4.9L Cadillac Information (Page 5/11)
Spadesluck AUG 14, 05:22 PM
I am building a 4.9 right now that will be mated with an F40 trans. I am most certainly know the 4.9 has its limitations. I already had this motor from a parts car so I figured why not. What I have done is:

1. Allante Intake and steel rocker arm supports
2. Delta cam
3. Johns longtube headers
4. Ported the heads myself and cut the valve seats for better springs to get rid of that choke point that the 4.9's suffer from. I took out almost 2lbs of material on each head.
5. Sinister tuning for the use of the allante intake and other odds and ends. (not really performance but annoying check lighys or limp mode)

I am not expecting miracles but I am sure this motor will be a blast to drive till I swap in something more modern down the road. Build whatever you want and your finances can handle.
pmbrunelle AUG 14, 06:45 PM

quote
Originally posted by Mickey_Moose:
The time an money I spend on my car didn't really make it a performer.



What expectations did you have?

From what I see on the present quarter mile list, it seems like slightly warmed over Cadillac 4.9s (naturally aspirated) should be in the high-13 / low-14 range... which for some people could be considered entertaining.

You wanted something quicker than that?
olejoedad AUG 14, 06:55 PM

quote
Originally posted by Warlordsix:

"I imagine the engine compartment is awfully cramped as it is with just an NA 4.9L crammed in there!"

Negative. Plenty of room in the engine bay around the 4.9. Frankly, there's much more room around the 4.9 in a Fiero than there is around a 4.9 in a DeVille. Just relocate the battery up front like most folks do anyway for other good reasons.

This is not the best shot, but I can easily change all my plugs, replace the belt, alternator, water pump, AC compressor, starter, etc., without disassembling anything else first.

Ernie






I have it from an extremely reputable source that the engine bay of the Fiero was designed from the very beginning for a transverse aluminum V-8.

The only transverse aluminum V-8 that GM had during the early stages of the Fiero design phase was made by Cadillac.....the 4.1.....

There are two signatures on my car. One of the signers is the source of that information, and was involved with the P-car project from the beginning.
Will AUG 14, 07:48 PM

quote
Originally posted by Spadesluck:

I am building a 4.9 right now that will be mated with an F40 trans. I am most certainly know the 4.9 has its limitations. I already had this motor from a parts car so I figured why not. What I have done is:

1. Allante Intake and steel rocker arm supports
2. Delta cam
3. Johns longtube headers
4. Ported the heads myself and cut the valve seats for better springs to get rid of that choke point that the 4.9's suffer from. I took out almost 2lbs of material on each head.
5. Sinister tuning for the use of the allante intake and other odds and ends. (not really performance but annoying check lighys or limp mode)

I am not expecting miracles but I am sure this motor will be a blast to drive till I swap in something more modern down the road. Build whatever you want and your finances can handle.



I'm curious about what numbers your build ends up producing. Are you going to have it dyno tuned? What ECM? What flywheel, for that matter?
Mickey_Moose AUG 14, 10:38 PM

quote
Originally posted by pmbrunelle:


What expectations did you have?

From what I see on the present quarter mile list, it seems like slightly warmed over Cadillac 4.9s (naturally aspirated) should be in the high-13 / low-14 range... which for some people could be considered entertaining.

You wanted something quicker than that?



I had no expectations, just wanted a project and came across a 4.9l that was cheap. Figured I would add the go fast stuff while it was apart. Don't get me wrong it was a fun car. Was in the low 14's when I took it to the track and would dominate a lot of cars for the first 1/4 - 1/2 of the 1/4 mile track.

I was perfectly fine with the 4.9l (since I built the car mainly as a daily driver with some track time - actually became a perpetual project with the f-body interior work, etc), but the OP seems to want a lot more (money is no object), and that is not going to happen with the 4.9l. As I said in my post a 3800SC Fiero would take the car in a 1/4 mile race.

Just trying to keep it real and if money was no object, there are easier ways get get more power into a Fiero.



[This message has been edited by Mickey_Moose (edited 08-14-2020).]

FieroWannaBe AUG 15, 12:46 PM

quote
Originally posted by Spadesluck:

I am building a 4.9 right now that will be mated with an F40 trans. I am most certainly know the 4.9 has its limitations. I already had this motor from a parts car so I figured why not. What I have done is:

1. Allante Intake and steel rocker arm supports
2. Delta cam
3. Johns longtube headers
4. Ported the heads myself and cut the valve seats for better springs to get rid of that choke point that the 4.9's suffer from. I took out almost 2lbs of material on each head.
5. Sinister tuning for the use of the allante intake and other odds and ends. (not really performance but annoying check lighys or limp mode)

I am not expecting miracles but I am sure this motor will be a blast to drive till I swap in something more modern down the road. Build whatever you want and your finances can handle.



Share some pictures of you head work, please! although it was never a performance oriented motor, i do have a soft spot for "bad" engines made better.
Johns 4.9 AUG 15, 03:00 PM
I've done some head work. 1.94 and 1.60 stainless steal valves.
Cheers
Reborn756 AUG 15, 05:16 PM
Hey guys, sorry I haven't responded recently, been hard at work with my business the past two days!

I'm not looking for mega power, by no means do I expect to make 3800 power with a 4.9l Cadillac. What I am looking for is more power than the stock engine (check) and an awesome sounding V8 (check again). That's the primary reason I'm looking at the 4.9L, or a similar sized V8. I love everything I'm seeing with the 4.9L so far.

OleJoeDad: I am not at all suprised to hear this info. After seeing the pictures of the 4.9L in the Fiero engine bay, it completely looks like it belongs in there!

------------------
- Darryl

Warlordsix AUG 15, 07:00 PM

quote
Originally posted by Johns 4.9:

I've done some head work. 1.94 and 1.60 stainless steal valves.
Cheers



John, both valves look about 2mm larger in diameter.. Am I close?

Ernie

------------------
'87 Fiero 4.9 5-speed

Johns 4.9 AUG 15, 08:53 PM
Stock 4.9 valves are 1.77 and 1.50. 4.3mm and 2.54mm increase.
Cheers