94 Bravada timing

[Toolwise]

I don't have a problem, but recently I was reading that you should have your vehcile's timing chain checked/replaced around 90,000 (which happens to be where my 94 is right now) or your timing belt around 125,000. So I was wondering, which does the Bravada have, a chain or a belt?

[Chris Stewart]

Our 4.3 Vortec motors have a timing chain and I changed mine the summer '04...170k, and the old one was still good (Kendall GT1 High Performance Oil since new & Slick 50 beginning at 64k). Timing chains are like water pumps...any motor could use a new one before it fails.

[ericn1300]

i've never had to change the timing chain on any of my 4.3 engines, and have never heard of one breaking. i got over 250,00 on one of the vehicles and it was still running strong when i sold it, but if Chris suggest changining at only 170k you might want to follow his example and do it then. i know he's going to baby his Bravada thru at least 500k.

some purist will tell you that the chain wears and gets some slop in it and that affects timing, but if it did it whould be minute and only show up on rapid rpm changes.

never did understand why auto manufactures went to belts that break every 70 to 100k instead of chains which seem to outlive the engine? noise reduction maybe?

if you want to check or replace it, diy instructions here:
http://www.autozone.com/servlet/UiBr...3d8018b36b.jsp

[old_master]

Timing chains stretch just like motorcycle chains and bicycle chains, but they are adjustable. A timing chain however, is not. You can check timing chain slack very easily. With a socket and breaker bar on the crankshaft bolt, slowly rotate the crankshaft in the normal direction of rotation until the timing mark lines up with TDC on the index. If you go past TDC, do not turn the crankshaft the opposite direction, go around again. The whole idea here is to keep the slack on one side of the gears. Remove the distributor cap and have an assistant hold the rotor tightly with their hand while you slowly rotate the crankshaft in the opposite direction. The instant the rotor begins to move, stop turning the crankshaft and read the degrees on the index. With any more than 12 degrees of slack, the chain can jump on the camshaft gear causing valve timing to retard.

[Chris Stewart]

Thanks OM, that's exactly what I was hoping to find when I replaced mine because it's been kinda sluggish the past coupla years and timing chain slack with retarded camshaft timing would explain it but I guess the next possibility will be the fuel pressure kinda on the low side around 50psi then valves and seats next.
An NHRA Stock Class style valve job wouldn't be bad though...we did Larry Hill's HT/SA '86 Chevy truck 4.3 Vortec heads and he did very well, in fact too well and has had horse power put on that combo to the point that he generally qualifies in the top 10 instead of #1 like he did for a coupla years.