To rebuild 3.5 or not,, that is the question..

[SLC99Disco]

Ok guys, what are your thoughts on this...

I bought an 88 Range for a smokin deal, and after a little tinkering I have decided that the motor is worn out (no torque, wont really rev over 4K RPM), I have done everything else I can think of to bring what little power the motor had to begin with back, but no luck. The miles on the motor is unknown, but it is high.

So if it was yours and you were on a budget would you do a simple rebuild on the 3.5, new rings and camshaft (well a used cam, but one in good condition) and then look for a 4.6 to replace it with.

Or option 2, I have access to a 91 RR with the 3.9 in it that is in decent running conditon, but is nowhere near new. I could swap the engine from the 91 into my 88.

Thoughts?

 

[Drillbit]

Are you sure its really worn out? 3.5's are pretty weak. The 3.9 is your best bet, it bolts right in and you are back in business. A 4.6 is fun but they are $$$ and a lot more work to put in.

 

[SLC99Disco]

Are you sure its really worn out? 3.5's are pretty weak. The 3.9 is your best bet, it bolts right in and you are back in business. A 4.6 is fun but they are $$$ and a lot more work to put in.

Yeah I am pretty confident that it is worn out,,, it shows low vacuum at idle when I checked it, compression is REALLY low, and it wont rev up much over 4K RPM (which suggests to me a worn camshaft) I have checked everything else that I can think, I wouldn't be surprised if this motor had close to 300,000 miles on it :rofl:

 

[benlittle]

Get a used 3.9 or 4.2 and rebuild.

 

[Ron]

if it runs, I would replace the cam and lifters in situ and go with that.

 

[SLC99Disco]

Yeah the more I think about it,, I am leaning towards a 3.9....

 

[lforgue8]

Yeah the more I think about it,, I am leaning towards a 3.9....

I was in the same boat low vac and rough running. took the 3.5 out and removed heads and found valves marks on the pisotns and 2 of them had burn holes in them!!! Found a 4.0 i thought was good, started to rebuild but found scoring on the crank and caps......$200 paid for that so not that big of a deal........got a parts d1 and it had a good comp. 3.9 in it so i start to tear that one down and i came across a 4.6 to rebuild so i did the 4.6 up but if i hadnt i would be more than happy to build a good 3.9, cam, ported heads, and a free flowing exhaust.

Take your time and be clean if your going to do it yourself

Good Luck

 

[ptschram]

if it runs, I would replace the cam and lifters in situ and go with that.

And once again, Ron brings the win!

If it has good oil pressure, throw a cam in it and be done.

 

[SLC99Disco]

I was in the same boat low vac and rough running. took the 3.5 out and removed heads and found valves marks on the pisotns and 2 of them had burn holes in them!!! Found a 4.0 i thought was good, started to rebuild but found scoring on the crank and caps......$200 paid for that so not that big of a deal........got a parts d1 and it had a good comp. 3.9 in it so i start to tear that one down and i came across a 4.6 to rebuild so i did the 4.6 up but if i hadnt i would be more than happy to build a good 3.9, cam, ported heads, and a free flowing exhaust.

Take your time and be clean if your going to do it yourself

Good Luck

Wow! Sounds like an ordeal! I have a 3.9 I can put in, and I am thinking that I might just do that and then I can take my time and build it up on an engine stand, and make sure everything is clean.

What are popular cams for the 3.9? I was under the impression that a fuel injected engine's camshaft was pretty good just from the factory, and that most aftermarket cams arent too much hotter

 

[lforgue8]

Give D&D a call and he should go over it with you and do some searching on the subject and you should find what other people have put in there 3.9 builds.

 

[ptschram]

What are popular cams for the 3.9? I was under the impression that a fuel injected engine's camshaft was pretty good just from the factory, and that most aftermarket cams arent too much hotter

LOL, there are a couple of really nice cams that are very effective for waking up the little Buick engines!

I've installed a handful of the Crowers that D&D sell. The 229 and 230 are very popular, the 230 will have an immediate and noticeable improvement on the engine.

 

[SLC99Disco]

Thanks guys! Yeah I did a compression check on the 3.5 today,,, all cylinders range from 80 as low to 110 as a high.... haha!