engine.) The 85, according to its previous owner, was in good condition. Assuming my assumption is correct, here are my questions.

1) I have heard from a couple of people that the 87 had a roller setup. Can this be verified or denied?

2) Assuming the block on the 87 is marred, and it is indeed a roller setup; would it make sense to take the head, cam, lifters, etc out of the 87 and put in the 85? Or are they so close in performance that it wouldnt make a difference to the 85 block?

3) For grins and giggles, could someone provide the factory hp/torque values for both engines?

Before any of you suggest just building an aftermarket engine, know that that is in the works. However, for now I am trying to get an engine together that will work. But I feel it would be foolish not to make the swap if it would benefit in the performance area.

Oh yeah, FWIW the engine will be going in an 87 T/A.

Clayton

IROC86

hey the 84 lg4 had a wussy 145 horsies, and the 87 165. both around 250 torque. good luck man.

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86 IROC LG4,DUAL SNORKEL,AMERICAN THUNDER,3.27 GEARS

five7kid

iTrader: (14)

I haven't seen an '87 LG4 (I have an '87 LB9), so I'm shooting from the hip a bit here.

A factory roller setup will not fit in the '85 non-roller block. You can make the cam work, but the lifters are kept from rotating by a "spider" setup that bolts in the center of the valley. There is no provision for bolting the spider into the '85 block. You could put in aftermarket roller hydraulic lifters (many $'s). The push rods are slightly shorter in a roller engine.

The '87 should have heads with the center two intake bolts at a different angle. This requires that the heads/intake go together. You may see some benefits from using the '87 heads, but the variables were more influenced by the compression (flat top vs. dished pistons) and the cam.

If the '87 has a thrown rod, forget that bottom end (block, crank, cam, lifters, pistons, rods, etc.). If you want to make one good running engine out of these two, I'd recommend flat top pistons in the '85, with an aftermarket flat tappet cam, and the '87 heads & intake. If you just want to get it running until your aftermarket engine is ready, just put in the '85 engine. You didn't say what you have for induction/computer control in the '87 T/A, but the '87 knock sensor and distributor would be best if you're staying with CC.

Keep in mind also that if the '87 is a roller block, it will also have a one-piece rear main seal crank, which requires a different flex plate or flywheel than the '85.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.73 unlimited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, TBD heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

RB83L69

There were LG4s in 87, just not in F cars. And not all 87 motors are rollers: my late brother's 87 Monte Carlo SS, L69, was not. We were quite surprised when we were putting a Performer intake on it and discovered the block was not even equipped for it (no bosses for the spiders). Trucks were not rollers either until very recently. So with 87 non-EFI blocks at least, you'll have to pull the intake to see if it's roller or not.

Apart from performance, the 87 heads have one improvement over the earlier ones. They have the taller valve cover rails and so are much less prone to leaking. Also, the 87 will be a one-piece-rear-main-seal block which has a bit less tendency to leak, so there will be interchange issues with the crank and flexplate.

You may find that you can crank-kit the 87 motor if all it did was stack the bearing or something, without damaging the rod or the block.

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"So many Mustangs, so little time..."

MilehighBird

iTrader: (1)

F-cars certainly did come with the LG4 in 1987!! My formula is an 87 and it came from the factory with an lg4.I don't believe it has a roller cam,i'm pretty sure only the tpi cars came with a roller that year.

El Guapo

I am going to keep the CCC system on the 87, for the moment. Thanks for the info so far. I have decided to keep the 85 engine, except for maybe the heads and intake from 87. I am going to try to port-match either set of heads I use.

Here is the question for this post. "is there a difference between 85 LG4 heads and 87 LG4 heads (besides the bolt angles)?"

Clayton

dan

The lg4 was availible in the camaro in 87, my sport coupe came with one. They are also roller motors, for sure, since I had it apart

zroc

If the 87 lg4 had the roller cam (doubt it)... it would not fit the 85... the heads from the 87 should bolt on but why... if you have the flex plate from the 85 use it and drop it in... build your other motor and burn the tires off... have fun...

zroc