TBI '87 R2500 454 Suburban Runs Like Crap

[MrSony]

What happens when you cycle the fuel pump? There should be a lead on the relay that’s on the firewall - hook up 12v to that guy and it will turn on your pump and run fuel thru the regulator and back to tank thru return line. You should hear it but you shouldn’t see any fuel in the injector bores or coming out of the injectors.

Have a fuel pressure gauge? What’s pressure? Should be between 9-13 psi


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12psi, KOEO, and running.

 

[MrSony]

Update: cam was wiped on a few lobes. Updates to follow.

 

[idahovette]

Yep , that'll do it. Looks like everything comes apart now

 

[bucket]

And it will be much better in the long run. I think even the most mild RV/towing type cam will be a big upgrade.

This is when things can REALLY start to snowball though. Valve springs, rockers, intake...

 

[4WDKC]

I use this chart for a starting point on cam selection.

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Remember that engine was built for low rpm towing and sucked when it down shifted and couldnt pull any better. 454/8= 56 ci per cylinder. Top chart 220-230 is what I would be looking at, try to stay 112+ lsa to ease tuning.

 

[bucket]

I use this chart for a starting point on cam selection.

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Remember that engine was built for low rpm towing and sucked when it down shifted and couldnt pull any better. 454/8= 56 ci per cylinder. Top chart 220-230 is what I would be looking at, try to stay 112+ lsa to ease tuning.

If the cam is the only thing being changed, you really have to be careful. The stock valve springs really can't handle much past the stock cam.

 

[Wumbo]

Comp makes a cam for TBI 454's, part number 11-302-4.

I wouldn't suggest that cam without springs though.

 

[4WDKC]

If the cam is the only thing being changed, you really have to be careful. The stock valve springs really can't handle much past the stock cam.

Comp makes a cam for TBI 454's, part number 11-302-4.

I wouldn't suggest that cam without springs though.

I always change the springs with cam, they shouldnt be sold separately the entire kit should be purchased, cam,springs, lifters.

 

[Wumbo]

I always change the springs with cam, they shouldnt be sold separately the entire kit should be purchased, cam,springs, lifters.

No doubt. I just bought the kit, Comp Cams K11-235-3, and I'm hoping to have it back together by this weekend.

(not the same cam as the TBI engine)

 

[QBuff02]

My 454 when I tore it down to rebuild it had the Comp Cams XE262H cam in it. (part number 11-238-3) and for a not really wild engine, it had great response, idled quite smooth and made gobs and gobs of torque. Once I looked up what it was on their site (it was in the engine when I bought the truck) i'll admit I was actually quite impressed by it. I'd strongly recommend it to someone looking for a step above in an rv/towing cam. You wouldn't be disappointed.

 

[MrSony]

I just ended up with a melling stock replacement cam and lifters. I was gonna get springs but I didn't know the stock specs. Reccomendations for springs? Stock replacement? Aftermarket?

 

[4WDKC]

I just ended up with a melling stock replacement cam and lifters. I was gonna get springs but I didn't know the stock specs. Reccomendations for springs? Stock replacement? Aftermarket?

if you havent put it in yet take it back

 

[MrSony]

If it's just from a performance standpoint, I dont really care. But if its a quality issue, I wouldnt mind upgrading to one of the aforementioned, providing they do 100% work with the stock ecm.

 

[4WDKC]

If it's just from a performance standpoint, I dont really care. But if its a quality issue, I wouldnt mind upgrading to one of the aforementioned, providing they do 100% work with the stock ecm.

Im assuming its installed by now. It wasnt a quality issue but definetly is a performance issue, the stock cam was just all wrong for that engine and the compression is low. Going with an aftermarket can get you in right rpm range and more importantly fill the cylinders up better.

 

[MrSony]

Cam has not been installed. Pan was full of crap (not metal... Just debris of some kind, old gasket material maybe...), and I found a piece of a pushrod that wasn't part of the 16 I replaced. Looks like it took its time going down too. Engine is coming out.

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