87 V3500 7.4 TBI Improvements

[GonicGM]

Recently acquired 87 V3500 Dually Standard cab with SM465, stock BBC TBI. Paperwork supplied indicates new GM Goodwrench motor in 1998, warrantied by GM Dealer in 2001 for cold temperature noise. Receipts indicated bored & new pistons. It may be a 462 at this point. Regardless, it has just a few thousand miles since. It starts up easily with zero engine noise. I figure I have a solid motor. It's a heavy truck, but I believe it could demonstrate better performance without the sacrifice of economy. I plan to verify basics for baseline function, vacuum leaks, EGR valve and solenoid function, MAP sensor function, IAC function, TPS function, static timing, temperature sender.

From there, I'm considering headers, better flowing exhaust, heated O2, 454 TBI Edelbrock, flow matched injectors.

Any feedback on what works, what doesn't, what I haven't considered.

 

[dyeager535]

Any feedback on what works, what doesn't, what I haven't considered.

I'm not a Big block guy. Not sure what is there inherent weakness(es) in terms of power.

O2 sensor does nothing for power. Heated isn't going to help, especially since 454's go open loop at idle anyway. Another TBI unit isn't going to help if the stock unit underflows. For a mild motor, I doubt it is a hindrance. Injectors, I doubt you can go wrong with at least sending them out to be rebuilt/matched. Not going to hurt anything anyway.

I would expect that being old tech, BBC's respond to headers just like SBC's....they need them. Exhaust....there are plenty of calcs out there to figure what size you need, but don't waste your time on duals unless you just have to have them. They waste space, cost more to install/get parts for, get in the way, and are simply not necessary with the exhaust tubing available today. Going with anything more than necessary may actually hurt performance, and is just going to cost you more anyway. If that thing has the factory "pancake" converter, get a high flow one to replace it.

A cam is probably on order. Even with headers you will need an ECM tune, the stock cam is probably pretty darn mild and could be bumped up a bit and would be handled with the same PROM tuning.

Another fuel pump (there is at least one Delco unit that fits the stock sender, think it might be an EP381?) with higher pressure would be a very, very good idea, as you may have to bump pressure up to provide enough fuel under high load conditions.

There are other TBI mods people do (the "salad bowl" is one that comes to mind) but I'd really want to see dyno numbers before bolting that stuff on.

Others can chime in to counter or add to what I've said, I have limited experience with the big block TBI units. The experience I have comes from a 1987 454 TBI setup with a "mild" cam, headers, and Edelbrock intake. It required about 20% more fuel than it did stock. And since the TBI fuel pump maxed out at 14PSI, we were lucky that was just barely enough to provide proper fueling. So a higher pressure pump would have been nice.

 

[GonicGM]

Exhaust....there are plenty of calcs out there to figure what size you need, but don't waste your time on duals unless you just have to have them. They waste space, cost more to install/get parts for, get in the way, and are simply not necessary with the exhaust tubing available today. Going with anything more than necessary may actually hurt performance, and is just going to cost you more anyway. If that thing has the factory "pancake" converter, get a high flow one to replace it.

Does have OEM cat now, not in good shape. Stock manifolds. Your input on the Dougs headers to single in another thread is valued and is well noted. I may go that way. It appears that the Dougs headers for Y-pipes on 4x4 appear very abbreviated on the passenger bank. They don't appear that they would be nearly as efficient as a true long tube 4-1 or 4-2-1. Any square body 4x4 with headers and a Y will be a task for the sake of a full length header tube.

I'm considering over the counter 84-back OEM dual intermediate, mufflers, tailpipes. Easily obtained over the counter, I have plenty of OEM hangers. I would just have to tie a 304-Y Dougs to that system. RH Cat. placement may be a little tricky but a new smaller high flow aft of the transfer case could work.

The OEM 84-back system is 2-1/2 heads into oval mufflers with 2-1/4 tail. I run a manifold stock system as such on my 83 K30. Noise level and sound are exactly to my taste. I believe it would be appropriately sized for the 454 TBI.

 

[dyeager535]

You can also check out walkers site, if you play around with the catalog they will show the layouts for different years. I've got one of the Quietflow SS mufflers to install someday. I'm not real impressed with their overall construction unfortunately. In terms of holding together and functioning they appear fine, but the way the edges were rolled to seal the ends to the body, looks like the machine was setup improperly or something. Kind of dented up if you will. Not real comforting.

I checked out Hedman for headers, doesn't appear they have any options for the 454 in this body style other than the one. No idea if it hangs down real low like the SBC one or not. But you are right....not much way to get a crossover with the really long tube headers that at least Hedman specifies. I didn't mind running shorter versions for that reason. Oddly, the 62230 that I run is noticeably shorter than what I took off that Hedman originally said to use with the truck, yet they still call them full length.

For the tradeoff on power, whatever there was, I am ok with it since fitment is so much better. As I stated in another thread, the before/after difference was unnoticeable.

 

[Team208Motorsports]

Attached is the timing and enrichment for an 87 manual 454.

You can see there is nothing for timing. You take an engine that should be in the 30s and put it in the teens and single digits. LOL.

 

[GonicGM]

Attached is the timing and enrichment for an 87 manual 454.

You can see there is nothing for timing. You take an engine that should be in the 30s and put it in the teens and single digits. LOL.

View attachment 192664

Interesting, that's based on OEM chip?

Does exhaust introduced, lack there of, A.I.R. affect O2 feedback/enrichment?

 

[GonicGM]

O2 sensor does nothing for power. Heated isn't going to help, especially since 454's go open loop at idle anyway.

Is this true for all likewise vintage TBI with O2 over minimum temp? Isn't it possible to go open loop above idle at cold temps with an O2 down stream in a header where heated O2 is a benefit for winter operation, low RPM, low load plowing?

A cam is probably on order. Even with headers you will need an ECM tune, the stock cam is probably pretty darn mild and could be bumped up a bit and would be handled with the same PROM tuning.

Probably don't want to swap cam. Might try to gain a little by bumping up rocker ratio a little.

I really like the 90 S10 4.3 (over-bored) TBI I have. It is bone stock, less heated O2, has very good power, starts every time, has a crystal clear tailpipe and perhaps 200K. I can get 27+ MPG.

I'm not expecting anywhere near the same numbers for a one ton dually 454. However, in my mind, it's just a bigger version of the same thing and I believe it should run as good.

 

[Team208Motorsports]

Interesting, that's based on OEM chip?

Does exhaust introduced, lack there of, A.I.R. affect O2 feedback/enrichment?

Yes and yes

Heated O2 and cross over MV tuning are always needed when going long tube. Non heated O2 may not warm up enough to function with long tube. Since heat is lost rich/lean cross over is no longer at 450mv.

 

[dyeager535]

Is this true for all likewise vintage TBI with O2 over minimum temp? Isn't it possible to go open loop above idle at cold temps with an O2 down stream in a header where heated O2 is a benefit for winter operation, low RPM, low load plowing?

My experience with heated vs. unheated was that it didn't matter, except idle. It went open loop as soon as the throttle closed essentially. As soon as you came up on the throttle (at all) it went closed loop. This was small block so theoretically closed loop idle, unlike the BBC TBI setups. However IMO if it won't idle open loop, your tune is bad, or something else is factoring in. There might be some cases where tune can't fix issues from things like massive overlap, but on a mild setup, open loop should have the same idle quality. You are talking hundreds of degrees in the exhaust stream (8-1200 at the port IIRC), ambient temps aren't going to make much difference, at least not noticeable.

 

[sreidmx]

OMG i had no Idea the timing was that bad.. kinda makes sense why they dont really feel that good.. I read a few times that a 502 crate motor cam is good plus the normal listed stuff..

 

[dyeager535]

You have to factor the PE SA in as well as base timing, whatever it is for that application. Still doesn't seem like much, but I'm used to the small block numbers.

 

[sreidmx]

Very true.. I haven't seen a Small block spark table either.. just seems really low looking at it though.