I know this is off topic, but . . . (1 Viewer)

[OCHO4I]

Okay folks, I just made purchase that I hope I’m not going to regret. I was able to convince a neighbor of mine to sell me his son’s long abandoned 72’ GMC Jimmy. It has a stock Dana 44 front, GM corporate 12 bolt rear and it looks like about a 6-inch lift. At some point, they put in a 454 of unknown origin which my neighbor says was a very strong runner.

I’m taking the 454 out for a rebuild and the last time I built up a 454 was my first car in high school! (I don’t want to date myself, but let’s just say that Pink Floyd’s “The Wall” had just come out when I was working on it!)

I am desperately seeking suggestions on how to rebuild the motor. All I know at this point is that it’s a steel block from the early 70’s with 4-bolt mains. My question to you all is this: I want to use it for the same general trial work and occasional rock crawling that I do with my FJ60. If you were to build up a 454 for torque, horsepower and durability, what components would you suggest? Any recommendations for carburetor/intake manifold combos that would be able to deal with the occasional extreme angles that we’ve all encountered on the rocks? (

So, go to town! If you were the one rebuilding my 454, how would you do it. No forced induction, fuel injection or turbos, just a good old fashioned single carb. What are your recommendations? Also, any links to reputable suppliers for the parts I’ll need. Thanks in advance.

 

[orangefj45]

whatever you do, make sure that all the components "match". that translates to running a cam, intake and compression ratio that are all designed to run at the same RPM range.
if you're going to wheel it some and cruise it around town, then i'd run an RV cam, an edelbrock performer intake and about 9-9.5:1 compression. msd ignition is a great upgrade as well.
a 454 will produce more than anough power at that point. any more, and you'll be replacing axle shafts and gears constanty. ask me how i know. i used to have a fullsize with that setup about twenty years ago..........i was in my late teens and had a heavy right foot. but it made for some fun wheeling trips.

hth

georg @ valley hybrids

 

[Spike Strip]

When you get it machined, there's a guy in Reseda who does great work ...

 

[lehiguy]

A cam with duration around 208 to 212 degrees at .050" and lift of .430" to .470" will get you monstrous torque without killing the mileage. Rochesters are excellent off-road carbs and are more finely tunable than any other mixer ever made short of FI. Learn how to tune one and it will reward you. They are more involved with more calculations required to nail it, but it is well worth the effort. Edelbrocks have a rear-pivot float with a crossover between the two huge float bowls. Let me put it this way; I ran one for a short time, I loved the power but it's shortcomings were made evident the first time I was pointed skyward on an old mining road. I watched my fuel spew out into the air in the form of blake smoke. That was the Edelbrock's last trip.

 

[ntsqd]

I will second using a matched cam/intake/carb/comp ratio; and using the stock Quadra-Jet carb for the reasons mentioned.

 

[Callahan Offroad]

I will third having matching top end and compressions.

I'd probably look into a stroker kit and a well designed free-flowing exhaust as well.

Make sure you get a wideband o2 sensor and a wideband o2 gauge so you don't have to guess if you are running at the right a/f ratio's

Not certain about carbs, thats someone else's territory.

 

[OCHO4I]

Thanks for all the input! (I knew that I’d get some thoughtful responses from the group!) As suggested, I don’t intent to randomly “pick-and-choose” individual parts for the rebuild, but instead get some suggestions for an RV cam/Edelbrock intake manifold/piston and Rochester carburetor combination that would work well. This project is going to run on pump gas, be driven around town on occasion and to and from the trials, so it will definitely not be a trailer queen. Georg, I agree that there is no need to build it up for impossible to maintain top-end horsepower given what I intend to use it for and that torque and durability (along with a little extra reserve for those occasions when I get in over my head), is what I’m shooting for. (By the way, I was already planning to go the msd ignition route with this build.)

I know of several members of the group who’ve used Summit Racing to purchase their non-Toyota parts and accessories. (I guess I won’t be able to run to Jim C on this one?) Any recommendations for reputable and reasonably priced on-line (or SoCal located) drive train parts suppliers?

One of my brother-in-laws ran a roller cam/roller lifter/roller rocker setup on his hot rod 70’ Chevelle 396 and he recommended that I do the same on this rebuild. I know that it is a little nosier than the traditional non-roller setup, but given the application, (and the fact that I plan to take it out wheelin’ with the top off whenever possible) I don’t think that the additional engine noise would be much of a problem for me! Anyone have any experience with this type of setup, or recommendations on a combo that would help get me in the 9-9.5 to 1 compression ratio goal?

Thanks again and keep the suggestions coming!

 

[ntsqd]

Most (all?) mechanical roller cams are going to be much too much cam for what you want. If there are hydraulic roller cams, then you might be onto something.....


Coast Driveline is in Ventura.

Colorado K5 - Full-Size Chevy K5 Blazer 4x4 Restoration and Off Road Community

 

[Callahan Offroad]

just remembered this thread!

your final compression ratio of 9.5 is totally do-able. I would be more interested in running even higher compression personally. 427 motors came with 12.5:1 compression stock. For every compression point you go up you can usually expect 5% more power, at least that was the formula that we had used when building imports. Also higher compression = better mileage too. But then again higher compression means less forgiveness in getting it right.

I guess the real question is how much money do you have? If you have $100k then the sky's the limit, but if you've only got $500 that changes your options significantly.