Any spreadbore carbs for Magnum heads?

[71dusterdan]

Hey everyone, in my years of aquiring parts I picked up a real affinity for Thermoquad carbs. I have 2 la blocks, and a set of magnum heads off of a 5.9. I also have a Performer intake. I havent mag'd the heads yet, so they may or may not be good. I would prefer to use what I have....I am not looking for big power 370-400 would be just fine. Is there an intake that will work with my carb and mag heads? Or is there an aftermarket magnum head that will use my old intake? I know the intake could be drilled, however I havent got the 1st idea how to do it, or if any of the area machine shops are qualified to do it! I figure a set of flat tops, a mopar .509 cam or even smaller variety of a Comp Cam or Hughes cam, good headers 3 angle valve job in the heads, and gasket match to the intake should get me right where I want to be. Thanks. Dan

 

[fishy68]

First off your probably not going to get 375-400 hp from a performer intake without a fair amount of work on it and very careful planning which is contradictory to the cam your considering. Next if you have LA blocks why don't you just use LA heads? If you insist on using magnum style heads the Iron Rams Hughes engines sells are a magnum style and can be bought with the LA intake bolt pattern.

Do you have experience tuning Thermoquads? They are great carbs when tuned right but are quite a bit more to tune than your average Holley or Eddelbrock. just sayin

 

[rumblefish360]

Dan, I agree that you'll make the power your looking for with the parts plan. The problem you face is the Magnum heads only come in 1 style. You can not bolt a "LA" intake to the Magnum heads unless you redrill the head. Huges does this and can surply a vast verity of items for yourself.

It seems that basicly your going to copy the create engine from MoPar. IMO, this is a good move since it has been proven top make power.

INTAKE.

MoPar has there TQ freindly single plane M1 that bolts to Magnum heads and was used in there create engine program. MoPar rated there "LA" Comando create engines @ 380 HP. Many mags and shops have dyno'd this engine with none reporting less than 400 HP. They used production long blocks and there purple 292/.509 cam, the M1 single plane intake, a 750 carb and large tube headers @ 1-3/4. IIRC, compresion was only 9.0-1.

The Magnum create engines used the same formula but only Magnum heads and intake of course (Again, TQ freindly, M1-single plane) and a roller cam. 288/292 I think the duration was.

When time and money allow, port these heads. You'll pick up a good 40HP with bowl porting.

 

[DionR]

I bolted a TQ on my M1 dual plane with an adapter. Haven't driven it much yet but it seems to run great. Just make sure to match the transition from the manifold to the adapter, there is a pretty good mis-match. I got the intake with the R/T heads and so I used what I had. Some day I might step up to a hotter cam and an M1 single plane so I can keep my TQ, if I don't go EFI that is.

Couple of things to watch for, though. My TQ would have had a huge vacuum leak that I had to fix with a flat plate from Edelbrock.

Also, I am not aware of an aftermarket intake that would work with the vertical bolt arrangement of the OEM Magnum heads, and that has a choke well for the divorced chole the factory TQ's used. Mine has been a bear to start due to that, so I am working on a integral choke conversion.

 

[71dusterdan]

thanks guys, Fishy, I know the Tq is a little more involved tuning than the other carbs. Had a Holley as a teen, and I just hated it. It has left me with a life long distate for Holley carbs and products. We all have our demons, mine just happens to be Holleys. Truth be known there are some TQ genuis' out there, I have a Demonsizzler modified TQ, that I cant wait to run. I bought the carb and had the work done for way less than a good Holley or Eddy carb.
I had never heard of the Mopar create engine program, but it sounds like it is right up my alley. My 1st engine as a teen was a .30 over 360, with a 3 angle valve job, 9-1 compression a Performer intake and a Crower .509 cam, headers and an 1860 holley. I loved everything about that engine except the carb. When the carb worked right, it ran like a scalded cat. It also put out 350hp. Cam tech, and heads have come along way since that 1st engine in 1987. Figure the mag heads and a modern version of the 509 cam, I should get really close. Thanks for the input guys.

 

[fishy68]

The TQ's are great carb's. I love them too. Not many guys know much about tuning them so that's why I mentioned it. Sounds like your very familiar with them and will do fine.

 

[RustyRatRod]

Thermoquads are not difficult to learn to tune. There is a small learning curve involved, but as long as you approach it one system at the time and TAKE your time, learning to tune them is not a nightmare. Understanding how they operate is more than half the battle.