Community Forums

mrblanche · 02-07-2011, 03:59 AM

Well, I would disagree with one thing here. I don't think the Edelbrock 600 would be large enough for a 454 in a motorhome. It could certainly be tweaked, but on the dyno with my 350 in my hotrod, it was a little lean on the top end.

GOLDWINGER2 · 02-07-2011, 08:43 AM

Quote:

Originally Posted by mrblanche

Well, I would disagree with one thing here. I don't think the Edelbrock 600 would be large enough for a 454 in a motorhome. It could certainly be tweaked, but on the dyno with my 350 in my hotrod, it was a little lean on the top end.

A larger jet should fix that unless you are running a monster, monster 350.
J

LVJ58 · 02-07-2011, 09:12 AM

I would also vote for the Quadra-Jet rebuild. Had one on the 454 in our old 84 Airstream coach and had it rebuilt rather than change.

Good luck & safe travels,

JimElliott · 02-07-2011, 12:18 PM

The "Quad" is almost the perfect carb for our rigs....
The primarys are smaller than the square bores hence that equals out to better fuel mileage (maybe) but the thang hasta be jetted out perfectly which is a PITA.....
Generally they show up on our engines with jet sizes much bigger then needed (my 87 had 76 jets) when all that was needed was 73s, Change out a few other items and it's good to go....

Jim

stangdoc · 02-08-2011, 07:49 AM

Jim,
Thanks very much for your knowledge and advice about the total timing settings on the 454. After checking, my initial timing was at 4 deg and it had the strong springs, so it was not getting near enough advance. Mine seems to run good at 8 deg initial, and I put a plastic collar on the vac rod that keeps it from advancing too much, and seems to have about .100 movement now, plus I put the weak springs from the distributor kit in it . Man, it now runs like a big block should and when you floor it, it doesn't bog down when the secondaries open, it just takes off. This engine has an off road cam in it and a Edelbrock Performer manifold and long tube headers, so I guess my richening of the primary and secondary jets seems fine now that it is getting correct advance. After replacing the PS gearbox, the drivers bell crank arm and both inner tie rods it is not wandering very much anymore. Do you know what GPH the lift pump should be? Mine had a marine electric pump by the tank and a factory mechanical pump. Thanks again for your great advice!! Don't know what mileage it will give now, but at least it will climb hills and is much smoother. Kevin

whem2fish · 02-08-2011, 08:18 AM

be sure to check lower ball joints that was my main issue
ill be in your area in a few weeks
dave

JimElliott · 02-08-2011, 09:08 AM

Quote:

Originally Posted by stangdoc

Jim,
Thanks very much for your knowledge and advice about the total timing settings on the 454. After checking, my initial timing was at 4 deg and it had the strong springs, so it was not getting near enough advance. Mine seems to run good at 8 deg initial, and I put a plastic collar on the vac rod that keeps it from advancing too much, and seems to have about .100 movement now, plus I put the weak springs from the distributor kit in it . Man, it now runs like a big block should and when you floor it, it doesn't bog down when the secondaries open, it just takes off. This engine has an off road cam in it and a Edelbrock Performer manifold and long tube headers, so I guess my richening of the primary and secondary jets seems fine now that it is getting correct advance. After replacing the PS gearbox, the drivers bell crank arm and both inner tie rods it is not wandering very much anymore. Do you know what GPH the lift pump should be? Mine had a marine electric pump by the tank and a factory mechanical pump. Thanks again for your great advice!! Don't know what mileage it will give now, but at least it will climb hills and is much smoother. Kevin

Kevin, Good going......My "lift pump" (fuel pump) is an Edelbrock 1722 which hands out 110 GPH at 6 psi.....I don't know what carb you have or CRS is setting in badly...
Carbs love high flow but don't like high pressure.
That .100 movement on the vacuum advance should work fine and give you about 9º of advance, Did you check the total advance at 3,000 RPM with the vacuum advance disconected?...Should be close to 30º----32º at that 3,000 RPM.
I cannot gauge a guess with your "Off road cam" but if you know what the .050 is on the cam I can get close....
On the flat & level at 62 MPH my "Indexed vacuum gauge" sitting in the dash reads out between 13 and 17 inches of vacuum and at idle it will read 18-19 inches out of gear @750 RPM.......
I strongly reccomend a vacuum gauge in the dash and please make sure it is indexed with 2 degree increments so you will know what your vacuum is 100%.

Jim

JimElliott · 02-08-2011, 01:23 PM

stangdoc, I've re-read the post and eliminated the "CRS" about your Edelbrock carb which IMHO is a decent carb and I have installed a few on 454s.
Some items about a Q-get
First is the A/F mixture screws, They stay in the circuit until approx 2600 RPMs, If they are rich your wasting fuel until the main jets take over.....
Next is the (CRO) "Channel restriction orifice" and a good carb guy will resize them for a crisp off idle and part throttle response.
Is your vacuum advance connected to the carb (ported) or is it connected to the manifold (full manifold vacuum), Full manifold vacuum will increase your RPMs about 300 or so and you can dial the idle screw down a dab for another fuel savings trick.
I still have some other tricks with the carb but e'nuf for now...

Jim

Iron Man · 02-08-2011, 07:42 PM

Engines built in the late 70's and 80's were built for "emissions" and poor performance. Anything you can replace on those engines will be a plus. You would be surprised what headers, dual exhaust and a good dual plane intake manifold would do to pep up a engine. This will help across the engine's entire rmp range. If you thow a good cam and heads into the mix, you can really wake up the engine.

stangdoc · 02-08-2011, 08:58 PM

I do have a vacuum gauge on the dash, and it was running pretty low vacuum before the timing change, but is now in the 17" range when cruising. I couldn't figure out how to have the light on the timing mark (can't see it from in the cab) from underneath AND rev it to verify total advance? My co-pilot doesn't have a steady foot so I usually figure out a way to do all work solo...may have to enlist her help. My vac advance is plumbed to the pass side front port and haven't tried it on straight manifold vacuum yet. I would like to stick with the AFB as it is one of the few carbs that I can work on. My carb is an Edelbrock AFB, but haven't remembered (CRS also) to check the numbers to know what CFM it is yet. My lift pump is a red label Holley(Edelbrock) and think it is rated at 100-ish gph. I am calling the machine shop this week to ask what the cam specs are and hope they are still in business. The idle has no lope, so it is probably a mild cam. I will get more specifics later in the week. Thanks for the ongoing help!

Wallaby Dan · 02-08-2011, 10:06 PM

I only had the old carb with no choke at all but it always started right up and ran smooth till towards the end before i rebuilt the engine. Iwas getting strange readings on the vacumn and had a 'miss'. I rebuilt the motor. added the goodies and put a new Edelbrock Qjet. Distribitor redone by the same guys that did the block. Right springs and carb jets. Runs smooth... Good power and fuel economy. Now if i could cut the fingers off my stupid daughter and her boyfriend too, for the handful of bolts and screws down the carb...Now i am finishing up the re-rebuild. She comes within about 300 foot and i will use her for targets!!!

:bang head: