Did someone throw a boat anchor behind my car at 4500?

[Steve Simmons]

Same here, this is one of the biggest threads on the forum, but each topic discussed within it is only a few posts!

I'd split it up but there's no point. It would be like splitting a virus.

[max71]

Never mind. I'm going to save up for a Honda S2000. That looked great in the UK show. Then all I'll need to tune up the car is a computer!!!

[Jimmy]

Great idea, Gary.
Then you can sell your pile...er, MGB to me, because I'd never notice any problems above 4,500 rpm.

[max71]

I'll swap you for your lady friend's Aston.

[malcolmr18zoy]

Hey Gary,
Have you tried driving without your air cleaners yet?
Malcolm

[max71]

Not yet. But that's the 1st thing I plan to do when I get a chance.

[max71]

ok BACK ON TOPIC!

I was talking to Jimmy Hilton who specializes in rebuilding SUs. Very, very nice guy. He asked what was happening and I told him about this nagging issue. He told me to check the float levels to be sure. Steve mentioned this but I'll do it because Jimmy said it still could be starvation and he's seen the new floats being off by as much as 3/8. I know the person who did the carbs and I would be surprised but then again not if they were off.

When we talked about lean at upper RPMs he said an easy way to check it is to just pull the choke when it hits 4500 and wall and see what happens. That is so brilliant and simple.

I'll check the floats. If they're fine, I'll run it without the cleaners. If that doesn't do it when I'm running without the cleaners I'll pull the choke.

[Larry Kluss]

I've also dynoed at least one MGB with one of Dave's VP11 cams and it made about 100 at the wheels with a non-ported head (just a three angle valve job)--very impressive.

Then why is my non bone stock toping out at 73HP??!!!! I completely baffled now....

Geez, how many different topics can be covered in one thread???

Gary, not to worry, you'd be lucky to be making 100 HP at the flywheel with a VP-11 cam. That posting must be an error. I talked to a vintage racer last year who was running an engine prepared virtually the same as mine - highly modified with a VP-14 cam - and he said his was 105-110HP at the flywheel on the dyno. I was surprised it was that low. Mine hasn't been on the dyno, but I can tell you it is plenty quick and continues to pull hard above 6,000 RPM. So, your 73HP at the wheels with the VP-11 sounds about right to me.

I'm not saying this is the problem with your car, but I thought I'd share it with you. Years ago, we had a Buick with a 455ci and it suddenly would not rev over 2,000 RPM. After a lot of diagnsis, we finally discovered that the exhaust was almost completely plugged due to a colapsed inner wall in the main exhaust pipe (dual wall construction). A similar thing happened to another car we had, but in the muffler this time. And more recently, yet another car had a bad catalytic converter that produced a similar problem.

Given everything you've tried, it's looking more likely to be a flow restriction. Don't underestimate the possibility of a partial flow restriction in the exhaust system or intake. Regardless of whether it wasn't there before, the parts are new, or whatever.

[Steve Simmons]

He told me to check the float levels to be sure. Steve mentioned this but I'll do it because Jimmy said it still could be starvation and he's seen the new floats being off by as much as 3/8.

Oh sure, do it because JIMMY said to! In reality you should have done that months ago, but better late than never.

When we talked about lean at upper RPMs he said an easy way to check it is to just pull the choke when it hits 4500 and wall and see what happens. That is so brilliant and simple.

You can also use this trick if you're running out of fuel. It will get you an extra block down the road. I used to have a car with worn-out carbs that I actually used the choke on to adjust the mixture. When you pull the choke, don't pull it way out, just a tiny bit into the mixture area. Remember that the mixture doesn't change in the first quarter of travel.

Larry, I think Carl was talking about a supercharged engine when he stated 100 HP at the wheels with a VP-11.

[VWNate1]

This is easily discerned with a vacuum gauge as the vacuum will drop as you rev. the engine , no need to test drive it....

[max71]

OK you MANIACS!!!!!

Here's some news.

First to Larry's point - Thanks Larry for keeping it on topic. Funny enough the whole muffler has been replaced within the last three years. Rear started to buzz. Center got crushed by a speed bump.

Steve - to be fair you asked if my jets could be clogging not the float height. Being Grose jets I DISCOUNTED YOUR ADVICE.

I just pulled the floats and they sit 7/32" -- almost 1/4 instead of 1/8". In playing with the two shims the closest to 1/8" clearance I can get is 5/32" so I'm lowering it 1/16". Does that sound ok? Or should I try to sand the shim. Its a fiber washer so it would be slightly tricky.

[malcolmr18zoy]

Oh no!!! you don't use grose jets do you??
Malcolm

[Steve Simmons]

Fair enough, I do remember talking about sticky floats, and also having the same reaction as Malcolm when you told me you had gross jets. Don't discount those, as they aren't invulnerable to problems.

[Jimmy]

You LOWERED the floats and expect more fuel to flow???
Okay, I'm certainly no SU whiz, but on a Holley, lowering the float level effectively leans out the fuel mixture just as if changing jets. Dunno why SUs would be all that different in that respect.

Oh, and I can't believe you never tried pulling the choke. That's how I get back up Kanan every time those darn SUs act up.
Except for the times the float (thankfully, usually only the rear one) gets stuck wide open. Maybe I have Grose jets?

[max71]

Yes, with the float plate up-side-down I lowered them to have a 1/8" clearance.

Ok, I raised them.

[max71]

Since this will be the 196th post to this thread outdoing all other threads on this board by 200% I think you all should chip in for a prize for Max. I think just some quality Exhaust Gas Analyzer time with Malcolm would do nicely. Jimmy alone could probably expense it. Jimmy, did I mention that if you buy me presents I'll be your best friend?

[Jimmy]

Not to stray off of topic here, but has anyone (Tanny included) considered having a run on Saturday, when it's not supposed to rain?
And, by the way, after quite a bit of research, I've settled - well, almost - on General Grabber HTS tires for my little Cherokee, primarily because of price and performance on ice and snow. Any other suggestions?

[max71]

Bastard. You got the 200th post. AND you used it to go off topic again!

Start your own threads on new topics. Otherwise, at least try to address the topic before you float off....

I will, again, be your best friend if you spring for Malcolm's time.

[Steve Simmons]

I dunno, the "Post a picture of your ride" thread also has 193 posts, all on-topic. I think you only have a 40-post thread here if we stay on topic.

Jimmy, you're evil. LOL!

[max71]

OK, Jimmy is banned from this thread. Then lets see if it becomes something that's actually useful.

[max71]

I think I'm going to start a new thread. I really was hoping in the end with constructive advice this could be a reference thread like on other boards but this one dissolved into a chat room. So while its fun to read your ramblings Jimmy please don't turn the new thread into a wash. I'll try to get all the technical information and suggestions into the new thread so someone can read it and make sense of it. There's a guy back east I wanted to read through but this ones such a mess its impossible.

[Steve Simmons]

At Gary's request (and I agree with him) I've split this thread into three topics.

See "BMC B-Series Origins", "Grose Jets" and "Engine Oil".

[max71]

I just got a reply from Carl who wrote that post about 100HP at the wheel. It clears up some things and asks some others.
Gary,

Dave Anton sent me your dyno curves just a couple days ago and we actually talked about your engine last night on the phone--your e-mail was timely.

Regarding my post, I hope you understand that the engine with 100HP at the wheels had a blower.

On the other hand, I'd expect your engine to make around 80 at the wheels. Your torque curve is strange in that it peaks so early. Alan Dalman at my shop has a similar engine and he makes about 78 with peak torque at around 4500 and peak HP at around 5500.

All we can think of is that either the cam timing is way off or the head just isn't performing. I've dynoed cars that had supposedly well-ported heads that just died like a stock head. I know it's unlikely if Huffaker and Sean have touched your head, but maybe there's something funny going on. Did Huffaker hog the ports out huge for a race motor?

I also wonder if something else weird is going on. I don't want to insult you, but things I have seen more than once are:
--Throttle not opening all the way (very common)
--Stuck brake, especially e-brake
--Lots of variation of the timing at higher RPMs due to worn dist gear

Have you actually cc'd the head and measured the CR. What are your compression test readings? They should be around 180 or so.

Sorry I don't have a silver bullet--hopefully those thoughts will give you something.

[malcolmr18zoy]

Well that tells you absolutely nothing!
Malcolm

[max71]

Well, my timing mark does bounce +/- 3 degrees at high RPM. I checked one method to see if the drive gear is worn. I'll have to try the last one which is to remove the dizzy and screw a bolt in and see if it rocks with play. I also saw the dwell increases fro 58 at idle to +65 as I climb in RPMs. The dizzy guy said points just can't hold a steady dwell but it shouldn't cause what I'm experiencing.

Don't you think its odd that the peak torque is so immediate? @2250 RPM? I would think it should be more as Carl described.

Anyway, if none of the methods discussed recently correct the problem then I have no choice but to assume the cam timing is off. Do you know how to check cam timing without pulling the head Malcolm?