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engine rebuilding help

1K views 7 replies 5 participants last post by  jopes 
#1 ·
this is going to be my first time rebuilding an engine and i dont want it to turn bad. my friend has a 87 4.9 that needs a rebuild. its got extreme blowbyand 0 compression on cylinder 6. even tho it had bent pushrods, they were in other cylinders so we think rings are gone. the cylinder seams undamaged so we were gonna try and do a rebuild without any machining. we dont have much time to get the truck running so i want to order parts as soon as i can and were gonna finish pulling the engine this week. im also gonna order parts for my truck to rebuild it cause my oil pressure has been very poor latley and i want to rebuild before real damage occurs. not to mention i have 2 other friends who want me to help them rebuild there trucks.

we dont have a high budget so a master rebuild kit was looking best in price. but i was wondering if its best to piece the rebuild together so i know what its got. but i really dont know what kind of parts to get. can someone explain the differences beterrn these options?
*iron vs chrome vs moly rings
*main bearings with 1/2, 3/4 or full groove.
*bi metal vs try metal bearings
*stock size bearings vs 0.001 over/under sizebearings
*upper vs lower vs both groove locations
*honning beads vs honning stones vs neither
*brands i should use or stay away from? sealed power? clevite P or H?

just some other info to add. he eventually plans on turboing his 4.9 if that means anything different in the parts i should pick out. i guess its something he found out about and really wants to but i havent looked into it myself to see what it involves. my engine is a DD, i might put some GT40 heads on igf there avalible at the JY. when im offroad tho i usually like the upper RPMs for extended periods of time never 6 but very often around 4-5k RPM so i want to make the engine more durable since i htink thats why my bearing are soo worn. all the other trucks are gonna be stock DDs
 
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#4 ·
i told him about it. but he perfer to rebuild his. i guess since he doesnt want to put in a motor with unknown condition. also he does want it setup the best for his future turbo as he can. engines at out JY s are expensive anyways and usually torn into already
 
#5 ·
I agree on the running engine swap, then rebuild the other. I would not want to build a turbo motor on a budget. From what I understand about forced induction you need to have that in mind when you build the engine as the compression ratio needs to be correct as well as the rotating assembly needing to be extra strong. This will depend a bit on how much boost he wants to run in the future as well.
The bearing size is relitive to the crank, the size you need will depend a lot on what the crank looks like when you take it apart. If it has some deep marks in it it should be machined which then means you will need a bigger size for the bearings as the crank is now smaller.

I think if I was him I would find a running 4.9 to swap in there for now, and then rebuild the one that's in it into the turbo motor that he wants, not cutting corners due to time frame or budget.
 
#6 ·
Building a motor for future turbo addition without the assistance of a COMPETENT, EXPERIENCED machinist is asking for a grenade launching party down the road! Budget builds are not worth wasting the time and money.

Chrome or moly-filled rings are the best . .flip a coin, the moly's seat faster but chrome lasts longer. Iron is cheaper.

You can't just drop in bearing inserts and hope for the best. Mic everything and refer to the machinist.

Glaze breaking with a berry bush is quick and easy as well as effective, stones are used after an overbore to finish the cylinders. If you have cylinder lip you'll need to use a cutting tool to remove it and you will probably need to bore it and use new pistons anyway.

good luck, have fun!
 
#7 ·
i talked to him again and he defiantly doesnt want to do a swap his motor now is already swapped once and it left alot of problems. he said that he looked at the junkyard last week and every engine looked like junk or was already torn into. i have to agree cause i never see a complete engine there and there always torn into. using car-parts website all engines seem to be like 500$ or so. im going to have him wait to get the parts ordered. figuered if he had to we would get a reman crank which incleuds bearings for like 200$.

idk if he will ever will turbo it but he wants to. he definatly wansts it right but not cost $1k to rebuild. were on budget but still willing to get the right stuff which is why hes having me look for parts. sounds like if cylinders are good that the dingle berries are what we need right. its an 87 motor so its not roller, would it be worthy of replacing the camshaft? its another hundred or so bucks that we could use if not
 
#8 ·
there is 2 ways to rebuild a engine, the cheap / wrong way and the costly / proper way.

if my memory serves me right usually just removing the ridge on the upper cyclinder, with cleaning the bores up usually = a engine that lasts less than 50k miles.

Now your talking about adding a turbo later, umm ya. Hold my beer and watch this comes to mind.

engines are a complex yet simple machine, they need proper tolerances and extreme cleanliness to live a long time. Start cutting corners and your shooting yourself in the foot.

Now if you want to get something running for a short period of time then sell it, cheap is the way to go.
 
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