Trojan Boat Forum

Has anyone experienced obtaining just 3000 rpm at wot with 318s and the AFBs. Both have been cleaned and kits installed. Max RPM under load is 3000. Hull clean, props cleaned and run through a prop service, in fact everything below water clean. This is with two new healthy 318s just installed.

I have suspicion that the secondary throttles are not opening or not feeding gas, however they are mechanically opened so should be open, but the air valve over the ventura may not be opening properly. Will check with the boat under way and a second skipper, by just removing the spark arrester and looking at them at wot.

Any thoughts not relating to momentarily removing the spark arrestor which is a calculated move and should not be dangerous while underway and hatch door open.

This was exactly the same as old engines with same carbies.

Larry, have you used the same distributors as before,if you push the throttles forward max and the secondary plates are full open that air valve will open if the engine asks for it,make sure the linkage is not restricting it.the air valve plate at the front of the carb is the choke plate which opens with the choke pull- off and choke heater

What is the model number,year of the carb.

Mechanically the secondaries seem to open when manually done and yes I know which is choke and witch is the secondary counter balanced plate, I know the choke operates a cam that locks out secondaries and could be the issue, choke not pulling off.

Interesting you posed an issue I did not think of the Distributors. However as I have two complete sets of 318s for the F28, the ones on the engines now are from the first f28 I junked out. I had the same thing happening with the newer f28 prior to removing engines. But sure is something to check on. Might not be advancing.

The new 318s run perfectly otherwise.

The reason I explained about the choke plate is because the early afb carbs are a little different ,so without knowing what year the carb is I was just trying to cover those bases ,not trying to be smart---

If you know someplace with a distributor machine it wouldn't hurt to have the advance curves checked---- Mike

thx mike will look for dist machine, did not think you were being smart. Mine do have the secondary air valves which are counterbalanced. I have read where quite a few, mostly in cars, were being adjusted by various weight changing means. I am not going to tamper with the weights. But will check advance with light first to be sure it is working, They only have a centrifugal advance unless the magic box for transistor ignition does something there, which I do not think so.

Larry--- I checked my carbs today (afb) to see if I could see if I could duplicate your problem and my stbd carb would not open the secondaries---- linkages all worn etc,found if I filed the edge of the tab that prevents the secondaries from opening ,it all worked again--- there was no way even with the the choke all the way off that the linkage would release that hanging tab which is on the opposite side from the choke---- Mike

Thx mike that was my suspicions.

Please keep us posted *when* (not if, lol) you resolve your AFB issue...

It has been the problem with a number of others over the years including myself!

Thanks,

Paul

I also suspicious that the old bimetallic springs in the intake manifold hot pocket that gradually opens the choke may be tired.

Was the rpm and power difference noticeable after filing adjustment?

larryeddington wrote:Has anyone experienced obtaining just 3000 rpm at wot with 318s and the AFBs. Both have been cleaned and kits installed. Max RPM under load is 3000. Hull clean, props cleaned and run through a prop service, in fact everything below water clean. This is with two new healthy 318s just installed.

Have you had any luck in getting your engines to WOT 4200 rpm?

Paul

Not yet paul, next trip to lake going to have son drive boat at "full Throttle" and remove spark arrestor and look down the carb with a light and see what I see.

Okay really getting frustrated now. Had boat driven at full throttle which currently is about 2800 RPM and 18 mph and not quite on plane. While underway pulled the spark arrestor and with a flashlight looked down the throat of the beast. Both primaries and secondaries were open but the secondary air baffle plate (counter balanced device) was not opening fully, ventura was providing some fuel as a fog could be seen. I talked with Edlebrock who would not talk about carter AFB even though they make them. The tech did opine that that baffle plate is to allow for a smooth transition from primaries to all four barrels open and that it should move to verticle and not restriction.

Next I am gonna try the second set of carbs I have, both sets were cleaned etc.

The marine tech that installed the engines opines that the boat is over propped. He says a lot of our older boats are over propped. My f28 has original clean and recupped screws, I would think it would do close to what Trojan intended.

Talked with a carb rebuilder. He does remanufacture AFB but was not forthcoming with any info. The charge to rebuild is 300 to 400. I would buy new ones instead.
Has anyone had experience with edelbrocks or Holleys?

Last year I had a major problem with my AFB. Someone recommended that I stay with the Carter as they are better built. Luckily I was put on to a great 'old' carb guy who totally rebuilt it and it works like new! Total cost $195, well worth it, couldn't be happier. This allowed me to simply bolt the carb back on with no modifications (such as the t-stat . linkage, gas line, pvc)). Search around, there are still some of these mechanics around. $300-400 is a total rip off and generally results in a poorly done and superficial job. Been there, done that.

who is he and how to contact?